But, but, Gary,
(at the risk of starting another silly thread)
If you start with a cylinder at 1 atm. and compress it to 1/9 its
original volume, (14.7 x 9) you get 9 atm or something like 130 psi.
But if you start with 1 atm. - 2.5 psi (14.7-2.5) and compress it to 1/9
its volume, you only get around 110 psi.
Or to think about it another way, in space there is no compression in a
roadster (!) because there's no air to compress (leaving out the fuel
vapor, of course). So as the air thins considerably, the number of
molecules are reduced, and the pressures go down accordingly. Fewer
molecules compressed into a closed space produce less pressure...
And from experience- you need to reduce the amount of fuel at high
altitudes since there's less air (and oxygen) and needs to be,
correspondingly, less fuel...
Or have the grey cells that were present for high school chem finally
died?
Toby
Gary McCormick wrote:
> Compression gage readings are PSIG (pounds per square inch - gage), which
>means the
> additive pressure above and beyond atmospheric pressure. Short answer to the
> question"Isn't altitude a factor?" is "No". Besides, the delta P between sea
>level and
> 6400 ft ABS is only a tad over 2-1/2 psi.
>
> Gary McCormick
> San Jose, CA (139 ft ABS)
> ---------------------------
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