Quoting Dave Ford <daveford1@xxxxxxxxxxx>:
> I wasn't a subscriber when this thread started but here's my 2 cents:
>
> As the timing is advanced it can cause the steadystate operating
> temperature to go up...
Actually, its usually the opposite (assuming that the timing is not advanced so
much that causes the engine to knock). As you advance the timing, the peak
cylinder pressure and temperature increase, but the temperature of the exhaust
gas drops (the mixture is expanded a bit more before the exhaust valve opens).
That means less waste heat in the exhaust. Since a large portion of the
coolant heat is from the exhaust gasses in the heads and exhaust ports, the
coolant temperature tends to drop (or the thermostat may close more often) as
the timing is advanced. Also, the peak cylinder temperature lasts a very short
period of time (just a few crank-angles duration, and right about 20 degrees
past TDC compression-expansion), so its effect on coolant temperature is a lot
smaller than exhaust gas temperature. So, overall, its good to keep your
timing as advanced as possible, but not as much as to cause knock. Then, you
may have to put carton boards on your radiator to help the engine warm up!
A consequence of over advanced timing is engine knock, which can have also bad
thermal effetcs on engine parts, especially pistons. So, all the above applies
assuming one does not advance the timing so much as to cause engine knock (or
as Paul calls it, "spark knock").
D^2
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