ORIGINAL: DarZeelon
You often choose to argue with what I say, often when I am right and I usually am.
And about detonation, a rich mixture can even cause detonation, due to the sheer volume of the fuel, increasing the resultant compression pressures (liquid fuel is incompressible).
Please see the current thread about "Engine throws the prop nut, starts backward...".
In this case you're completely wrong Dar. For assumptions sake, let's say the Enya can run for 10 minutes at full throttle on 150cc (about 5 ounces) of fuel at 10,000rpm. In that time the engine has turned 100,000 times or 50,000 power strokes. This means that each power stroke needs 0.003cc of fuel (which contains about 0.0006cc of oil).
The Enya in question is 8.7cc so it'll have a combustion chamber volume of approximately 1cc to give a C/R of 9.7:1. Now let's run that engine terribly rich by doubling the amount of fuel that goes in per power stroke to 0.006cc of fuel and let's assume that
none of that fuel vapourises into a compressible gas. The combustion chamber volume shrinks to 0.994cc and the compression rises to 9.75:1, hardly enough for detonation even if it could ignite.
In the real world the fuel component vapourises and gets compressed so it's only the miniscule volume of oil remaining that can add anything to the compression.