OK so I'm leaning towards twins now... but have hit a roadblock. I would LOVE to use the MPI set-up but I want to use my own turbos for cost reasons. So the MPI set-up is out of the picture as Nathan wouldn't sell just his plumbing and I don't blame the guy one bit. Can't think of anyone else to hit up, but I doubt anyone else would sell just their plumbing either...lol. So made a call to a good buddy who owns a machine shop and w/ the help of his killer fab. guy, guess we're gonna go at it ourselves. Luckily he was a GM mechanic in his former life so hopefully won't screw to much up.

So off we go to researching everything a bit more and just can't find much info. But what I did find confused me. I stumbled upon this on ATS's site. "Air enters the low-pressure turbo (the larger of the two) and is fed into the high-pressure turbo (the smaller of the two), then directed into the engine or intercooler."

I was under the impression that the smaller turbo was used to spool up the larger turbo. If that was the case wouldn't the air enter the smaller turbo then go to the larger turbo, then into the engine or intercooler? Wouldn't the other way around like listed on ATS's site choke out the larger turbo under high boost? As you have to go from the high flow of the large turbo down through the smaller sized turbo.

Can anyone help explain? Thanks guys!

Well either way it has to go through the smaller charger, right? Whether it be first in line or second...

I believe thats how all compounds are set up though, at least from what I've seen.

A lot of fabrication goes into a twin turbo setup. And knowledge. You could spend considerable money and time getting the right combination of turbos and making them perform well together. Nathan's been through all that and over a bunch of years has learned what works. You'd likely be money ahead selling what you don't know will work, then getting it done right the first time by someone who really does know this stuff.

A lot of fabrication goes into a twin turbo setup. And knowledge. You could spend considerable money and time getting the right combination of turbos and making them perform well together. Nathan's been through all that and over a bunch of years has learned what works. You'd likely be money ahead selling what you don't know will work, then getting it done right the first time by someone who really does know this stuff.

It took Nathan 15 consecutive 10 hour days getting everything lined up, deburred, tack welded, finding turbo supports, Oiling, re routing, and clearancing to get it done.

After that, it all had to be taken apart, pressure tested, finish ground and coated.

Then reassembled, and road tested.

Then tweaked, and road tested again.

Then ripped apart because the results were not what he wanted.

Changed bottom turbo for a different one, then remake piping and go through 80% of the steps above again so it was just right.

And he KNOWS what it takes to make compounded turbos work. Hell, I have a decent handle on it, but still would not attempt to do it myself.

If you want bigger, Nate can set you up. But a person simply cannot go through all that hand labour, and get it working correctly for the cost that MPI's setup goes for.

I know Nathan pretty good, and his finished kits are nothing short of amazing. The prototype he did on my truck worked awesome, and I understand the new tubing he has jig made is much better flowing than the welded ones in my truck.

Nathan WILL be installing Twins on my truck when i get some time off. I'm not the easiest person to deal with when it comes to my truck (Very Anal about it) but with Nathan, I trust him and his knowledge without question.

Is it a little more expensive than single charger setups? Yup. But it can do so much more.... the cost becomes only a memory when you need the power to tow a load, or the power to blow away that Red Testarossa at the next stoplight... all the while your EGT's are a nice cool, safe number.
No Funny Gas
No BBQ Juice
No Water
No Methanol
Nothing.

Just fill it and go. The midrange torque is something to lust for, and I can't wait to have him work his magic on my new truck.:)

Air is ingested from the bottom (big) turbo through the AFE Filter. And compressed. And sent to the top turbo (small) where it get's further compressed and then from the discharge volute to the Intercooler, then to the motor.

Exhaust gasses are first sent to the small turbo. Gated from 7-11 psig, it is hardly working, and right in it's efficiency map so it is hardly heating the charge at all. The exhaust gasses leave the turbine side of the top turbo, and enter into the bottom turbo, where that charger is regulated to a relatively small boost number (if using the deltagate)
Then the exhaust leaves the bottom turbo, and then to your 4" system.

That's the basics.

Of course, the top turbo does most of the work until 7 PSIG where the discharge flow of the bottom turbo overcomes that of the top turbo... there is a lot to this equation, as you can see. Nathan has made it his business to know how to solve it :)

I've been running the math and I know the set-up I was looking at will... (correction... lets say SHOULD) work (we all know how things work out on paper vs. reality).

The man hours are free.... so nothing but time and materials. Fab guys is excited and he's already done a couple twin set-ups just not in diesels (not that it's any different).

Like I Said.... honestly I would prefer to use Nathan's set-up as I truly appreciate the work and skill he put in, just want to use my turbo's, and that's not an option there unfortunately :(

This question is for my curiousity, as I'm not the one doing the work.

Now if any of the vendors here see this post and want to work around my turbo's then hit me up and I'll gladly purchase from you!!!

I had considered Driving down to Dallas to Forced Induction and letting those guys use my truck as a "Donor Car".

looks like you will be needing those rods sooner then later :D

from my findings the big turbo neeed to be roughly ~175-200% bigger than the small turbo...

for a stock small turbo twined... this is the rough target area
stock turbo do about 50-60lb min bigger turbo ~80-100lbmin

Malibu what I was looking at was the GT3788R and the GT4294R .... I really don't want all the power the GT42 is going to give me, but If I went to the GT4094, I think that's just to small and at that point I should just run the GT4094.

And yep Fire... man this bug sucks. Who knows what I'll end up with... my mind literally changes daily... one day I say lets just run the single and be done with it. Then I say the cooler running twins are gonna be better for the engine.... not to mention the quicker spool.

Malibu what I was looking at was the GT3788R and the GT4294R .... I really don't want all the power the GT42 is going to give me, but If I went to the GT4094, I think that's just to small and at that point I should just run the GT4094.

the 4294 will max out the single cp3 but not the other way around ~600rwhp with a LBZ cp3

honestly you can waste gate the big turbo/4294 and limit boost that is sent to the small turbo thus limiting power.. or by tuning


3788/stock-4294/4202 would deff work... personally i would get the 1.01 a/r or smallest turbine housing for quicker/sooner spooling and waste gate the turbo for the top end... put you 650-750rwhp range with a moddd cp3
and get you close to 750-850 with dual cp3 with the 4202



i dont have expereince in building them.:(... all i can give is advice off the papers that i have read and from what i have seen others build..


side note... one of the diesel mag did a test ppe-4094 dual cp3 and next artile was MPI twins single cp3... MPI out did the PPE truck ;)

Nathan does very good work.

But hearing a twined truck with a single stock CP3 out running a GT40 truck with a dual fueler?

That will not happen for many (if any) folk.

Chad ran Twins at LACR and ran mid 13's. I ran a GT4088 with a dual fueler with a medium tune at the same track and went 11.8. Yeah, Chad's truck is somewhat heavier, but realistically that is not a safe bet.

Joe at PPE ran 11's in an LBZ crewcab with the GT40 + 2CP3 in Vegas (altitude similiar) as well.

Air does NOT replace fuel. You need both.

That being said, you can extract more HP out of twins than a single with the same fuel supply.

Currently the only Fuel Only Dmax running 9's is a twin'd truck. Ditto for the Dodges, IIRC.

11.89 @ 112 MPH on #2, single stock CP3 from idaho rob's sig


both articles were diesel power same month nov or dec. cant remeber

nathan had an article in the same month as well....

the diesel power mag site is going the right links........:mad:

Nobody doubts Rob's truck is fast, but giving folk unrealistic expectations from a given modification does nothing helpful either.

Basically you are saying that if you have a stock truck with a built trans, you can put twins and a lift pump on it and make 650rwhp.

Nobody doubts Rob's truck is fast, but giving folk unrealistic expectations from a given modification does nothing helpful either.

Basically you are saying that if you have a stock truck with a built trans, you can put twins and a lift pump on it and make 650rwhp.
http://www.dieselpowermag.com/tech/chevy/0712dp_twin_turbo_duramax/index.html

or am i missing something

I guess I'll have to personally witness it I suppose.

Neither Subman's truck (dual fueled) or Chad's truck (single CP3) matched the internet or magazine claims, which are the only two I've seen run so far, unless there was one lurking at the DHRA events last year that I didn't see. Both trucks ran good, but not magical.

Yes, it adds performance. No, it doesn't eliminate the need for fuel from what I can tell.

i know brayden did ~600 with stock lbz cp3 and a cheetah

I guess I'll add my .02. The LBZ in the Magazine was not my truck. It had my tuning in it, and a tranny and lift pump. That truck dyno'd 650+/- a few weeks after my truck dyno'd 648HP on a completely different dyno in another part of the state. Seems very repeatable. I have nothing secret on my truck except I use a good track setup.

My truck ran 11.89 at 5500' D/A with many witnesses (diesel event) and I think PPE went 11.8 something also. Both powerful set-ups.

I feel very comfortable with my set-up and one cp3. This truck is my only transportation.

America is about, "i want it now, instant gratification".

Both are good set ups.

I can walk in to PPE right now tell Dan i want all those parts and walk out with them, 650 HP shazam. With EFI it prolly makes more than 650 HP!

Nobody doubts Rob's truck is fast, but giving folk unrealistic expectations from a given modification does nothing helpful either.

Basically you are saying that if you have a stock truck with a built trans, you can put twins and a lift pump on it and make 650rwhp.

Yes, I think that is a correct statement on a LBZ with proper tuning. My dyno#'s were corrected for 2800' elevation, so does it put out those #'s? Track times seem to back it up.

I don't want to make this a mine is better than yours thread. Just thought I'd add my opinion since my setup was brought up.

Thanks,
Rob

Nobody doubts Rob's truck is fast, but giving folk unrealistic expectations from a given modification does nothing helpful either.

Basically you are saying that if you have a stock truck with a built trans, you can put twins and a lift pump on it and make 650rwhp.

Not unrealistic at all. I am fairly certain DP magazine would not mislead it's core group of enthusiasts.

Quoted from DP Magazine

"Driving a Twin-Turbo Duramax
Driving the truck on the road with the twin turbos was quite an experience because they build boost very quickly without any lag. They actually boost like the stock turbo, but with a lot more airflow on the top end. Probably the most impressive feature was that the exhaust gas temperatures stayed comparatively low for the amount of performance. With the tow tune, we could easily pull a large load without ever having to worry about overheating. For the Duramax owner who still wants to use his truck every day without sacrificing driveability, the MPI twin-turbo kit could be ideal.

Before installing the turbos, this '07 LBZ Duramax had an output of 275 hp and 455 lb-ft of torque. The first run after the installation using the tow tune yielded an output of 569 hp and 1,124 lb-ft of torque. For the third run, Powerlabs Diesel hooked up a FASS lift-pump system and upgraded the ECU with the max-horsepower tune. This resulted in an output of 650 hp and 1,215 lb-ft of torque, so the overall gain was 375 hp and 760 lb-ft of torque at the rear wheels."

I guess we will see as more trucks get twin'd with no additional fuel.

There are more trucks running fast with dual fuelers and medium chargers than twins currently, perhaps someday that will change.

I might twin Casper this year to do some tests, but horsepower from a single and a dual fueler seems to be good.

I guess we will see as more trucks get twin'd with no additional fuel.

There are more trucks running fast with dual fuelers and medium chargers than twins currently, perhaps someday that will change.

I might twin Casper this year to do some tests, but horsepower from a single and a dual fueler seems to be good.
nice casper with twins...hmm GT4202 and a GT6041:rolleyes:


you might need to your nozzles up to get more fuel in there:eek: might get you low 10s high 9s:D

nice casper with twins...hmm GT4202 and a GT6041:rolleyes:


you might need to your nozzles up to get more fuel in there:eek: might get you low 10s high 9s:D


I shudder to think how fast Casper would be with Twins. :cool:

I shudder to think how fast Casper would be with Twins. :cool:
90lbmin turbo casper is a 10.6X truck/ 800-850rwhp

and another 100 lbmin from a thumber, big brother or GT60

finally put bigger INJ in there i think everhting else is max out rail, pulse width... only thing left is the holes it going through....

speculation.... ~30% over would put him ~1000-1100 easily with twins:drool:

i think pat found the limit to stock LLY injectors ~800-900rwhp #2

Naw, the limit is 400HP.

What I don't tell anyone is I run 2 complete sets of LLY injectors! :D

What some folk don't understand is that HP is just one piece of the puzzle. Putting in more power past a point doesn't make you faster, it just makes your life more expensive.

Old Fart Story:

A long time ago there used to be something called Open Class Motorcross. Every year the bikes got more and more power. They dominated. At first. But when the HP got past a certain point, the 250cc bikes started out lapping them. They even started de-tuning the Open Classers to try and regain the crown, but the 250's were getting faster too. The 250's ran into the HP limit too, which killed the Open Class 2-strokes.

But...

Much like too much power in a car or truck, there is something to be said for stupid amounts of power. The old RM500's, CR500's, YZ490's, and KX500's are still a lot of fun to play around on, even it they do cut slower laps.

What some folk don't understand is that HP is just one piece of the puzzle. Putting in more power past a point doesn't make you faster, it just makes your life more expensive.

Old Fart Story:

A long time ago there used to be something called Open Class Motorcross. Every year the bikes got more and more power. They dominated. At first. But when the HP got past a certain point, the 250cc bikes started out lapping them. They even started de-tuning the Open Classers to try and regain the crown, but the 250's were getting faster too. The 250's ran into the HP limit too, which killed the Open Class 2-strokes.

But...

Much like too much power in a car or truck, there is something to be said for stupid amounts of power. The old RM500's, CR500's, YZ490's, and KX500's are still a lot of fun to play around on, even it they do cut slower laps.


whacha saying pat.........


you sceerred:p:

or wisdom saying enough is enough:)

I appreciate the input Pat.

Something I should point out is the whole reason I'm considering twins is the simple fact that they run cooler and the decreased lag time over a larger turbo.

I still haven't completely ruled out the single GT4094R. My concern is spool up compared to stock. I'm not going for major hp (although I would consider anything over 500 pretty major...lol) ... in all honesty I REALLY don't want to go over 650. I'd really rather things be closer to 600. Thus I was going to keep things tuned down and definately was gonna have the turbo's wastegated.

My main concern is keeping things cool, therefore increasing overall life. Part of the reason I don't want twin fuelers.

I guess I'll add my .02. The LBZ in the Magazine was not my truck. It had my tuning in it, and a tranny and lift pump. That truck dyno'd 650+/- a few weeks after my truck dyno'd 648HP on a completely different dyno in another part of the state. Seems very repeatable. I have nothing secret on my truck except I use a good track setup.

My truck ran 11.89 at 5500' D/A with many witnesses (diesel event) and I think PPE went 11.8 something also. Both powerful set-ups.

I feel very comfortable with my set-up and one cp3. This truck is my only transportation.


What was your 60ft's?

I appreciate the input Pat.

Something I should point out is the whole reason I'm considering twins is the simple fact that they run cooler and the decreased lag time over a larger turbo.

I still haven't completely ruled out the single GT4094R. My concern is spool up compared to stock. I'm not going for major hp (although I would consider anything over 500 pretty major...lol) ... in all honesty I REALLY don't want to go over 650. I'd really rather things be closer to 600. Thus I was going to keep things tuned down and definately was gonna have the turbo's wastegated.

My main concern is keeping things cool, therefore increasing overall life. Part of the reason I don't want twin fuelers.

Read this it might make your decision easier.... http://www.pacificp.com/includes/templates/ppe/images/DieselPowerDec07_lrg.jpg or just click here and scroll down about half way.... www.ppediesel.com "The Next Level"

Thanks dan... Seen that before though ;) ...it doesn't make things any easier as I don't want twin CP3's (at least not right now :D).

Pat,

Ken's truck had shortened rods in it so it was down on power. Chad's truck had the original version of twins which were smaller and were unwastegated on the primary.

The point is Rob's truck and many others with twins consistently out run the single charger trucks with a single cp3 and with bigger twins the dual cp3 arena will be dominated by twins as well. Of course the PPE truck will run fast with twice the fuel available in dual cp3's.

... Of course the PPE truck will run fast with twice the fuel available in dual cp3's.

Exactly the point. A medium charger + second CP3 is not second fiddle to just adding a compound charger by itself. We will run out of fuel.

The Dmax engine is fairly well "balanced" from the factory. The fuel system runs out of steam about the same time the turbo does. We can add just air and gain power, but we will run out of fuel at some point. It's interesting that we also gain HP by just adding fuel as well with a stock charger, but doing both multiplies the effect.

A GT40 is only modestly bigger than our factory charger, and with the right tuning has the same lag the factory charger does, and will even improve the mileage. Heck, even the 42 is completely streetable now and does well towing when combined with transmission tuning. And we know a second CP3 with a GT42 is serious power.

Like I've said, twins are certainly a good way to go, but telling folk they will outrun a single with a dual CP3 is very misleading.

Wow I'm more confused than ever! I come from a gasser background and have a little knowledge of diesels but the basics are similar (more fuel and more airflow equals more power). How do twins achieve lower EGT's than a comparatively similar (airflow wise) single? It seems to me that in order to make the same power it take the same amount of fuel and air, right? If so, then how can one setup need dual fuelers and another not to make the same power?

un like a gasser which uses a small portion of the turbo... a diesel will use the entire map..

also unlike a gasser that normally runs parrellel twins... majority of diesel run compounded turbos. meaning a small turbo and a large turbo.
conversion formula lbmin/.061=cfm and cfm*.061= lbmin

a singe turbo like a cam has a range of what the said turbo flow effeciently out side the rang the said item is laggy and unresponsive unlike when the engine is in the operating range. the bigger the turbo is on the top end you lose on the bottom end just like a cam.

so how does this work...

a small turbo is great and repsonsive at low rpm and air flow and suck at high rpm and air flow. on the other hand the big turbo is great at high rpm and air flow and suck at low rpm and air flow...

on the dmax the turbo is roughly rated max @ 50lbmin or ~800cfm. it is very effective between 350-750cfm low egt good spool response and what not. above that the egt rise and the compressor wheel start loosing effeciency.. and on the dmax the turbo is abuot done around 3000rpm

now we get a bigger turbo that is maxed at say 100lbmin charger or a charger that can flow ~1600cfm. it nice range is from 500-1300cfm

now the dmax can run the 100lbmin charge as a single but normal drivablity will be lacking especialy in the stop and go traffic..

so how do we bassicly do away with high egts?
the small charger take care of the off idle and low rpm conditions. it is also waste gated. for two reasons that are basicly one in the same. we only need enough of the small charger to get enough air moving to spool the large charger. once the larger charger is lite and making boost. the waste gate on the small charger opens allowing the exhaust to bypass the turbine on the small turbo. this does two things
1 eliminate the restriction going through the small turbo example: the turbine housing on the small turbo will not safely handle the vast amount of airflow the big charger is moving.
2 allowing the exhaust gases bypass the small turbine housing keeps the small turbo from over spinning.

then how can one setup need dual fuelers and another not to make the same power
fuel equals boost/power to spin the turbo.. more fuel negate more power.

large singles suck down low. now you can offset the some by dumping mass amount of fuel to get the turbo spooling.

with compound twins you dont need to dump mass amount of fuel down low to get the big turbo spooling... that is the job of the small turbo. you basicly dont need to change the bottom end fuel at all. just dump mor fuel in the top part of the tune.

onther thing to think about..
when we are running a compound setup. we have made our operating band almost twice as big as a single charger would allow.

hope that makes sense..... clear as mudd:)

nice, adam....

think that's the most longwinded i've evr seen you.... :D

but telling folk they will outrun a single with a dual CP3 is very misleading.


No one said a single cp3 would out run a dual set up. In this case both trucks ran roughly the same time and dyno the same. So it looks a lot like they are truely making the same power. It's doesn't mean the dual cp3 set up can't be tuned to make more but then again the single cp3 set up can be tweeked to make more too.

Actually that is the reason for my post.

Based on that magazine article, I should be able to put on a second charger and make well over 700rwhp at our local dyno with just a FASS pump and stock CP3. LBZ's dyno about 310rwhp around here. Nick dyno'd 720rwhp there, Doug about 700, and Casper pushed just over 750. Diesel Power Mag uses this dyno. A GT40+2CP3 goes 670 there.

Like I said, I'm impressed with the product and results, but I'm not impressed with the claims. They do not line up from what I can see so far. I could be wrong, and if I am, you will see lots of mid 11 second twin+single stock CP3 trucks, even at high altitude.

Thanks Malibu GREAT post (nice avatar btw)! That does clear up a lot. Let's make sure. The smaller turbo needs less fuel to spool up and has less lag (greater low engine rpm efficiency), which in turn helps spool the large turbo which now requires less fuel to get spinning since it is getting help from the smaller one. Once fully spooled, the larger turbo (which has greater high engine rpm efficiency) requires less fuel to keep increasing airflow and boost? Would twins therefore create less smoke? I know smoke is unburnt fuel hence high EGT's with lots of smoke and am assuming that this is where the reduction in EGT's over a large single comes from.
Airflow + fuel = Horsepower.

Maybe I'm still thinking like a gasser. My old fart of a brain gets stuck in gear once and a while and it takes some fiddlin' to get it to grasp some new things. Something about and old dog I think.;)

Thanks Malibu GREAT post (nice avatar btw)! That does clear up a lot. Let's make sure.
The smaller turbo needs less fuel to spool up and has less lag (greater low engine rpm efficiency),yes
which in turn helps spool the large turbo which now requires less fuel to get spinning since it is getting help from the smaller one. correct
Once fully spooled, the larger turbo (which has greater high engine rpm efficiency) requires less fuel to keep increasing airflow and boost? for the most part yes.. you will always need X amont of fuel to make Y amount of power. twins are more effecient at using all the fuel than a single turbo is.
Would twins therefore create less smoke? yep

I know smoke is unburnt fuel hence high EGT's with lots of smoke and am assuming that this is where the reduction in EGT's over a large single comes from. yes
Airflow + fuel = Horsepower. all ways does

Maybe I'm still thinking like a gasser. My old fart of a brain gets stuck in gear once and a while and it takes some fiddlin' to get it to grasp some new things. Something about and old dog I think.;)
you saying your mental synchros need rebuilt?? ):h

making power on any engine gas/diesel is the same principle.. add fuel... then you need more airflow gasser are just more anal about A/F ratio then diesel are

alot of stuff isnt much diff then a gasser in all out principle.. just the way we go about it is a little different;)

No one said a single cp3 would out run a dual set up. In this case both trucks ran roughly the same time and dyno the same. So it looks a lot like they are truely making the same power. It's doesn't mean the dual cp3 set up can't be tuned to make more but then again the single cp3 set up can be tweeked to make more too.

How can we do a far comparison if we dont have the FACTS? where were the runs made? what was the eleveation? air temp? truck weight? Downhill track? was the Cp3 modded? was the tune modded to allow the stock cp3 to flow more volume? What Was his 60 ft (like I asked in a earlier post)? How about the 1/8 mile time and speed? How about the 1/4 mile speed.

Dyno numbers mean very little unless the tests are done on the same dyno same day....

Lets do a little comparing!

Actually that is the reason for my post.

Based on that magazine article, I should be able to put on a second charger and make well over 700rwhp at our local dyno with just a FASS pump and stock CP3. LBZ's dyno about 310rwhp around here. Nick dyno'd 720rwhp there, Doug about 700, and Casper pushed just over 750. Diesel Power Mag uses this dyno. A GT40+2CP3 goes 670 there.

Like I said, I'm impressed with the product and results, but I'm not impressed with the claims. They do not line up from what I can see so far. I could be wrong, and if I am, you will see lots of mid 11 second twin+single stock CP3 trucks, even at high altitude.


There wasn't anyone claiming any of this nonsense. The claim was the truck made 647hp or so on that particular dyno, not 700. There was also no claim that a stock cp3 truck will run mid 11's. Rob's truck ran high 11's. Those are facts (another words it actually happened).

Would twins therefore create less smoke? I know smoke is unburnt fuel hence high EGT's with lots of smoke and am assuming that this is where the reduction in EGT's over a large single comes from.
Airflow + fuel = Horsepower.

.;)

Look in the video link in my sig for the smoke. Some on launch (10-15lbs of boost) then nothing. This was the biggest reason I went with twins three years ago. I drive it everyday and like power, but here in the great northwest, smoke is a bad thing, even worse at high altitude.

Actually that is the reason for my post.

Based on that magazine article, I should be able to put on a second charger and make well over 700rwhp at our local dyno with just a FASS pump and stock CP3. LBZ's dyno about 310rwhp around here. Nick dyno'd 720rwhp there, Doug about 700, and Casper pushed just over 750. Diesel Power Mag uses this dyno. A GT40+2CP3 goes 670 there.

Like I said, I'm impressed with the product and results, but I'm not impressed with the claims. They do not line up from what I can see so far. I could be wrong, and if I am, you will see lots of mid 11 second twin+single stock CP3 trucks, even at high altitude.

Pat, I'd have to reread the article, but I don't remember claims of 700+HP in the article. One thing to ponder, the fastest stock charger LBZ's are in the 12.8-9 range and 520-30HP range. With basically the same tuning w/different boost tables the twin trucks make 600+hp and run low 12's all day long. My truck with the daily tune of 2300 max us and max 18* of timing runs 12.8-9, and is a great driving rig.

Edit: Opps Nathan you type faster than me.

How can we do a far comparison if we dont have the FACTS? where were the runs made? what was the eleveation? air temp? truck weight? Downhill track? was the Cp3 modded? was the tune modded to allow the stock cp3 to flow more volume? What Was his 60 ft (like I asked in a earlier post)? How about the 1/8 mile time and speed? How about the 1/4 mile speed.

Dyno numbers mean very little unless the tests are done on the same dyno same day....

Lets do a little comparing!

My 60' time was high 1.6 on the 11.8 run. I have 60'd in the 1.7 and run 12.0. The D/A was a documented 5500' at the time of run 90+ amb. temps at a track elevation of 2800'. I have a totally stock cp3 and regulator, and didn't have the option (like we do now) of ramping cp3 pressure up with efi. I'll try to dig up the time slip on 11 sec runs and post those. The truck is a crew cab with the tail gate on and normal stuff unbolted, hitch, spare, etc.

I'd like to keep posting here but I don't like the way things are turning in the thead. Only product of mine is the tuning, soooo, I'm backing out of this one.

My phone# is 208.484.3670 if anyone wants to talk to me about things. Dan, I'd love to talk with you if you'd like and Pat we have spoken many times. I'm not hiding anything and the big groups that go to the track and dyno when I'm there will back this up.

Take care,
Rob

Now we're getting places w/ this thread. Def. on of the more informative threads I've seen on twins on here.

Malibu you mentioned the smaller being turbo being wastegated and bypassed once the larger turbo spools up. I had wondered about this once I found out the larger turbo goes between the intake and smaller turbo. I had wondered if the larger turbo would over speed the smaller turbo.

Let me see if I got this straight. So there's a wastegate between the smaller turbo and the larger turbo, acting much like a butterfly valve that when triggered, diverts gas around the smaller turbo through secondary plumbing into the motor. Instead of into the exhaust system or like most wastegates, or into the atmosphere like in the case of screamer pipes.

So you would have to a manifold w/ two inlets on top of the motor. One for the smaller turbo to tie into, and the other for the secondary plumbing of the larger turbo to flow into.

Do I got this right or am I wayyyy off?

way off

Now we're getting places w/ this thread. Def. on of the more informative threads I've seen on twins on here.

Malibu you mentioned the smaller being turbo being wastegated and bypassed once the larger turbo spools up. I had wondered about this once I found out the larger turbo goes between the intake and smaller turbo. I had wondered if the larger turbo would over speed the smaller turbo. if the small turbo is not waste gated it WILL over speed the small turbo

Let me see if I got this straight. So there's a wastegate between the smaller turbo and the larger turbo, acting much like a butterfly valve that when triggered, diverts gas around the smaller turbo through secondary plumbing into the motor except for this part.
Instead of into the exhaust system or like most wastegates, or into the atmosphere like in the case of screamer pipes.

So you would have to a manifold w/ two inlets on top of the motor. One for the smaller turbo to tie into, and the other for the secondary plumbing of the larger turbo to flow into. you off on this part;)

Do I got this right or am I wayyyy off?

almost got it;)

the simple form is
flow path
exhasut flow. from engine to small turbo, small turbo to big turbo.
intake flow filter to big turbo, big turbo to through the small turbo, small turbo to the intercooler. then to the engine

the purpose of a waste gate is to control boost on the intake side.
on a simple/standard compound one waste gate is needed. it goes between the engine and the small turbo.. the waste gate allows youto bleed off exhaust pressure that would normally be used to spool the said turbo. thus acting like a govener.. for lack of better words. or your "screamer pipes"
this is a LB7 turbo and it is waste gated
http://www.pacificp.com/images/medium/lb7%20turbo%20view2_MED.jpg (http://www.pacificp.com/images/large/lb7%20turbo%20view2_LRG.jpg)
the valve on the right in the picture is hte waste gate. that allows the exhaust to bypass the turbine wheel

VVT turbos dont need waste gates. the way you "waste gate" a VVT turbo is open the vane up and the air slows down limiting spool

in my senario the turbine housing on the 50lbmin charger is good for 50lbmin....60lb tops anything more than that will cause the small turbo to overspeed and blow up.

so since we are use thing big 100# turbo compounded we have to allow some of new exhaust gas from the extra air the big turbo is pushing bypass the turbine on the small turbo. this is done by a waste gate..
we can send this bypasse exhaust either into the atmosphere(screamer pipes) or into the exhaust down stream of the small turbo.. and allow the big turbo to use it

so right now with the said setup we have a waste gated small turbo and a non waste gated big turbo.. thus all the exhaust has to go through the turbine on the big turbo... for more control we can put a waste gate on the big turbo.. this allows us to control how much exhaust the big turbo can use. thus controlling the big turbo and over all boost with the big turbo making boost

way off
im milking this cow ;)





you posted to fast:p:

im milking this cow ;)





you posted to fast:p:


Milk away, my utter is getting full and I have the bucket sitting there waiting for you! ):h

On a side note... it's amazing how little in depth information there is on the web on this particular subject. I realize it's a pretty complicated subject, so I would think there would be tons. But everything I find just seems to have three to four sentences describing theory, but doesn't go into the actual mechanics.

Milk away, my utter is getting full and I have the bucket sitting there waiting for you! ):h

On a side note... it's amazing how little in depth information there is on the web on this particular subject. I realize it's a pretty complicated subject, so I would think there would be tons. But everything I find just seems to have three to four sentences describing theory, but doesn't go into the actual mechanics.
currently there is 1-2 poeple acctually making compound twins as a kit... for the duramax.

MPI and merchant... i know they are some what tight lipped and dont blame them on what excatly they are running

i wanted to know. so i went looking. dodge boys have been running compounds for years... and the are quite a few DIY out there that have done it sussecfully.. but are not making kits

ATS runs compound twin for dodge boys A3k/A5k max hp in the 700 on #2 only
same with BD turbo the small is roughly 50-60% of the big turbo......

another thing unlike hte I6 boys twining a V8 aint easy with the need piping

Well I'm just talking about the compounding turbos in general. Not specifically for our trucks. I didn't even know Merchant was making twins... I only knew of MPI's kit. I def. don't blame the guys for not spilling info either.

Like I said though... my main issue is I want to use MY turbo's as my cost on them is substantially less those manuf. can buy them for.

well lit looks like im going a diffrent route as well now tige the darn quest for more power

Well I'm just talking about the compounding turbos in general. Not specifically for our trucks. I didn't even know Merchant was making twins... I only knew of MPI's kit. I def. don't blame the guys for not spilling info either.

Like I said though... my main issue is I want to use MY turbo's as my cost on them is substantially less those manuf. can buy them for.
im sure MPI has a kit comming through the pipe for LMM in hte 4000-4500 range;)

well lit looks like im going a diffrent route as well now tige the darn quest for more power

HAHA.... fire you crack me up. Looks like it's gonna be me and you being the guinea pigs on the LMM's. Not that they're that much different than the LBZ's. It's just a few 1/1000's of an inch here and there that throw things off

On a side note.... I think we're gonna be setting up the jigs to be able to mass produce the twin kit plumbing. Allowing others to use their choice of turbos... they'll just have to produce their own pedastal.

you saying your mental synchros need rebuilt?? ):h


Probably. Know any good mental trans guys?:)

IdahoRob - me likey linky very much!

There wasn't anyone claiming any of this nonsense. The claim was the truck made 647hp or so on that particular dyno, not 700. There was also no claim that a stock cp3 truck will run mid 11's. Rob's truck ran high 11's. Those are facts (another words it actually happened).


Their dyno said 275? for a stock LBZ. So their dyno is lower than the one I use by about 10%. Take 647 and add 10%.

659hp (at my dyno) will go 11.7.

Exactly the point. A medium charger + second CP3 is not second fiddle to just adding a compound charger by itself. We will run out of fuel.

The Dmax engine is fairly well "balanced" from the factory. The fuel system runs out of steam about the same time the turbo does. We can add just air and gain power, but we will run out of fuel at some point. It's interesting that we also gain HP by just adding fuel as well with a stock charger, but doing both multiplies the effect.I agree as I have been in a few twin trucks and have spent extensive time in one big one ! They do spool quick, That being said the feel you get when the second one (the big one) lights is like a rocket launch.:D......... I have not dynoed mine yet and we are still tweaking the tunes. I will be hopefully dynoing on a Mustang DYNO this Jan 19 with Merchant and a few others at a local shop here in MI. 700 is the Goal ! But I wont cry at 650 as its a fun truck to drive and is as street able as a stock truck.

A GT40 is only modestly bigger than our factory charger,That is a understatement at best ! The Factory charger is a much smaller charger.:( Come on Pat 94mm is not a factory compressor! and with the right tuning has the same lag the factory charger does,My 4094 is the fastest spooling turbo I have had on my truck or been in with a single. Way faster than stock. I think tunning takes care of that. ;) and will even improve the mileage. Heck, even the 42 is completely streetable now and does well towing when combined with transmission tuning. And we know a second CP3 with a GT42 is serious power.

Like I've said, twins are certainly a good way to go, but telling folk they will outrun a single with a dual CP3 is very misleading.I totally agree. Twins are great, its just a concept that needs more vehicles to run them and get feedback

currently there is 1-2 poeple acctually making compound twins as a kit... for the duramax. That is just a matter of time as all Duramax hard parts are cloned and the price drops as they flood the market ! (Dual cp3, Tie rod sleeves, Centerlink, lift pumps, ...) Even tunning is now being given away !

MPI and merchant... i know they are some what tight lipped and dont blame them on what excatly they are running looks like you are on to something Adam!;) Its just matching the air to air ratios and knowing what to gate and where to plumb it !



I love the feel of both Twins and a good tuned single. I have been in many of both HUGE ones and such. They both get it done in different ways and achieve a goal in a deferent way. With twins you have a distinct sound and feel to drive. A big single is different too. As I said there are more than 1 way to skin a cat !;)

At our high elevation track (7-11000'DA)the twins definitely seem to have an advantage. Single cp3 single turbo trucks seem to loose at least .5 second, or more. The twin trucks I have seen are virtually un effeced.

Fire let me know what you end up doing.

I'm really kind of tossed up on rather to do the twins or the single.

[quote=C.A.P;2300214]
currently there is 1-2 poeple acctually making compound twins as a kit... for the duramax. That is just a matter of time as all Duramax hard parts are cloned and the price drops as they flood the market ! (Dual cp3, Tie rod sleeves, Centerlink, lift pumps, ...) Even tunning is now being given away !

MPI and merchant... i know they are some what tight lipped and dont blame them on what excatly they are running looks like you are on to something Adam!;) Its just matching the air to air ratios and knowing what to gate and where to plumb it !
quote]
;)

:D

So kind of been kicking things around and picking Malibu's brain (thanks by the way) and more stuff popped into my head.

Since w/ a twin kit you don't really have the lag and you have the smaller turbo driving the larger.... could you not get away w/ running journal bearings for the bottom turbo to cut costs w/o any drop in performace. I wouldn't think there would be a discernable difference to the driver.

oem is a journal


yes a journal will be cheaper than the ball bearing counter part

Think you beat me b4 I got to edit some info

i did;)

Somehow I just knew someone would. I even hit refresh right b4 I posted to make sure no one had posted...lol.

But on the bottom turbo.... would there really not be a notable difference between a journal bearing and a BB turbo... assuming you had identical turbos other than that.

You can't effectively use a Ball bearing bottom turbo without a ball bearing top turbo (I believe)

Ballbearing CRA's actually need a restrictor to DECREASE oilflow as the bearings do not require the same amount of lubrication to act as a hydro cushion.

If you went BB on the bottom, you would need to go BB on top as well.

That will get spendy.

i wnat duall bb turbos :D

Feed the journal bearing from the factory oil port. Feed the roller bearing from the side like a BD.

But it really would matter little. The roller bearing uses very little oil.

Perhaps the biggest reason to use two roller bearing chargers would be just that. To use less oil, hence heating up the oil less, and helping to maintain oil pressure.

hey tige i have beeen leaning realy strongly towards a gt4094 and dual cp3 with mild tuening to hopefully keep the rods from going out the side of the motor. but if i can i will put the rods in as well just dont want to pull the motor at this point but will see. i want twins but dont want the complication tht comes with it.

You can't effectively use a Ball bearing bottom turbo without a ball bearing top turbo (I believe)

Ballbearing CRA's actually need a restrictor to DECREASE oilflow as the bearings do not require the same amount of lubrication to act as a hydro cushion.

If you went BB on the bottom, you would need to go BB on top as well.

That will get spendy.

Aren't the garret's internally restricted?

Aren't the garret's internally restricted?

I was under the impression that they are not. If that is wrong information, feel free to correct me on it:)

hey tige i have beeen leaning realy strongly towards a gt4094 and dual cp3 with mild tuening to hopefully keep the rods from going out the side of the motor. but if i can i will put the rods in as well just dont want to pull the motor at this point but will see. i want twins but dont want the complication tht comes with it.

Hold on, you are going to run Dual CP3 and NOT WORRY about the rods?
Knock Knock..... is anyone there?

why not run a single CP3.... we know Rods start bending at 500+, and you can do 640 on an lb7 CP3, 670 on an LBZ CP3.

So why?

I had heard this from a distributor a while back, So I tried searching a few mins ago and pulled this.

"Well I spent the weekend at JGTC, and had a chance to talk to severalGarrett Reps about their GT turbos, and specifically restrictors. Here is what Brian Reigner of Garrett, and two other reps at the booth said, (it is noteworthy that I had a friend ask a different rep the same question seperately, and got the same response)
1- are the GT turbos internally restricted? answer; YES
2- Do DBB GTR turbos require an oil restrictor? answer; if the oil pressure at the inlet is over 40psi, then YES.
3- how do you recomend restricting the pressure? answer; You can use the .035 restrictor from ATP or make your own, so long as pressure at idle does not fall below 15psi at the inlet.
4- what is the recomended range in psi for the GT turbos while boosting? answer; 30-40 psi, NO MORE, or you will get oil blowing by the piston ring (for lack of a better term) seal, and YOU WILL LIKELY HAVE PREMATURE FAILURE OF THE CHRA.
5- So, if users have oil blow by, could that be considered normal, or is that ALWAY indicative of a problem? answer; IT is a problem, and must be addressed for max life of the CHRA.
6- If a CHRA fails, do you have to replace the entire cartridge? answer; Yes, but Garrett is working on an exchange/rebuild program for the BB turbos, that should be available in the near future."

Now the question is.... what type of pressure is getting to the inlet on our trucks? I know my truck cruises around with an oil pressure of 30psi ....but that's the stock guage and we all know how accurate those are ;) But like I asked above.... how does that correlate to the pressure that would be seen at the turbo inlet.

I just found this on the Garrett site.

"Garrett ball bearing turbochargers require less oil than journal bearing turbos. Therefore an oil inlet restrictor is recommended if you have oil pressure over about 60 psig. "

I've never once seen anything above 60psi even under full throttle. But once again, this is on a stock guage.

I wonder what size of restrictor that would make us use then. I also wonder what kind of real world pressures we would really see at the inlet.

I just found this on the Garrett site.

"Garrett ball bearing turbochargers require less oil than journal bearing turbos. Therefore an oil inlet restrictor is recommended if you have oil pressure over about 60 psig. "

I've never once seen anything above 60psi even under full throttle. But once again, this is on a stock guage.

I wonder what size of restrictor that would make us use then. I also wonder what kind of real world pressures we would really see at the inlet.

Exacto. I would ASSume, that some type of restrictor is needed. Garrett themselves would be the best to ask in that situation, and tell them where you plan on sourcing your oil incoming to the turbo.

on my GT 4094 there is a restrictor on the top oil inlet ! I dont know if Garrett or PPE supplies that part . The kits comes from PPE.

I think my PPE kit had the restrictor like C.A.P's kit,before with the stock turbo oil pressure was low now with the Gt40 I get around 60psi.

I think my PPE kit had the restrictor like C.A.P's kit,before with the stock turbo oil pressure was low now with the Gt40 I get around 60psi.

I would venture to say that PPE is supplying one with their kit. Although I do know there is one built into the GT40. It, however, can only handle so much.

Pat,

What's your take on Twins and a single CP3 with lift pump now that IdahoRob won his class at Famoso? Just curious since you stated in this thread that you'd have to "see it to believe it". How did Dan and the PPE truck do this weekend and do you still question Rob's 650 hp number?

BoiseRob