[s-cars] Question about compression ratios and tuning

M Pederson mlped at qwest.net
Mon Feb 2 10:23:04 EST 2004


Has anyone actually measured the combustion chamber volumes for any of these
heads?

What's the source for the information a 3B motor's default compression ratio
is 7.8 to 1?  IMO, a difference of 1.5 vis-à-vis the AAN's 9.3 to 1 is too
large to be accounted for by a head gasket, so that pretty much leaves
either: 

(a) a substantially different piston; or
(b) a larger head chamber.

I doubt (but I don't know for a fact) it's the head chamber, so that would
leave the piston.  

Anyone have a photo of the 3b piston to compare to the AAn or can they
describe the differences? 

Mike  

-----Original Message-----
From: s-car-list On Behalf Of James Bufkin

3B engines have a default compression ratio of 7.8:1 with a displacement of 
2226ccs.
AANs have a CR of 9.3:1 with a displacement of 2226ccs
S1 blocks have a CR of 7:1 with a displacement of 2100ccs.

What effect would using a 3B or AAN ECU in conjunction have on an S1 
block?   What power band characteristics would such an engine have?

James
Austin TX

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