On Oct 14, 9:28am, SCHWANGAU@aol.com wrote:
> Subject: Re: Compression Tests--real world
> Why don't the numbers work for my application? I am measuring 180 psi on a
> 9.6 to 1 motor, and a 150 on a 7.5 to one motor. There must be some other
> factor we are not considering. Inertia? Chamber shape? Latitude? Left
> Coast?
>
> Brian N.
>
> 65 Spitfire 9.6 cr
> 79 Spitfire 7.5 cr
> (California)
>
>-- End of excerpt from SCHWANGAU@aol.com
Brian and others,
I just talked to a friend of mine who works in engines, and he tells me
that you *cannot* calculate the compression ratio from the measured
compression. He further states that you *cannot* accurately predict
compression from the known (or idealized) compression ratio.
One of the variables affecting the compression is valve timing. As the
intake valve opens later and later, compression will drop.
Doug Mitchell
dmitchel@ford.com
dmitchel@ismi.net
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