All condescension aside, good compound setups have boost hit you like a brick wall at any rpm.Fred wrote:Yes, I think most people on this site can read a turbo compressor map just fine...
I think most people on this site would also rather that they were in the upper right at peak RPM/Boost. If not, you've got something laggier than need be. Which is the entire point of the above design. Minimal sized turbos for minimum lag and maximum output in the same package. The point isn't to obtain high pressure ratios, it's to obtain high pressure at low rpm and low restriction at high rpm. It's NOT a compound setup.
The entire point of a compound setup is to reduce lag and stay away from the surge line. Spinning the larger turbo up to to only 3/4 the normal speed is faster and reduces lag over spinning the same turbo up to the far right of the map.
Multi-stage turbo systems often fail because people have this incessant need to introduce check valves, diverting valves, bypass valves etc into the mix to try and eliminate ill-conceived "problems" that they see with compounding. The reality is that successful multi-stage setups simply feed one into the other with no tricks.
