Vizard's book has excellent instructions for computing the CR as well as
tables of values for the volumes of the various 'forgotten' volumes that
need to be added into the calculation. (like between piston and cylinder
wall above the first ring).
For my next rebuild of the turbo motor I'm coating the valves, combustion
chambers, and the insides of the intake and exhaust headers. This reduces
the tendency to pre-ignite by lowering the heat of all the involved
surfaces.
With a 0.040 overbore, block decked to piston height, 23cc CC volume and a
13cc dish, I'm looking at about 8.7 to 1 for 91 octane. For a non-turbo
motor, I'd check Vizard's book. Its my new bible, residing on the coffee
table for light evening reading.
Glen
>> compression that is realistic to run on said street motor?
>
> Other issues... What is the standard 1275 piston diameter in both inches
> and mm? What is the best way of determining the volume of a dish in an
> installed piston? Assuming that I have the measurement of the bore
> (70.5mm), the distance from the top of the block to the piston (1.6mm),
and
> can figure out the volume of the dish in the piston (small dish), then
what
> would be the methodology to determine the combustion chamber volume needed
> to reach a particular compression ratio?
>
> Suggestions? Anyone have thoughts on getting thermal barrier coatings on
> the head and valves?
>
> Jackson Zimmermann
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