Babyjoy

In other words, one that has to

a) make big power in the straights

b) have near-instantaneous throttle response

c) wide-powerband

It seems to me, perhaps mistakenly, that the turbo on the Speedcraft kit is too big for an optimal track set up. I think from one thread I remember reading that the T60 is capable of 20+psi. If you just want to run say 10-14, or even 6-8, is it really the most efficient turbo to be using?

The Power House Amuse turbo kit uses a Trust T06-20g I believe. How does this compare?

Would appreciate all your thoughts.

Thanks.

Babyjoy

Okay, then I'll start. Wouldn't a T28 or T03 give you much better throttle response than the current turbo offerings AND allow you to boost up to 10-14 psi? Am I missing something?

If not, why is it that is has not been offered yet? I'm by no means a turbo expert and would have thought that the turbo companies would have thought of this already.

Again, all thoughts appreciated. Especially from the turbo experts.

KYS2000

I'm by no means a turbo expert but I believe that a T28 would be more of a restriction on exhaust flow and inturn would have more parasitic loss in HP then a 60-1 trim. Also it would be hard to fill a large FMIC and all the plumbing with just a T28 turbo. The ballbearing turbo that Speedcraft uses spools fast from what I hear and our engines are ingesting the 60lbs/min that that turbo outputs. Hence the use of the larger turbo.

I may be wrong also.

The turbo is also not the limiting factor in the amount of boost used. Our compression does not allow for over 8psi without getting larger amounts of knock. To run 10-14 psi, the compression would have to lower and 116 octance must be used.

I've wondered however how a 56trim dual ball bearing turbo found here might do:
http://www.slowboyracing.com/GT_turbo.html

jzr

I'm by no means a turbo expert either, this thread really needs someone like UL to chime in. But in the meantime...

The Speedcraft Turbo, from what I've heard, sounds like it would work fine at the track. I hear it's making full boost by ~4500rpm, and at the track, you're very rarely, if ever, below 6000rpm.

In trying to get something like that to work in reality, the problem is going to be cooling. It is my opinion that a stock S2000's cooling system is already very close to capacity when run hard for a full session at a hot, desert track. A turbo and all the doodads add a lot of power, but also a TON more heat. I wouldn't even consider taking such a beast out on the track without having massively upgraded the radiator, added an auxillary oil cooler, and done a host of other things. What fun is it if you can only run 1 or 2 laps without cooking everything?

If one were building a turbo S2000 for autocross, then you'd probably want something that spools up very quickly, to help out on those corners where you're looking for "first and a half gear". Cooling would be less of an issue there too.

Babyjoy

So is it an issue of balance then? i.e., a turbo that is big enough to create ample exhaust flow but that is small enough such that it does not adversely affect throttle response?

I know the ball-bearing turbo spools quickly which reduces turbo lag. However, I believe turbo lag means both a) rpm lag and b) throttle response lag. I have read in posts that rpm lag is minimal with the T60-1 with full boost coming on by 3500rpms. However, I have not heard a whole lot about throttle response lag. This is my big concern.

I am wondering if this can be solved by a smaller turbo/different trim etc. or if this engine "is not ideal for race setting turbos". I put it in quotations because I know some will argue that you can learn to drive with throttle lag.

When I read the Amuse article, it said they tried a small turbo first (can't remember the exact size) and the power maxed out at 220ps or something. So, perhaps Speedcraft et al did choose the optimum turbo and turbo is just not what I am looking for for this car.

What puzzles me though is how nissan's sr20det is is only 2 liters yet it works great as a turbo engine. People get great power out of it by simply upping the boost or putting a bigger turbo in it. Yet, it is still one of the most popular drifting engines in Japan, a "sport" requiring very acute throttle response. How are these engines different from the F20C in that they can boost high pressures, are low displacement, yet have acute throttle response. Or, do I not have my facts straight.

Thanks for the input KY. Would appreciate all other input as well.