> In a sense, you absolutely correct. It actually has to do with the density
> of the air. Cooler air (including moister air) is denser. That does provide
> more O2 for out cars to burn. Pilots learn about a factor called density
> altitude, which teaches us that hotter air makes less power in the engine
> and lee lift from the wings, which leads to longer take-off run. Same
> principle applies here - cooler air, more power - car runs better.
Sam, you're right on about the denser air, power and density altitude.
Here in No California we have weekend pilots flying from the Bay Area
(basically sea level) to Lake Tahoe at about 6200' in the morning it's
40 degrees and the air acts like 6200' while in the aftenoon it can be
90 and the altitude effectively acts like you're at 10,500. Those shiny
decorations in the pines at the end of the runway aren't for Christmas,
they're Cessnas. As a corollary, on a 100 degree day, your LBC runs like
you are in Denver!
There is one other factor, the moisture acts to retard the flame
propagation in the combustion chamber. A slower flame means more even
and complete burning and therefore more power. A very fast flame is
actually an explosion, you can hear it as a knock or "detonation".
Climbing hills, towing, and high compression pistons increase heat and
flame speed which is why motor homes, tow vehicles and hot rodded cars
sometimes install water injection systems. I know of several drivers who
have rigged a windshield washer to "squirt" into the air cleaners for
occasional climbing of hills while using cheap gas. It beats buying new
pistons or rings! Jarl
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