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Re: Compression Ratio/Was: Looooooow Gas Mileage Question

To: <tigers@autox.team.net>,
Subject: Re: Compression Ratio/Was: Looooooow Gas Mileage Question
From: "Tom Witt" <wittsend@jps.net>
Date: Fri, 6 Jan 2006 22:23:55 -0800
David,
Since you theoretically would keep everything else the same (including the
cam) it would prove interesting. As cam duration increases so does the time
the valve is open. Hence, there is static compression which is a mathematic
formula of the bore, stroke and combustion chamber (discounting duration,
overlap etc.) and there is.... well I'm not sure what it is called, but it
factors in the "real" compression of the fuel/air mixture in relationship to
the cam.  I guess the point I'm getting to is a 12:1 compression ratio may
result in a significantly higher "true" pressure with a stock cam than the
"race" cam (with longer duration and typically overlap) general found in
engines with that type of compression ratio. I would think there is a limit
(perhaps at the point of diesel!) that relates to compression and cam timing
(duration, overlap etc.). Basically I'm saying that a 12:1 ratio with a race
cam may generate similar True pressures to that of a stock cam with a lower
ratio. So, the bottom line is, "do you even want to go there?" Frankly I
don't know, but thought that my pose might have some merit worth
consideration.
Tom Witt




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