First of all...i realize that this is not the tech forum. i just wanted to see if any of you guys could help me understand this a little better.
I've seen a lot of pics of TT Supras and i'm just a little confused about the setup of it all. is one turbo smaller than the other and at a certain pressure level the big one takes over for the little one or do they both blow at the same time or what? if anyone could post a pic of a TT Supra engine OUTside of the engine bay so you can see the piping it would be greatly appreciated....or if anyone would be cool enough to make a diagram of how this TT setup is organized, that would be equally as cool. just looking to understand how it works a little better...

 

to my knowledge most TT setups are made so that the smaller one goes while the bigger one spools up.

or i could be wrong...

 

so is there some kind of pressure activated valve where the "small" turbo pipe and the big turbo pipe meet that determines which one gets to blow it's load into the engine?

 

they have some that are two stage...

and some that go on @ the same time--sequential...

 

Considering I've worked with many supras (including my dad's) I think I can answer this the best...or I will try to I guess...

The Supra TT uses the same size turbos (CT-12) which share the same inlet (intake) tube. Both turbos are always flowing (whether it be vacuum or boost), but the rear turbo has a piece of plumbing sitting between it and the intercooler piping. This piece looks very similar to a throtte body, in that it has a butterfly valve in the main tube. There is a chamber that is unrestricted, but very very small that flows over the butterfly valve and on into the intercooler piping. So when the exhaust gasses start spinning the turbos, the first turbo is completely unrestricted, and its boost goes into the engine with ease. But the second turbo starts building up boost (at the same rate as the first) but its restricted by the butterfly valve. Small amounts of boost creep through the chamber above the valve to smooth out the transition, and when enough pressure is built up behind the valve, it opens, allowing all of its boost to move freely into the engine. The purpose behind the sequential setup (which is almost identical to that in the FD-S RX-7) is to smooth out the boost curve, and give it a more "stable" transition from vacuum to full boost.

I hope that makes some sense.

There aren't many twin turbo designs or setups that use the "bigger turbo/smaller turbo" method. That is mainly a custom setup, and as far as I know, there are no kits offered for Hondas or Supras that use it.

 

wow, very good explanation 92TypeR...thanks a lot. I always wondered how that setup worked but no one was ever able to adequately explain it to me.
thanks man.

 

No prob. I actually had to go in the garage and make sure what I was thinking was right, never had to explain it in writing before...

I would also add that the one small turbo - one big turbo TT setup would be inneficient. It would be smarter to run a small shot of nitrous with either 2 big twins or one big single. The Motec system that the Titan Motorsports supra uses has a variating Nitrous Express delivery system, where the nitrous amount decreases from a ~180shot to zero when their big turbo reaches full boost. It is quite impressive.