GT35R Secondary - 12v Compounds

Thekid760

Thekid760

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Im slowly (way to slow) gathering parts for my compound build on my 12v.

Im shooting for around 600-650hp, however spool-up and torque curve or more important.

Engine has a Colt Stage 4 cam, 7x.011" Injectors (want to try 5x.014 or .016 as well) weston 7mm DV, pump will be benched by seth, mild ported head.

I currently have a Steed T4 with ext WG, a Super B & a GTA4202 Turbo.


I know the super B and gta4202 would be a fast spooling setup, but cant help but wonder if a GT35R with divided 1.06 T4 wouldnt spool faster. I hear they spool crazy fast but not many cummins people seem to be using them. Shouldnt the ext WG be able to keep DP in check?
 
Im gonna say not a lot of people don't use them because the turbine is too small. Its very close to the same size as a he351 which can bought much cheaper. Personally I think a better choice would be a stage 1 power max, s360, or even an he351
 
Yes nearly same size however the gt35r should spool up much sooner being BB. Also the GTX wheel has great efficiency in higher PR which should be great for a secondary.

I know the holsets and s300's are cheaper but with that aside. Shouldn't the gt35r work better if ext gated?

Gt35r:

Compressor: 61.5mm x 83mm 76 lb/min
Turbine: 68mm x 62mm
T3 or T4 housings available.


Misspelling courtesy of my fat fingers...
 
The 1.06 housing you reference is a lot bigger than what comes on an he351. They make smaller ones but to my knowledge are only available in t3.
 
Thekid760 said:
Yes nearly same size however the gt35r should spool up much sooner being BB. Also the GTX wheel has great efficiency in higher PR which should be great for a secondary.

I know the holsets and s300's are cheaper but with that aside. Shouldn't the gt35r work better if ext gated?

Gt35r:

Compressor: 61.5mm x 83mm 76 lb/min
Turbine: 68mm x 62mm
T3 or T4 housings available.


Misspelling courtesy of my fat fingers...
Click to expand...

You don't run a high PR with your secondary turbo unless you are trying to impress your friends with how much boost you make. A PR of 2.0 is as high as I like to go on towing twins, less if trying to make decent power.
 
Thanks for your input.


Am I wrong in assuming it will spool faster than a super B? And ext gate will be used of coarse.

ATP turbo has 3 T4 housings available for the GT35. a 0.63 & 0.82 Open and a 1.06 Divided. I'm thinking the divided would spool best without completely choking it out, although the 0.82 might be worth a try. Thoughts?

I know a few guys such as Tate run a GT35 as the secondary, however finding any information seems to be very hard.
 
Have done it on a couple of trucks, it works very well as a secondary. Spools as faster than an He351 and even though the turbine is close to the same size doesn't choke as early as the he351. Makes an excellent secondary.

Tate runs a gt37 currently as a secondary and is building a dd "tow" setup that will run a gtx3076R which is smaller yet, but it has some impressive numbers on paper.
 
Thank you, I appreciate the info.

It seems there are a few people running smaller Garrett's as a secondary but not much talk about them.

What size turbine housing would you recommend?

D2 was saying the 1.06 T4 spools well, but that's CR.

I was also reading a few posts saying that it would build 10psi with just 1/4 throttle off idle and another stating can build 10psi in neutral free revving.

I would ideally like a T4, but I think I found they make a divided .82 T3.

That's interesting about him running a gtx30. I was thinking that would be too small, but I guess if gated properly it would work fine. Where do you think that would choke out and limit max hp?


Please keep info and experiences coming. I'm hoping the becomes a good informative thread with experiences, not the typical "it's too expensive" or "same size as holset so run that" type of thread.




Misspelling courtesy of my fat fingers...
 
The gtx30 twin set will still easily make over 600hp, it will be on his 12v.

Both trucks we did had T3 manifolds already as such we stuck with the T3 housings. Iirc they were .83 divided.

One truck had an S478 as a primary one had a gt4202. Both were CR's and only around 600hp, so overkill on air either way.
 
Thank you.

I could only find a 1.06 divided as the smallest t4. So I might just run a adapter and the .82 divided T3.

I can't believe even with a gate the gtx30 isn't too small. But that's why I try and solicit opinion from people who have actually done it, not theorized about it.


Misspelling courtesy of my fat fingers...
 
I have a GTX 3582 for my own truck, an 06 dodge. If you gate around the back pressure, and keep the two sides divided until the gate, you will not have any back pressure issues, and it will spool like crazy. Your modest overall power goals will be fine with the 35 as a secondary, and if you feed it with a simple 475 or similar, neither turbo will be working hard at all. Everybody wants huge turbos, and then use half of what they can do. I believe, and have experienced, that it's all in the wastegate setup on setups like this. Is your Steed the newest style with the divider in the gate mount? If not, Leen will set you up with one, which will keep the front and back banks of cylinders separate, as the divided turbine housing requires, to be functional. If you mix the banks of exhaust flow, you loose the benefits of the divided housing. I vote yes, go for it!!

On edit, I would like that 4202 as a primary, assuming it's a 76 like a GT or GTX... nice pair....
 
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Thanks for the reply.

The manifold isn't fully divided up the gate, but I got one of the retro fit spacers in there so it'll be fine.

And yes the gta4202 is the same as the gt variants but was boreless compressor wheel. It also has a gated 1.15 ar turbine housing.

And metal miner sent me his Dyno graphs & At 1900 rpm was 25 HP / 75 TQ and at 2100 rpm was 70 HP / 175 TQ gains vs running a super B/gtx4202r. Only changes he made were the secondary and udc tuner from smarty.

I think the spool up differences alone will be worth it.


Misspelling courtesy of my fat fingers...
 
I've always towed with the idea of a 3582/4202 gated as a Dd/tow setup. That would spool really nice and clean

Be curious about how the 3076/4202 runs
 
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Exactly but conventional thoughs say the gtx30 is too small. However it says the same for gtx35 and says to stick with cheaper s300's...

I'd love to see how that setup runs.
 
Thekid760 said:
Exactly but conventional thoughs say the gtx30 is too small. However it says the same for gtx35 and says to stick with cheaper s300's...

I'd love to see how that setup runs.
Click to expand...
Now that I think about it...
LB7 IHI charger is a 60/82mm conp 68/61 turbine. First twins was GT4202 ran ~500-550 on stock fuel system with lift pump and barely hit 1100° doing.. That said its really not that far off what's been done already
 
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My GTX3076 has the 1.06 housing on it, which flows just as much as the GT35's mid range housings which work well for the power range. Due to work schedule, progress has come to a stand still on it, although I am wanting to try to rig it up as a single to see how it responds. On paper, it looks like a promising single. As a secondary in a 600hp truck, it should be just fine.
 
Could always toss a 74/65 wheel in the GT35R hotside and make a BB version of the GT3574, which is a nice spooling journal bearing setup, at least on our bigger engines. May not have to gate it at that point...
 
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