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From: Terry Smith
>Jarrid
>I'd like to know how much of a dish you would consider adequate and what
>compression ratio should I be looking to go for. Why can't the additives
be
>used to compensate for todays gas?
Gosh I dont know what you expect in an alpine motor.
If you want a good running stock motor, 9.2/1 is a good fugure,
in which case, the 1725 pistons have 7 ccs of dish volume.
My measurements of a OEM dished pistons showed close to
7cc dish volume, head gasket volume loss was 3.6cc and basic
chamber volume was 37ccs.
Add it all up, and you get 47.6cc
divide that by the swepped volume 431.25 (std 1725 disp) to 441.8 (.040
over)
give a net compression ratio between 9.06 and 9.28 to 1 depending on your
bore situation.
If you want more, compression will generally give you 4bhp per compression
integer increase.
You will have to mill the head, or use flat top pistons to go beyond
9.3 to 1.
If you want more than that, camming is the strategy.
Jarrid
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