This discussion reminds me of the sonic shockwave effects on 2 cycle tuned expansion chamber type exhaust pipes. The sonic shockwave has enough energy to actually reverse the exhaust flow of an over scavenged cylinder, and push the mixture back thru the exhaust port, into the cylinder, effectively supercharging it. There are some common gas dynamics effects. The elevated temperature raises the local speed of sound significantly in both cases.
Wow, did that ever bring back motocross memories from 40 years ago!
Mike
