L19, L21 and L29

[n0dih]

Well, might be easier to have a 454 thread to cover gasser mods, as the 8100 is so vastly different, even though it is still a Mark VI (Gen VI) BBC.

I can say, the single most best mod I have done to my L29 454, aka, Vortec 7400, aka, L-29... Is to have the PCM tuned by Jesse @ Wait4mePerformance. I would have to say that 40-50 lb/ft torque improvement is probably on the conservative side. It really runs better, more power is an understatement.

Attached is what the Hypertech programmer can do with the L29 and the L18 (that is the RPO for the 8100 BBC). I am quite confident that Jesse can do far more than a Hypertech handheld can do. I have been compiling HP/Torque data for a while, so this gives you a good comparisson where the 454's stack up....

I do feel torque management is a good thing, but removing it would make a far nicer truck to drive.

For comparison, here is the Ford V10. So if anyone tries to tell you the Ford V10 is stronger than the 454, you can laugh at them.....

And to think, the 496 is stronger over 2500 rpm in torque and 3500 rpm in hp. There is just no comparison of the best gas Ford to the Chevy gassers!!

[steady eddie]

About the F**d V-10.

The newest versions are much more beefy. The V-10
has a smaller displacement than the BB Chevy.
Your charts chop it off at 4500 RPMs, but it'll safely
wind out much higher. On flat level road, using the
same final drive, same 19.5" tires, it'll blow right on
by--simply because it has higher RPMs than the BB
Chevy and I have a rev limit. The V-10 does too, but
it is higher...I have seen the V10's tailights getting
smaller and smaller on the final I-10 leg on entering
Phoenix--I just wave and smile..adios F**d, see ya
at the Races....

Steady Eddie
Go Kevin #29

[n0dih]

I agree, the factory L21/L29 cam is puny, more like the specs of the TPI 305 cam! Toss in a ZZ502 cam and go have a ball.

I can say a friend of mine has a V10 Excursion and compared to my 454, low end, I can move out and GO far faster than he can. 0-30 in that thing takes an eternity. Mine flat out flies. Yeah, 0-60 is only 11 seconds. Not stellar at all, it seems to die out around 4000 rpm or so, the cam is just all done.

His does seem to do ok way up at higher rpms, but at least in my Suburban, I don't drive high rpm.

GM could have done lots better with the 454 (wanna rare tidbit? The Mark IV was actually a Pontiac design, but the designer got transferred to Chevy and took his design with him, so Chevy ended up getting, not Pontiac....). The 454 could make SOOOO much more power. Even the 8100/496 should be doing much better.

[steady eddie]

Ya gotta remember that in the P12's configuration
the L-21 is built to go 200,000 miles and tested to run
WFO for 1000 hours. Back in the day (mid-80s) there
were lots of RV 454s that broke. What did they break
most often? Valves...whose head broke off, then holed a piston....
end of vacation. Most of the valve issues were caused
by engine pinging and knocking, along with extreme heat..In the L-21, Chevy addressed that with dual
knock sensors, a huge radiator, and etc. The L-21
runs so cool that there are no electric aux fans on it
at all, just the one big 7-blade de-clutching fan...
the engine is governed to a fuel-cut off, governed to
a max road speed, and governed to a max tire rating
speed..these governors reside with-in the PCM and
can be neutered, via a tuner program. But---in the P12,
there is a Maximum Input RPM for the Allison Transmission, and IT is governed mechanically to 4000 RPM input. No tuner would help...

All of this I'm thinking about as I wave good-bye to
the guy driving the F**d V-10...

Steady Eddie
Rabbit vs. Turtle

[n0dih]

The L29 has a 9 blade declutching fan, with an additional electric pusher in front, external trans oil cooler, radiator engine oil cooler, massive radiator (this sucker is as fat as my T/A's 4 core rad, and wider). The L29's have dual knock sensors also (as does my LT1). I put in a 180 thermostat, I didn't like how hot this engine runs (almost unbearable with the hood popped on a hot summer day).

Mine is governed to 98 mph stock, not sure now (I don't push it anyway), but I did on the stock PCM and was just getting into 3rd when the speed limited kicked in....

Seems the L29 and L21 are still VERY close cousins, even in the P12 and the C/K trucks. Just I have a 4L80E and not a Allison....

[steady eddie]

Tom wrote:
"...The L29 has a 9 blade declutching fan.." Shoot, now
I gotta count the blades on mine again. I thought for
sure that it only had 7 big blades..hmmmm..

About the thermostat temperature rating: I thought
about changing mine to a lower temperature like what
you did. But doesn't the stock PCM have to "see" a
certain temperature before it puts the fuel injection
into a closed loop mode??

Steady Eddie
cooler would be better... ..

[n0dih]

Yup, the PCM does. BUT, what people don't realize is that temp is around 130F. You pretty much have to have NO thermostat to make any PCM problems.

There are a few things to get it into closed loop:
Coolant temp (typically 120-135 F)
Intake Air Temp (this only delays it, but won't prevent it)
O2's must be up to 600F or higher
O2's must be functioning (if missing, or dead wont' go into closed loop that side)
And probably a few other things like some DTC's set won't allow it, but for the most part, it will force the issue of going to closed loop if it can.

Yup, my fan is a monster, bet you got at least a 9 blade one.....

Feel free to go to a cooler stat with no issues. I don't care for a 160, but it won't hurt. 160 is pretty cool to use. I think 180 is more ideal. I perfer to keep the head temp down if I can. But being we have the goofy backwards cooling the block first cooling system, the block stays too cool and the heads too hot. I would rather it be reverse cooled like my LT1. It makes much more sense. Heck, Pontiac came out with reverse cooling back in 1955!

[TA Dave]

You'll also get better MPG with the 180 vs the 160 stat.
Tom's correct about the temps going into open/closed loop.

BTW, Tom I've seen that "Resurfacing Wisconsin highways 2 long black strips at a time..." line over on PY...

[n0dih]

I think I have been there a time or 2! I can't remember who I swiped that from, but I tweaked it a tad and added it to my signature line.... aka 427HemiPontiac on Sal's Pontiac forum....

Long time no hear! How goes the T/A and the Burb?

[steady eddie]

OK--you guys have talked me into it, arm twisting
and all..

I did some research today and found that the Robert
Shaw thermostat is well thought of by just about everyone..but..they are not sold under that name anymore. They are now made by Cooper Standard
and some of their t-stats are made in Germany, even.
The Germans are sticklers for the details and these
t-stats run with-in 4-degrees of their rated temperature.
I have an Internet addy for this t-stat, which shows a
picture and everything, but I am nervous about posting
it here--it is good enough to say it's a very good once-
in-a-lifetime t-stat. By me putting a 180 in my Motorcoach, I will allow my Allison to run at coolant
temperature, a full 15-degrees less...WOW

This t-stat swap should be or could be an 8.1 easy mod.

Steady Eddie
who is becoming