February 08, 2007
by: jovial_cynic
I'm trying to figure out how I came to a 9.5:1 CR calculation that I mentioned early on in this project.

Right now, I've entered in some stats into the CR calculator, with the following values:

Bore size: 87.75mm (Z22 bored out .75mm)
Stroke: 86mm (L20b crank)
Headgasket bore: 88mm (that's a guess; I just figure it's gonna be 1mm over the stock bore)
Compressed gasket thickness: 1.2mm
Combustion chamber volume: 42.5cc (A87 head)
Piston dish volume: -9.32cc (stock Z22e pistons, but they are shaved down a bit...)
Deck clearance: .2mm over deck (shaved down from .4mm)

The calculator says I'm going to run 9.98:1 CR, which is a bit higher than I originally calculated. Weird.

I had considered running a turbo or supercharge previously, but with the CR so high, I think I'll wait to do that with another engine in the future. 9.98 is probably just fine for an old NA datsun engine.
np category: 510


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