20g potential
10-14-2009, 08:07 PM
#67
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The good ol' 18g's should be able to carry you to a bit over 600whp on 93 octane (without spray) and tend to run out of their efficientcy range around 20-22psi. I once saw a Z33 lay down close to 800 with 20g's, but it was also sleeved to around 4.0.
10-14-2009, 08:34 PM
#69
Assuming the rest of the build is up to snuff, my calculations show that a 3.5L motor 20-22 psi should get someone to around 675-700 whp on a DD dyno, and around 750-775 whp on a DJ. These calculations are based on a 105 deg. F intake air temperature. The I/C makes a big difference when pushing the limits of the turbos, and every little bit of temperature drop helps.
10-14-2009, 08:36 PM
#70
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Yea there was a guy named Tim Jander that made a bit over 600whp with the 18g's (although dynapacks tend to read a little high) and on pump gas no less. With a built engine at 8.5:1 compression.
http://turbohightechperformance.auto...ec-b-spec.html
edit: the math can only get you so close. any small changes in any of the variables will throw everything off. Especially when you have to estimate BSFC and VE.
And I know of at least 2 other cars that made >600whp with 18g's. With supporting mods of course, but that is just about all you will get out of those turbos before they become fire-breathers.
http://turbohightechperformance.auto...ec-b-spec.html
edit: the math can only get you so close. any small changes in any of the variables will throw everything off. Especially when you have to estimate BSFC and VE.
And I know of at least 2 other cars that made >600whp with 18g's. With supporting mods of course, but that is just about all you will get out of those turbos before they become fire-breathers.
Last edited by Brett@AwesomeZ; 10-14-2009 at 08:39 PM.
10-14-2009, 09:50 PM
#71
Yea there was a guy named Tim Jander that made a bit over 600whp with the 18g's (although dynapacks tend to read a little high) and on pump gas no less. With a built engine at 8.5:1 compression.
http://turbohightechperformance.auto...ec-b-spec.html
edit: the math can only get you so close. any small changes in any of the variables will throw everything off. Especially when you have to estimate BSFC and VE.
And I know of at least 2 other cars that made >600whp with 18g's. With supporting mods of course, but that is just about all you will get out of those turbos before they become fire-breathers.
http://turbohightechperformance.auto...ec-b-spec.html
edit: the math can only get you so close. any small changes in any of the variables will throw everything off. Especially when you have to estimate BSFC and VE.
And I know of at least 2 other cars that made >600whp with 18g's. With supporting mods of course, but that is just about all you will get out of those turbos before they become fire-breathers.
I made 609 whp (603 weather corrected) on Japtrix's Mustang dyno on 93 octane. We were at 17.5 psi. Alberto made something like 665 whp on 93 octane on a DynoJet. I think he was at 17 psi.
EDIT: Instead of using BSFC, I have the spreadsheet setup to use energy conversion efficiency as a %. It's easier to deal with since I have the calculations setup to work with meth/water injection, E85, etc. If you want a copy, PM me your e-mail address and I'll send it.
Last edited by ttg35fort; 10-14-2009 at 10:07 PM.
10-15-2009, 05:25 AM
#72
Ya I hear Mark Gust is a fairly reliable source of info on these boards. and that the SGP builds were done quite nicely. 
Yea there was a guy named Tim Jander that made a bit over 600whp with the 18g's (although dynapacks tend to read a little high) and on pump gas no less. With a built engine at 8.5:1 compression.
http://turbohightechperformance.auto...ec-b-spec.html
edit: the math can only get you so close. any small changes in any of the variables will throw everything off. Especially when you have to estimate BSFC and VE.
And I know of at least 2 other cars that made >600whp with 18g's. With supporting mods of course, but that is just about all you will get out of those turbos before they become fire-breathers.
http://turbohightechperformance.auto...ec-b-spec.html
edit: the math can only get you so close. any small changes in any of the variables will throw everything off. Especially when you have to estimate BSFC and VE.
And I know of at least 2 other cars that made >600whp with 18g's. With supporting mods of course, but that is just about all you will get out of those turbos before they become fire-breathers.
10-15-2009, 06:52 AM
#76
I agree that the Greddy kit is pricey, but I disagree with your statement about the power it is capable of producing.
Alberto hit 665 whp on 18g's at 17 psi, or there abouts. Compare the size of the 20G turbine and compressor to the 18G. If someone cannot get to 700 whp with a pair of the the 20G's (with high octane fuel and/or meth injection of course), then there is something else lacking in their build. Maybe the wrong cams, wrong exhaust, stock intake plenum without a spacer, wrong injectors, wrong ems, lack of W/G relocation kit, clutch that is slipping with that level of power, etc. Something is definitely missing.
Heck, check out this link. It is a 4.2L stroker, but this guy got almost 680 whp out of the Greddy TT kit on 93 octane at 13 psi....
https://my350z.com/forum/shop-builds...tt-13-psi.html
I'm not sure it was the 18G's or 20G's, but given the date the thread was started, and the lack of indication, it was probably the 18G's. I had the Greddy TT kit and, with the right build, it makes a lot of power.
Last edited by ttg35fort; 10-15-2009 at 07:22 AM.
10-15-2009, 07:22 AM
#79
On my build, the power came very easy. But, I had the supporting modifications in place, i.e., wastegate relocation kit (this is needed for the Greddy's to make high power), downpipes, Greddy Evo TT exhaust, Cosworth Plenum, heat wrapping, etc., etc...
Now that I think about it, I'll bet you most people struggling to make power are lacking the wastegate relocation kit or their clutch is slipping. Without the W/G relocatoin kit, the Greddy's experience boost creep at high boost levels.
Last edited by ttg35fort; 10-15-2009 at 07:23 AM.
