Egil Kvaleberg wrote:
>
> On 11 Oct 1997, Mark Stahlke wrote:
>
> > Sounds like a reasonable theory. I can measure atmospheric pressure with
>a
> > barometer. Anyone know how to convert inches of mercury or millibars to
>pounds
> > per square inch?
>
> $ units
>
> You have: mbar
> You want: psi
> * 0.014503774
> / 68.947573
> You have: in Hg
> You want: psi
> * 0.49115415
> / 2.0360207
> You have: ^D
> $
>
> Problem with your theory is that you seem to get a higher pressure from
> the compression reading than you get by multiplying the atmospheric
> pressure by the compression ratio. For instance, my 10:1 compression
> engine gives a reading of around 180 PSI.
>
> Egil
> --
> Email: egil@kvaleberg.no Voice: +47 22523641, 92022780 Fax: +47 22525899
> Snail: Egil Kvaleberg, Husebybakken 14A, 0379 Oslo, Norway
> URL: http://home.sn.no/home/egilk/ PGP: finger:egilk@sn.no
Please correct me if I am wrong, but I always thought the compression
ratio was the amount that a given volume of gas was compressed. In
other words, if the compression ratio was 10:1, then the gas would be
compressed to 1 tenth of its original volume and the resulting pressure
would be ten times the original pressure regardless of what the ambient
pressure is.
There should be a formula whereby if you know the volume of the cylinder
(which you do... Spitfire 1147 would be 1147/4 or 286.75cc etc) and you
know the compression ratio of the pistons (you should be given this in
the engine specs. or the piston mfg. specs.) you should be able to
calculate the correct compression for that engine.
Since I am no math whiz, I don't know what this formula is. However
I'll ask my engine rebuilder and see if he knows.
Joe '63 Spit
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