Comments by "David Elliott" (@davidelliott5843) on "Beyond Clever - How Two Stroke Exhaust Pipes Really Work" video.

  1. Exhaust shock wave tuning was invented in 1950s East Germany by MZ (previously DKW) engineer Walter Kaaden. It’s been significantly improved by Rotax in their direct injected ETECH engines. The shock wave travels down the pipe at a constant speed. The divergent cone causes a pressure drop behind the shock wave. This sucks exhaust and unburnt gas out of the cylinder. The shock wave hits the convergent cone and reflects back. This compresses the gas moving down the pipe and pushes it back into the engine. The pipe length and shape is made so the reverse gas flow stops as the port closes. When correctly timed, this gives a supercharger effect.
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