TRD3000GT Posted June 14, 2005 Share Posted June 14, 2005 OK, I want anyone to correct me if Im wrong on this as I think quite a few poople are confused about turbo sizes and why bigger is better for power but bad for lag... The smaller the turbo the quicker it spools also the hotter it runs. A T67 turbo like Im running pushing out a steady 1.4 bar of boost pressure will NOT be as powerfull as a T77 turbo putting out the same 1.4 bar of boost. The reasons for this are completely down to the temprature of the air leaving the smaller turbo have much higher tempratures and this means the density of the air and explosivness is much reduced. We in the UK running 98 RON Optimax are LIMITED to 1.4 bar if we are not inteding on doing any trickery with water injection or anything else to reduce intake charge tempratures. In an ideal world for the most power we would all have a T88 turbo pushing out 1.4 bar of turbo pressure and also keeping the intake tempratures as low as possible but this is NOT the case as the cars will have a massive ammount of lag and not be good for street use as the powerband would be far to high in the RPM. Can some of the people who are in the know please confirm this or tell me is Im talking complete B**ocks Link to comment Share on other sites More sharing options...
Steve W2 Posted June 14, 2005 Share Posted June 14, 2005 The bigger the turbine housing the longer it will take to spool up. Regardless of turbo size, hotter outlet temperatures will mean reduced efficiency and thus power. The heat is mainly generated by the friction caused of the turbine spinning and is loosly proportional to RPM of the turbine. It's difficult compare likenesses between different turbos without actually like for like testing them. The explosiveness of the air is not effected by the temperature. Beacuse the air is hotter and has expanded, you require more of it. The mass air flow used will be the same, however, the volumetric flow (corrected for pressure and temperature) will be much higher. This effect gets gretaer and greater with increasing pressures and temperatures. Not really a proper answer to your question but I hope it helps a little. Link to comment Share on other sites More sharing options...
TRD3000GT Posted June 14, 2005 Author Share Posted June 14, 2005 I am happy with the power that my car is producing but theoretically if I was to get my hands on a specialist turbo that was a 76 mm regardless of spool at 1.4 bar the turbo would be producing a significant increase in power.. Link to comment Share on other sites More sharing options...
Nic Posted June 14, 2005 Share Posted June 14, 2005 Can't vouch for the accuracy of this, found it on the interweb the other day, may be useful guide to compare different makes/model of turbo. Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 14, 2005 Share Posted June 14, 2005 OK, I want anyone to correct me if Im wrong on this as I think quite a few poople are confused about turbo sizes and why bigger is better for power but bad for lag... The smaller the turbo the quicker it spools also the hotter it runs. A T67 turbo like Im running pushing out a steady 1.4 bar of boost pressure will NOT be as powerfull as a T77 turbo putting out the same 1.4 bar of boost. The reasons for this are completely down to the temprature of the air leaving the smaller turbo have much higher tempratures and this means the density of the air and explosivness is much reduced. We in the UK running 98 RON Optimax are LIMITED to 1.4 bar if we are not inteding on doing any trickery with water injection or anything else to reduce intake charge tempratures. In an ideal world for the most power we would all have a T88 turbo pushing out 1.4 bar of turbo pressure and also keeping the intake tempratures as low as possible but this is NOT the case as the cars will have a massive ammount of lag and not be good for street use as the powerband would be far to high in the RPM. Can some of the people who are in the know please confirm this or tell me is Im talking complete B**ocks A T88 is smaller than a T76 Chris Link to comment Share on other sites More sharing options...
TRD3000GT Posted June 14, 2005 Author Share Posted June 14, 2005 Not really sure what you mean Terry.. I have been led to beleive that the turbos that ended in a 67-77-88 were all to do with the turbo blade size in mm? Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 14, 2005 Share Posted June 14, 2005 The T88 is a GReddy turbo and it doesnt denote an 88mm inducer, just like a T78 isnt a 78mm inducer Link to comment Share on other sites More sharing options...
TRD3000GT Posted June 14, 2005 Author Share Posted June 14, 2005 thanks for clearing that up as I did not know that... Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 14, 2005 Share Posted June 14, 2005 thanks for clearing that up as I did not know that... No problem Link to comment Share on other sites More sharing options...
TRD3000GT Posted June 14, 2005 Author Share Posted June 14, 2005 Terry I know you think Im completely mad Link to comment Share on other sites More sharing options...
CJ Posted June 14, 2005 Share Posted June 14, 2005 Terry I know you think Im completely mad Me too Why are you looking to change the turbo? Link to comment Share on other sites More sharing options...
TRD3000GT Posted June 14, 2005 Author Share Posted June 14, 2005 Im just looking in to what is available Link to comment Share on other sites More sharing options...
michael Posted June 14, 2005 Share Posted June 14, 2005 Why are you looking to change the turbo? Because he's an attention whore? Link to comment Share on other sites More sharing options...
TRD3000GT Posted June 14, 2005 Author Share Posted June 14, 2005 Because he's an attention whore? Link to comment Share on other sites More sharing options...
how_supra Posted June 14, 2005 Share Posted June 14, 2005 hmmmmmmmmmm am I still allowed to be confused? I think I need to read it slowly to understand. T61 is smaller than a T67? No actually I am really confused........... Link to comment Share on other sites More sharing options...
Alex Posted June 14, 2005 Share Posted June 14, 2005 FYI, T78 has a 67mm compressor Basically what you're saying is right....but you have to be careful as helpfully some turbo manufacturers don't actually call the turbo's what they are spec wise (ie such as GReddy. (Mcanny, bizzare - that was my first thought to ) Link to comment Share on other sites More sharing options...
Alex Posted June 14, 2005 Share Posted June 14, 2005 hmmmmmmmmmm am I still allowed to be confused? I think I need to read it slowly to understand. T61 is smaller than a T67? No actually I am really confused........... Yes a T61 has a 61mm compressor and a T67 has a 67mm compressor The exhaust A/R (my T61 is .68) dictates how quick they spool - in a very simplistic explanation. Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 14, 2005 Share Posted June 14, 2005 hmmmmmmmmmm am I still allowed to be confused? I think I need to read it slowly to understand. T61 is smaller than a T67? No actually I am really confused........... No a T67 is bigger than a T61. The manufactures all use different # to denote their configurations. There are "T70's" kicking about in cheaper kits that are actually the rough equivalent to a T61, all depends where you source your turbo from. Link to comment Share on other sites More sharing options...
CJ Posted June 14, 2005 Share Posted June 14, 2005 Because he's an attention whore? There have to be cheaper ways of gaining attention Link to comment Share on other sites More sharing options...
Ian C Posted June 14, 2005 Share Posted June 14, 2005 The heat is mainly generated by the friction caused of the turbine spinning and is loosly proportional to RPM of the turbine. Nope, the heat is caused by the act of compressing the air The friction of the turbo bearings is probably the smallest heat-generating function. Part of it is the exhaust side, part of it is the oil flow trying to take the heat out. But mostly the air is heated by compression. The 'bigger' the turbo the less it heats the air up as it compresses it. This means when it spits out 1.4bar it's cooler and therefore denser and therefore needs more air mass to make 1.4bar of pressure - therefore more air gets in the engine. Of course, charge cooling helps enormously here (air to air, air to water, water injection, even NO2 injection can help) but it can only compensate for a too-small turbo so far. -Ian Link to comment Share on other sites More sharing options...
Guest Terry S Posted June 14, 2005 Share Posted June 14, 2005 Not a case of banging on the biggest turbo you can get your hands on though, it needs to be matched to your requirements, and more importantly your engine configuration. Link to comment Share on other sites More sharing options...
JustGav Posted June 14, 2005 Share Posted June 14, 2005 Diesel truck turbo...one of the big daddy's??? Give you plenty of power.... Link to comment Share on other sites More sharing options...
TRD3000GT Posted June 14, 2005 Author Share Posted June 14, 2005 ok, Done enough research here is what Im strapping on http://racepics.net/board/uploads/post-51-1095294715.jpg Joke Link to comment Share on other sites More sharing options...
Guest Usmann A Posted June 14, 2005 Share Posted June 14, 2005 one step ahead of u mate. Link to comment Share on other sites More sharing options...
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