> But surprisingly, one of the main
>sources of the internal friction was the pumping loss that occurred
>when the pistons tried to pull air past a barely-cracked throttle
>butterfly. Opening the throttle past the 50-60% mark reduced this
>source of drag, and as long as the driver shifted low enough in the
>RPM range, overall fuel consumption was low.
I would have thought that the fact that the cylinder isn't fully
filled at low-opening high-rpm conditions, and thus has less _effective_
compression would be more important than pumping loss. At low-rpm open-
throttle, the cylinder gets to fill completely, generating maximum effective
compression.
At low-throttle, high rpm conditions, I wouldn't be suprised if the
effective compression ratio was less than 3 to 1. (But then I'm not an
automotive engineer, so what do I know?) :-) Does anyone here know how much
loss of compression affects the efficiency of the Carnot cycle? I know each
point of compression is worth a number of percent in power (and I would guess
in efficiency).
Randell Jesup
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