I didn't compare it to my build. I actually run race gas for anything over 14 psi (about 500whp), btw. I didn't suggest that he run race gas all the time, and you know that isn't what I said. You are trying to twist things around. My very valid point is that he hasn't even tried doing a race gas tune to see what it does. He sounds like he wants a certain dyno number....great, throw race gas in, get your number, print your chart, done. He doesn't seem the least bit concerned about how the car is actually performing. If he were, he'd be worried about low trap speeds, etc (which is what I was upset about and it led to finding some issues on my car).

Just FYI, Q16 is the most expensive gas you could use for this and it doesn't even run $300/tank. Its about $225. He could go get 110 octane or even 100 octane (about 1/2 as much as Q16) to see if it improves his AIT, WHP, and efficiency of the turbos.

 

^^^+1...and If he runs meth...he could 1st start with 100% distiled water 4 starters too

 

i say solid rocket boosters. I'm a genius, problem solved!

 

 

^^ BUMP for answers to this post... ^^

 

Can somebody provide this info to the thread?

 

C'mon OP. I asked first.

 

dont expect much more. its just not that much bigger of a turbo... same compressor with a lil bigger turbine. PL would need to tell you what exactly they mean by 37r..

For less money you could just get a new turbine housing for your GT35. get like a .8 or 1.06 A/R

 

That's incorrect. Per the Garrett website, the compressor and turbine are both larger.

 

There are multiple versions of the GT37R posted on the Garret website, namely the GT3776, the GT3782 and the GT3788R. The GT3788R has the largest compressor, and will be the best suited for a single turbo application on a 3.5L motor.

Here is a the compressor map:



The efficiency of every motor will be different depending on the modifications, etc. Nonetheless, the GT3788R should be good for about 550-600 whp in a single turbo setup on a 3.5L motor on pump gas on something like a Mustang dyno. Probably higher on a DJ, and lower on a DD.

If the efficiency were the same as my first build, it would around 600 whp at 15.3 psi of boost and 64 lb/min at the choke line. It would probably need a bigger intercooler (and maybe a bar and plate IC) than I was running, which was a Greddy, because I don't think I was anywhere near the choke line and my IAT was probably lower. With the Greddy Intercooler, I'm thinking it would be down closer to 550 whp.

 

so are they using a true 3788r? Thats never been advertised. It was said before that it was a bastardized gt3582 with a bigger turbine

 

It appears to me that the first two numbers in the turbo part number relate to the turbine size and the second two numbers relate to the compressor size.

I don't think the issue with the GT3582R turbo is the turbine, it's more likely the compressor. I think a larger compressor, say something like a GT3588R, would perform better than the GT3582 in a single turbo setup on a 3.5L motor.

I already stated this, but it bears worth repeating. To me, based on the compressor maps, it appears that the GT35 turbos are designed for a small displacement motor, like something in the 1.5L-2.5L range. Of course, in a twin turbo setup that is what you end up with on a 3.5L motor (each turbo is effectively handling 1/2 the displacement). More displacement requires a larger compressor.

Also, I keep suggesting that a higher trim value be used, but this is based on what I see in the compressor maps. Maybe I am taking too much liberty there because I really don't know if they will run into other issues by increasing the trim. Maybe they will, maybe they won't. I guess that is a good question for a Garrett engineer. If there are no issues, a higher trim value is definitely beneficial for larger displacement motors.

 

I would think he would want to hit the number every time he went WOT, not dyno-queen, hit-it-and-quit-it number...at least that is what I would want. I guess people do carry around dyno printouts to meets though...

 

Forgot he actually emailed it to me years ago

I believe he made ~520whp on Sharif's dyno as well.

 

The GT3776 and GT3782 turbos listed on the Garrett website are journal bearing turbos and thus don't have the "R" designation.

 

You are correct. Brain fart on my part. I'll edit my post.

 

One thing I failed to consider.... back pressure. With a larger turbine, the GT37R will have less back pressure, which will help peak torque/hp in the higher rpm range. So, I would think that a GT3788R will perform better than the GT3588R in the higher rpm range, though will have slower spoolup (assuming the same A/R). A larger A/R on the turbine will help alleviate some of the backpressure on the GT35R. Maybe some of the issue is back pressure, as Rich eluded to.

 

Wow, this thread has gone places that that I never expected it to go. My issue with the Gt35r Powerlab kit is the fact that I was unable to achieve the same numbers that in conversation with Performance Factory, Intense/Powerlab, and Injected Performance felt it would. Knowing what I do now, I would have look into another kit (such as an Greddy twin kit) , different turbo at time of purchase from Powerlab or different set up with my build . The technical info that has been posted on the thread has furthered my FI knowledge at this point but at time of purchase I relied heavily on the info provide by Intense/Powerlab on their website, threads and personal conversations to steer me in the direction of my final decision on purchasing this kit. At this point, I just want to get to my goal and am looking for solid data versus info based on race gas, dynos from different turbos, claims of somebody's buddy who achieved these numbers with this kit but have not come forward on this thread, etc, etc. Thank you to all the members of the forum who have sincerely tried to add information to this thread to come up with a final solution to help get me to the goal that I have set. At this point, I am looking for the most cost effective way to pull an extra safe ~40-50 whp out of this setup without going to any extremes like swapping to twins.

 

I find the Garrett compressor maps to be an invaluable resource for turbo selection. Those are solid data. On round 2 of my build, that is where I started. Also, I developed a spreadsheet with the computations that I need, somewhat similar to what is available on the Squirrel website. If you want a copy, PM me your e-mail address and I'll send it to you. That is where I calculate pressure, air flow, fuel flow, etc. The formulas to calculate some of this are published on the Garrett website under their "Turbo Tech" section. Those are not the formulas that I used, but the end results should be fairly close. Indeed, the one time I stepped through Garrett's formulas, I ended up with the exact same turbo selection that I did using mine.

 

Here is one option that I have considered, I have spoke with a person with an GT3782R who is willing to swap turbos because the 37 is too laggy on his car(not a 350z).