Changing Compression

Clint F. stungun68 at
Thu Jul 19 00:32:44 EDT 2001

I'm guessing at how many cc's the heads are, so bear with me.

In any engine, if you increase bore or stroke, and leave the compression 
area alone (combustion chamber) you will increase compression.

If you change chamber size (mill head) and leave the bottom end, you will 
increase compression.

Try the formula:
E= compression ratio
Vh= displacement of individual cyl.
Vc= compression space (basically cc's of head, taking into account piston 
reach in chamber) of individual cyl.

E  =   Vh+Vc

Unless someone know exactly what the Vc is for both heads and different 
types of pistons, hard to say what the actual ratio is.

A 2.2, 70 cc Vc, .........   7.28
  2.3  70 cc                 7.57
  2.2  60 cc                 8.33
  2.3  60 cc                 8.66

My guess, unless the size of the chambers in the head are alot different, 
bore and pistons did it.

Remember, there is no substitute for cubic inches.

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