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Old 08-01-2010, 08:25 PM   #54 (permalink)
Scribe
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Quote:
Originally Posted by mikey1600 View Post
you've missed 1L of displacement :P, 1.85L per side. having said that, this is also across 3 cylinders and not 4, but I know where you are coming from.

You still want a turbo that can be efficient at higher RPM to take advantage of the engine though, no point putting too small of a turbo into a kit which runs out of efficiency at 5500RPM for eg stock CA18/SR20 turbo's.

on topic of kit - what kind of RPM are you expecting to hit full boost by with this kit? any expected upgrade path of stages for slightly higher or lower HP applications?
Yeah, don't know what I was thinking, 1.85. But I did say 3, not 4 cylinders.

I come from a DSM background, so I am not new to turbocharged engines at all. I can get as technical as you want if that will help this discussion.

That being said, a certain power level corresponds to a certain airflow rate. Thinking of the VQ37 with twin turbos as two 1.85L engines with their individual turbos is a great place to start. If your goal is say somewhere in the 500 whp range (550-600 crank), then you only need a turbo capable of flowing efficiently at the given boost level at half the CFM to support this goal. Considering the lower boost levels run on a high compression engine like the VQ, a big T28, or even a 16g (again, coming from a DSM background) could conceivably reach those goals and have drastically better manners on the street. People get too obsessed with big turbos that could flow enough air to make 500+ each and they don't really understand what they are giving up by selecting a good turbo.

Too large a turbo mean you will never really be operating within the ideal area of the compressor map just as much as turbo that is too small, leading to excessive lag on the low end where smaller turbos run out of steam up top. All you need is a turbo that produce maybe 7-9psi max efficiently to a 1.85L three cylinder to 7500K.

Let me know if there is real interest in this discussion and I'll start looking for compressor maps, but otherwise I'd just be screaming in the wind. Also, if you want, start a new thread and PM me so we can publicly discuss what would be the ideal street kit for our cars.

Don't get me wrong, if this kit were to come out, I'd be one of the first in line, although I may make a few calls to get a better turbo match if they go the 'bigger is better' route.
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