Hello all,

I have a 2001 2500 suburban, and i was wondering if there are any really easy and inexpensive modifications that you can do to gain some power. my friend cut off his snorkel in his airbox, and that seemed to give somewhat more power....

any suggestions like that would help a lot =)

Thanks,
Mike

I hear getting rid of the electronic torque managenment through a tune can really wake those motors up.

lol, i was more going for like, air filter, ecu reset, something that i can do in my garage... something me mum would be okay with.

are you old enough to drive yet? Is this your burb or your folks burb? Are you sure they'd be cool with you messing with it?

Anyways, I had an 8.1 for a while and nothing I did made any significant gains. I had a hypertech (which I recommend you stay away from unless you want replace the knock sensor), I had a K&N airfilter (which mucked up the mass airflow sensor and really screwed up the shifting), and I dualled out the exhuast. The duals made it feel more alive, but it was LOUD. I hear Westers makes some good tunes.

Otherwise, there's not much I know of that you can do.

1. no
2. folks
3. as long as i can put the stock stuff back, yes

Well if the folks don't mind you modding their rig, I would ask them for some xtra cash! Then go all out and make mom's grocery getter a mean prom ride.

lol, no on that

What does your mom need more power for? Have you been getting to school late?

Vernon

lol, actually, it does have to do with school, and, that in 4 months, it will be mine :D

we have this nasty turn, and its really hard to get out of.

so, 90% of the days we have to floor it to get out. the tires will chirp, but after about 4k rpm, it dies, and people behind us have to slow down a lot.

i was thinking just air filter, and that should do some good....

and, i dont need moral or lifestyle things on here...

if you have a performance suggestion, please speak up.

if you want to say something about my life, me, or why i want this. then go away

Oh geez, didn't mean to open up a can of worms.

Lets give the poor kid a break for once and focus on these trucks. I for one, would be interested in learning about a no cost upgrade that you can do in the garage that would give it more power. I don't think it exists, but it would be interesting to hear about.

i wasnt thinkin no cost, i was thinkin low cost.

I'm not saying you're a bad kid, I was the same way but when you live in a major city area like I do you see the results of 17 year olds given too much power too early. Especially ones already adicticed to power and looking for more. It's not pretty, people die. I say the 8.1 has enough if not too much power for you stock. Just tune it up, it probably needs a fuel filter. Learn to drive it responcibly first.

Example: http://www.ls1tech.com/forums/showthread.php?t=753563

Vernon

if you have a performance suggestion, please speak up.

if you want to say something about my life, me, or why i want this. then go away

Im not going to be street racing... its a damn suburban..

Kid, take a chill pill. :chillpill :chillpill

You might get a lot of grief from us, but if you start getting short with the member here, then you will only get more.

The truth is that even a suburban has a lot of power for a new driver, especially the 8100. I know you don't want to hear that because I didn't when I was your age. I also know that your ability to drive will improve as you get more experience. I hope you don't have to learn the hard way that a Burb has enough power to be a challenge to drive. Good luck with it and be safe! :cool:

With most of these vehicles you don't have cheap mods that are going to net you any substantial power, sadly. The older systems were much better for that, but the new systems are really engineered as a complete system to get the maximum out of its configuration that is possible. The real power mods you're going to find are going to be from exhaust (and even that won't be as much as you'd think) and putting a supercharger on it. Superchargers are expensive.

From what you're saying, it sounds to me like the engine definitely is in need of a tune-up. It shouldn't die, it should pull hard to redline. Try changing the fuel filter and the spark plugs first, you'll probably be surprised how fast the thing is once it's running right. I have a '95 'Burb with a 454 TBI (which only makes 230 hp) and, running properly, that thing is still no slouch.

The members here are looking out for you, because we've all been there and we've also all known new drivers who died because they were doing stupid things behind the wheel. I know you've heard it all before and will continue hearing it, but that also doesn't make it not true. A Suburban is a bad car for a new driver because it's too big and doesn't handle well, and the big block does have plenty of power to get you in trouble with. I'm 23, so I'm not too far from where you are. I can tell you, though, 7 years and 270,000 miles of experience has helped me quite a bit, even though I started out well ahead of the curve. For that matter, so did 1 month and 1000 miles of experience. :)

With most of these vehicles you don't have cheap mods that are going to net you any substantial power, sadly. The older systems were much better for that, but the new systems are really engineered as a complete system to get the maximum out of its configuration that is possible. The real power mods you're going to find are going to be from exhaust (and even that won't be as much as you'd think) and putting a supercharger on it. Superchargers are expensive.

From what you're saying, it sounds to me like the engine definitely is in need of a tune-up. It shouldn't die, it should pull hard to redline. Try changing the fuel filter and the spark plugs first, you'll probably be surprised how fast the thing is once it's running right. I have a '95 'Burb with a 454 TBI (which only makes 230 hp) and, running properly, that thing is still no slouch.

The members here are looking out for you, because we've all been there and we've also all known new drivers who died because they were doing stupid things behind the wheel. I know you've heard it all before and will continue hearing it, but that also doesn't make it not true. A Suburban is a bad car for a new driver because it's too big and doesn't handle well, and the big block does have plenty of power to get you in trouble with. I'm 23, so I'm not too far from where you are. I can tell you, though, 7 years and 270,000 miles of experience has helped me quite a bit, even though I started out well ahead of the curve. For that matter, so did 1 month and 1000 miles of experience. :)


Well put!!

Thank you, Ranger22! :)

Spark Plugs and Taylor wires.

The plugs to use are AC Type 41-932 (platinum tip).
The gap used is what makes the power. The book says
(I believe) to gap the plugs at 60-thou.. You need to close them up to a narrower 40-thou.

At Brezel's RV Shop they have a Chassis Dyno and these
two mods were/are worth 18 honest RWHP. The Taylor
brand wires assure that all the spark created by the
coils gets to each plug. This 18 free (darned nearly)
horsepower mod has worked on each and every 8.1
that has ever rolled onto their dyno. No other mods
are needed. No re-programming, no fancy exhaust,
no fresh air intake filter box, just plugs and wires.:)

I will double check the AC Plug numbers and post back.

Steady Eddie
1998 P12 Chassis

your getting a gas sucker for your first truck.hope you have a good job!,,,I love my 8.1,watch what you do you might go the wrong way,,(performance,,,,vs,,,, millage).good luck, I would try to keep it stock,dont try t out smart the engineers who made it.its that way for a reason.

:D

The plug #s were right, but the gapping has changed
to 45-thou (not 40 thou)....I do not know if Brazel's
had some pinging issues or not, but now they say
to gap them at 45-thou...the # of the Taylor plug wire
set is 99615.

+18 HP *at the rear wheels* is nothing to sneeze at.

Check it out at:

http://www.brazelsrv.com

Steady Eddie

thx eddie for the most helpful and thanks ford crucher.

Ill try new filters all around.

new oil, fuel, and air, and get new wires and plugs and see how it goes.

Spark Plugs and Taylor wires.

The plugs to use are AC Type 41-932 (platinum tip).
The gap used is what makes the power. The book says
(I believe) to gap the plugs at 60-thou.. You need to close them up to a narrower 40-thou.



Steady Eddie
1998 P12 Chassis

Eddie, I have '01 HD w/ 8.1L w/ K&N, and some other mods. So what u r saying is I can use these in lui of the stock plugs? Do I have to get the wires also cause I just changed my factory ones and were quit $. Thx buddy.

aren't Iridium the way to go now???, only asking cause my 8100 is going to need a tune-up soon.

ACDelco Spark Plug: Professional Platinum; Price Is Per Spark Plug (http://www.partsamerica.com/productdetail.aspx?MfrCode=ACD&MfrPartNumber=41983&PartType=960&PTSet=A) IRIDIUM; @ GAP .060 @
http://www.partsamerica.com/ProductList.aspx?PartType=960&PTSet=A&SearchFor=Spark+Plugs

aren't Iridium the way to go now???, only asking cause my 8100 is going to need a tune-up soon.

ACDelco Spark Plug: Professional Platinum; Price Is Per Spark Plug (http://www.partsamerica.com/productdetail.aspx?MfrCode=ACD&MfrPartNumber=41983&PartType=960&PTSet=A)IRIDIUM; @ GAP .060 @
http://www.partsamerica.com/ProductList.aspx?PartType=960&PTSet=A&SearchFor=Spark+Plugs

Iridium's are made by NGK for AC, and the AC Platinums are pure GM.... Personally, I would run the AC Platinums. Unless it is a small engine or a ricer, I don't run NGK.

JMHO.

Everybody---

The Brazel's RV Guys are no dummies. They seem to
have knowledge, proven on their Chassis Dyno, that
nobody else has (?)...

They began offering the narrowed gap "boost" with their
"Ultrapower Upgrade" as a part of it. These results were
obtained with the Workhorse 8.1 Liter BB Chevy. Originally, they simply removed the Iridium OEM Denso
Plugs and re-gapped them. They had mixed results, because now, they are recommending the AC 41-932s,
gapped at 45 thou. It just so happens :D that the
932s are OEM for my BB Vortec. So I know they'll fit
and work well in the 8.1. The install of the Taylor wire
set is just a positive way (CYA) of making sure that ALL
the sparking current gets to the plug. Some 8.1s, in some Motorcoach Chassis, tend to burn the wires and
the Taylor kit is fairly burn-proof.

This 18 HP Boost is a no-brainer and it works with
EVERYTHING else---bone stock. Just remember,
932s, 45-thou--easy to remember...

Steady Eddie

I have a few customers with 8100's and I sell power kit which includes AEM Brute force cai, Magnaflow exhaust and an efilive tune and it makes these trucks haul the mail.

Mark--

I am happy to see a Supporting Vendor join into our
thread..welcome!

Sometimes we lose sight of the fact that not everything
in the world is Diesel-powered.

There are literally tons of BB Chevy OBD2 Owners out
there that can do just as you said: cold air induction,
a free-flow exhaust, and a Pro PCM Upgrade....
all for a huge boost in performance...

Thanks again for the post.

Steady Eddie
posting from the home
of the World's Fastest
Diesel Truck..the "J. V."

Mark--

I am happy to see a Supporting Vendor join into our
thread..welcome!

Sometimes we lose sight of the fact that not everything
in the world is Diesel-powered.

There are literally tons of BB Chevy OBD2 Owners out
there that can do just as you said: cold air induction,
a free-flow exhaust, and a Pro PCM Upgrade....
all for a huge boost in performance...

Thanks again for the post.

Steady Eddie
posting from the home
of the World's Fastest
Diesel Truck..the "J. V."


Thanks Eddie, I actual got my start building and tuning gassers so I still enjoy them and you are right it is a big difference in the over all performance of the vehicle. My customers usually report back the fuel economy actual went up and not down during normal driving due to the efficiency going up from the performance upgrades which is what I always like to see! If you guys have any questions feel free to ask.

This mod has got to be the cheapest 18HP you can buy for the 8.1L

DEWFPO

whoa, a lot more actual power responses now...
im liking it...

ill see if my dad is cool with home mods, and putting the gap down to 45 thou...

and im guessing, 45 thousandths of an inch?

I have a few customers with 8100's and I sell power kit which includes AEM Brute force cai, Magnaflow exhaust and an efilive tune and it makes these trucks haul the mail.

Mark,

Is the Workhorse 8.1 in the RV the same engine specs as the one in the HD pickups? Same cams, ECM, etc..... Could we expect the same results in our HD's?

Thanks,

DEWFPO

Mark,

Is the Workhorse 8.1 in the RV the same engine specs as the one in the HD pickups? Same cams, ECM, etc..... Could we expect the same results in our HD's?

Thanks,

DEWFPO

The workhorse uses the same ECM and operating systems as the standard 8.1's. We've had plenty of users tune them.

Cheers
Cindy

We have had a posting from another Supporting Vendor.
Thank you, Cindy!! :)

EFILive has said that the Workhorse 8.1 is a Standard 8.1...but there IS a difference in weight...a Motorcoach
is heavy, much heavier than a GM Truck. And so, probably, the advance tables and fuel management tables are different--simply because ya gotta get all that
*stuff* moving from a stoplight.

Cindy--could you comment, please, on which year models had the octane tables, inside the PCM, installed
*backwards*??

Steady Eddie
1998 P12 Chassis

[quote=steady eddie;1906119;]We have had a posting from another Supporting Vendor.
Thank you, Cindy!! :)

EFILive has said that the Workhorse 8.1 is a Standard 8.1...but there IS a difference in weight...a Motorcoach
is heavy, much heavier than a GM Truck. And so, probably, the advance tables and fuel management tables are different--simply because ya gotta get all that
*stuff* moving from a stoplight.

Cindy--could you comment, please, on which year models had the octane tables, inside the PCM, installed
*backwards*??

Yes the engine would be the same but the tune would be different do to being in a different application. Should have a completely different calibration as well. I don't know as far as fitment but the gains should be close for them if the parts fit or you make them fit.

whoa, a lot more actual power responses now...
im liking it...

ill see if my dad is cool with home mods, and putting the gap down to 45 thou...

and im guessing, 45 thousandths of an inch?

yes, .045 of an inch. If you go down to advance auto parts or auto zone they will have plug gappers for cheap that will make it easy to regap the plugs.

Please be careful when changing the spark plugs in a
Vortec BB if they haven't been changed ever.

Use compressed air (or the air-in-a-can from the
computer store) and blow out around each plug.
You do not want any crud to get into the cylinders
when you remove the old plugs. I know that I passed
on the fact or statement that Taylor wires were good.
These Taylor wires are about $89 dollars per set. If
you can retain the OEM AC Delco wires--do it. Even if
you break one at the plug boot, go to Chevy
and buy another one wire. Why? Because you may not need the
new wires at all and the AC Delco 8.1 BB coil-near-plug
wire sets are $269 dollars!! High quality.
I had no idea that they cost that much...Some times the spark plug OEM boot is stuck to the plug. The GM Service Manual says to twist it a half-turn and pull it outward off the plug. They make a special set of gripper pliers just for this. The pliers may be a smart investment
in saving the high-buck wires. Overnight, soak each old plug
while it is still in the head(s) with PB Blaster-because I
do not think that GM used any Never-Seize on the plug threads. I use the Never-Seize as a matter of personal
choice, as it makes it far easier to change the plugs, next time. When re-installing the OEM wires on the new
plugs, use spark plug silicone boot grease on them.
Also be careful in gapping the new plugs, and use a wire
type gapping tool, NOT a slider-scale one.

Lastly--and I had to read this twice--the Service Manual
for my engine says that, when installing new plugs into
"old" heads, they should be torqued to 14-ft lbs--only.

Steady Eddie

well, thanks guys for the responses, but my pop is awfully reluctant to do ANYTHING. even this.

he uses the excuse "well, dont you think the engineers would have thought of that?"

eh, cant argue with him... after all, it is his.

well, thanks guys for the responses, but my pop is awfully reluctant to do ANYTHING. even this.

he uses the excuse "well, dont you think the engineers would have thought of that?"

eh, cant argue with him... after all, it is his.

I hate old people like that. My dad gives me that crap sometimes. Engeneers have to balance price and performance. Your adding extra price for extra performance.

Yes the engine would be the same but the tune would be different do to being in a different application. Should have a completely different calibration as well. I don't know as far as fitment but the gains should be close for them if the parts fit or you make them fit.
You are right, I should have pointed out that although the Engine, PCM and OS are the same, the actual calibration is tailored to it's end use.


Cindy--could you comment, please, on which year models had the octane tables, inside the PCM, installed *backwards*??


Can you explain your *backwards* comments a little further for me?

Cheers
Cindy

Cindy--

It has been reported in the IRV2 Forums that
Brazel's RV has had to "re-do" late model
Workhorse Ultrapower Upgrades because,
within those PCMs affected, the "octane"
tables contained with-in, were programmed
"backwards"...(?)

I am ass-uming that the values for low-octane
regular were swapped for high(er) octane premium.
And vice-versa. I am also ass-uming that if a table
begins at a low octane number and ends at a high
octane number and the advance curves or timing
rates, and etc., are computed off these pre-set numbers, and
then they get swapped end-for-end, that would make
the "tune" not work so good (?)....don't know whose
programming error is was--OEM GM or Aftermarket--
just thought that maybe you had heard of it....
if it was a GM Powertrain Engineering snafu, then
more than just the Workhorse Chassis were affected.
It would grow into a bigger problem, and that may
be "down your alley and up your block"...


Steady Eddie

well, thanks guys for the responses, but my pop is awfully reluctant to do ANYTHING. even this.

he uses the excuse "well, dont you think the engineers would have thought of that?"


I can tell you what the engineers thought of... They thought about how to reduce power output... You will never actually see the 340hp the engine is rated at. The factory PCM is like one big computerized governor on your truck.
They do this to reduce parts breakage and warranty claims.

I got a reprogrammed PCM from Nelson Performance... and I can tell you, it feels like a whole 'nuther animal. Before the tuned PCM, it felt lazy and unresponsive. It actually felt faster at 1/2 throttle than it did at full throttle.

After installing the Nelson tuned PCM, I'll bet my foot hasn't had to go past 1/4 throttle... to do the same thing it use to take full throttle to do.
Shifts are more firm, drivability is improved 100%, power is unreal.
The customer service sucked, but otherwise it was $385 well spent.

OK, who makes the best PCM for these 8.1's?? (I don't want to change octane rating)

Does anyone supply the whole PCM?? My truck is under warranty so I want to go back to stock if I ever need to take the truck in.

I assume a CAI and the spark plug trick would also be a good idea?

I'm not ready to do any exhaust work.

Dave--

How about a spare PCM from an alike rig from a
re-cycle yard?? It is a good CYA move to have a
stock PCM, for those trips in to see Mr. Goodwrench.
Alot of the Pro-tune re-flashes require premium fuel,
and your wanting to stay with the octane you are
using now, may be a rub.

The plugs and the re-gap are a no-brainer. A fresh
OEM air cleaner element is a no-brainer. There is
really not much you can do with an OBD2 stocker
to boost things, except having an understanding
of the spark knock control and octane requirements.
As Yullose pointed out, most 8.1 owners will never
see the 340 HP that these engines are rated at.
The PCM can, and does, monitor spark knock all
the time, and begins to pull the timing back right
away. It is a double-edged sword, if you run premium
it carbons up and pings, if you run el-cheapo regular,
it may knock and retard the spark. A catch 22...

Steady Eddie
L21 7.4 Vortec
coil-near-plug
SPFI and roller lifters

Dave--

How about a spare PCM from an alike rig from a
re-cycle yard?? It is a good CYA move to have a
stock PCM, for those trips in to see Mr. Goodwrench.
Alot of the Pro-tune re-flashes require premium fuel,
and your wanting to stay with the octane you are
using now, may be a rub.

The plugs and the re-gap are a no-brainer. A fresh
OEM air cleaner element is a no-brainer. There is
really not much you can do with an OBD2 stocker
to boost things, except having an understanding
of the spark knock control and octane requirements.
As Yullose pointed out, most 8.1 owners will never
see the 340 HP that these engines are rated at.
The PCM can, and does, monitor spark knock all
the time, and begins to pull the timing back right
away. It is a double-edged sword, if you run premium
it carbons up and pings, if you run el-cheapo regular,
it may knock and retard the spark. A catch 22...

Steady Eddie
L21 7.4 Vortec
coil-near-plug
SPFI and roller lifters

Thanks.

I'll start by trying the sparkplug trick. (41-932's at .045). I think I'll also open up the airbox (it seems pretty restrictive).

Finding a spare PCM for an 8.1 might be tough since these engines are pretty rare. Will other truck PCM's serve as cores if I send it to a tuner?

Does Tow mode do anything for overall performance. Does it remove any torque management?

A friend with an 01 2500HD, 8.1/Allison got a tune from Jesse Bubb @ wait4meperformance. He said he picked up a little MPG and power too. And Jessie had a spare PCM in stock so he could keep his stocker for dealer trips and no downtime.

Will a custom tune add to the benefits of the spark plug gap mod?? Or will the spark plug gap mod screw up the custom settings the tuner's use??

I'm leaning towards opening the air box, spark plug mod and a Pcmforless 87 octane custom tune. (PCM core is only $125 at Pcmforless vs. Westers who charges an extra $550 just for the core. I need to keep my stock PCM.)

For less then 500 bones that seems like the best bang for the buck and everything is easy to turn back to stock again for warrantee purposes.

Does this sound like a decent gameplan??

Dave--

Brazel's RV does the 45-thou plug gap thing with
their Ultrapower Upgrade in the PCM..

So, at the very least, it works for them...

Now, WHY it works is another thing altogether. I think,
for whatever that is worth, that the narrow gap
quickens the timing a tad, thereby shining-on the
OEM timing advance tables a bit. Best info that I
ever got from them was when they said that the 18-
Free-HP trick would work in an otherwise stock rig.
Now, what they DIDN'T say was if the BB needed to
run premium fuel after the re-gap. Dunno. And they never said, one way or the other, so once again, I ass-
ume that it does not.

My Grampa used to advance the timing in one of his
cars by closing the plug gaps up a bit. He said it was a small amount and he did not have a timing light.
Pure BS? Dunno that one either, but it sure sounds good.

Steady Eddie;)

With a smaller gap, the coil takes less time to saturate before it can build enough energy to jump the gap. So in a way it does advance the timing a little. How much, I do not know.

DEWFPO

That is a pretty bad mistake if that is the situation. However, there is two scenarios that will force the PCM to use ONLY the low octane table -

MAF Sensor failure.
Knock Sensor failure.

If the Workhorse is not fitted with either of these (it's possible) then the calibrators would only have been using the low octane table so it would appear the high might be lower?

Cheers

FWIW guys...

My Nelson PCM came complete and ready to plug in for $385 shipped to my door.
I decided to keep my original PCM... the core charge is only $55.
It would cost me more than that to buy a core in the junkyard and ship it back.
I'm thrilled with the trucks performance, and wouldn't hesitate to do it again.
I am however, very disappointed in the customer service. Not once did I talk to anyone of importance. Every time I called back, I never got a return call... just kept leaving messages with a secretary... the same ditz that took my order.
I have no idea what was done to my PCM to improve performance... only that I need to run 93 octane. No spec sheet, no nothing... just a "93 octane" sticker on the PCM.

The only time I received a return call was after the core return was overdue... they at least had the courtesy to let me know they were going to charge an add'l $55 to my card.

In hindsight, I'd probably give another vendor a try... like EFI Live, Westers, PCMforless, etc....

Cindy (EFI Support)...

Good Morning..:)

Thanks for the post. So, you can see the can of worms
that would occur if the octane tables were "backwards"?

From personal experience, my greatest OBD2 fear is
having a fault that doesn't (or won't) throw a code
and set the SES light. My OBD2 Vortec burnt a wire
off one of the 2 O2 sensors and DID NOT throw a code.
Or light up the SES light. I see a post here, over on the
Medium Duty Forum, where an Owner had a dashboard
warning light come on, for Low Coolant Level. His rig
went right into a tizzy and refused to run. These MD
Trucks (Kodiak, Top-kick, my P12) all have a "surge
tank" above the radiator, that flows coolant through
it 100% of the time. It is a "different" set-up, like
an overflow tank but with a level probe in it. In my
situation, I flushed the cooling system and had a
Low Coolant "event"--the surge tank was empty...
and I got NO warning lights anywhere. hmmm?
So, here are at least 2 times when I believe there
should have been a code thrown but it did not happen.
My knowledge of the OBD2 System is (like 90% of us)
limited, but I AM learning. I have the P12 Factory OEM
Service Manuals and a Code Reader, which I feel are
needed to figure out what to do, and when..

Steady Eddie

FWIW guys...

My Nelson PCM came complete and ready to plug in for $385 shipped to my door.
I decided to keep my original PCM... the core charge is only $55.
It would cost me more than that to buy a core in the junkyard and ship it back.
I'm thrilled with the trucks performance, and wouldn't hesitate to do it again.
I am however, very disappointed in the customer service. Not once did I talk to anyone of importance. Every time I called back, I never got a return call... just kept leaving messages with a secretary... the same ditz that took my order.
I have no idea what was done to my PCM to improve performance... only that I need to run 93 octane. No spec sheet, no nothing... just a "93 octane" sticker on the PCM.

The only time I received a return call was after the core return was overdue... they at least had the courtesy to let me know they were going to charge an add'l $55 to my card.

In hindsight, I'd probably give another vendor a try... like EFI Live, Westers, PCMforless, etc....

Nelson's hasn't responded to my pre-sale questions so they're off the list. Meanwhile Bryan at Pcmforless has been great. That's who I'll likely choose.

Does anyone else have experience with a 8.1 PCM from Bryan???

no but i would like to contact him on info,supporting vender i assume?

OK, this weekend I did two mods. I opened up a section of the airbox right behind the headlight and gave it an extra 15-16 sq in. (The factory airbox looks pretty restrictive for an 8.1 trying to suck air from the inner fender!!)

I also swapped plugs to AC Delco 41-932 at .045".

I must say that the result are pretty impressive. It sure seems to have made a difference

OK, this weekend I did two mods. I opened up a section of the airbox right behind the headlight and gave it an extra 15-16 sq in. (The factory airbox looks pretty restrictive for an 8.1 trying to suck air from the inner fender!!)

I also swapped plugs to AC Delco 41-932 at .045".

I must say that the result are pretty impressive. It sure seems to have made a difference
=============================
Dave--

Now---because of the increased throttle response,
try running a tankful of Premium fuel through it and check the gas mileage very carefully. It's gonna be
difficult to keep your foot out of it, but just try to
drive it "normally"..I think you might
be pleased with the results.

Steady Eddie
L21 Vortec 7400

I am currently having a 8.1 installed in my Jeep. I had the entire harness sent to Jims Performance and had it reworked and the computer tuned. Had all the extra crap taken out of the harness, since I don't need it in my Rockcrawler.
I didn't know EFI made a tune for the 8.1. I am curious if I could still use EFI since my computer has already been tweeked a little?

8.1 in a rock crawler?,,last time i checked they didnt put gas stations on the trail,,,,,lol,,,lol,,..sounds like a cool mod,,,hope you have good luck with it,,keep us informed.Did you use the allison in the switch?

I am currently having a 8.1 installed in my Jeep. I had the entire harness sent to Jims Performance and had it reworked and the computer tuned. Had all the extra crap taken out of the harness, since I don't need it in my Rockcrawler.
I didn't know EFI made a tune for the 8.1. I am curious if I could still use EFI since my computer has already been tweeked a little?


The 8.1 uses the same engine controller as the other gas trucks so EFILive is definitely an option. As long as the guy who tuned your truck to start didn't lock the ECM, you should have no trouble re-tuning it if you choose to go this route.

Guys who are shy of the $749 price should consider EFILive V1 for $550. This link shows which vehicles are supported by V1

http://www.efilive.com/supvehicle.aspx

Cool, I will check and make sure he didn't lock the ECM. Since I have a Duramax also, can I buy EFI Live and be able to tune both?
I didn't go with the allison, gonna run a built Turbo 350 with reverse manual valve body.
http://i58.photobucket.com/albums/g280/Madram11/DSC_022320Small.jpg
http://i58.photobucket.com/albums/g280/Madram11/DSC00393.jpg

Cool, I will check and make sure he didn't lock the ECM. Since I have a Duramax also, can I buy EFI Live and be able to tune both?
I didn't go with the allison, gonna run a built Turbo 350 with reverse manual valve body.




EFILive would be an excellent choice for your tuning needs. You could tune both vehicles with the VIN licenses included in the original purchase. V1 and V2 both support your platforms.

Nick

ps- Badass Jeep, how's the hydraulic steering setup drive?

Will the spark plug re-gap to .045 work on my 5.3?

Will the spark plug re-gap to .045 work on my 5.3?
====================
Hoss---

I don't know. I know for sure that the plug change
and the re-gap trick works on the 8.1 BB. I never
heard of anyone trying it on a 5.3....

Steady Eddie

=============================
Dave--

Now---because of the increased throttle response,
try running a tankful of Premium fuel through it and check the gas mileage very carefully. It's gonna be
difficult to keep your foot out of it, but just try to
drive it "normally"..I think you might
be pleased with the results.

Steady Eddie
L21 Vortec 7400

OK I'll splurge and get a tank of premium next fillup. (that won't take too long)!!

Do you think the knock sensor is holding anything back? Will these mods and premium fuel give me better MPG? (average is 11.5 to date)

I'm still comtemplating a PCM upgrade but these two mods really seem to help. What's left?? I assume a PCM tune will remove some TM?? There's still a 1/2 second delay between full throttle and "lift off".

I absolutely love the big block 8.1. This thing comes alive like a Corvette.

Dave---

The only yardstick I have to measure by is my own
BBC and its' PCM and knock retard set-up. When
we bought our rig used, the previous owner had
been using the cheapest unleaded regular that
he could buy. Did you know that 87 octane can
be legally sold as such, even though it only tests
out be 85 octane? I was totally ignorant of the
knock sensors ability to yank timing out of the motor.
In a big block Chevy, one degree of retard = a loss
of 4 HP. My PCM can pull up to 20 degrees of timing
out, if it "hears" a knock or ping. By using Top Tier
gasoline (Chevron) and moving to 92 octane Premium,
I can feel confident that the PCM is using all the
spark advance that is there. It sure runs good now.
Most BBC Guys will swallow the unleaded Regular
line, and never even experience the full power of what
the GM Powertrain Group placed under the hood.
So, the question remains, do you really need a Pro-tune?

Steady Eddie

When the gas goes up in price it's the cheaper that looks better but for me going from 87 to 91 is only $2-$3 dollars more but it hard to drive the 8.1 easy when ya start getting those pesky mods:D

Dave---

In a big block Chevy, one degree of retard = a loss
of 4 HP.
So, the question remains, do you really need a Pro-tune?

Steady Eddie

Eddie,

You're keen on the engine's ability to pull power with the knock sensor at a rate of 4 hp/degree. Consider what happens when you run decent gas and tune for it by adding timing. Now understand you can't just keep adding power with timing, but stock timing tables leave a lot to be desired in an 8100 (I haven't looked at a 7400).

If anyone in the Mn. area wants to stop by and try a tune, I'll get you set up for very fair price. Then we can get some hard results. PM me if you'd like details.

Nick

When I got my truck (new) I accepted the fact it would get lousy gas mileage. Being the cheap bastard that I am I ran regular gas. I am extremely reluctant to do much of anything to mod for power/economy because 1. I'm cheap and 2. the cost of the mod usually means you have to drive quite a bit to recover the cost of buying the mod and I'm lucky to put 10,000 miles/year on my beast. However after reading a fair amount of stuff on the internet about knock sensors and timing adjustment I decided to do an experiment starting Jan 1, 07.

In my area going from 87 to 91 octane is .10c/gallon more. After doing a little math I found out that if I could average just 1 mpg more running 91 it would be cheaper to run 91 than 87. I'm also one of those anal people who keep a log book of all gas fillups so I decided to compare two different calendar years. 2006 was all 87 octane and for 2007 I'm running 91 (ok I might have forgotten a couple times and put 87 in). My average mpg for 2006 was 10.8 So far this year I'm running closer to 11.5 mpg for an average. Haven't done all the math yet, but I do a quick estimate once in a while at the pump. I'm waiting until Dec 31 to crunch the final numbers so I can eliminate time of year as a factor in mileage.

As for more power? Don't notice anything different. This spark plug trick has peaked my interest though.

My PCM is quick to pull timing and very slow to
add it back..in a Motorcoach the effects of just
one tankful of bad gas will haunt you for quite
awhile..I cannot imagine any other results, but the same, with
a HD GM Pick-up. Today's gas *quality* is terrible.
Who in your state is checking the quality (octane)
of the gas as delivered at the pumps?? In my
state, the answer is no one..the State comes
around and makes sure that a gallon shown
as pumped = a gallon in a gallon jug, but other
than that, the burden of proof falls on you and me,
the consumer.

All we have is the Ol' Butt Dyno...if it feels like it
is starting quicker, and the throttle response is
crisper, and the gas mileage is up--maybe what
we have done is the correct path to take. With the
simple change-back to AC Delco Platinum plugs
along with the 45-thou re-gap, the 18 RWHP
boost is nothing to sneeze at. That is a difference
you can feel, and as slow as the PCM is to restore
yanked timing advance, it can only get better as
one GM Drive Cycle comes after another...the
Techron Additive in the fuel begins to actually
clean the carbon out of your engine and it gets
better..pretty soon you'll have a big grin plastered
all over your face..just like me..:D

Steady Eddie

Can you regap the factory plugs down to .045 and get the same improvement, or do I need to get the A/C ones? I just have 15,000 on my 8.1 and don't really want to put new plugs if these will do the trick.
Thanks.

99%sure that will work.

i believe delcos were the ones on page #1

**EDIT** unless you do not have PLATINUM tipped ones

Yeah i would like to know to if it has to be platium and a/c delco plugs to do this i just put vpower ngk plugs in mine?

can you regap the factory plugs down to .045 and get the same improvement, or do i need to get the a/c ones? i just have 15,000 on my 8.1 and don't really want to put new plugs if these will do the trick. Thanks. x2.

:chevy: The big GM Parts Supplier was/is Delphi. Remember
when Delphi went belly-up? And filed for a Chapter 11
or a "re-structure"? During this point in time, GM was
in a tizzy, going elsewhere for parts suppliers. Along
came Denso and the NGK Iridium tipped spark plugs.
Brands "X", I call them. These plugs found their way
into the BBC production engines...
the boys at Brazel's RV found fault with the iridium tipped plugs, even
though they were full-on OEM spark plugs.
I can only guess at the reasons why the recommendation was to go back to the platinum
tipped ACs. One reason could be internal spark
plug electrical resistance and spark size. The
iridiums have a really small tip size. Something
happens when you break up the AC Delco ignition
"team" by adding different parts to it. We all know
of resistance and induced current. The BBC never did
change (to my knowledge) the coil packs OR the OEM
spark plug wires. By introducing an odd duck spark
plug, it became a mis-deal. Too many cards in the hand.

The AC Delco Platinums were engineered to work with
the rest of the ignition system.:cool:

Steady Eddie
1998 P12 Chassis
L21 Vortec 454
Allison

Can you regap the factory plugs down to .045 and get the same improvement, or do I need to get the A/C ones? I just have 15,000 on my 8.1 and don't really want to put new plugs if these will do the trick.
Thanks.


x3

Maybe I wasn't clear enough... by all means,
if a narrower gap gives a boost by altering the static
timing, you should try narrowing the existing plug gaps.
However, and you only have to do this once for up to
100K miles, *while* you have the OEM plugs out, why
not (other than money) make the change-over to the
AC Delco Platinums?? I mean, if they handle the mod
better, or work better with the OEM coil packs and etc.
then why not do it right the first time?? The boys at
Brazel's RV do not mess around, esp. when it involves
a 180-thousand-dollar Motorcoach--so what if the plugs
cost 80-dollars??--:D

See where I am coming from?

Steady Eddie
1999 Newmar Kountry Star
34 feet, two slide-outs,
P12 Chassis....

Thanks Steady
That is what I was wondering. My truck probably has the Denso Iridiums in it. I thought they were the best plug to have, but maybe not on this setup. I will take a look at one of them this weekend and see what the deal is.
Thanks for your help.

Okay, I went down the parts store and bought those A/C Delco plugs. When I got home, I yanked out a plug on the 8.1 and low and behold, it was an A/C plug, and not a Denso. However, it wasn't the same plug as the one that I bought. It is a different part number. Also, it had a longer tip that extended past the threaded part of the plug. Question, which one is better? I am going to try and attach a photo of the two together. One other thing. Look how much crud is on this plug, with 15,000 miles on it. Should they look that bad? What causes that? Bad fuel?
The plug on the left is the OE plug, and the other is the new one that was recomended on here.
Thanks for your help.

you sure left is oe? :rolleyes:

looks dam clean to me

Duromax04---

There is so much confusion over what plug
goes into the BBC that I am not shocked at
the plug type that you found..I must ass-ume
that the cleanest plug shown in your pics is
a pic of the new AC Delco Platinums..the deposits
we all see on the old plug are an example of what
Brazel's RV began finding on the plugs taken out of
brand-new low mileage 8.1 L engines. It appears
as a coating that did not burn off, just like the plug
was too cold of a heat range. What causes these deposits?? IMHO--they are are caused by the plug being the wrong one for the application.

The AC Delco branded
Iridiums are made by NKG and the "other" Iridiums
are made by Denso. They physically look different.
Then you have the correct AC Delco Platinums and
they look different still.

I have to ask: What is/was the plug gap on the old
plugs?? It looks pretty wide for the mileage indicated.
You can imagine all sorts of drive-ability issues with
plugs that look like your old ones did. The PCM "will"
throw a code if a plug mis-fires but WILL NOT throw a
code for a weak spark....

Thanks for the post...:cool:

Steady Eddie

The clean plug is a brand new plug that I just bought based on this thread, the 41-932. The OE (original equipment) one that came out of it is of a different type 41-983. If you look at the tips of both of them, you will see that the OE one has the tip that is extended further away from the plug. Is that an issue? What I mean is will the new plug get the spark down in there as well?

The gap on the old plug was about .058. So was the new ones as well. As you can see, they are both Delco Platinums. Do you think I should go ahead and change them to the 41-932's or should I get a set of the 41-983?

A couple of these plugs are going to be hard to get to, so I am thinking about just changing them while I have them out.
Thanks for the help.

At the Denso Web-site, the 41-983s are listed as
an AC Delco plug. I did not know that they are
listed as a Platinum-tipped plug. This is a change from Iridium, a change that I did not know of. The Platinum-tipped 41-932s are the ones being retro-
fitted into each and every 8.1 L that rolls thru Brazel's shop.

Densos would work in a ricer--:D

Gap the 932s at 45 thou and stick 'em in there, you'll
be happy.....

Steady Eddie

Steady,
Thanks for the help. I noticed when out in the shop that the 41-983 is made in Japan, and the 41-932 is made in USA. I think I will go American on this deal. Sad to see that some Delco stuff is now being made over there as well. I will let you know if I feel any difference. The problem is that I don't run this truck very often. I think it has been out of the shed 3 times since 4th of July. So, I might not be able to tell any difference, but I am going to do it anyway.
Thanks again.

At the Denso Web-site, the 41-983s are listed as
an AC Delco plug. I did not know that they are
listed as a Platinum-tipped plug. This is a change from Iridium, a change that I did not know of. The Platinum-tipped 41-932s are the ones being retro-
fitted into each and every 8.1 L that rolls thru Brazel's shop.

Densos would work in a ricer--:D

Gap the 932s at 45 thou and stick 'em in there, you'll
be happy.....

Steady Eddie


I made the change and it's too early to tell the results but I was wondering if you could post the graphs from the dyno runs, before and after would be great.

Steady,
Thanks for the help. I noticed when out in the shop that the 41-983 is made in Japan, and the 41-932 is made in USA. I think I will go American on this deal. Sad to see that some Delco stuff is now being made over there as well. I will let you know if I feel any difference. The problem is that I don't run this truck very often. I think it has been out of the shed 3 times since 4th of July. So, I might not be able to tell any difference, but I am going to do it anyway.
Thanks again.

Hmm, you're making me really consider pulling the plugs on mine and gettting some 41-932's. How much did it cost for the plugs? Sounds like my truck is in the same boat as yours....sits for extended periods. I drive my P.O.S. cherokee to town unless I need to get something big.

Any of you try the Autolite double platnum plugs part # APP5245

sbm wrote:
"....I was wondering if you could post the graphs from the dyno runs, before and after would be great...."
==========================
Sorry, but I do not have them...the Chassis Dyno is
the sole property of Brazel's RV as are the results of
literally hundreds of Motorcoach run-ups on it. Heck,
the only dyno I have is The Ol' Butt Dyno...
but know this:
Brazel's RV sells their Ultrapower Up-grade Tune
for 8.1 L Workhorse Chassis by the gross (lots of them)
and every Coach tuned, contains a set of AC Delco 41-932s gapped at 45 thou..some engines show more of a boost than others, but all show an improvement....as for the "other" brand names of plugs--they have tried them all and always came back to the 932s...

Steady Eddie

I am not doubting that Brazel's RV has found more power in the 8.1's. I just have done a LOT of engine dynoing (mostly race engines) and have never seen any HP gains from one brand of plug to another or plug wires, and we have tried it all.. I will have to try this and see if their is a difference..

nn---

You are not just changing plug brands and plug wires.
You are changing the plug gaps to a narrower 45 thou.
from the OEM setting of 60 thou.

Steady Eddie

nn---

You are not just changing plug brands and plug wires.
You are changing the plug gaps to a narrower 45 thou.
from the OEM setting of 60 thou.

Steady Eddie

thats where the power comes from

nn---

You are not just changing plug brands and plug wires.
You are changing the plug gaps to a narrower 45 thou.
from the OEM setting of 60 thou.

Steady Eddie
I understand that

My L21 454 Vortec, like the 8.1 L, has no real way
to manually advance the timing. It has the coil-near-
plug coil packs and no distributor. The PCM handles
the timing, based upon timing tables programmed
into it by the GM Powertrain Group. To protect the
engine from low-quality 87- (minus) Octane gasoline,
the OEM tables are a set up to eliminate (or greatly
lessen) the chances of pinging and the resulting
hole-ing of a piston or burning of a valve. As Nick has
pointed out, the tables are VERY conservative, he says
"corked"--both in advance dialed in and in fuel delivered.
By narrowing the spark gap, the plug will fire
sooner, as it is easier for a plug to "spark over" a
narrow(er) gap than a wide one. The boys at Brazel's
began this trick by simply re-gapping the OEM Densos
at 40 thou. At 40 thou. gap the 8.1 L engines showed
an increase, across the board, of an average of 18 RWHP. If one degree of spark retard equals a loss of
4 HP, then, by reverse logic, one degree of extra advance equals a GAIN of 4 HP. Following along, it appears that the narrow(er)
gap advances the static timing by some 4 degrees, just
as if you loosened the distributor clamp and turned the
distributor towards "advanced". Now then, there is a point where too much advance leads to pinging. I think,
(don't really know) that the introduction of pinging is
why Brazel's went to a wider gap (45 vs. 40 thou.) At
45 thou., there will be a reduction in the power that this
simple mod will produce. Because by going wider you
are retarding the spark advance across the board. The
41-932 Platinum-tipped AC Delco plugs simply were found to work better with this easy mod....

Steady Eddie

Well, I got mine changed out yesterday and drove it to town. (this truck seldom sees a stop light). When i was putting them in, I gorilla torqued one and heard a little (peank sound) Thought to myself if I possibly broke that one. Anyway, I started it up and is sounded good, so I took off to town and tripped the check engine light. Noticed a miss when in overdrive pulling a hill. Thought about that plug. Went to the parts store and they scanned it for me and I told them that it could be the #5 cylinder. Sure enough, that is what it came back as. So I bought another plug and this morning before church, I yanked that one out, and it was split in 3 places. Put another new one in, and it is fine now. Drove to church, and back with 95 mph flat floor blast and it felt strong. I can't really say that it feels a lot different than it did before, becuase I don't drive mine all that often. Doesn't idle all that smooth, but I think that is from removing the screen from the MAF.

Steddy, what brand of plug wires did they put on these engines? The wires are basically all the same length, so they would be easy to replace.

By the way, the plugs were about 5.60/piece. Not sure I couldn't have just cleaned the old ones and gapped them to .045 and gotten the same results. I was surprised how much buildup they had on them. See pictures in earlier post.

My books say with used heads, to only torque the
plugs to 14 foot pounds..that ain't much and explains why you broke one...I hope you put a dab of Never-Sieze
on the threads to make the plug removal easier on the
next guy that changes the plugs...your price per plug was a steal, here they are $10.80 per each. At Brazel's,
they favor Taylor Plug Wires, the # 409 set. However,
the OEM Plug Wires are super, and if they do not spark
to ground, they are fine..the stock wire set runs big
bucks, and usually one gets broken during a plug
change, and that is why you can buy a single plug
wire easily from GM Parts. The coil-near-plug set-up
on the 8.1 L engine has 50% more spark power than
the distributor (L29) Big Block, so you know that they
need really well insulated wires to work. To help prevent
boot sticking next time, you should use spark plug boot
silicone grease on the insides of the plug boots, just a
bit, smeared around with a Q-tip. You may need several
complete Drive Cycles to re-time the ignition system.
Your rough idle probably comes from a couple of things,
one, the removal of the MAF screen, and dirty fuel injectors from just sitting....BTW..no more high speed
blasts down the road, your OEM tires are probably only
rated to stay together up to a 75 MPH speed rating....(on edit: I see that the Truck has Michelin
LTXs on it---they are good out to over 120 MPH)---BUT---
we don't want any of our Members here to be either
dead or in jail...:D

Steady Eddie

so then you understand its not really the brand its the gapping?

originally, someone had said that the taylor wires were used because in some cases under heavy RV loads, the wires burn up.

:)
Other than being cheap, I would think that an
Owner would like to put in the brand and type of
plug that Brazel's (and thousands of user miles)
has/have shown to work well with this mod. You must
take the plugs out, you must gap a set, and you
must re-install the plugs. Why not put in the 932s?
It isn't any more work.
I see it like changing the oil and leaving the old
cruddy oil filter on the engine.

Some Motorcoach makers have goofy airflow around
the 8.1 L because of the Coachwork that they use.
The front grille opening is odd sized and the 8.1
sits in there and bakes. For insurance against
cooking the spark plug wires, Brazel's installs
the Taylor Wire Set, which have a hi-heat-proof
wrap on the wire. The Taylor Wires have shown
no issues after installation.

Steady Eddie

. Changing the plug gap doesnt change the timing of when the spark pulse is sent or reached. Or if it does it is in milliseconds that might change the timing by .000001 of a degree.

As long as the mixture is being burned and your not burning up or fouling spark plugs there will be NO power to be gained by changing plugs or the gap.

Wide gaps are for lean mixtures, narrow gaps are needed for high cylinder pressures.

The only way to gain power by changing the wires is if the old ones are cracked or broken and leaking current, or if they are experiencing crossfire.

10.000 RPM did dyno testing years ago with various spark plugs that they sold and found no difference in HP.

The only thing to be gained in a daily driver is longetivity by using a platinum or other hard metal plug. We have 25 years of engine dyno experence with many different types and brands of engines.. And I can only wish getting more "Hp" was as easy as changing gap and wires ;)

then why does the dyno show it working?

Go to the IRV2 Forums page. Go to the Workhorse
Custom Chassis Motorhome Forum. Scroll down to the
thread Ultrapower Evaluation. There was a Part 1,
which got 100,000+ page views. It has since been
deleted. This is Part 2. What you see are 29 pages
of Owner Evaluations. Please note the signature lines of
some of the posts. They will include a listing of mods
done to the Poster's 8.1 L engine, and they include
items like the Taylor Wires and..tah da!..
41-932 AC Delco Platinums, gapped at 45 thou...

In the now deleted Part 1 of the Ultrapower PCM
Update Evaluations, I hammered Brazel's on
the whys and how's of the spark plug re-gap mod.
Finally, after extreme pressure, Steve Brazel said,
right on the Forum, that they had discovered this
little power booster-either by accident or by design-
and he also said that the boost happens with an
otherwise OEM Stock PCM. The trick worked so well,
and was consistent with every 8.1 L that they tried
it on, that they decided to include it with every
Ultrapower PCM Upgrade that they sell. I just re-read
ALL 29 pages of Part 2 and discovered that there WERE
pinging issues and to me pinging here is the result of
OVER ADVANCE, which must be why they changed
from a re-gap of 40 thou. to a re-gap of 45 thou....

Dam--there were some really good point/counterpoint
discussions in Part 1....

Steady Eddie
P12 Chevy HD Motorhome Chassis
L-21 Vortec
Allison
4.78 to 1/13,500# rear

thanks for the good post eddie

Go to the IRV2 Forums page. Go to the Workhorse
Custom Chassis Motorhome Forum. Scroll down to the
thread Ultrapower Evaluation. There was a Part 1,
which got 100,000+ page views. It has since been
deleted. This is Part 2. What you see are 29 pages
of Owner Evaluations. Please note the signature lines of
some of the posts. They will include a listing of mods
done to the Poster's 8.1 L engine, and they include
items like the Taylor Wires and..tah da!..
41-932 AC Delco Platinums, gapped at 45 thou...

In the now deleted Part 1 of the Ultrapower PCM
Update Evaluations, I hammered Brazel's on
the whys and how's of the spark plug re-gap mod.
Finally, after extreme pressure, Steve Brazel said,
right on the Forum, that they had discovered this
little power booster-either by accident or by design-
and he also said that the boost happens with an
otherwise OEM Stock PCM. The trick worked so well,
and was consistent with every 8.1 L that they tried
it on, that they decided to include it with every
Ultrapower PCM Upgrade that they sell. I just re-read
ALL 29 pages of Part 2 and discovered that there WERE
pinging issues and to me pinging here is the result of
OVER ADVANCE, which must be why they changed
from a re-gap of 40 thou. to a re-gap of 45 thou....

Dam--there were some really good point/counterpoint
discussions in Part 1....

Steady Eddie
P12 Chevy HD Motorhome Chassis
L-21 Vortec
Allison
4.78 to 1/13,500# rear Whatever. Untill you build and dyno engines for a living Mr Steady Eddie, don't believe everything you read. I am in NO way knocking this Co. I am sure they do aw-sum work BUT think about it 18HP at the rear wheels.... Thats 30-40 at the motor!!!..... Have a nice day

The power gain is real. The smaller gap greatly reduces misfires under WOT, that is where the power comes from. It in no significant way effects ignition timing. It effects part throttle power not at all. Air is an excellent electrical insulator. The more air you trap in the cylinder the more voltage it takes to jump the gap filled with it. Wider gaps are only good for igniting lean mixtures at low cylinder pressures where the fuel is spread thin, the larger spark will get to the fuel with less misfires at part throttle. When you are concerned with part throttle emissions and mileage that's what you do; build a high power ignition and spec as wide a gap as possible. When you are concerned about maximum WOT horsepower you want to eliminate the possiblitly of a misfire under maximum ignition system load so you reduce the gap until the ignition's power will always jump the air gap with the engines maximum cylinder air pressure.

The manufacturer has to go wide gap to meet standards at a great exspence to WOT power. Considering they aren't building race trucks that is a justifiable trade off.

If we as truck owners want maximum speed, tow power, or just good efficiency and heavy throttle then goto a smaller gap and get a very slight decrease in mileage and increase in emmissions, so small it's almost immeasureable. You would have to be concerned with it's effects over millions of vehicles for it to matter. So for many of us the smaller gap is a justifiable trade off.

With the 8.1 reduce the gap and run any good name brand non-projected plugs one step colder than stock for maximum WOT horsepower. A low cost example of those are the ones listed in my sig and how I've been doing it for a while. Copper is cheap, runs cooler than any precious metal (prevents WOT pre-ignition), and is good for at least 20K miles on this powerful ignition with a smaller gap because it will still fire as the gap grows.

What about 100K? Who cares? The plugs are cheap and super easy to get to. The federal goverment is who specs 100K plugs, it isn't what the manufacturers would do if given a choice. Before when they had a choice, they didn't. Note the 8.1's oil consumption will foul plugs causing misfires long before the gap grows enough to cause it. If you are really concerned about peak efficiency, long engine and converter life, etc. Run cheap copper plugs with a smaller gap and change them often.

This is my $0.02, spend it wisely.

Vernon

I've been avoiding this post because I was asked early on to stay out if I didn't agree with youngsters souping up (or screwing up) their 8.1 powered anything. Well the post has grown way beyond just him and now it seems it's about it get nasty so I want to set the record stait before it gets out of hand.

I just realized I didn't explain something. Occaisional misfires at WOT are not the same thing as a dead miss. You'll feel a dead cylinder the worst at idle and all the way up. A cylinder that never misses at idle and only misses 10% of the time at WOT will never be felt. Especially when the WOT misfires are spread around more than one cylinder and all or many are missing about 1 out of 10 strikes. It just feels smooth and yet will post higher power levels when the misses you never felt are eliminated all together. Like I said, the elimination of WOT misfiring is where the smaller gap adds power to an otherwise good running engine. This is especially true with forced induction (more insulating air). Also an engine that misfires under heavy loads will give inaccurate readings on a A/F meter because a lot of air never gets burned. So if you're going to dyno tune with a wide band A/F meter, eliminate WOT misfires.

It saves on convertor life by reducing the raw fuel going into them and combusting there because it didn't light in the cylinder.

Some common causes of misfires. When a plug air gap has more resistance than a fouled insulator the spark will jump up the insulator to the grounded shell. When a bad wire or broken insulator is present then the path of least resistance for the spark voltage is there and that's where it grounds instead of the high resistance air gap.

Late model wires in just about everything are spiral metal core, it's hard to improve much on the conductivity although thicker silicone offers more abrasion protection and insulation. But not much improvement if any in spark energy over good OEM type wires. Heat resistant wires only help resist burning through the insulation but don't improve spark energy at all.

Vernon

wow, now that its about an engine, vernon, you really have a lot to say.

thanks bud =)

With the 8.1 reduce the gap and run any good name brand non-projected plugs one step colder than stock for maximum WOT horsepower. A low cost example of those are the ones listed in my sig and how I've been doing it for a while.

I'm not trying to keep posting like a know-it-all but rather share what I know and be specific with the reasoning. Also this is the internet and I have to be sure and cover myself and prevent someone from making big mistakes. What is old hat to me will be uncharted waters for some, especially 15 year olds wanting to wrench on the family's thirty-thousand dollar vehicle.

When I say "any good brand name" plug I mean any manufacturers plug that matches all the design parameters for the engine. Plug size, reach, threads, etc. have to be the same to prevent major engine damage or plain malfunctions. Every plug company numbers things different. You have to reasearch it to make sure you are getting the proper plug with the features you want. Some things you can change others you can't. Always compare the new plugs side by side with the old before installing them. If you are in doubt seek a professional engine builders advice. The Champion plugs in my sig are 8.1 specific but three things are changed, electrode material, heat range (-1), and non-prodjected tip as apposed to a projected one. The prodjected tip puts the spark out into the combustion chamber where it has the best chance of lighting lean, low density, part throttle mixtures. It also absorbs and then reflects the most heat there and under WOT will get hot enough to cause pre-ignition on the sensitive 8.1, sort of like a glow plug. So by pulling the electrode flush with the chamber wall residual heat is greatly reduced.

The web site sparkplugs.com is a great reasource for learning and then choosing alternative plugs. Look hard and the information is there. Write down your specific specs and then search for different heat etc. within those parameters.

Vernon

You all can debate this all day long but I believe Edie and Manic are right. I did the spark plug mod and opened the air box and my "butt dyno" definately feels the difference especially at the top end. (total cost was about $50).

I also have a tuned PCM on order from wait4meperformance.com and am anxious to try it out with the above mods. Jesse's custom tune will scale with octane level. I'll post back once I try the new PCM.

I've also considered headers and dual exhaust but that will have to wait. (maybe forever)

Vernon---

Under the conditions which you describe, wouldn't the
PCM throw a PO0300 code?? And at that point, wouldn't
the random mis-fires become apparent?? And, if the
condition of WOT mis-firings were bad enough to
perhaps cause damage to the exhaust cats, wouldn't
the SES light begin to flash?? Or--worst case--does this
form of mis-fire cause an "invisible" fault, one not seen by the PCM??
Much has been posted on the 'Net about
how GM is now not honoring the warranty on those
engines whose PCMs have a "tune" programmed into
them. A big deal was made in Part 1 of the
UP Evaluation of how the PCM was re-programmed in GM's exclusive
computer language so as to make the PCM mod "unseen" by an average Tech using one of GM's Scan Tools. For sure, a narrower plug gap would be unseen. Unless, of course, the Tech yanked one plug and measured the gap--not likely. I never got it out of
Brazel's *when* the narrow(er) gap produced the
extra power, and ass-umed that it was created from
idle to WOT. The pinging issue and coil-pack saturation
led me to believe that the narrow(er) gapped plugs
DID advance the timing by firing the plug sooner in
the ignition cycle. And if it did, that also caused me to
believe that this simple mod, changed the engine's
static timing over the whole range of the spark advance
tables, from idle to WOT. The narrow gap mod is the
ONLY way (other than PCM advance table mods) that
an average Joe could advance the static timing in a
rig supported by an OBD2 PCM.

Steady Eddie

That is about how my plugs looked with at least the 40K I drove on them in my L29 454.

Now I went the other way, I put in 8100 plugs (single tip platinum Auto Lites, they had wider fatter electrodes, in turbo applications AC Delco/Autolite nickel plugs are best recommendations) in my 99 K2500 Suburban with the 7400/L29/454 with the projected tip. The reason is to push the tip farther out into the A/F mix to have a better unshrouded plug, not like the stock plug that is so far recessed. At least when I pulled them out after a week or so to look, they did not have the appearance of overheating or extreme temps, and they did seem to run better than the older plugs (which still had good clean electrodes).

I used stock gap at first, 0.060, then pulled it down to 0.052, which seemed to help, but I do get some idle random miss (no codes). Narrowing the gap helped a good percentage. But still has some. So maybe I will go down to 0.045". The old HEI's could spark 0.060" easily, are the new ignitions that much weaker? Or are we increasing cyl pressure so much more these coils, even cnp/cop ignitions can't handle it??

I completely agree, plug brand is not an issue. Other than quality. I have seen 2 plugs FAIL in the 2 sets of Champions I have ever used. I don't use them anymore. I have had good long life out of plain jane AC Delco's and Autolites. Even double tipped platinum Autolites have done well for me.

Okay, I went down the parts store and bought those A/C Delco plugs. When I got home, I yanked out a plug on the 8.1 and low and behold, it was an A/C plug, and not a Denso. However, it wasn't the same plug as the one that I bought. It is a different part number. Also, it had a longer tip that extended past the threaded part of the plug. Question, which one is better? I am going to try and attach a photo of the two together. One other thing. Look how much crud is on this plug, with 15,000 miles on it. Should they look that bad? What causes that? Bad fuel?
The plug on the left is the OE plug, and the other is the new one that was recomended on here.
Thanks for your help.

i agree for durability and long life and plugs (and goes for almost all parts) use OEM plugs they should last longer than most

I know this ? has been asked but what octane gas do you have to run or does it matter?

I know this ? has been asked but what octane gas do you have to run or does it matter?
========================
Mid--

I don't know. My PCM is box-stock, and I am scared
to death of the Knock Retard built into it. I have
made sure that the KR circuits are working, having
replaced one burnt unit and had it checked by Mr.
Goodwrench using the GM Scan Tool. My (and all of
us) only weapon to use against power loss is to run
better quality gasoline at a higher octane. Today's
gasoline quality is horrible at best. Down in Portland,
Tigard, Oregon I believe it was, there was a News
Report on TV of a man who was suffering from a
tank of bad gas. He took the Bull-by-the-Horns and
went back to the Perp Service Station for
gasoline samples, pumped into clean Mason Jars.
As the story
went, he got caught in the act, because in Oregon
you cannot pump your own gas and the Attendant
ratted him out to the Manager who banned the guy
from his property for life. And the Manager made it
stick!!

My plan is to use AT LEAST mid-range octane gasoline
from a Top Tier dealer like Chevron/Shell/Texaco and
if my travel plans include towing over mountain passes,
then before I hit the pass, I fill up with Premium. The
goal here is to encounter NO engine knock and to let
the PCM "learn" what octane I am running. My PCM
can pull 80 HP out of the Vortec BB. A loss of 80 HP
on a 6% Grade = the slow lane at 25 to 30 MPH.

I ask everyone here to have a heart and realize that
the old guy in the GM-powered Motorcoach is doing
everything he can to just make it up the hill, but the
KR has him in handcuffs....:(

Steady Eddie
L21 Vortec 454
Allison
P12 Chassis

Will closing the gap hurt anything long term on the truck if not i am going to do it and get 932's i am guessing it will work on a 6.0 motor!

Will closing the gap hurt anything long term on the truck if not i am going to do it and get 932's i am guessing it will work on a 6.0 motor!
=====================
Mid--
You can surely be the first here with a 6.0 to try a
narrow gap mod...but if it pings wildly or knocks
like the Avon Lady, then you can quickly change
it back...:D

Steady Eddie

I would look for LTFT or BLM (whichever you like to call it) changes, or look for exhaust temp changing.

If gap is too narrow, the emissions will soar also, look for high HC. Also, too narrow gap will cause idle misfire. But in high compression, especially turbo/supercharged applications narrow gaps become requirement due to the high boost puts out the spark too easily, as the density of the A/F is high and requires more voltage to arc the gap. Higher energy ignitions are required if you want to run a wider gap....

The smaller gap will not hurt your engine. Anything below 0.045" in my opinion is not giving enough gain to worry about. These coils are powerful and have plenty of time to build voltage since they only fire one plug each. You don't have to go down to Briggs and Straton gap sizes to benefit from this. I seem to remember my plugs are set at 0.050".

Eddie, these high RPM and power load misfires rarely if ever set a misfire code or will be felt. The spark voltage path has to degrade to the point where it will always misfire at a certain load point before you will feel it or the computer will start setting a light.
Also since you're so scared of knock retard think about this. By increasing power through burning all charges you now produce higher combustion chamber average temperatures. So with a stock heat range plug you are now more succeptable to pre-ignition and knock. So if you're going to do the gap mod for increased power make sure you drop a heat range. Perhaps the plug you found recommended is, I don't know. But I would find out before I put it in my engine and stood on it pulling a load. Gap itself will not effect detonation or pinging. Heat range, electrode depth into the chamber, and type of metal will.

Vernon

This kind of suprised me and made me more willing to do the trick.

I was on Sparkplugs.com looking at the 8.1 plugs and found that the Denso AND NGK Iridium plugs BOTH use a gap less then .045"

are you old enough to drive yet? Is this your burb or your folks burb? Are you sure they'd be cool with you messing with it?

Anyways, I had an 8.1 for a while and nothing I did made any significant gains. I had a hypertech (which I recommend you stay away from unless you want replace the knock sensor), I had a K&N airfilter (which mucked up the mass airflow sensor and really screwed up the shifting), and I dualled out the exhuast. The duals made it feel more alive, but it was LOUD. I hear Westers makes some good tunes.

Otherwise, there's not much I know of that you can do.
Please Delet

From Vernon:

"...I seem to remember my plugs are set at 0.050"..."
=====================
Vernon--
You are within 5 thou. of perfection..:D
===================
"...Eddie, these high RPM and power load misfires rarely if ever set a misfire code or will be felt...."
====================
That's exactly what I was afraid of. It has been
drummed into me that ANY mis-fire of ANY plug
at ANY time, WILL set a SES light...yikes..:eek:
====================
"...Also since you're so scared of knock retard...."
====================
I am--and with good reason. Through no fault
of my own, other than buying a bad tank of gas (80-gallons), I can
stand to lose up to 80 HP....
=====================
"....So with a stock heat range plug you are now more succeptable to pre-ignition and knock. So if you're going to do the gap mod for increased power make sure you drop a heat range. Perhaps the plug you found recommended is, I don't know..."
======================
I'm good with this one..the 41-932s are OEM for my
L-21 Vortec and are "the" plug for the job...
======================
"... But I would find out before I put it in my engine and stood on it pulling a load....."
======================
"stood on it" is a relative term. I still believe that the
PCM will only allow enough throttle for the load, and
any further pushing down on the gas pedal does
nothing...
==================
From n0dih:
".... or look for exhaust temp changing..."
===================
How am I supposed to do that? I have no EGT sender or gage??
===================
"....If gap is too narrow, the emissions will soar also...."
===================
Brazel's says this mod will pass emissions testing anywhere.
===================
"...Also, too narrow gap will cause idle misfire. .."
===================
No reported problems....
===================
"....especially turbo/supercharged applications narrow gaps become a requirement..."
===================
We are talking OEM bone stock here..
===================
"...Higher energy ignitions are required if you want to run a wider gap..."
===================
This is a true statement. The OEM coil-near-plug set-up
is very high energy....and why they will fire a worn-out,
very wide gap...

Steady Eddie

Actually, a narrower gap will make the coil run cooler and last longer.

Will closing the gap hurt anything long term on the truck if not i am going to do it and get 932's i am guessing it will work on a 6.0 motor!

The 11th. Commandment reads as follows:

"Believe thy PCM.."

Now, we see that the holy PCM does not always
alert you of run-ability issues..such as WOT mis-fires.
These types of mis-fires seem to be beyond the range
of what the OBD2 sensors can handle...:eek: ...

In actual day-to-day practice, I know that my L-21
Vortec makes maximum power (torque) at 3200 RPMs.
For me, towing a 4K# Jeep, and weighing 18K empty,
any effort much beyond about 3000 RPMs is just wasting
gas. So I practice limiting the RPMs, using the OEM tach,
to about 3500 RPMs max...at about 4K RPMs (under load, in high gear) the Allison's internal, mechanical governor kicks in, limiting
it even further. It is a complex set of issues, and ones
that I am learning all the time...tricks like the plug gap mod are easy and work...:)

Steady Eddie

My tuned L29 runs great up to 4500 rpm, even to 5500 rpm, but the cam is really too small for the upper rpm ranges. But there is seldom needs to go over 3200 rpm, agreed wholeheartedly....

I have towed 6000# with 3.73's and it was quite easy, no issues at all. Truck is only 6-6500#. Didn't need to downshift to D from OD, even on moderate hills. I towed around the same weight as a friend of mines 7.3L TD (non intercooled) with 4.10's and I did nearly as good as he did with similar weights, but he had an enclosed trailer, and I had a open.

who won?

(this may echo what some have said on this uber long thread...sorry for the repeat....this is comments from another racer)

I talked to a friend of mine who races and he said unless you have a real high power ignition, gaps in the 0.042 to 0.055 are what he feels are normal and best for power. He said that though the coils do make good power and voltage, the higher rpm operation the coil isn't sufficient to keep up the voltage over the larger gaps, the resistance is just to high. He doesn't feel there is significant power to be made from ultra wide gaps, even with an arcwelder like ignition either. It is good for boosted/nitrous ingitions, but for std street, unless you are up in the rpms, the smaller gaps are overall better for the reduction of misfires.

So overall, he wasn't terribly surprised to see a hp gain for a narrower gap.

Another 8.1 easy mod: Use an AC Delco paper pleated
OEM air filter element. And change it often. All of the
information to back this claim is right here in the Diesel
Place Archives. Also, does anyone know the CFM
flow rate of the OEM air cleaner housing?? I'm thinking here that the housings flow at least or more than what the WO Throttle Body can flow, and if so, spending a ton of cash for a high flow element and piping and etc., for more flow, is a pure waste of your gas money.

Now then, there ARE benefits to getting cold(er) ambient outside air to the OEM Air Cleaner inlet.
And in the pick-up applications, I'm not sure if
the "thru-the-fenderwell" air feed is the best.

That big "ugly" black box in the OEM Air cleaner is
an engineered air "stilling" chamber and the "walls"
inside the unit form an acoustic device known as a
Hemholtz (sp?) Resonator that simply cancels out
offensive air inlet noise. There's been a ton of GM
R&D Money spent on its' design...

Steady Eddie
'98 P12 Chassis
OEM Donaldson Air Cleaner
1300+ CFM Flow Rate
Inlet behind grille.

I don't know on the 8100 trucks, but I am looking to get a 96 C/K Truck air cleaner (for all engines, Gen I small block V8/V6, and Mark VI BB and 6.5L TD), it is a much more opened up design than the 97-00 OBS C/K trucks. And much better material. It lacks the intake helmholz resonator before the air filter, and has a much larger air box inlet opening.

Do NOT get into the camp to remove the intake resonators between the throttle body and the MAF. This one is needed. The one before the MAF, go for it. The one before is needed to cancel out the reflected standing waves from the intake valves opening/closing causing pressure waves that distrurb the sensitive MAF readings, which will cause unstable A/F mixtures at lower rpms.

I have a K&N on there now, it does seem to run slightly better than a HD paper, I always run the HD version, over the light duty version. My truck has 2 filters (Dondaldson air cleaner) available. The bigger one costs MAYBE a $1 more in most cases.

I am always a fan of the AC Delco filters (oil and air), as they are GM Engineering spec'd for the application. The aftermarket is whatever they want to do, and most are junk quality and performance, capitolizing on cheap (read FRAM, STP, etc). AC Delco filters are required to meet GM specifications. The others, meet ???? Nothing, and no requirement to do so.

The Duramax Guys use and install Exhaust Gas
Temperature Gages. From their postings of before
and after getting cool(er) outside air to the air
cleaner, they are reporting from between 10 and
20 degrees cooler EGTs. From a Gasser Owner's
view, what does that mean to us? Well, for some examples,
it means less chance to warp the OEM exhaust manifolds. and less chance of warping exhaust valve
stems. It will take a 10 to 20 degree load off the rig's
cooling system. It will probably instill some integrity
into the head gaskets' seal. I live in the banana belt,
where it seldom gets below 20 degrees above. For
those of you that live in much colder climates, you
may want to figure some way to warm the incoming
air, during the cold months. It looks like cold air induction to the OEM air cleaner and filter element
is all pluses and nearly no minuses...and cooler air
is denser air. Denser air is more power.

Steady Eddie

I knew I had seen this posted someplace and I
found it again: If you can reduce the temperature
of the incoming air by 11 degrees F.--then--that equals
a 1% Horsepower increase. If the air cleaner pulls intake
air from under the hood, it *could* be at 200 degrees hot. If you then install a cold air induction and draw in outside air at 80 degrees, that is a net reduction of
120 degrees. Or a shade over a 10% Power Increase!!

Which is a better increase than some header installs...:cool:

Steady Eddie
454 roller cam
Steel crank
L21 MD

My 94 Fleetwood even with an open K&N filter underhood runs within 2-4 degerees C of ambient temp with the car moving, the only time it warms up is when you stop. My 99 K2500 Burb OTOH I tried running with the air cleaner box lid off ran significantly warmer with the lid off (20-30C more than ambient), and with the lid much closer to ambient, within 5-10 degrees C or so when moving. But the truck always runs much warmer than the car does for intake air temp.

Keep them lids on! Don't ever draw in underhood air.

Tom--
I agree. And, if you do the math, based on an 8.1's
advertised HP of 340, a 10% gain equals a whopping
34 HP increase as well as cooler running temperature
for the whole powertrain. All of this fits right in with
the thread's title of 8.1 easy mods. Now, in the ice cold
of wintertime, the results may change.

Right in the air intake of the P12's L21 there sits a cap
over the intake opening. I believe it is both a sound
diffuser and a rain water intake preventer. It comes
right off and I have noted a boost while running and
towing without it. Banks makes an air scoop with a
"rain diverter" in the back wall of the scoop, that could
be copied by a handy DIY'er--an easy mod.

Steady Eddie
454 Vortec L21

Ram Air does help, looking at the MAF tables for the LT1 with Corvette, Std Z28/Trans AM, Ram Air Trans AM/Z28 and B/D Body they are all quite different. So to be really dialed in with the Banks or other setup, resetting the MAF Translation Table would be ideal. But most people don't, basically it runs the BLM's (LTFT) higher (leaner) but does correct for it. But if it runs leaner (>128 BLM) the PCM may add extra fuel in PE mode that isn't normally added when =<128 BLM, so you might find WOT performance not as good as it could be.

Ram Air is a GOOD thing!

Tom---
The kicker is in the fact that you'd be using the OEM
Air Cleaner (easy 8.1 Mod) engineered to (hopefully)
flow as much air as the OEM thottle body, maybe more.
At the factory-engineered air flow rate, I'd think that
the fuel tables would be close. The plus side is the intake of cooler (denser) air, probably any ram-air
effect would be lost due to the constrictions of the
OEM cleaner, but air IS a liquid, and a positive (+)
atm pressure at the scoop inlet would/could transfer
right through the entire inlet-to-throttle body plumbing. 100psi at the inlet end of a garden hose
is equal to 100psi at the outlet end, no matter how
many twists and turns are in it.
Dunno--but like you said: cool air is good. I see an ad
for a K&N CAI scoop set-up that claims a 37 HP increase
on a Corvette, so my estimated boost numbers for the
8.1 are not far off...

Steady Eddie
L21 454 w/ roller cam
SPFI

You might have 100 psi at both ends, but you will lose velocity, and most likely won't actually have 100 psi coming out, as it will have lost energy in the bends and corrugated hoses (those are terrible at airflow).

What is the 8100 air cleaner like? Panel filter or like the 7400, a round one like Semi's use?

panel

One of the nice things about the Website of NAPA is that
it shows what the air cleaner element actually looks like.

Even the Workhorse Chassis 8.1 has the flat panel element. My Class 6 Chassis has the round Donaldson
Air Cleaner and Element which I think came from the
Cat Diesel engine that was used by Chevy in the same
Chassis. Of course, Chevy changed the plumbing to fit
the 454 Vortec a bit. I have just found out that I should
be changing the element every 3 years, dirty or clean.
Because the center section of the long round element
"pulls loose" and gets into the engine, sometimes
causing engine failure..yikes!! And the loose element
guts thing begins to happen after 36 months....

Perhaps my garden hose example was a poor one.LOL..
but cool air is a real power gainer, and a scoop is just
a bonus to that..an easy 8.1 mod..

Steady Eddie
Vortec 7400

thats where the power comes from

>YOUR QUOTE IS FORM HERE,8-19-07< "Where?" Are you saying the power comes from the gap so don't go down in gap size? Old school times with points/condensers and carbs, we would run the point gap a just a little smaller and the plug gap a little bigger then spec & run 1 hotter plug level if there was a choice like for VW's,& increase the fuel line diameter from the tank to the carb's. We did this thinking it was giving us more power. In fact I still do these things today to our VW powered sand rail. Have we been full of s#^$ all these years, or what do you think??

It really comes down to what the ignition system can handle. Even if you have some monster flamethrower ignition, if you have so high combustion chamber pressures (turbos and other forms of supercharging require smaller gaps, even down to 0.028"!) , it WILL put out the spark if too wide. I can't imagine the VW's having super high pressures compared to a modern headed high compression big block (could be wrong on the modified motors though!).

The narrower gap ensures 100% no misfires with said combustion chamber pressures. Any miss will appear to be a LEAN condition on the O2's. Not good either. Narrowing the point gap increases the coil saturation time, which increases the spark energy, so a wider spark plug gap is warranted or higher combustion chamber pressures allowed without missing.

And it has to ensure no miss for every single possible condition, from cool temps and rich mixtures to towing that 12K# trailer or 35K# RV up the mountain passes of Colorado on I70 or US25, at high altitude and hot conditions with leaner mixtures.

Tom wrote:
"... Narrowing the point gap *increases* the coil saturation time, which increases the spark energy, so a wider spark plug gap is warranted or higher combustion chamber pressures allowed without missing..."
==========================
Tom--

Am I looking at this wrong? Doesn't narrowing the gap
of the plugs used, DECREASE the coils saturation time?
One of the things pointed out with narrowing the plug
gaps on an 8.1 L was that the plug fired sooner in the
power stroke, thereby advancing the static ignition timing. Timewise, I mean. Because it takes LESS spark
energy to fire across a narrowed gap, with everything
else being OEM. As the piston comes up on the power
stroke, the coil sits there and builds and builds energy,
aimed at the spark plug gap. Then the PCM says "fire
the plug" and it sparks across. The difference in time-of-
spark is defined by the gap of the plug. It may be only
micro-seconds but it is there. And, aSSuming that it IS
there, that equals static advance. Right?

Steady Eddie
L21 Vortec 454

Narrowing the "point" gap, not the spark gap. With our CNP or HEI distributors, it is controlled by the ignition module and is a varying dwell design allowing the coil saturation time to vary or be more optimized over a wider rpm range. Which is more of what the old dual point distributors helped with.

Tom wrote:
..."Narrowing the "point" gap, not the spark gap...."
===================
LOL--:D

I WAS looking at it wrong!! At least "point gap" and
"plug gap" start with the same letter!!

We have a 2110 cc VW 4-seat sandrail and I cannot
fuss with the dwell because it has a module in the
Bosch 009 distributor that eliminates the points.
Bummer...

Steady Eddie

Another 8.1 easy mod is to *slightly* change the
OEM exhaust system..

Look at the high-dollar "cat-back" exhaust systems, and
try to copy that. We had a 1993 Chevy 350 Z-71 short-
wide 4x4 with an OEM cat and muffler. I looked at a
379-dollar cat back system and said: "Hey, I can do that..."

I observed that the OEM muffler was clamped in place
and featured a 3-inch diameter IN pipe to a 2 and 1/2
inch OUT pipe. I looked at low-restriction, fairly quiet
mufflers and bought a Flowmaster 40-series that had
a 3" IN and OUT pipe size. I clamped it on the OEM
exhaust system and headed for the muffler shop. At
the muffler shop, they bent me a 3-inch sized new
tailpipe on their mandrel bender. All connections at
both the muffler and tailpipe were welded. Out the
door I went...and for $72 (plus the muffler) I had myself a cat-back
exhaust system--3 inches big, all the way back....

An 8.1 could probably benefit from the same type of
set-up..for cheap...another 8.1 easy mod...

Steady Eddie
L21 454 Vortec

THANKS you two. That helps,but I guess I'm still a little confused on the plug gap thing though as far as to should I go smaller on the gap. In my 8.1L all EOM, except for a K&N and a SuperChips programmer,I change out my plugs about 2 times a year if not 3 and I have always gone on the bigger end of the gap range in my book thinking that would give me a little BIGGER spark and therefore a little HARDER push down on the piston with end result being just a little more power. I have never sensed a miss fire or any 'pinging' even when I run regular(87) gas as apposed to premium(91), I usually run premium gas in it all the time though. The only thing is after idling for several min in park without touching the gas peddle it will start to run rough until i speed up the idle for a few sec. I just got anther set of plugs for it since its almost Dune Season and I'll be hauling heavy and fast from Phx to Glamis/ButterCup 3x mo until about March. I think I'll set the new ones at the smaller end of the gap range and see what I think & if I can sense any diff at all.
>>> By the way for "steady eddie" good shot on staying VW and not caving in for a Subaru motor like others seem to be doing. We need more VW Stingers out there drowning out those V-8's. But more important,,,, WOW to the picture of the Jeep Burn-Out in your garage!!! I know you cant power brake it in 4 wheel drive and it looks like you've got all 4 BURNING HARD. What motor are you running in there?? I nail the gas in 4 wheel drive and all I do is launch forward, hard but just launch not a full blowen BURN-OUT like you've got there. THATS COOL!! :cool: I didn't see where you live, do you ever go to Glamis Sand Dunes just inside Calif with your rail ??

The narrower gap guarantees a solid spark. For any miss, even if undetectable (I don't think GM's misfire detection is set up to be very sensitive...) is loss of hp. A wide gap IS better, but if you can't light it off every single time it is fired, it is too wide. A miss at 5000 rpm is undetectable.

As for running premium. It guarantees that spark knock will be as minimal as possible. I am an LT1 tuner, and the stock GM tune for the LT1 (iron head) yanks back from anywhere between 9 and 15 degrees timing at the first HINT of knock. That is a significant chunk of power lost.

Running premium is pricey, especially when you get only 10-14 mpg.

The key to know if you should would be getting a datalogger like AutoTap or HPT Tuners datalogger, or the scan tool from EFILive, and watch for any signs of knock, and see what effects it has on the running of the car/truck.

I do this and tune out so I see NO pinging under any conditions. It takes effort and time, but to truly accurately model it, takes time.

But the timing pulls back for a predetermined amount of time, more timing pulled out depending on what rpm the ping occurred at. So to protect the engine, GM is very conservative in the ping protection arena.

Well, just played around with the 454 today to make a homebrew CAI. Sorry, not really a 8100 mod, but for old grandpappy the 7400/454/L29.... Maybe even the 454 L21 too, not sure it looks on that one.

Well, probably should be called a HAI (hot air intake...).... But it eliminates the terrible bends in the 454 L29's intake tract.

1. Remove air box and all existing duct work.
2. Take elbow that goes to the MAF and Throttle Body and install it backwards, with the MAF end on the TB, and the MAF connected to the TB end (connector at the top facing the firewall).
3. Take IAT and pull back the plastic protective loom over the wire and drop into the hole for the resonator. Reinstall resonator and snug down the clamp.
4. Connect a stock Vortec K&N to the other side of the MAF.

Voila, you just took out some of the significant bends in the L-29 454 intake tract.

I'll work on a box for it later on, and eventually get my Fernco coupler (can't seem to find it) to replace the crummy bend in elbow at the TB.

More to come. I'll drive it tomorrow and see how it does.

I could really use a L30/L31 accordion tube to help with my setup. But I have to do a box. I would like to use the factory box still, maybe just modify it to accept air from the back side in the stock air inlet from the fender.

Anyone got any ideas?

Sandhead wrote:

"... By the way for "steady eddie" good shot on staying VW and not caving in for a Subaru motor like others seem to be doing. We need more VW Stingers out there drowning out those V-8's. But more important,,,, WOW to the picture of the Jeep Burn-Out in your garage!!! I know you cant power brake it in 4 wheel drive and it looks like you've got all 4 BURNING HARD. What motor are you running in there?? I nail the gas in 4 wheel drive and all I do is launch forward, hard but just launch not a full blowen BURN-OUT like you've got there. THATS COOL!! :cool: I didn't see where you live, do you ever go to Glamis Sand Dunes just inside Calif with your rail ??..."
=================
Good evening---
The 2110 was built for bottom end torque. Little heads,
smaller valves, and a Comp Cams custom grind "torque
cam", made just for me, very mild. The engine features
small, dual 45mm Dellortos for faster flow off idle. It has
one of Mr. Demillo's "heavy" full-circle stroker crankshafts in it as well as a full Type 2 Bus flywheel.
On the other end of the crankshaft it is twirling a Gene
Berg "Equalizer" 5.5 pound crankshaft pulley. With all
the weight turning it lugs like a tractor, down to the
point of being able to hear each cylinder fire. As a matter of fact, it will run on one spark plug. It handles
the 16.50 Paddle Tires with ease...been to Dumont,
been to St. Tony's in Idaho, been to Pismo, and always do the Oregon Coast, but never have done Glamis.

The Jeep Grand Cherokee is a freak of nature..it has what has proven to be the oddest 4WD System ever
put in a Jeep. It is a 2001 Grand Cherokee Limited
with "all the time" 4WD that is different. There are
no less than three-- (for want of a better term) -- "limited-
slip" diffs in the drive train. One in the front pumpkin,
one in the rear pumpkin and one in the transfer case. The diffs are expensive and now only the
Land Rover has them....
QuadraTrac, they call it. The transfer of torque from the
slipping wheel to the non-slipping wheel happens within
a half turn (milliseconds) and ALSO from front to rear
via the Transfer case limited slip. When ALL tires are
slipping it locks all 4 up tight and sits there and fries
the Michelins....:eek:...there is ALOT of mechanical
stuff going on just under your feet....motor is a
OHC V-8--4.7 liter--like a 283 Chevy only OHC.

Steady Eddie
L21 Vortec P12

Tom wrote:
"..The narrower gap guarantees a solid spark. ... any miss, is (a) loss of hp...."
And...
"...As for running premium. It guarantees that spark knock will be as minimal as possible... the stock GM tune yanks back from anywhere between 9 and 15 degrees timing (my P12 Manual says a total of 20 degrees is
possible) at the first HINT of knock. That is a significant chunk of power lost...."
And..
"...Running premium is pricey, especially when you get only 10-14 mpg..." Try 5 to 8 MPG.. :eek:
And..
"...the timing pulls back for a predetermined amount of time, more timing pulled out depending on what rpm the ping occurred at. So to protect the engine, GM is very conservative in the ping (knock) protection arena..."

So, for those of us that would like to see maximum
HP at all RPM ranges, our only fight-back is to run
Premium Fuel. With OEM PCMs we have our
hands tied. We need the HP on hills and when towing,
which is when the timing and power is pulled away from us..a catch 22...Premium, Top-Tier Gasoline is an easy
8.1 BB mod...

Steady Eddie
L21 Vortec

Tom wrote:
"...Well, just played around with the 454 today to make a homebrew CAI. Sorry, not really a 8100 mod, but for old grandpappy the 7400/454/L29.... Maybe even the 454 L21 too, not sure (how) it looks on that one..."

Tom, it's in the P12 Manual. It cautions against moving
the MAF. It says that the distance between the MAF and
the Thottle Body is fixed and it even says to not change
the angle the MAF sit at. It does not sit in the intake
air cleaner tubing plumb (straight up and down) to the
road surface, but rather it is tilted forward at the top.
Donaldson and the GM Powertrain Group engineered
the air cleaner to pull cool air from the positive pressure
area, just in front of the bulkhead wall that contains the
radiator. They had no way of knowing where the body
up-fitters were going to position the grille opening, so
they did the best they could, with limited knowledge.
My job is to extend the intake opening forward, and
secure a scoop or tubing opening just behind and to
the aluminum bars in the grille opening.

So ya gotta be careful when modding the OEM set-up...

Steady Eddie
L21 Vortec P12 Chassis

Yup....

With my LT1, even in stone stock form I get occasional ping at WOT, and it jerks back 15 degrees (over 3000 rpm or so 15 degrees is the number, below, around 9). That is a LOT of timing.

If you datalog the L29 454 (likely the L21 and L18 are the same), you find timing in the 0-10 range @ WOT, if you get lucky or get up in the rpms, you MIGHT be lucky enough to get to as high as 25, but don't count on it. With stock PCM tune, these engines are VERY VERY restricted.

I have Jesse @ Wait4MePerformance (.com) tune my L29 and it is an animal now. Before, it was pretty lame. How good? 50-90 against a Toyota Tundra 5.7L with 1 or 2 people, vs my 99 K2500 Suburban with 6 people was nearly dead even, he might have got a LITTLE ground on me. And I feel it STILL has a lot of room to make more power.

Note the power graphs I asked about on FullSizeChevy.com show the 454 is actually stronger than the 496 (8100) from idle to 2500 in torque and 0-3500 in hp. Go figure that one out. Tuned and untuned, same, the 7400 L29 454 made more power. Above that the 8100 made more, but not enough to really brag like you would think a 496 should be able to. I still think it is pretty held back.....

Get your PCM tuned, he can setup the low and high octane tables properly, so that if you put in high octane, it will use it, right now high and low tables are set the same, so no power improvement short of ping control is ever realized.

Best $75 you will ever put into the truck..... I HIGHLY recommend this mod! Tell Jesse that Tom sent you so he knows. He does Most all OBDII GM and even Fords now, possibly Dodges. He is very good and a safe tuner, he won't set it up to be a risky or damaging tune.

Can you take pictures of the stock air cleaner on yours? Just curious. What page in the P12 book, I will look in my 99 P12 book and see, probably the same.

The distance and clocking do make a difference, clocking more so. Ideally you don't want the blade of the MAF to split the air top/bottom, but left right to the sensor. This keeps the air from trying to go too much top/bottom of the sensor. You want it divided equally left right so the airflow is as close to even through the MAF and across the elements. Distance, not really a big deal though. The important thing is NOT to descreen a MAF. There are very specific rules in cases TO descreen, but it is almost NEVER a hp gain, and almost always a hurt somewhere in the range, typically in emissions and low rpm operation where the MAF is most sensitive. I have been hacking at my LT1 MAF tables and it IS very sensitive! The Vortec MAF we have it the "big one" and can support 450-500 hp easily before maxing out. Don't mess with it....

I have a lot of MAF tables that I am studying, air intake placement DOES affect them, so if you put ram air on the front of the air cleaner, the MAF tables need to be updated. The LT1 T/A with Ram Air has a different table than the Corvette, and the LT1 non Ram Air T/A has a different one also. I can export a 00 L29 MAF table and compare (I think I have this in my spreadsheet). If I can post here I will if anyone wants to look. But the rammed air will affect the airflow across it and needs some tweaking. Will it hurt the engine? No, but you won't see the best gains without doing it, and it takes datalogging and tuning to do, no mail order tune will get it right on the first time, you'll need a few iterations to dial it in. A very experienced tuner will have the tables already figured out and can do a good job first time (Jesse can).

Tom

Tom wrote:
"...Well, just played around with the 454 today to make a homebrew CAI. Sorry, not really a 8100 mod, but for old grandpappy the 7400/454/L29.... Maybe even the 454 L21 too, not sure (how) it looks on that one..."

Tom, it's in the P12 Manual. It cautions against moving
the MAF. It says that the distance between the MAF and
the Thottle Body is fixed and it even says to not change
the angle the MAF sit at. It does not sit in the intake
air cleaner tubing plumb (straight up and down) to the
road surface, but rather it is tilted forward at the top.
Donaldson and the GM Powertrain Group engineered
the air cleaner to pull cool air from the positive pressure
area, just in front of the bulkhead wall that contains the
radiator. They had no way of knowing where the body
up-fitters were going to position the grille opening, so
they did the best they could, with limited knowledge.
My job is to extend the intake opening forward, and
secure a scoop or tubing opening just behind and to
the aluminum bars in the grille opening.

So ya gotta be careful when modding the OEM set-up...

Steady Eddie
L21 Vortec P12 Chassis

Tom..

Our two Manuals are the same but different, I think.
My book(s) are 1998 issue and yours (IIRC) is a 1999
single big book. The Donaldson Air Cleaner Set-up is
a line drawing in the Engine Section....the difference
in power (torque) between the two BBs (454 vs 8.1)
is in the intake manifold(s)...the 454s is a "low rise"
torque manifold vs. the 8.1s "high rise" center flow
throttle body..or so I have been told by the Marine
Drag Boat Guys...

Steady Eddie
L21 that no one ever saw before...:D

Would love to find me a L21 and build it up for my Burb! Toss in a ZZ502 cam with some porting on the heads, higher flow exhaust and a full ram air and then tune the PCM for it all....

Still thinking of doing CNP when I get my 0411 PCM in..... IF I can get the sensors installed somehow...

I have heard some say the 454 L21/L29 intake is a better flowing one.

The Number One Reason for NOT getting a tune
is Allison Transmission life...me esp...

Why? I have a nearly maxxed out Allison. There
is a 40 ft. lb. window for power adders. The L-21
produces a whopping 405 ft. lbs. of torque at a
very low 3200 RPMs (some MD Truck guys say
400+ at 2600 RPMs) --now here is where it gets
interesting--my old-style, freshly re-built, 100%
Hydraulic Allison has what they call a "thru-put"
maximum torque rating. That is not flywheel
measured torque, really, but is what power you can
put thru the Allison just before it grenades. I am
very close now. Being how the Motorcoach weighs
18K#s it is VERY close..the Ally Guys say it'll handle
445 ft. lbs. and be reliable. So, no tune for me, unless
I want to buy another Ally..NOT...:D

Steady Eddie
L21 w/ non-electronic Ally

The Number One Reason for NOT getting a tune
is Allison Transmission life...me esp...

Why? I have a nearly maxxed out Allison. There
is a 40 ft. lb. window for power adders. The L-21
produces a whopping 405 ft. lbs. of torque at a
very low 3200 RPMs (some MD Truck guys say
400+ at 2600 RPMs) --now here is where it gets
interesting--my old-style, freshly re-built, 100%
Hydraulic Allison has what they call a "thru-put"
maximum torque rating. That is not flywheel
measured torque, really, but is what power you can
put thru the Allison just before it grenades. I am
very close now. Being how the Motorcoach weighs
18K#s it is VERY close..the Ally Guys say it'll handle
445 ft. lbs. and be reliable. So, no tune for me, unless
I want to buy another Ally..NOT...:D

Steady Eddie
L21 w/ non-electronic Ally

The DM's are putting out around 650 Ft. Lbs. pulling very heavy loads and the Allsions are doing fine. They have a different torque convertor and programming than the 8.1's but there pretty much the same.

DEWFPO

Dewfpo wrote:
"...The DM's are putting out around 650 Ft. Lbs. pulling very heavy loads and the Allisons are doing fine..."

Perhaps the electronic five and (newer) six speed
Allys, but mine is an old-school AT-542 four-speed..

At the Allison Service Center in Ridgefield, Washington
there are always about 50 to 100 Allison-equipped
rigs waiting for some type of service work..not very
heart-warming..there are fried Allisons there that are
bigger in size than an office desk...huge transmissions,
awesome, but cooked. And the Allison Guild Members
that work there are banging the work orders out. Just
flat flying, busy...while I was there there were no less
than 6 more rigs pulled in (literally) via tow truck.

Some Allys are tough, others are not..

Steady Eddie
L21 Vortec
P12 MD Chassis

So is the AT-542 any better than the THM400(3L80) or 4L80E?

Tom--
The Ally is stronger. It is rated for 33K#s.

Steady Eddie
L21/Ally
P12 Chassis

I still want to toss in a 6.6L DMax and Allison A1000 into my 99 K2500 Burb. Not sure what all is needed, but would love to do it. I think the biggest problem is the trans and the 4L80E tunnel size.

Tom--

Somebody's already making them. I saw it somewhere
I am sure, probably in a magazine article. The guys
were yanking the OEM drivetrain out of new Burbs
and doing the new DMax/Ally swap.

Steady Eddie
P12 HD Chevy Chassis
4-wheel ABS disc brakes

I want that!!!!!

That was on the decelleration =)

trust me there are NO upgrades unless you have around 5 or 6 grand! I have been looking for years, but they just didnt make very many of these engines so there is not much of a demand for aftermarket parts.

the only way to get more power is with a supercharger, which will probably rip your weak suburban transmission out in no time.

theres also a company called Raylar engines, they focus on the 496, that engine is a very popular marine engine but this company makes awesome upgrades for the engine, heads, pistons, etc.

My advice, since apparently you are getting a nice vehicle for free, you should save up or get a loan and make this the baddest suburban in town. Minimum of 5 grand needed, thats why everybodies buying diesels, there a lot cheaper to get power out of. Good luck

yeh, ive decided on a 94-98 f-350 7.3TD

but for now, i stick with burb

A friend of mine picked up a 97 F350 Crew Cab 4.10's 7.3L TD and does ok, but he REALLY wishes it had a larger turbo and an intercooler. For $7K too. Nice ride. He just towed 11K+ lbs half way across country at around 8 mpg towing, and 18.5 unloaded on the way home.

Ideal? 7.3L TD, 2002. AVOID 6.0L's!!! They are PROBLEM children. They serve no purpose except to spend your money FIXING them. Turbos and Injectors and Injector Pumps get awfully expensive. A friend of mine bought one new and went through over 20 some injectors in 50 K miles.

Just make sure you have the F**d Owners Kit handy..

A big paper bag with eye-holes, worn over your head, so no one will know who you are.....

Steady Eddie
who only ever owned
ONE F**d in 55 years
of owning vehicles....:eek:

as with any sued vehicle, i am expecting to have problems and repair it.

also, i am looking for a work truck, not a racecar. if i cant tow a horse trailer and soe hay, then theres something wrong with the truck. im not looking to run 11 second quarters.

As a matter of fact, people ARE suing Ford over the 6.0L diesel..... And likely the 6.4L with it trying to burn people!!!

as with any sued vehicle, i am expecting to have problems and repair it......

dyslexic people of the world UNTIE!

lol, it was a mac keyboard (cant type on it) but anyways. i dont think there are any lawsuits over the 7.3

I dont know if anyone posted this before (too many pages to read) but they are discontinuing AC Delco's 41-932. I wonder if there will be a replacement.

Typically they don't leave us hanging, especially on such a "new" engine. What is the 2008 8100's getting?

ACDelco.com is a good source...

They are listing 41-983 as the current plug for all 8100's.

The 2000 MD Truck 454 uses the 41-993, and the RapidFire 12's.

The plug that is probably the direct interchange for the 41-932 is likely the 41-993. This is the small block LT1 dual tipped platinum plug that is NOT as projected as the 41-983. But else pretty much the same identical plug.

I dont know if anyone posted this before (too many pages to read) but they are discontinuing AC Delco's 41-932. I wonder if there will be a replacement.
=====================
jbone---
Thanks for the heads-up note...

At 100,000 miles per set, maybe I should buy
two sets--??

Steady Eddie

What year do you think you will hit 100K on the L21?

Tom---

At 64 K miles it still has the OE ACDelco Platinums
in it. No codes and doing fine. We have run up about
7K miles per year since we got it. I may kick the bucket
before it ever sees 100K miles. (I hope not--:D )...

But. it WILL get a 45-thou-gapped set of 41-932s BEFORE we head to Phoenix--AND--an outside, ambient
air temperature source (CAI)--AND--a 180 degree t-stat.

Steady Eddie
waiting for the
Paint Shop to
GET 'er DONE!

This is the first mention of a 180 thermostat for an 8.1. Emissions would go up slightly but spark retard should drop slightly. On the surface it sound like a good mod to go with the gap, plugs, intake and tune.

Has anyone done it?? Any experiences?

This is the first mention of a 180 thermostat for an 8.1.
Has anyone done it?? Any experiences?
I.ve been wondering the same thing as I've been thinking about trying a 180 T-stat. Anyone know where to get one?

I run a 160* t-stat in my 8.1, though I do have a blower, headers, full exhaust, intake, upgraded ignition, custom tune...I have had zero problems running the 160*...but some of you cold weather guys would have to wait a little bit longer for heat.

Nope, you don't have to wait longer, you just don't get as much, the ramp time from cold to 160 is the same for a 160 or 180 or 195. I ran my 180 last winter and my wife and kids never once complained, so I haven't stuck the 195 back in. We live in Wisconsin, it got down in the sub 0 for a while....

Dave wrote:
"...This is the first mention of a 180 thermostat for an 8.1. Emissions would go up slightly but spark retard should drop slightly....."
=========================
Dave--

Spark retard and loss of HP should improve a bunch...
If, as Tom has said, the PCM begins to pull timing at
a coolant temperature of 212-degrees, the 180 t-stat
will give us all a 32-degree F. cushion between normal,
modulated running temperature and the point of
timing retard. This is a$$uming that everything else
is normal. You can beat the PCM at it's own game on
this one. You want to use a quality thermostat, one
made to last a lifetime, which contains material made
of stainless steel and a pressure relief valve which
equalizes the coolant pressure on the high and low sides
of the t-stat. For years and years, that would have been a "Robert Shaw" brand, as they had all of the above
features, plus they flowed the most. The design has been sold to "Cooper-Standard" and their "Generation 2"
t-stat is the one you want. C-S packages the same deluxe t-stat for Prestone, and it too, is called a Generation 2 t-stat. It is fairly difficult to find on store
shelves, as production is smallish. Auto Zone, and
others, know of this t-stat and can order it.

This is truly an 8.1 easy mod...

Steady Eddie
cool is as cool does

Since mention was made of coolant temperature being
a point of timing retard, I've been doing some digging
about coolant. Water, or rather distilled water, with no
mineral content, cools an engine the very best. Water has a much higher rate of heat absorbing ability than a common 50-50 mix of water and
coolant. To say that anti-freeze is a "coolant" implies that it somehow out-cools water. So, calling it a a coolant is a bit of a stretch. BMW knows some about
high performance sedans. I read that their engineers
spec a mix of 40% anti-freeze and 60% distilled water
because the heat transfer is just that much greater.
For those of us that do not live where it freezes or gets
down to 10-above, a 40-60 mix, along with a "water-
wetter" additive, just may be "the" set-up....esp. those
of us that tow heavy.

Another 8.1 easy mod.

Steady Eddie
L21 454

Agreed, water transfers heat better than antifreeze/water mix, but the temp range improving properties are hard to beat.

I have run cars for the entire summer on pure water alone.

Always use distilled water to keep the minerals and hard water out.

I have heard the Toyota antifreeze is a very good one (the red color stuff), got to admit, I haven't seen many Toyota's with cruddy cooling systems like the green stuff always did. But once you see the price you may think 2x about using it....

This post is like the Energizer Bunny. It keeps going and going. I have really enjoyed all the good info. Have had the new plugs with the narrow gap mod in for about a month or so, and I do think it runs better. Thanks for all the help. This post could almost be a sticky.

It keeps going and going. I have really enjoyed all the good info. Thanks for all the help. This post could almost be a sticky. Couldn't agree more Duromax! I'm not new to the performance aspects of the truck market but I'm new to the likes and dislikes of the 8.1 so I'm learnin a lot here!

Getting the full advertised HP from an OBD2 controlled
BB Chevy is a "game" with Rules. Who sets the Rules?
The GM Powertrain Group. No doubt there are many that
do not know what parameters cause a loss of timing advance and HP. I am certainly one of those. But, with
some knowledge, and some inventive ideas, the 340 HP
of an 8.1L, for example, may be approached. I consider the BB to be like a sleeping Frankenstein Monster, with
enough torque capabilty, in stock form, to amaze anyone. He needs to wake up. But, you can shoot yourself in the foot, unknowingly...like a tank of bad gasoline will ruin your
good time, intake air temperature above 86-degrees F.
will cause spark retard, and on that 6% Grade, towing
heavy, engine coolant temperature at or above 212-degrees F. will kill the power, JUST when you need it the
most. So, knowing these Rules we can go after them.
Cold air to the stock air cleaner is a biggie..not anything
like a GTO Ram Air, this is a low-buck thread, but just
get the intake air horn plumbed out to ambient air, where at least you know how hot it is and can expect a
power loss above 86-degrees. It is a Knowledge of the
Rules. And we are playing a HP Game. The narrow gap
spark plug trick is another Knowledge Thing. Who'd of
thought that a wide gap causes misfire at high RPMs??
My thanks go to Members of the Forum who have pointed these items out to all of us. And, thanks, esp. to Tom,
who says there are more opportunies living in the
stock PCM....

Steady Eddie
P12 Chassis
26,000# CGVWR

Been reading this thread since it began and i have to say, thank you all for just a good well written, highly informatioal, NON p!ssing match thread!

Bill

If you are into the RV Lifestyle you will know what I am
about to talk about.

"Campfire-side BS sessions" are where everyone (or at least a few) campground campers sit around ane shoot the "stuff" about RV-ing and their rigs. All you have to
do is open your ears and really listen to what these guys
and gals have to say. What works and what doesn't work, what was money well spent and what was a waste.
Many are gearheads, been there done that, I once got into a lively session about Flathead F**d Hot-rods.....

But here is the 8.1 easy mod:

How many of us have EVER cleaned their rig's radiator??
And, how many of us know how to do it right and not
damage anything? Here's the tip: Use a 50-50 mix of
Simple Green and water, in a spray bottle. Spray this
mix through the front of the entire condenser and radiator. Get in behind the radiator and spray the whole
radiator surface, being careful around the fan blades, making sure you get Simple Green into the "shadow" of the fan blades. Leave it sit on there. Have an adult beverage, if you'd like..maybe fire one up. After about 15-minutes, take the nozzle OFF the garden hose, get
inside the engine bay, and, using ONLY the water pressure from the hose, spray FORWARD, rinsing the
dead bugs, dirt, and road film out of the radiator and
AC condenser....you'll be amazed at how much crud
comes out.

Is it worth it? The old-timers around the campfire claim
a 15 to 20 degree cooling bonus....

Another 8.1 easy mod.

Steady Eddie
be cool:cool:

A p.s. here:
We all know of radiator "misters" that spray a mist of water ahead of the radiator when on a grade, towing heavy. They will bring the coolant temp.
down right away. Well, I met this retired guy who
was an HVAC engineer. He said that "Ultra Flat
Black" is the right color to paint a radiator for the
most heat transfer. This was the same guy who had a canvas water bag hanging 2 inches in front of his
radiator when in hilly, mountainous country. The canvas "seeps" water and it cools the radiator on those 6% Grades. Pretty smart, I thought.

I've done some 180 degree thermostat research. So far I've only found one and only one. It's the Duralast #15898 at Autozone.

Neither NAPA, Prestone or Stant offer anything for an 8.1 other then the stock 195 degree thermostat. (ex: the stock thermostat at Stant is #13899. Nothing comes up in a #13898. The last digit indicates the temp.)

Dave---
I am still looking, too...the Duralast is reviewed in a video on the 'Net, am looking at further reviews....
am finding the t-stat (of the Duralast #) fits a whole bunch of different GM rigs..found a posting where the Owner complained that the spring used
in the Duralast t-stat was too weak to hold closed--
caused over-cooling...

Steady Eddie

Wow--
What a can of worms and a real eye-opener..:eek:

I figured on strolling right on in and buying a 180
t-stat and then sticking it there...but.... all
of the crosses on
the stat part # come back as an OE type of a 195-degree stat.
The pre-OBD2 454s, you can get a 180-degree t-stat.
Then the Vortecs came out in the late 90's and the 180
option vanished (?). Checking the part numbers shows a
different OE thermostat for the OBD1 to the OBD2..not
knowing for sure, but they look like two different critters,
and maybe one won't fit the other (?).

Seems like Big Brother doesn't want us to play with
smog motors by coolant temperature control...there's
gotta be an answer (?)....

Steady Eddie

Wow--
What a can of worms and a real eye-opener..:eek:

I figured on strolling right on in and buying a 180
t-stat and then sticking it there...but.... all
of the crosses on
the stat part # come back as an OE type of a 195-degree stat.
The pre-OBD2 454s, you can get a 180-degree t-stat.
Then the Vortecs came out in the late 90's and the 180
option vanished (?). Checking the part numbers shows a
different OE thermostat for the OBD1 to the OBD2..not
knowing for sure, but they look like two different critters,
and maybe one won't fit the other (?).

Seems like Big Brother doesn't want us to play with
smog motors by coolant temperature control...there's
gotta be an answer (?)....

Steady Eddie

Yeah, you'll probably find the stipulation that the 180 degree thermostat is for Off-Road use only since it screws up the emissions calibrations on the OBD-II equipped vehicles and would violate federal law.

DEWFPO

I just installed an AZ Duralast #15898 this afternoon (180 degree). It looks like a decent thermostat - almost identical to OEM. The box say's made in Israel. (refreshing to find something that isn't from China).

I'm not expecting any dramatic results but engines do run better a tad on the cooler side. My temp guage shows about 10-15 degree drop in normal driving.

I'll see how it does over time. I can always go back to stock. It's a 15 minute task to swap out.

So far I've done the following:
Spark plug swap and reduced gap to .045
Wait4Me Custom PCM Tune
Opened up front of airbox right in back of headlight
180 degree thermostat

So far the truck runs great.

I would keep an eye on mpg and see what it does too, I am curious which way, if anyway, it will go...

After reading this through about 3 times I went out and bought 8 41-932 AC sparkplugs. It was about 4 plugs until I figured out how to use the spark plug pulling pliars, at first I pulled on the rubber then I saw how to pull on the metal sheild. So after instalation I started it up and it seems to run fine. Its raining out so going out to see it it has more power probably wont work since the roads are wet.
I read in here someplace about someone who changed plugs and thought he broke a wire while pulling it off. Will the check engine light come on if I broke a plug wire?
Thanks,
Martin

It should, it will give a P0300 or a P030x where x = the bad cyl.

Basically the PCM has an estimation on what the time should be between crankshaft firings and how long it should take to get to the next pulse, if it is slower, it figures it must be a miss. It knows if you are accelerating or decelerating. It makes this determination on the acceleration of the engine rpm.

So, simple answer, it should. I don't think it is as sensitive as people preach, at least not on the 454 L29.

Tom---

What Brand of 180 thermostat did you use?
A part number??

Steady Eddie
L21/P12 Chassis

Hmmm, good question! I think one from Autozone or NAPA. I shoot for RobertShaw stuff or a quality looking piece.

Logfarmer, I changed mine to this and over torqued the #5 plug and split the ceramic part in three places. It only missed when I was lugging the engine in a high gear at a slower speed. Otherwise it ran normal. I had the parts store scan it for me. I told them if the #5 cylinder shows a miss, then I know exactly what happened. That was it, so another plug later, I got it running normal again. Didn't break any plug wires, but thought I was going to. Somer were hard to get ahold of.

Duromax04,
Yours is the post I remembered I thought it was a broken wire but it was the broken ceramic. When I think broken wire I'm thinking of plugwires a few years ago that you could pull on the wire and separate the core of the wire but it wouldnt showbut still be broken . Thats what I thought I might have done but it sounds like maybye plug wires today are stronger?
I didnt break any plug wires but I thought maybye pulling on the rubber boot would have hurt them. The service engine light has not come on so I guess its ok.
Martin

Tom wrote:
"...Hmmm, good question! I think one from Autozone or NAPA. I shoot for RobertShaw stuff or a quality looking piece...."
==================
I found one...

MotoRad Part # 7267-180

It is way good...it has a Fail-Safe feature that locks the
t-stat wide-open to prevent cooling system failure from
overheating. It is a special order through your nearest
Auto-zone Store. Arrives in 3 to 5 days @ $16.95 U.S.
It is the only Fail-safe t-stat on the Market.

The MotoRad Search Engine even knew of my odd-ball
L-21 Vortec Vin "B" engine.

Steady Eddie
P12 Motorcoach HD Chassis
Allison

There are 3 454's amazingly enough.

L29 = J
L21 = B
L?? = D

The B and D are listed for Medium Duty trucks. Remember the old 454 intakes with dual thermostats? One for each bank....

Tom---

Ya got me on the Vin "D" 454s....

I do not remember the dual t-stat BBs either....

He!!, I though I wuz doin' good just to find a 180
t-stat that failed open..:D

Steady Eddie

Sorry guys I messed up. Even though summit and amazon say they are being discontinued I found out that they are simply changing part numbers.

The new part number is 41-993

Well--

A couple of things here: The 41-993s are listed as a
plug made for the late 454s and 8.1s. The 41-932s
are OEM for my BB..the 932s are still available, and
will be for a while yet..the 932s will last a long time.
Probably, in my case, they will outlast me. It is good to
know that in the future the 932s won't be available..
I guess the real questions are: What are the heat ranges?
And: Why did AC Delco change numbers and phase out
the 932s? The Marine Guys are gonna be pissed because
the 932s are a Platinum Replacement for their regular
AC Marine Plugs....

Steady Eddie
L21 454 Vortec

Once the 180-degree t-stat is installed there are
side benefits that I never thought of...

I understand from looking at postings that the plastic
and rubber underhood parts begin to last a lot longer.
Case in point: the plastic overflow coolant puke tank and
windshield washer bottles no longer get brittle and break. The hoses and fan belt(s) last longer. The little
black plastic vacuum lines last longer, even the insulation on the wiring doesn't get brittle.

There is less heat intrusion into the cab, so the AC even
cools better. For those of us that have Class A Motorcoaches, the engine dog-house cover runs cooler.

And, the real big one: The transmission runs cooler, so
it lasts longer....:D

Steady Eddie
L21 Vortec
Allison

lol, i think the t stat mod is good for a motorcoach, but wouldnt help a whole lot on an suv

Well, on my L29 454 with a 180 stat I can actually open the hood on a warm day and tolerate it, with the 195, it is mindbending how hot it is with that killer 9 blade fan pulling a ton of air through.

I would run a 160 if I didn't think it was too cool for my (we live in Wisconsin) rig.

wana wrote:
"... but wouldnt help a whole lot on an suv..."
======================
Ya gotta think in the abstract..reverse logic..

"If I do this up here (in the process) then what happens
down here?" Or..in the abstract: "If I did this down here
(in the process) what did I do *TO* the process up there?"

As a 8.1 easy mod, we are using the 180 t-stat to keep
away from the 212-degree F. point at where the OE PCM
begins to pull out timing. The anti-freeze and water
coolant mix will prevent boil-over, even at 212 degrees.
On the goofy Chevy temperature gage there's not a hairs' width of difference between 195 and 212. On a
grade, towing heavy or not, you can find yourself into
spark retard, without even knowing. We are all just looking at the 32-degree cushion between coolant
temperature at the bottom of the hill and coolant
temperature at the top of the hill, and hoping that the
rig doesn't ever get to 212-degrees, and start pulling out power. It is better to start a grade climb at 180 than
at 195....

All the rest of the benefits are just a nice little sideshow.
Cooler engine bay, cooler feet, cooler brow, no sweat.

Steady Eddie
P12 HD Motorcoach Chassis

Oh, and min IS an SUV.... 454 powered as well... Yes, it makes a difference....

lol, i think the t stat mod is good for a motorcoach, but wouldnt help a whole lot on an suv

never mind... ill pull my nose out of it then

Hello, a quick question or two,....when using a cooler t-stat what is the efffect on the smog stuff, gas mileage, and does the newer engines go into closed loop mode? Any disadvantages? Thanks

Sir-Col

Hello, a quick question or two,....when using a cooler t-stat what is the efffect on the smog stuff, gas mileage, and does the newer engines go into closed loop mode? Any disadvantages? Thanks

Sir-Col


I can't quantify it but your gas mileage should drop slightly and your emissions should increase slightly.

It seems like a 180 is the sweet spot. If you go lower then you really risk throwing a code and failing any emissions tests.

I've done 180 mods on other vehicles and have been happy with the results. I just did the 180 mod on my 8.1 Sierra but haven't driven it enough to draw any conclusions. However going back to OEM is a very simple task with this engine.

I e-mailed Motorad about where I can buy a "Fail-safe"
180 t-stat and received back an amazing answer.
Motorad seems to not have any real retail outlets here
in The Great Pacific Northwet. A great, workable product, I just have to phone a window-less Parts Warehouse in
Spokane, Washington to set up a purchase...I'd bet the
shipping charges equal the purchase price. Kinda reminds me of an under-cover drug deal....

but I am convinced that this t-stat will allow me to pull
my rig off the Interstate if I blow off a cooling system hose or have some other major cooling system overheating failure, like a t-stat failure where it remains
closed and no further coolant can flow....

Tom has said that the PCM will go into closed-loop at
about or near 130-degrees F.---that is the point of coolant temperature where the O2 sensors begin controlling the A/F ratio. Once the sensors take over,
I can't see any increase in emissions, but maybe...
BTW..AC Delco does list an "alternate" 180 stat in their
catalog: #12T55D--this is an OE part, made by GM, so
no warranty issues...

Steady Eddie
454 L-21 Vortec

I e-mailed Motorad about where I can buy a "Fail-safe"
180 t-stat and received back an amazing answer.
Motorad seems to not have any real retail outlets here
in The Great Pacific Northwet. A great, workable product, I just have to phone a window-less Parts Warehouse in
Spokane, Washington to set up a purchase...I'd bet the
shipping charges equal the purchase price. Kinda reminds me of an under-cover drug deal....

but I am convinced that this t-stat will allow me to pull
my rig off the Interstate if I blow off a cooling system hose or have some other major cooling system overheating failure, like a t-stat failure where it remains
closed and no further coolant can flow....

Tom has said that the PCM will go into closed-loop at
about or near 130-degrees F.---that is the point of coolant temperature where the O2 sensors begin controlling the A/F ratio. Once the sensors take over,
I can't see any increase in emissions, but maybe...
BTW..AC Delco does list an "alternate" 180 stat in their
catalog: #12T55D--this is an OE part, made by GM, so
no warranty issues...

Steady Eddie
454 L-21 Vortec

Eddie,
My Autozone Duralast #15898 (180 thermostat) is a Motorad. However I'm not sure if it's fail safe. It looks just like OEM. How do you tell fail safe from std or can you?

Dave---

The Fail-safe Motorad T-stats are best explained on their
web-site, they have a movie there and everything.

The Fail-safe t-stat would have said so, on the box. I'd
think.

Motorad Part #s for 180 t-stats:

OE type--- 267-180
Hi Flow type--- 2067-180
Fail-safe type--- 7267-180

Your Duralast should have (IIRC) a Motorad number
stamped on it, maybe on the flange?

Steady Eddie
180 is :cool:

this is a long thread =) glad i started it

lol, actually, it does have to do with school, and, that in 4 months, it will be mine :D

we have this nasty turn, and its really hard to get out of.

so, 90% of the days we have to floor it to get out. the tires will chirp, but after about 4k rpm, it dies, and people behind us have to slow down a lot.

i was thinking just air filter, and that should do some good....

and, i dont need moral or lifestyle things on here...

if you have a performance suggestion, please speak up.

if you want to say something about my life, me, or why i want this. then go away

Going back to the start of this tread, most 8.1L's fuel shut off is set at 5000 r.p.m.'s, some are even lower. Even if it is mechanically O.K., going much over 4000 r.p.m. might be getting close to the fuel cut off. I can't imagine under what circumstances you would need to spin a big block that fast, the peak torque is developed at a much lower r.p.m.. If this is an off-road situation, wheel spin is very counter-productive. You would be much better off with approriate tires for the conditions.

Going back to the start of this tread, most 8.1L's fuel shut off is set at 5000 r.p.m.'s, some are even lower. Even if it is mechanically O.K., going much over 4000 r.p.m. might be getting close to the fuel cut off. I can't imagine under what circumstances you would need to spin a big block that fast, the peak torque is developed at a much lower r.p.m.. If this is an off-road situation, wheel spin is very counter-productive. You would be much better off with approriate tires for the conditions.

passing people going up to tahoe. i might as well get out and push... its really slow

My 454/7400 has a factory imposed redline of 4500 rpm.... Terrible... I can't believe they would limit the 454 THAT low, it is just plain wrong!

Fortunately Jesse @ Wait4MePerformance fixed that... 5500 rpm now. Shame the cam isn't much good over 4500 rpm though.... It needs a MUCH larger cam, more on the order of 215/224 degrees MINIMUM. I would like to see 224/232 on mine with around 0.550 to 0.600 lift on a 112 LS.

I think that would wake it up really good....

A couple of things to mention here...

The cast crankshaft has limits.

The OEM transmission's pumps have limits.

Both tied to maximum input RPMs. The BB is a truck
engine. I would say that every BB has the ability to
see 6000 RPMs one time. In Marine applications the
BB makes up to 525 ft. lbs. of torque and 525 HP.
That kind of power is made using Edelbrock heads
and a special Marine camshaft and at the same time,
that kind of thru-put power would grenade my old-
school Allison, which is mechanically governed to
4000 RPMs input anyway. Peak torque comes in way
down low and depending on which source you believe,
is either at 2600 or 3200 RPMs. Using your example
of the OE camshaft profile, you can see from various
engine dyno charts that the power falls off after 3200
RPMs so any real power after that is moot. The BB ain't a LT1...

Wana's example of charging Donner Pass and running
out of steam is a story in itself. Been there and done
that one (on the way up to Tahoe). The OE knock retard
won't allow much "charging forward" at that elevation and grade being climbed. The PCM has to calculate its'
little brains out to do it at all, having memorized all of
the low altitude tables, and now, quickly, it finds itself
at over 7000 feet elevation in a short running time on
maybe low altitude 87- octane regular....at WFO throttle
and yanking timing like crazy just trying to keep from
hole-ing a piston.

Donner Pass is a b!tch.

Steady Eddie
L21 Vortec

Here's an Update on the (Anti-Spark-Retard) Mods
I have done just this week...

As posted in this thread the 41-932 AC Delco plugs
are no longer stocked--anywhere--I guess. The sub
is an AC Delco 41-993--gapped at 45-thousandths...
old 41-932s had a 100+ thou gap and deposits @ 60-K
miles. I used PB Blaster slippery spray down around the
OE spark plugs and let it sit overnight. All plugs came
right out, except for the driver's side front, on that I
had to remove the heat shield, then it came out....
it starts quicker and idles smoother...but do not know yet, how it will run under a load.

Steady Eddie
P12 Chassis

http://photobucket.com/albums/v304/watchsteady/screenedhood.jpg<---This is the Raw Material..$4...




http://photobucket.com/albums/v304/watchsteady/13.jpg

This is the location, right in the cool high pressure
area, behind the grill. Grill bars direct air upward.

Installed view...

http://photobucket.com/albums/v304/watchsteady/23.jpg

Simple, clean, and it works....

The Dryer Vent needs some attention prior. The White
Screened Hood has a check valve flapper in it, that must
be removed, so that the cool air can get in. The Alloy
tubing attached to the back is paper thin, throw it away,
it just pulls off the white part. In its' place, I used a 6"
section of galvanized, heavy wall dryer vent pipe, at a
cost of an additional 4 bucks--so in total I have 8 dollars
invested in cooler intake air...anything less than 86* F.
is "no spark retard"...and more power. denser A/F mix...

Steady "cheepazzed" Eddie
P12 L21 SPFI 454

I had to drive 50-miles for this one. An easy 8.1 L mod.
Available at Autozone, this is their #15898 Duralast
"alternate" temperature t-stat for the BB Chevy Vortec. It says "Motorad" right on it.
The install was straightforeward, but my OE 195* F.
t-stat was stuck in the hole and required some wiggling
to get it out. After the install I had lost some coolant, so
I topped off the 50-50 mix with distilled water from Wal-mart...the OE GM/Chevy temp gage runs two notches cooler (15 degrees) with (I expect) a loss of some fuel
economy, but fuel economy is not the reason for this
easy 8.1 Mod. The PCM/ECU begins to pull timing out
at a coolant temperature of 212* F...with this Mod and
combined with heavy towing, you start the bottom of the
Grade at 180* , and depending on the time and duration
of the hill climb, you might not ever reach 212* by the
time you crest the Grade. No spark retard. More Power...
and a cooler Allison...

Steady Eddie
L21 Vortec

I had to drive 50-miles for this one. An easy 8.1 L mod.
Available at Autozone, this is their #15898 Duralast
"alternate" temperature t-stat for the BB Chevy Vortec. It says "Motorad" right on it.
The install was straightforeward, but my OE 195* F.
t-stat was stuck in the hole and required some wiggling
to get it out. After the install I had lost some coolant, so
I topped off the 50-50 mix with distilled water from Wal-mart...the OE GM/Chevy temp gage runs two notches cooler (15 degrees) with (I expect) a loss of some fuel
economy, but fuel economy is not the reason for this
easy 8.1 Mod. The PCM/ECU begins to pull timing out
at a coolant temperature of 212* F...with this Mod and
combined with heavy towing, you start the bottom of the
Grade at 180* , and depending on the time and duration
of the hill climb, you might not ever reach 212* by the
time you crest the Grade. No spark retard. More Power...
and a cooler Allison...

Steady Eddie
L21 Vortec

Just a point... not all Motorad thermostats are failsafe. The one you ordered may be, you'll have to check the P/N against the P/n's on their website.

DEWFPO

I haven't ever had a thermostat fail in the closed position, but hung open? Yup.... The guts came out the wax pellet, and it hung open.....

Nah--

It was any port in a storm-Katy bar the door-and-press on...I had to buy what was available locally..I got more
deer in the headlights looks from more ignorant counter
persons at more auto parts places than I'd care to count..."What's a Motorad??"

The Duralast Box says, (for what that is worth), that the
#15898 is a "High Flow" thermostat. Which should be
the same as a Motorad 180* F. #2067-180...

It works well..the heater heats, no SES lights, no set codes, just cooler running--so far--:D

Steady Eddie
:cool:

It ain't all peaches and cream..

Mororad claims that their Fail-safe protects against
cooling system failures, but...

It doesn't fail open until the coolant temperature
reaches 280* F....by then the combustion chamber
temperatures have to be nearing 1300* F.--which is the
melting point of aluminum pistons :eek:

At that point (280* F.) the only water left is that which
is in the block. With the stat failed open, the remaining
water gets pumped onto the ground in a hurry, if you
suffered a ruptured hose. I think that a complete loss
of water spells the end...

Steady Eddie
L21 454

Steel glows at 1300F.....

280F is WAAAAY to hot for me to live with. I got my BB up to 250-260ish last winter with weak coolant.... It froze up the rad... I had a hard time getting it fluid again, the cap was destroyed too...

It has been fine, no issues since....

The OE temperature gage is really strange.
The span is 0% = 100*F
50% = 210* F.
100% = 260* F.

So..if I understand it correctly..there is a 110* F.
"span" between 0 and 50%. So the 1/4 mark =
155* F..correct??

With the OE t-stat the gage ran at one hash mark
below 210* F.--which is probably pretty close to 195*
F.--with the 180* t-stat it runs (at hot idle, no load) at one
hash mark ABOVE 1/4 or at least ABOVE 155* F.

Considering a 2% error on the sender and a 2% error
on the gage, that is pretty close for the new 180* F.
t-stat...correct?

Steady Eddie
L21 Vortec

If it is like my 99 K2500 Burb gauge, I suspect GM put in the wrong sender, my 96 Suburban K1500 (350) read pretty accurate, the 454 has always read pretty high. I read 205F with a 180 stat, the PCM agrees with the 180-190 number, the old stat was up to 210 on the gauge, but was in the 195-200 range with the PCM reading...

Get a small block sender....IF it will fit.

Tom--
I think I'll wait and see what happens to the reading when I hitch the 4K# Jeep Grand to the back end...

BTW: The L21 has a five-bladed fan, a big one..

BTW2: Brazel's just dyno'd a P12, after a tune, 258 RWHP...

Steady Eddie
P12 Vortec

258 RWHP, nice. I am curious what my 454 would do. I hope to get it to the dyno one of these days....

Tom wrote:
"..258 RWHP, nice..."
================
Mike from Brazel's wrote me, over on my Yahoo!
Group, The_P12_Chassis_Group, aking for advise.
This P12 had issues, burnt wiring, one knock sensor
burnt, one O2 gone, etc., and it STILL pulled 210
RWHP, just as it rolled into their shop. After repairs
and one of their tunes, Mike said the 258 RWHP was
very respectable, and compared to any 8.1L Workhorse
that they had ever tuned.

So, knowing that, the L21 CAN produce HP...two very
big parts of the tune are the CAI and the spark plug
gap trick, two parts that I already have...

BTW: My new NAPA Max Wires come in today...new
spark plug wires, another 8.1L easy mod...

Steady Eddie
L21 Vortec BB

Make sure you use a feeler gauge, not those junk spark gap tools that the parts stores sell (I used the crap round one). I used one of them, setting for 0.052", and the real feeler gauge came in around 0.045". I already had the mod and didn't know it....

Tom wrote:
"...(I used the crap round one)..."
============
Tom--
I agree. There are levels of "crap" plug gapping
tools out there. The Champion Plug "sliding scale"
wedge/ramp one is probably the worst of the bunch.
Then follows the K&D round wire gapping tool and
the best is the feeler gage. One must be careful
of the Platinum Tips. They are reported to "pop off"
the base metal, although I have never had this
happen with an AC Delco plug.

One concern that I had: The 41-993s say (right on the
box) "Assembled in the USA from Parts Made in Japan."

I have never seen a 41-932 that said that.

But, they (the 993s) seem to work and all the Guys at IRV2 Forums
use them in their 200K$ Workhorse 8.1Ls--gapped at
45-thou.

Steady Eddie
L21 454 Vortec
180*F. t-stat
41-993 plugs @ 45-thou
Cold air intake
Napa Max Wires

The benefits of the 180* F. t-stat are amazing when
it comes to the life of the ATF and the Allison.

We are talking about reducing the over-the-road NOT
(Normal Operating Temp).

A reduction of 20* F. NOT results in DOUBLE the life of the
Dexron ATF and the automatic transmission (Allison or
otherwise). With the simple, easy 8.1L Mod of adding
a 180* F. t-stat, you pick up a 15* F. reduction in
NOT at the transmission

I read that heat kills automatics.

My replacement co$t for a rebuilt AT500 Series
was $4800...cheap by today's Standards, but
a suprise expense, none the less.

The t-stat mod is inexpensive, much more
so than adding parts like a series-plumbed
aftermarket ATF cooler....:)

Steady Eddie
L21/Allison

A friend of mine knows someone who knows those AT500's, they race A1000's. And the A1000 CAN be made to go in place of the AT500, which is highly recommended. Don't rebuild! Upgrade!!!!

How much do they know on the A1000? The truck with the Duramax is the cover of Diesel Power magazine, and runs 9.72 in the quarter mile now (on the bottle of N2O), and 10.01 on the engine..... No propane, and the N20 was shut down at 1000 foot mark....

Yeah, they can make the A1000 live for say 1 or 2 passes..... 4 passes and they are amazed....

The truck is Orange Crush, a 70 C10 Chevy with a A1000 and a Duramax.... And the plans for next year are faster yet! Fastest DMax on the planet!

Tom wrote:
"...A friend of mine knows someone who knows those AT500's, they race A1000's. And the A1000 CAN be made to go in place of the AT500, which is highly recommended. Don't rebuild! Upgrade!!!! ..."
====================
Tom---
No thanks on the replacing the AT500 Series with the
newer Electronic 1000 Series...my Old School Allison
hasn't forced me to buy not one $220 sensor or relay
yet..LOL..I DID just spend 280 dollars (plus) on a
filter change, tho. I took the rig to Pacific Power Products for its' 5000-mile-since-rebuilt check up, where they
check over the shift points, test drive it (FIVE times) and they replaced the OE vacuum modulator. It still
has the 2-1 downshift bump at about 6 to 8 MPH, but
the up-shifts are wonderful...as I posted over on the Allison OEM Forum, they DID install a damn Fram HD
Filter instead of a Genuine Allison Filter and IT LEAKED!!
So, rather than take it back, a distance of some 100 miles, I changed the filter out to a NAPA/Wix Gold 1268.
NO LEAKS! A 8.1L easy Mod...BTW..the Tech also discovered a leaky PTO Cover Plate and said the gasket
needed fixed/replaced, so rather than pay them $100
per hour Shop Time, I bought a fresh Allison gasket and
changed it out in my driveway. I will never have a PTO
so I flew in the face of the advice offered and glued it
to the plate and the case with Copper Kote..NO LEAKS..

Steady Eddie
L21 easy Mods..

I just got my new set of NAPA MAX Wires...they are
swell. Really well made. The L21 ran with the OE plug
wires, and I'll use one of them for a spare on-board,
but at their age and brittleness, I thought I'd step up
to newer wire tech and go with the Lifetime Warranty
MAX Wires.

It is almost impossible to screw up the install, as the
short Plug-Near-Coil wires are all the same length, and
each wire will only reach its' coil above it. Just like with
everything I do, I checked on the 'Net and found out some FYI things....all C-N-P GM Engines seem to use the
same coils--from the lowest Model to the C-Series Corvette, the same Part #s apply, interesting, i thought.
One Corvette Guy fried several of his coils by not shoving the plug wire far enough into the coil tower, he
reported that the install is a "two-click" push in, UNLIKE
the one-click install on the spark plug end. A one click
coil tower install results in an air gap inside the tower,
that the spark jumps across, and it carbon tracks and
finally fries from the additional Ohm Load...

New Spark Plug Wires--an 8.1L Easy Mod....

Steady Eddie
One DIY step at a time...:)

There are 3 coils for the LSx engines:

Truck (larger heat sinks, considered best)
Car - Round
Car - Rectangular

All interchangeable....

I just got my new set of NAPA MAX Wires...they are
swell. Really well made. The L21 ran with the OE plug
wires, and I'll use one of them for a spare on-board,
but at their age and brittleness, I thought I'd step up
to newer wire tech and go with the Lifetime Warranty
MAX Wires.

It is almost impossible to screw up the install, as the
short Plug-Near-Coil wires are all the same length, and
each wire will only reach its' coil above it. Just like with
everything I do, I checked on the 'Net and found out some FYI things....all C-N-P GM Engines seem to use the
same coils--from the lowest Model to the C-Series Corvette, the same Part #s apply, interesting, i thought.
One Corvette Guy fried several of his coils by not shoving the plug wire far enough into the coil tower, he
reported that the install is a "two-click" push in, UNLIKE
the one-click install on the spark plug end. A one click
coil tower install results in an air gap inside the tower,
that the spark jumps across, and it carbon tracks and
finally fries from the additional Ohm Load...

New Spark Plug Wires--an 8.1L Easy Mod....

Steady Eddie
One DIY step at a time...:)

There are 3 coils for the LSx engines:

Truck (larger heat sinks, considered best)
Car - Round
Car - Rectangular

All interchangeable....
So I could run a set of MSD's coils designated for the corvette/camaro LS1's on my 8.1?

I don't know the details on the 8100 coils, but likely you can. Check the connectors at the local autozone or Napa or ? and see....

OR go to acdelco.com and check the part number there and then do a where used in the Vehicle list and see if they interchange.

im pulling myself outta this super long post.

its drifting away from easy 8.1 stuff to T-stats.

i might pop in every once n a while. just FYI

Wana--

The t-stat swap IS an easy 8.1L mod. One ground nut, two studs and it's out. And then you are 15 more degrees F. away from Spark Retard and a loss of torque.

Truly an easy Mod...cost? $9.99 plus tax....:D

Steady Eddie
L21 454/Allison

maybe so, but im too lazy. dont want to do it anymore, and parents would have a shitfit if i did

"Borrow" the truck for a night.... Go over to some friend's house and fix....

But, I would be ticked if my son did it. But if he had a good case for it, I would listen. My dad didn't listen for years, but he does now that I am older.

I was doing Lube-Oil-and Filter changes on the Family
Cars and Trucks at 13-years old..Owned my first car at 15, the only and last F**d I ever owned. it was 8 years
old, had 29K original miles on it, ran like a top, and I bought it for $200...A V-8 OHV, three-speed, overdrive.

MY Dad was happy I wanted to do the work...

Steady Eddie
L21 Vortec/Allison

Lots of things have changed since then. The biggest problem with my profession is that many people still think it's that simple and a 13 year old could do it so why should they pay me much money.

Like I said in the first page, two things that shouldn't be happening. Teens working on the family vehicles and wanting to go faster.

Vernon

Vernon said...
".... many people still think it's that simple and a 13 year old could do it so why should they pay me much money...."
=================
Vernon---

Being able and willing to pull wrenches on a vehicle is
an ability that will pay big time over the years. A kid
spending time working on a car is time that he (or she)
is not out doing drugs, or spray painting a fence. It is an opportunity for a Dad
to bond with his kid(s)..my Dad helped me learn the
Metric System because, as he said 50 years ago (God Bless Him), "the Metric System is the wave of the future" and I'd best be learning it..." so I did. How else
would I know that a 13mm wrench is almost a 1/2"
wrench?? It ain't something that my "less than a Man"
English teacher taught me...he could not wrench his way
out of a paper bag and I feel very
sorry for children whose Dads are mechanical zeros...and I feel extremely sorry for those children
that DON'T even have a Dad and look elsewhere for a "Dad" and all they have is an English Teacher who
taps his foot in the Men's Room....

Steady Eddie
L21 Vortec 454