Jon,
My 1972 workshop manual gives MG compression ratios and pressures for 8.0:1
at 130 lbs/sq in and 8.8:1 at 160 lbs/sq in. Compression ratios and
pressures don't really relate to any simple formula, but for the sake of
simplicity you can develop a simple linear formula based on the above givens
and arrive at pressure = 37.5 x c.r. -170 lb/sq in, or c.r. = (your reading
in lbs/sq in) + 170 all divided by 37.5. (P + 170)/37.5 = c.r. Thus 188
lbs would yield by that formula a compression ratio of a bit more than
9.5:1. It's been over 30 years since I took a course in heat and
thermodynamics in college, but I know that pressure and volume and
temperature are related in a rather complex formula much more complex than
my simple linear formulas above. I think that they could be used for
approximate compression ratios and pressure with close enough results.
Lawrey and other mechanics who deal with c.r. and pressure by empirical
(measured) data can probably guess better than those formulas.
Hope this helps,
Dave 72 B
>>
> How do you calculate this.
>My 'compresson preasures' are 188 !
>
>Jon Arikstad
>1970 MGB GT
>
>
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