SupraPL Posted July 26, 2007 Share Posted July 26, 2007 Hello. I have to put my N/A-T conversion off for a few months but i want to do some homework properly. Now as a personal preference i prefer faster response and lower top speed. So i'm looking for a turbo with the least lag [broadest torque curve] i can get and still get 450hp at crank. Sounds like the ball bearing turbos from Garrett are a great piece of art as they are supposed to spool up hundreds/thousands of RPMs quicker. I can't decide between two turbo's [GT3076R versus GT3582R] and i want to know what you guys all think. I have a feeling that the GT3076R is slightly too small for my goal and a GT3582R will yield better results overall ... but ... everybody knows the famous video with the Amuse Supra (GT30, 450fwhp) and the Mines Skyline... http://www.youtube.com/watch?v=tDiTWaIhLNw It looks like the only manifold flanges available [from what i can find] for the GT30R are T3 flanges and the NA-T manifolds are all made with a T4 flange. GT35R can be so many different turbos depending on how they are spec'd up with regards to compressor wheel size and trim and different exhaust A/R ratios. I'm confused. Am i making sense, and do you have some turbo suggestions? Thanks for listening. Tomasz Quote Link to comment Share on other sites More sharing options...
kieren1234 Posted July 26, 2007 Share Posted July 26, 2007 Xs power sell flanges to convert from a T3 - T4 or vise versa mate. They are about £80 IIRC. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted July 26, 2007 Share Posted July 26, 2007 Have you lowered the cars compression, or is it still stock NA? This will make a big difference to the spool time. Quote Link to comment Share on other sites More sharing options...
kieren1234 Posted July 26, 2007 Share Posted July 26, 2007 /here ya go mate: http://cgi.ebay.co.uk/T3-TO-T4-TURBO-FLANGE-ADAPTER_W0QQitemZ250146526595QQihZ015QQcategoryZ38786QQrdZ1QQcmdZViewItem It does raise the height of the turbo slightly which could be a bonus even to clear the distributor. Quote Link to comment Share on other sites More sharing options...
kieren1234 Posted July 26, 2007 Share Posted July 26, 2007 Also the thickness of the intercooler piping can have an effect on the lag i have heard?? Quote Link to comment Share on other sites More sharing options...
Jake Posted July 26, 2007 Share Posted July 26, 2007 Also the thickness of the intercooler piping can have an effect on the lag i have heard?? The diameter? Only by milliseconds. You'd never notice the difference. Quote Link to comment Share on other sites More sharing options...
SupraPL Posted July 26, 2007 Author Share Posted July 26, 2007 Have you lowered the cars compression, or is it still stock NA? This will make a big difference to the spool time. I bought Boostlogic 2.5mm head gasket. This will reduce compression to 8.5:1 [same as a tt]. I know that the proper way to do it is with new pistons, but all the US guys change only the gasket to reduce the compression and they haven't any problems. Quote Link to comment Share on other sites More sharing options...
SupraPL Posted July 26, 2007 Author Share Posted July 26, 2007 /here ya go mate: http://cgi.ebay.co.uk/T3-TO-T4-TURBO-FLANGE-ADAPTER_W0QQitemZ250146526595QQihZ015QQcategoryZ38786QQrdZ1QQcmdZViewItem It does raise the height of the turbo slightly which could be a bonus even to clear the distributor. Thanks mate. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted July 26, 2007 Share Posted July 26, 2007 Ok that's cool. Anyway IMHO a GT35R or T61 is a small as you want to go in a street supra. I think with a smaller turbo it would produce it's torque so low down it come be a nightmare to drive. Quote Link to comment Share on other sites More sharing options...
SupraPL Posted July 26, 2007 Author Share Posted July 26, 2007 Ok that's cool. Anyway IMHO a GT35R or T61 is a small as you want to go in a street supra. I think with a smaller turbo it would produce it's torque so low down it come be a nightmare to drive. I think that it will be a great fun Quote Link to comment Share on other sites More sharing options...
kieren1234 Posted July 26, 2007 Share Posted July 26, 2007 Thanks mate. No problem mate. Yeah jake sorry i mean diameter. It was just something i heard Quote Link to comment Share on other sites More sharing options...
Matt H Posted July 26, 2007 Share Posted July 26, 2007 you could get a TT up to 450bhp with hybrids, BPU, some 550's and a remap. seems a small goal to achieve for the money to go single. i know your NA but surely just getting a TT would be better for what your after. then you have the lower down grunt at well Quote Link to comment Share on other sites More sharing options...
SupraPL Posted July 26, 2007 Author Share Posted July 26, 2007 you could get a TT up to 450bhp with hybrids, BPU, some 550's and a remap. seems a small goal to achieve for the money to go single. i know your NA but surely just getting a TT would be better for what your after. then you have the lower down grunt at well Yes, you are right, but i love my car and can't buy 2002 TT. Quote Link to comment Share on other sites More sharing options...
SupraPL Posted July 27, 2007 Author Share Posted July 27, 2007 What's your opinion? First and last bump. Quote Link to comment Share on other sites More sharing options...
SupraPL Posted August 10, 2007 Author Share Posted August 10, 2007 N/A-T, rev limiter 6800rpm, peak boost 1.2 bar from 2750rpm (prediction) Pressure ratio. 1.2bar+1.0=2.2 Air flow rate. air flow rate=(L x RPM x VE x Pr) / 5660 L -> engine capacity in litres VE -> volumetric efficiency -> stock engine 4 valves/cylinder = 90 Pr -> pressure ratio 6800rpm: (3x6800x90x2,20)/5660=714cfm 714/14,27=50lb/min 2750rpm (3x2750x90x2,20)/5660=20.2lb/min Surge line. 50lb/min*20%=10lb/min http://img374.imageshack.us/img374/3402/gt3076r3cu4.gif[/b] What do you think about this graph? Which turbine i should choose? A/R 1.06? A/R 0.82? or A/R 0.63? http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/GT30/GT3076R_700382_12.htm Thanks in advance. Quote Link to comment Share on other sites More sharing options...
Wez Posted August 10, 2007 Share Posted August 10, 2007 Nice write up, can a mod seperate this post and make it a sticky Quote Link to comment Share on other sites More sharing options...
Nic Posted August 11, 2007 Share Posted August 11, 2007 Ok that's cool. Anyway IMHO a GT35R or T61 is a small as you want to go in a street supra. I think with a smaller turbo it would produce it's torque so low down it come be a nightmare to drive. Tomasz, you already have your answer here, Terry is one of, if not the most knowledgeable guy on here when it comes to turbos. I would listen to what he says, ie. the GT3076R is too small. Don't get too obsessed with responsiveness, the GT3076 may spool up quickly, but you'll just end up spinning the wheels up initially, then the turbo will run out of puff higher up the rpms. GT3582R is very responsive and the smallest you'd want IMO. Quote Link to comment Share on other sites More sharing options...
SupraPL Posted August 11, 2007 Author Share Posted August 11, 2007 Tomasz, you already have your answer here, Terry is one of, if not the most knowledgeable guy on here when it comes to turbos. I would listen to what he says, ie. the GT3076R is too small. Don't get too obsessed with responsiveness, the GT3076 may spool up quickly, but you'll just end up spinning the wheels up initially, then the turbo will run out of puff higher up the rpms. GT3582R is very responsive and the smallest you'd want IMO. Hi Nic. What A/R can you recommend? GT3582R A/R 0.63 or 0.82? BTW Can you answer to my PM please. Graph of GT3582R, peak boost 0.9 bar from 3000rpm. http://img177.imageshack.us/img177/1306/gt3582r1tu2.gif Quote Link to comment Share on other sites More sharing options...
Nic Posted August 11, 2007 Share Posted August 11, 2007 Hi Nic. What A/R can you recommend? GT3582R A/R 0.63 or 0.82? BTW Can you answer to my PM please. Graph of GT3582R, peak boost 0.9 bar from 3000rpm. http://img177.imageshack.us/img177/1306/gt3582r1tu2.gif Mine is 0.82 AR, I think Terry use to have a 0.63 on his old car. The 0.63 will give slightly less lag (probably only around 100rpm), at the sacrifice of some top end power. As a guide mine makes positive boost at around 2K rpm, peak boost of 1.3bar at around 3K rpm. Quote Link to comment Share on other sites More sharing options...
SupraPL Posted August 11, 2007 Author Share Posted August 11, 2007 Mine is 0.82 AR, I think Terry use to have a 0.63 on his old car. The 0.63 will give slightly less lag (probably only around 100rpm), at the sacrifice of some top end power. As a guide mine makes positive boost at around 2K rpm, peak boost of 1.3bar at around 3K rpm. Thank you for info. GT3582R A/R 0.63 vs GT3076R A/R 0.82 - I'm going to read technical book about turbochargers during the weekend then i will make a decision. Quote Link to comment Share on other sites More sharing options...
SupraPL Posted August 11, 2007 Author Share Posted August 11, 2007 Graph of 450bhp Supra, Garrett GT3076R. http://img508.imageshack.us/img508/6973/gt3076rnowe2mj4.gif All needed formulas you can find there: http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech103.html All comments are welcome. Quote Link to comment Share on other sites More sharing options...
Mike B Posted August 11, 2007 Share Posted August 11, 2007 I have Terry's GT3582R sat on my bench here; I just fitted a GT4088R. I'll probably sell the 35 shortly. It is a very responsive turbo, with a precision '68ar turbine housing. It's very early spooling and responsive.. as well as being as quick as you would ever need for normal driving / track driving. Also your engine would run cooler with a slightly bigger turbo than a small one wound up to the max. Quote Link to comment Share on other sites More sharing options...
SupraPL Posted August 12, 2007 Author Share Posted August 12, 2007 I have Terry's GT3582R sat on my bench here; I just fitted a GT4088R. I'll probably sell the 35 shortly. It is a very responsive turbo, with a precision '68ar turbine housing. It's very early spooling and responsive.. as well as being as quick as you would ever need for normal driving / track driving. Also your engine would run cooler with a slightly bigger turbo than a small one wound up to the max. Thanks for information. Quote Link to comment Share on other sites More sharing options...
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