A new thought for twins - Compound Turbos? Maybe?

dudemaaan · 03-09-2010, 12:11 PM

I spoke to a guy running a compound turbo setup on a eagle talon running 8.97 at 156 mph. He said he did it because the turbo he was running, a 1.32 T6 s475 wouldn't spool until 7000 rpms on his car, so he was using nitrous to help spool it. Then he added a t3 50 trim in a compound setup and it sees full boost around 4000 rpms.

This is what I found out from him, peak power is pretty much the same at the same boost levels. In his case he runs about 40 psi, which is medium boost for his engine. You do not have to run extremely high boost levels in a compound setup.

You choose the large turbo for whatever max power you want, and you choose the smaller turbo for whatever spool you want. Obviously they will have to be somewhat matched or you won't have the large turbo spooled before the little one runs out of breath.

His intake temps are the same, though he never measured pre-intercooler temps which would be more accurate. He said his drive pressure to manifold pressure is really good being 1:1, "Which is not going to happen on a single turbo that will actually spool on the car" (his words)

The advantage of the setup is much faster spool with a high top end, disadvantage is complexity and cost. He's running 2 wastegates on the first turbo to keep it from boost creeping, the second turbo also has a wastgate that he uses to adjust the boost level.

It sounds like a really good way to go, and the concern of needing to run high boost is not the case. The pressure ratios are divided between the 2 turbos. Almost like it's one turbo with a very broad map. Exhaust restriction and high AFR's are also not the case.

03-09-2010, 12:11 PM	#34
dudemaaan Rotary Fanatic Join Date: Mar 2008 Location: Brenham, TX Posts: 335 Rep Power: 18	I spoke to a guy running a compound turbo setup on a eagle talon running 8.97 at 156 mph. He said he did it because the turbo he was running, a 1.32 T6 s475 wouldn't spool until 7000 rpms on his car, so he was using nitrous to help spool it. Then he added a t3 50 trim in a compound setup and it sees full boost around 4000 rpms. This is what I found out from him, peak power is pretty much the same at the same boost levels. In his case he runs about 40 psi, which is medium boost for his engine. You do not have to run extremely high boost levels in a compound setup. You choose the large turbo for whatever max power you want, and you choose the smaller turbo for whatever spool you want. Obviously they will have to be somewhat matched or you won't have the large turbo spooled before the little one runs out of breath. His intake temps are the same, though he never measured pre-intercooler temps which would be more accurate. He said his drive pressure to manifold pressure is really good being 1:1, "Which is not going to happen on a single turbo that will actually spool on the car" (his words) The advantage of the setup is much faster spool with a high top end, disadvantage is complexity and cost. He's running 2 wastegates on the first turbo to keep it from boost creeping, the second turbo also has a wastgate that he uses to adjust the boost level. It sounds like a really good way to go, and the concern of needing to run high boost is not the case. The pressure ratios are divided between the 2 turbos. Almost like it's one turbo with a very broad map. Exhaust restriction and high AFR's are also not the case. __________________ 500+ HP thanks to: Fast reacting IAT sensor thread! Mechanical Pre-turbo Water Injection Thread Dual Stock fuel pumps Thread T2 differential swap!