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Re: Compression Ratios

To: "Peter J. Thomas" <pjthomas01@snet.net>
Subject: Re: Compression Ratios
From: Bob Hamilton <hamilton@navnet.net>
Date: Fri, 27 Mar 1998 07:43:13 -0400
Peter and others,

        I believe that the compression ratio has very little correlation the
readings you will obtain from a compression gauge. The compression ratio 
is  the ratio between the cylinder volume at the bottom of the stroke and the 
volume of the cylinder at the top of the compression stroke. A 10:1
compression
ratio means the volume at the bottom of the stroke is 10 times the volume at
the top of the stroke.

        The readings you will get from a compression gauge are obtained
by the compression of the gasses in the cylinder and will be dependent on
the condition of the rings and valve seats and each cylinder reading should 
be close to each other if the engine is in good shape.  Of course an engine
designed with a low compression ratio will give you lower psi readings on the
compression gauge than an engine with a H.C. ratio.

Regards,
Bob

        


At 09:05 PM 3/26/1998 -0500, you wrote:
>
>Ok, here is where I show my stupidity.
>
>Bought my first compression guage.  It is calibrated in psi.  How do I
>determine the compression ratio? Ie. how do I convert  x psi to n:1?
>
>Peter Thomas
>
>
>
>
=========================================================
Robert (Bob) A.C. Hamilton, Waverley, Nova Scotia, Canada
The Man of Many Sunbeams - Alpine, Drophead and Saloon 1953-1954
Home Page: http://www.navnet.net/~hamilton/index.htm
E-Mail: hamilton@cast.navnet.net 
=========================================================

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