To be on the safe side bro jumping str8 to 1000hp prob not the best idea for a street driven car. Not knockin your goals or anything but that much horse power on the street is not really gonna be fun to drive.

 

looking at the dynos, try 5000 rpms. you need a gt28 for 3500-4000

for your goals i think the $600 price difference will be better spent on dual pumps, turbo blankets, injectors, or towards a haltech, etc

 

I don't think the GT30 is all that laggy on a VQ35. Even on the VQ37's which have significantly less trq, it's still not too bad.

 

This is exactly what Sam @ GTM said. But still others feel that the power doesn't really hit until later in the tach range (like 5K+, as str8dum1 mentioned), and thus this would not really be so fun to drive around town. Sharif, in your experience, does the boost on the GT30's kick in closer to 4000 or 5000 RPM? And since I'm considering the smaller A/R (.64) on the GT30, maybe that would let it kick in even earlier?

 

4000rpm, it's really getting fun, and at 4500rpm is at full bore. A GT35 twin would be more like 5000-5300rpm before the party starts.

 

well this is a 3071 with alot of headwork, nice cams, etc so probably i would figure, a normal car without either of those would shift the curve right.
You can see full boost isnt til 5000-5500 rpms and less than half boost at 4000 rpms

but without having driven in such a car, default to Sharif.

 

Yeah, I'm getting my heads redone at HeadGames (with a full new Ferrea performance valvetrain and port/polish), JWT S2 camshafts, completely built engine (Wiseco extreme duty pistons and Cosworth rods), 1000cc injectors with dual fuel pumps/rails, Haltech, etc. So I don't evision the HP line in that graph would be sliding to the right much if at all! I am probably going with an aftermarket differential gearset to stretch out my shifts too. Not sure how that factors into this but figured I'd mention it.

According to that graph, even at 4000rpm, it looks like we'd be at 300+hp and it just gets sicker from there. One nice thing about this setup is that if I want to just cruise around town and not boost out, I can just shift below 3500rpm and never really get into any serious power.

And maybe I'm reading the graph wrong, so please correct me if I'm off-base guys. The lower HP line depicts the OEM powerband, right? If I'm reading the graph correctly, it seems that the top line (3071-boosted), is about 100+ HP higher than the other line through the entire RPM range up until it just breaks away at 4500. So wouldn't that mean the car would still be significantly faster at those lower RPMs, despite the turbos not having really opened up yet? Or if that lower line is just another turbo run at lower PSI, then I'm way off...

 

Loower line is manifold pressure, the units are on the right

 

you can shift at 5000 and not be on any boost as well. longer gears wont change the boost curve

gt28 are full on at 4200rpms @14psi as seen by the peak trq at of 500 ft-lbs at 4200 rpms and they probably still have another 5-7 psi in them still.

 

Nice... I don't think those 2871's go high enough for the power I'm seeking. Unless that dyno was on a car that has few supporting mods. I really want 650whp to be my "peak" for now.

Supposedly the GTM Stage 2 twin 2871's (.86 A/R) kick out 800whp (GTM website). But if they're gonna struggle to hit that then I should really look toward the 3071's, I suppose. If Sharif (Forged) and Sam (GTM) say there's not much lag then they will probably make me happy! Especially considering how much I'm dumping into this project to build it the "right way".

Also, will the 3.3 final drive pumpkin with diff gears (vs. OEM) affect my power band at all?

 

^ ya i would go with what they are saying.

the gt28s will make 650 (same as the JWT 700 kit almost). those are bigger than the greddy's i think and they have made 700+ (see Alberto)
http://my350z.com/forum/shop-builds/...te-atlast.html

 

What you have to understand also is that the power rating that are posted on the site are not WHP

 

A dyno graph is not a good indication for determining lag. An operator can start a run anywhere in the rpm band and boost takes time to build from there. Flooring it from idle is just not done on the dyno. I don't know exactly why not (perhaps that is considered abuse ?), but the local dyno operator here in NC makes me hold rpms steady above 3000 rpms before letting me floor it (I'm in the car and he's got the control box).

I have to admit, I'm thinking about GT30s when it comes time to rebuild the turbos... The other thing you guys should keep in mind is that the chp ratings of the turbos is the absolute limit on race fuel without heat soak, etc. I'd say take whatever the rated value is and multiply by 0.7 for a conservative whp estimate on pump gas, which is what you'll be running most of the time. I think a pair of GT2871s will get you into the mid 500s on pump gas. The GT30s will get you into the mid 600s!

 

Based on what you've posted thus far, what I would do is prep the GTM kit for a stage 5, but go with the stage 3 for now as Sharif recommended. Sharif will be putting in a stage 5 kit shortly into XKR's car. Have him mock up your kit to hold the GT35s so if you decide to upgrade in the future, all the clearancing has been done and you can just swap out turbos.

Nothing like doing two similar installs at the same time. I don't think anyone other than Forged and GTM will have had experience with the stage 5 kit.

 

This is a great idea, thanks! I'll call up Sharif today to see what else he "recommends" to prepare for the GTM S5 kit (minus the turbos). I'd like to have all the internals done so we can just do a "simple" turbo swap to take me to the next level...