Your table on compression ratio vs head thickness should be helpful. Much
of this information appears in the MG Special Tuning handbook. My copy of
this booklet was issued in 1954.
I was able to spot check five of your figures. Four of the numbers were OK,
but the XPEG 9.0 ratio for a 2.959" head seems to be in error. The handbook
shows 9.45 for this ratio.
Also, it should be pointed out that if the engine has been bored, or if the
head has been ported/reliever, then the table would not apply. Also, you
may have used the original compressed head-gasket volumes in your
calculations (4.5 cc per cylinder for the XPAG and 5.25 cc for the XPEG).
Today's gaskets may have different compressed volumes.
Ben 54 TF 1500
----- Original Message -----
From: Bullwinkle <email@example.com>
To: mgt <firstname.lastname@example.org>
Sent: Wednesday, September 06, 2000 3:39 PM
Subject: Re: Compression Ratio Calculation
> If you can accurately measure the head thickness with it still on the
> then perhaps this will help.
> Head thickness chamber ratio
> inches size 1 1/4 litre 1 1/2 litre
> 3.022 200cc 7.25 8.33
> 2.959 175 8.1 9.0
> 2.928 165 8.6 9.9
> 2.898 150 9.3 10.7
> Bill Loubiere wrote:
> > Is there a calculation which you can use the compression test data to
> > calculate the compression ratio on your car?