Re: COMPRESSION TEST -Reply

From: Derrick Pero (dpero@frontiernet.net)
Date: Wed Feb 19 1997 - 22:54:43 EST


"Compression ratio" and "cylinder pressure" (aka..cranking pressure, compression
test) are two different animals. Compression ratio is a calculation based on the design
of the engine (volume at TDC compared to BDC). Cylinder pressure is the actual pressure
that the engine is producing. The difference being mostly due to pressure bleedoff from
the cam. It is possible to have a high compression ratio (11:1), and pump gas, by
bleeding off some of the pressure with the propper cam design. This is benificial
because you get more "squeeze" from the gasses. Do the opposite and you get high
pressure with low a compression ratio (9:1).
Later...
Derrick

DesignTech@worldnet.att.net wrote:

> how the hell does someone get 160 psi from 9.1:1 CR?

 



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