[Miles in Michigan]

I've seen the big 800+hp dynos, and they have a jump in the torque curve of ~250ft-lbs around 4000rpm. I assume that people that roadrace would have a flatter torque curve. Do you guys keep the stock (sequential) turbos? Can you get over 500rwhp with a user-friendly torque curve? Or can you use a big single turbo on the track, and just watch out to make sure you keep it at a high enough rpm for good boost?

Don't mean to sound like a troll, I'm just curious. I posted on the corvetteforum first (because I have a C5), so that I wouldn't seem like a troll over here, but it turned into an argument pretty quickly.

Thanks.

 

[Andi]

For road racing a Supra, I'd recommend getting a single that has good spool below 4000RPM. Sequential even on stock twins is AWFUL on the road course because it's difficult to predict when the 2nd turbo will come online when exiting a slow corner.

As for any car but even more importantly for a turbo one, you have to keep the revs up to make sure you get good exit speed out of a corner. When I'm road racing I'm never below 4000RPM except for some very slow corners where I have enough torque at 3500 that traction is already limited and a lower gear would be useless.

This is my dyno in road racing trim on stock twins at 16psi..

This spool curve is excellent and I never find myself not having enough boost (torque).. And a good single like a T61 or a Powerhouse Stage 2 should be able to have similar spool to this while making about 100rwhp more at the same boost.

That having been said, there's nothing like the instant NA torque that you don't have to wait for. Driving a turbo is more like a chess game.. you have to predict the surge and drive around it.. give it gas to spool, then start letting off slightly to manage your rear traction as you exit the corner at the limits of adhesion of all 4 tires.. It can be modulated but it's not nearly as easy as an NA where you can simply dial in and out more torque linearly with the accelerator pedal w/ no spool delay.

But then the spool-up surge is half the fun...

Andi

 

[Miles in Michigan]

Your torque curve looks a heck of a lot better than the ones I've been looking at. Check out this graph:
http://store5.yimg.com/I/supra_1644_37812532

Your car has more torque than the Supra on that page up until about 4000rpm, at which point that car is in the midst of a psychotic episode, where it gains 250ft-lbs in ~600rpm. Hell, yours is as flat as the Lingenfelter C5 TT on that page, just 120ft-lbs lower.

Thanks for the post.

 

[Andi]

The dyno chart you showed is for a T66, which is really just a drag/highway racing turbo. Not a good choice for road racing IMHO.

Check out this dyno chart.. Powerhouse Racing Stage 2...
http://www.mkiv.com/readersrides/readersrides/peter_blach/14psi-21psi.jpg

Similar spool to mine but with 500rwhp in road race trim at 14-16psi..

Andi