Try the easy way. Log on to
SmokemUp.com
Click on the selections that lead you to the CR calculator.
Enter the capacities you have measured or are assuming.
Ring land is estimated from bore size (close enough).
Gasket requires you to measure the thickness and the size of a hole.
Plug it in. Push 'go', and you have your CR.
--JohnD
===================
Date: Thu, 18 Apr 2002 20:24:17 -0700
From Doug Ingram <dougi at shaw.ca>
Subject: Compression ratio calculation
The rebuild of my 948 is nearing completion, and I turned to David Vizard's
"Tuning the A-Series Engine" for instructions on determining the compression
ratio.
For any of you who are familiar with David's book, or the whole business of
C/R, I would appreciate your help.
My copy is the 3rd edition, published in 1999. On pages 222-223 he gives the
procedure for C/R calculation. What I'm missing is the gasket volume and the
ring land volume. In Fig 9.42 David gives these figures for 850/948 engines,
but not for 998/1100 or 970/1071/1275 engines. My 948 is bored out to a
standard 998 bore (2.542 in), so that's the info I need. Confusing me more,
he gives a couple of examples in the text on page 222 and 223 quoting gasket
and ring land volume from Fig 9.42, but I can't see where the numbers come
from.
Hopefully I'm just blind or something. Anyone?
TIA,
Doug Ingram
Victoria BC
1958 Sprite (AN5L/636) soon getting a renewed heart!
1963 Sprite Mk II project (HAN7L/30003) cryogenically preserved for now....
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