Robert.Gardner wrote:Its beyond most people to measure their compression ratios with two stroke engines.
Most two strokes advertise their static compression ratio as between 6.5-9:1, and rarely list any dynamic ratio.
Robert.Gardiner,
If you were genuinely interested in studying the effects on performance of static and dynamic CR's in a typical loop-scavenged 2-stroke piston engine, it is not too difficult or expensive.
You would first disassemble the upper cylinder and head, and take measurements of the piston, cylinder and combustion chamber.
Then you would drill and tap a small diameter instrumentation port in the cylinder head. To this port you would attach a check valve, a short length of tubing and a pressure gauge. This would give you peak combustion pressure during operation, over several cycles.
Then you can use a standard automotive compression gauge to measure cranking compression pressure.
The final step would be to download this free single cylinder engine simulator software from Lotus Engineering, and build an analytical model of your engine. Then tweak the model to match your engine's measured parameters. Once you have a validated engine model, you can make changes to any of your engine's parameters and immediately see what effects they have without doing anything further to your actual engine.
http://www.lotuscars.com/engineering/en ... -downloads
Good luck and have fun!
riff_raff