I know this is a tried & tested upgraded path, so I was wondering which Stage 3 hybrids (i.e. CCs & nozzle size e.g. 238/80, 238/100, 250/100) are best suited to the Garrett GTP38R turbo?

At some point in the future, after I have beefed up my trans, I plan to get the Garrett GTP 38R (probably with 1.0 A/R housing to retain reasonable spool up time while also reducing EGTs some). I am not sure yet whether I want to do a valvetrain upgrade (Comp Cams 910 valve springs & heavy duty pushrods), though I obviously would, if not doing so is inadvisable. I may try & stick with my stock HPOP if it can supply enough pressure, but since my Excursion has ~ 150k on it already, I would consider upgrading to a Stealth SRP 1.1 HPOP. Also, at what boost pressure / power levels are head studs advisable?

Ideally, I'd like to make 500 whp & 1000 wtq, though that is more because those numbers are nice & round rather than a specific need to make those numbers exactly. My main use is as a daily driver, and it would be nice to get somewhere in a hurry when desired (i.e. something akin to a street rod setup), though I would like the ability to bumper pull up to 10k lbs, even though my occasional use load is actually closer to ~ 6k lbs (race car on open trailer). Fuel mpg is a consideration, though not an overriding factor, as the 8" lift, 37" offroad tires, 4.56 gears & roof rack already put a damper on that, and will never yield great mpg.

I obviously understand I would need special tunes to handle the upgraded single shot injectors, and would likely go with either a DP Tuner F6 (I like the ability to be emailed tunes to download & try out, and for tweaks to current tuning) or one of the TS 6-position chips from one of the respected vendors e.g. Tony Wildman, Matt @ Gearhead, Bill @ PHP, Jonathan @ Beans etc. I do have boost, EGT & trans gauges already installed & hooked up.

Edit: I forgot to mention that my Excursion is a 2000, so I assume though have not verified for sure that it has forged rods, rather than PMRs (I think pretty much all MY 2000s had forged rods, no?). Also, I already have a DDIY 6637 intake, and a 5" exhaust (I assume from downpipe back, since 4" is the max diameter for the downpipe next to the firewall?).

Anyway, I am wondering which Stage 3 hybrids (i.e. CCs & nozzle size e.g. 238/80, 238/100, 250/100) are ideally suited to the Garrett GTP38R turbo? I am tempted to just get the 250/100 Stage 3 hybrids, so I have some room to grow in the future if required, since it seems most tunes can be programed to simply inject less diesel if necessary. However, given that I am probably not going to upgrade the turbo to anything more elaborate than the Garrett GTP38R turbo, there doesn't seem to be a lot of point of upgrading beyond, say, 238/80s if it is the case that the 238/80s are already able to supply more fuel than needed at reasonable injector duty cycles, when maxing out the GTP38R. If it makes any difference, the injectors I would get would probably be reman'd Full Force Diesel / Casserlys.

So, which Stage 3 hybrids do people suggest for my intended setup & use?

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P.S. Any feedback on the 1.0 A/R housing vs. the larger 1.15 housing for Garrett GTP38R turbo? I am currently thinking that the 1.0 A/R housing is most likely the right choice for me, as it would retain quicker spool up for driving around town, and it's cheaper. But if e.g. the difference in spool up is marginal, and the 1.15 A/R housing significantly reduces EGTs or surging, I could be convinced to go with the 1.15 A/R housing. Any thoughts or feedback from those who have run either the 1.0 or 1.15 A/R housings or if there is even anyone that has tried both & can provide a comparison?

 

Anyone have any input or feedback on this?

 

I'm running 250/200's with a 38R.

The turbo doesn't care what size injector or nozzle you run.

What will happen is that with a larger nozzle, you get more fuel per time. This can, when tweaked correctly, reduce your EGT's by quite a significant margin over smaller nozzles. This makes your 500 hp goal easier to obtain without the engine wanting to go into thermonuclear meltdown quite as fast.

My opinion is that you should go with a larger injector than your ultimate power goal. Don't settle for an injector that will "just" get you there.

Granted..... larger nozzles are a bit harder to tune, especially at lower RPM's and idle. I just had a thread over at PSA about idle quality with larger nozzles. The support I got in return really helped me tweak my tuning significantly over the past few days. My truck now idles almost like a stock OBS truck.

But anything above idle and my truck is an unstoppable machine. It tows like nothing else I've ever had or driven before.

As for the 1.0 vs. 1.15 turbine housing.... I am still running the 1.0. I have heard there isn't really much of a difference on the bottom end when switching to a 1.15. So I guess take your pick. Some folks who have switched to the 1.15 seem to recommend that more. Plus with your power goal, it makes sense. That turbo is going to struggle at 500 hp anyway.

 

I dont think that turbo will be happy with that kind of power levels. You need to step it up. YOu have to do the valve train upgrades you have listed! If you want to be worried all the time if your going to blow a head gasket dont put the studs in, if you dont want to do it! You will have to confirm your HPOP pressure to be sure its ok, Clay told me a T500 will support 250/200, single shots, but twins are much better. I asked about single shots and mpg a long time ago and most guys said they got some mpg from them, not much but they did. Its a toss up if you have PMRs or forged.
If you want room to "grow" go with a set of 250/200 and a modded H2e, theres a few others but the H2e can "grow" with you.
1.0 or 1.15? I had the stock turbo and it spooled good, I have a van turbo and it spools the same. Theres more to it than just how it spools though you need to find someone who is more knowledgable on that topic though, Im not the guy for that one.

 

As far as the 1.0 vs 1.15 I know Bill at PHP just put a bunch of info up on the Army with dyno results and data on the difference between the two. He concluded that with 250/200's the benefit for the EGT's was not worth the loss in HP. Just some food for thought.

 

I tend to agree. My -38R has lived a long and happy life (9 years and roughly 200,000 miles) down around 400hp, but I don't think that would have been the case putting 100 additional HP to it for all that time.

That being said, if I were to do it right now based on the criteria of the OP I'd do the 250/100 and use the 1.15 housing and tune accordingly. I've never been all that content with the 1.0 housing.

 

With 238cc's hybrids. Do most people do 80, 100, or 200% nozzles?

Matt @ GH likes the Unlimited 80%. I was pretty set on getting FF/Cass with the 100% nozzle as they don't offer the 80%.

 

I would go no smaller then a 100% nozzle...

 

Thanks Joe!