jjs wrote:
> "Volksrod70" > wrote in message
> m...
>
>>Does altitude have any effect on compression ratio?
>
>
> It lowers compression, but the ratio is the same.

At elevation, the pressure in the combustion chamber will be lower at
BDC /and/ TDC; this because you start out with less dense air: at one
mile elevation, air density is only 85.5% of sea level density, so
presumably when the piston is at TDC, the compressed version is 14.5%
less pressure than it would be at sea level.

The compression ratio does not change: If you have an 8:1 compression
ratio at sea level, it remains 8:1 in Denver. The swept volume of the
piston does not change, nor does the the volume of the combustion chamber.

--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westphalia: "Mellow Yellow (The Electrical Banana)"
KG6RCR
-=-=-
When asked *why* he was dragging a lobster through the the Bois de Boulogne
on a length of pink(?) ribbon, Nerval replied "it does not bark and it
knows the secrets of the sea." The same goes for a good cat except that, I
fancy, it knows everything.
-- Jane Skinner
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