Twins vs. Large Single and reliablilty?

[Alligator]

Why is it that you can use a GT42 in a twin setup on a stock bottom end motor with good success (like Rob on his two stock Dmax's) but you can't use a GT42 as a single on the same motor?

Is it because you don't need huge tuning to be streetable with twins and you do with a single charger?

I am sure there are success stories of guys running a single GT42 on a stock bottom end motor so lets hear the details of those too. What tuning, injector size, etc...

 

[RENODMAX]

The MPI kits mostly use 42s. Your operating RPM is going to be alot higher for a single charger most of the time. Twins are a beautiful thing, especially if you have a VNT charger.

 

[LarryJewell]

moved here

 

[05_LLY]

MY guess would be that your boost psi regulated buy the wastegate and vane pos on the twin kit? Drive pressure and EGTS are much much lower in a twin setup aswell!

 

[ChevyDieselLLY]

im sure you would be able to run a gt42 on a stock bottom is just i wouldnt think it would last very long, from everyone ive been talking to you need to turn some pretty nice RPMs for it where as a twin setup you still have a smaller turbo so you can drive it on the street with out any problems with lower RPMs so it makes the stock bottom end last longer. im sure it also has alot to do with the timing and PW and all that other good stuff. maybe if you had large injectors a stock bottom end it might last a little long then it would with stock injectors when running a gt42. just my .02

 

[dmaxlover]

MY guess would be that your boost psi regulated buy the wastegate and vane pos on the twin kit? Drive pressure and EGTS are much much lower in a twin setup aswell!

Why would drive pressure be much lower with twins? Isn't drive pressure created by restrictions in the exhaust, i.e. the turbo?? If this is the case, a twin setup would have more drive pressure.

 

[jrad12381]

Why would drive pressure be much lower with twins? Isn't drive pressure created by restrictions in the exhaust, i.e. the turbo?? If this is the case, a twin setup would have more drive pressure.

With twins and the right tuning drive pressure is nearly 1:1. Twins definitely will run lower EGT's, and you can get away with less fule dow low since you dont need it to light the big charger.

 

[jrad12381]

Chad I dont know if your considering a twin setup, but I would definitely recomend it, I promise you wont be let down.

 

[RENODMAX]

I think for a street driven truck twins are king of the hill for speed. Just look at the evidence, Submans old truck went 12.0s how many LB7s with singles and stock motor do you know going that fast? Rob is a freak of nature but still hes going 11.70s. Plenty of LBZs and LLYs hovering right around the 12.0 mark with twins. I think they are alot easier to tune for and you can take alot of stress off the motor for a DD truck.

 

[ChevyDieselLLY]

i think twins are great, but they make it so you cant really pull any more. and id still like to be able to pull and race.

 

[never satisfied]

With twins and the right tuning drive pressure is nearly 1:1. Twins definitely will run lower EGT's, and you can get away with less fule dow low since you dont need it to light the big charger.

Nearly 1:1... my single is 50psi bosst and 60 psi DP. That is nearly 1:1, how close are your twins?

 

[SIKDMAX]

How long can you really expect a bottom end to last with a set of MPI twins? Its really all in the tuning huh?

 

[RENODMAX]

How long can you really expect a bottom end to last with a set of MPI twins? Its really all in the tuning huh?

Matt your still alive! It is all tuning. Heat be killer of pistons

 

[McRat]

Folks have bent their rods with twins, just like singles, and just about the same HP.

 

[IdahoRob]

My old twinned LLY is still running very well last I heard(few months ago). The truck now is used to tow heavy equipment and heavy street playing. That truck had upwards of 500 1/4 mile passes, before I sold it. Been twinned for over 3 years.

Any truck needs smart tuning when running big power.

 

[Micheal Tomac]

there are several guys that have gone 12.5 or faster on a stock turbo and 11.5 or faster on a streetable single turbo

 

[jrad12381]

there are several guys that have gone 12.5 or faster on a stock turbo and 11.5 or faster on a streetable single turbo

Yes and probably on drugs or dual fuelers, or a modded cp3. Rob although a freak ran 11.7's on a single stock cp3, qnde stock injectors. Plus streetable vs. better daily driver than compared to stock is a big difference. I know you have a ton of diesel experience but you cant deny the fact that twins are going to give you much better driveability.

As for my DP I am not sure. Rob tuned my truck, and did DP testing on Nathans truck for the LMM twins, so he can anwser this better than me.

 

[05_LLY]

How long can you really expect a bottom end to last with a set of MPI twins? Its really all in the tuning huh?

WE will see, Ive lived for 2 years with dual pumps and a larger turbo, but im not gready with my tuning!

Now we can see if a allready abused engine can live with twins and dual pumps?

I still feel egts are the biggest killer of engines most dual fueler/big turbo trucks live short lives, I dont sled pull which gives you long high heat cycles, and when i drag race the heat cycle on my engine breaks three times giving things a split second to cool! Just my thoughts!

 

[jrad12381]

WE will see, Ive lived for 2 years with dual pumps and a larger turbo, but im not gready with my tuning!

Now we can see if a allready abused engine can live with twins and dual pumps?

I still feel egts are the biggest killer of engines most dual fueler/big turbo trucks live short lives, I dont sled pull which gives you long high heat cycles, and when i drag race the heat cycle on my engine breaks three times giving things a split second to cool! Just my thoughts!

How high are your EGT's at the end of the track?

 

[jrad12381]

WE will see, Ive lived for 2 years with dual pumps and a larger turbo, but im not gready with my tuning!

Now we can see if a allready abused engine can live with twins and dual pumps?

I still feel egts are the biggest killer of engines most dual fueler/big turbo trucks live short lives, I dont sled pull which gives you long high heat cycles, and when i drag race the heat cycle on my engine breaks three times giving things a split second to cool! Just my thoughts!

What turbo setup are you going with on your twins? Are you keeping the 4094, and going with oh say a gt45. Be nice with your tuning because if you use those dual cp3's because you can be pushing 800rwhp plus .