Greddy 20G vs. APS Extreme TT kits
#46
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Just talked to Nick and Sam again. I kind of caught in between these two options:
STG 2 kit (Garrett 2871R) with .86 AR and .800 BAR (11.6 PSI) wastegate springs, rated to 800hp
or
STG 3 kit (Garrett 3071R) with .64 AR and .800 BAR (11.6 PSI) wastegate springs, rated to 900hp
My dilemma is that I still want to maintain good mid-range power so daily driving is fun. Some say the GT30 turbos will have more lag and not really hit their efficiency zone until higher up on the tachometer. Yes, they'll crank out more power but they argue that I will lose some low-mid-range fun that I would get with the the GT28's. But of course, the GT28's will absolutely MAX OUT at 800whp so no room to grow.
Anyone have any experience with the GT28's vs the GT30's in this regard? I think I've got my choice now down to one of these two kits. Just looking for some of your experiences and/or advice, guys.
I guess the beauty of the GTM kit is that upgrading is really just about as easy as just dropping in a new set of turbos. Sam said they're currently working on developing a "trade-in" plan for past customers who've outgrown their originally purchased turbos and just want to pay the difference in cost to get their new ones!
Thanks!
B
STG 2 kit (Garrett 2871R) with .86 AR and .800 BAR (11.6 PSI) wastegate springs, rated to 800hp
or
STG 3 kit (Garrett 3071R) with .64 AR and .800 BAR (11.6 PSI) wastegate springs, rated to 900hp
My dilemma is that I still want to maintain good mid-range power so daily driving is fun. Some say the GT30 turbos will have more lag and not really hit their efficiency zone until higher up on the tachometer. Yes, they'll crank out more power but they argue that I will lose some low-mid-range fun that I would get with the the GT28's. But of course, the GT28's will absolutely MAX OUT at 800whp so no room to grow.
Anyone have any experience with the GT28's vs the GT30's in this regard? I think I've got my choice now down to one of these two kits. Just looking for some of your experiences and/or advice, guys.
I guess the beauty of the GTM kit is that upgrading is really just about as easy as just dropping in a new set of turbos. Sam said they're currently working on developing a "trade-in" plan for past customers who've outgrown their originally purchased turbos and just want to pay the difference in cost to get their new ones!
Thanks!
B
#47
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
for your goals i think the $600 price difference will be better spent on dual pumps, turbo blankets, injectors, or towards a haltech, etc
#49
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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?
#50
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?
#51
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.
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.
#52
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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...
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...
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.
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.
#54
#55
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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?
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?
#56
^ 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
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
Last edited by str8dum1; 06-10-2009 at 10:24 AM.
#57
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?
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?
#58
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!
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!
Last edited by rcdash; 06-10-2009 at 12:23 PM.
#59
Hey Sharif,
If I go with the APS Extreme TT kit (keeping their 880cc injectors and dual fuel rail/dual in-tank pump setup) and using the GT30's along with a Haltech, could I have 450-550whp daily "fun" driver and still get to 800whp with a quick tune or boost dial-up? I guess I'd like to have the 800whp there on tap but still be able to cruise around town without getting spinning wheels all day long!
Thanks,
B
If I go with the APS Extreme TT kit (keeping their 880cc injectors and dual fuel rail/dual in-tank pump setup) and using the GT30's along with a Haltech, could I have 450-550whp daily "fun" driver and still get to 800whp with a quick tune or boost dial-up? I guess I'd like to have the 800whp there on tap but still be able to cruise around town without getting spinning wheels all day long!
Thanks,
B
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.
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