Ok guys this is very crude at this point, but courious on what you guys think? Still haven't landed on primary brace exactly. Would you guys want to leave the heat exchanger in the stock position or move it? The air tube is still a work in progress, this is off another project I had laying in the garage.

By the way the turbos are Garrett GT3782Rstage3 over a S475/1.32 T-6.

 

Why so little Mike,, LOL

 

Ya I know, I know. Maybe sooner than later, still working on locating a decent primary. We have been trying out several different configurations to use. This is a wicked street/strip twins set-up. I've ran it before.

 

I get the flu, and you almost have it built.

 

Looks like it will be a fun setup!

I just ordered a GT3782R Stage 2 this morning.

Is yours a GT3782R Stage 2 or GT3788R Stage 3?

 

Nan don't worry, still working stuff. Lots of stuff to do still.

 

I don't know, the book says GT3788R the box says GT3782R. It doesn't matter, I'm only going to use map upto Pratio of 3:1, the S475 will helpout. This set-up is good for 600-700rwhp trucks, just lsightly slowly intial spool than stock, but boost build-up pretty quick. It makes a diesel perform the way its suppose to. Garrett stuff is top notch. I want to try one of those new EFR borg warner turbos one day.

 

Should be easy to tell, measure your comp wheel. OD of 88 and its a Stage 3 3788, OD of 82 Stage 2 3782.

Either way, it should be a sweet setup!

 

Its a stage 3, it has 7 blades impeller, stage 2 has 6 six. The OD dimension isn't that important to me. The turbine has the 0.99 housing and the larger turbine disk. The inducer size is 63.5mm

 

Gotcha. All stage 3's are the GT3788R with a 63.5x88mm comp wheel. All 3 stages have the same turbine wheel 72.5x64, and as you noted the Stage 3 has the .99 ar vs the .89 on Stage 1/2.

That's going to be a very nice set of twins. I bought the Stage 2 hoping to someday put a big brother under it.

 

I thought the same thing, this is a brand new garrett turbo stage 3, with GT3782R on the box. I measured it up prior to buying. Garrett keeps changing things, suppose to help with turbo stall, which isn't as big of deal in twins. If anything the smaller compressor impeller will help spool-up by reducing rotating mass/interia.

This set-up is going onto a 12V truck with a few tweaks for extra fueling.

 

In researching the powermax's for the last few months I finally figured out what they are doing. All 3 of them use the GT3788R center section and turbine wheel, as there isn't a GT3782"R" available, the GT3782 is a journal bearing.

I beleive the Stage 1 has a typo in the brochure, and really has a 52 trim comp wheel and its 59.1x82.

The Stage 2 uses a GT3582R comp wheel and is 61.4x82.

The Stage 3 uses a GT3788R comp wheel/turbine and is 63.5x88.

Both the .89 and .99 housings are unique to the Cummins application.

The Stage 3 is the one that has the most reported issues of compressor surge, probably becuase its a 64/64/.99. Tom at Turbo Resource sells the Stage 3 with a .89 housing and it's supposed to work much better.

 

stage two is 59.5mm and 0.89, I have one on my truck. Garrett changes stuff, so their is nothing set in stone. The GT37 powerstroke stuff, spins in the opposite direction and is a totally different turbo. I wanted the larger turbine housing for this set-up. This truck will tow and there is no external gate on this build. The 0.99 has a larger internal wastegate flapper, also the S475 will lite harder with the larger GT-37 turbine housing. This is a budget friendly build-up.

 

Based on the current data the 59.1 is the stage 1, and the Stage 2 is 61.4. If you look at the brochure it says its an 82mm OD wheel with a 56 trim for Stage 2, that calculates to a 61.4 inducer.

I'll have the Stage 2 in my hands in a few days, so i'll post up if its different than what I was told.

 

Measure the compressor wheel not the housing. We have had this discussion a few times. Guys thinking that they have the 61.5 inducer and really have a 59.5

I had one of the original ones, it was a true 61.5mm compressor size. I feel that the stage 2 guys get ripped off. The stage 2 turbo works awesome, and I have run it for years now. It barks pretty good, when worked. The stage 3 is a way better single, you'll feel the difference between the two different turbos.

Garrett gets pretty upset if one of their reps mess with the stock configuration. Garrett and borg warner are going to factory only built turbos, trying to remove the issue of getting non garrett parts on a garret turbo. Ran into this rebuilding a duramax turbo with a larger compressor wheel (powerstroke impeller).