While Dave and I don't always agree, well, hardly ever, he did pose a very
good question when he asked "Why can't I run 22 to 1 compression ratio?".
Well, ok...a little math. Air acts as an ideal gas so we can use ideal gas
laws. One of the equations used in the Otto engine cycle analysis, yes,
Dave, I do use P-V diagrams, is
T1/T2 = (V2/V1)^ gamma-1
T1 = temperature of air going in in Rankine or in this case 460 + 60 =
520Deg R
T2 is the compressed gas temperature in Rankine
V1/V2 = compression ratio = 22
gamma is the gas constant for air = 1.4
^ means raised to the power
520/T2 = (1/22)^1.4-1
T2 = 520/(1/22)^.4
T2 = 1790 deg R = 1330 Deg F
So I would guess that really really bad detonation would occur. Not to
mention that valve timing events would have to be nearly perfect. I only
ever saw but one engine that had a mechanical compression ratio this high
and That was a Yamaha racing 2 stroke. There was only a few thousandth's of
an inch clearance between the piston and head and most of the chamber volume
was in the spark plug area. Just a tiny dish and the plug iself.
Now as to the big ompression ratio is mentioned, it has to be pointed out
that I said effective compression ratio. For those of you who don't agree
with me, shoot, hit that old delete key. I do this for my own stimulation of
what few brain cells I have left.
Mayf, the ignorant desert rat.
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