Bob:
Well, lets see:
Remember that I have a 1974 motor with a stock compression ratio of
7.75:1, so I need to go a looooong ways to get to 9.5:1.
The milling of the head took the combustion chamber volume to 44.5cc
(I cc'ed the head to determine how much to remove). The TR6 gasket space is
4.5cc according to David Vizard in "The Theory and Practice of Cylinder Head
Modification", so I end up at 49cc for the combustion chamber volume (CCV).
The stroke is 3.74", and with the 0.020" overbore the bore is 2.96".
So one cylinder displaces -
Pi x R^2 x STROKE
or
3.1415 x 1.48^2 x 3.74 = 25.7 cu in, or 421.22 cm^3 (DISP)
The compression ratio is defined as:
CR = (DISP + CCV) / CCV
or
CR - 1 = DISP/CCV, so
CR - 1 = 421/49 = 8.60
and
CR = 1 + 8.60, or
CR = 9.60:1
Close enough.
Vance
-----Original Message-----
From: RazorBobSr@aol.com [mailto:RazorBobSr@aol.com]
Sent: Friday, December 19, 2003 2:49 PM
To: Navarrette, Vance
Subject: Re: Update on TR6 motor rebuild
I would think that .120 off head and .10 decked and .20 overbore would give u
more that 9.5????? Are u sure?????? Something that I would WANT to know!!!
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