Next round of interesting data, captured with my prototype ADCCAN. (EFR8374, 2008 STI)

Three boost settings (Wastegate, 22.5PSI, and 24.5PSI) with exhaust backpressure measurements. All three of these are still relatively low boost pressures, so the exhaust backpressure to manifold pressure ratio is not particularly high. It is typical to have exhaust pressure to intake pressure ratios of 2:1 to 3:1. Much above 3:1 and there must be some significant restrictions or the size of the engine is poorly matched to the turbine flow.

In the wastegate run, peak EGBP:IP was about 1.28:1. At 22.5PSI it was 1.32:1, and at 24.5PSI it was about 1.34:1. All of those are pretty low ratios, indicating adequate turbine flow. The really interesting data will come at higher pressures. The last graph show spool in each gear, starting at around the same point (~2000rpm). I have not done any optimization for gear comp, which would help a lot in 2nd gear. 1st gear is difficult to improve dramatically, but the solution there is launch control. With LC running I can be at 10-12psi before launching. I still need to get the compressor/turbine wheel speed sensor logging, which will be valuable to see at higher manifold pressures.