Originally Posted by bmoses

I understand how an internal combustion engine works and dynamics behind them. I think you are wrong. Latent exhaust gas that hasn't been discharged from the engine will result in a lower VE (volumetric efficiency, or the amount of combustible air/fuel available in the cylinder relative to the displacement of the cylinder). Leftover exhaust gas that has not escaped will do nothing to increase your power anywhere in the RPM range at any time. All leftover exhaust gas will do is dissallow or displace more fresh air and fuel from getting in. Obviously it will not increase your mechanical, or static, compression. It will also not increase your dynamic compression. What your talking about is more like EGR. Exhaust gas in the cylinder is inert and not combustible and lowers exhaust gas temps, which lowers NOX emmissions. This is why there is an EGR system on our cars.

The issue at hand was backpressure. Backpressure is not necessarily something that is desired. Backpressure is never a good thing. However backpressure is a result of having smaller diameter exhaust tubing which is necessary to create strong exhaust pulses and exhaust velocities at midrange RPMs. The downside is that the smaller diameter tubing becomes a bottleneck at higher RPMs. It's the strong exhaust pulses and velocities which create effective scavenging at lower to mid RPMs, not the backpressure. Backpressure is just a result of having smaller sized tubing and is a necessary evil that can't be avoided.