I have a set of wiseco domed pistons that I want to have local machine shop cut down to lower the cc's so I can achieve my desired compression ratio. Is there an aprox measurement for how much cut per cc. Like when you get your heads milled its approx 6-7 thou cut it equals 1 cc. THX

 

Two ways that I know to do it.

First and most time consuming is to actually mock up, with top ring and some grease to seal the chambe, install the head wtihout gasket and, using a buretee and ATF measure the chamber volume. The before/after chamber volume will verify the actual dome volume; they do vary from the manufacturers spec. Then, mill off .001", re-measure and you will know how much to mill to hit your target.

Easier way is to determin the alloy, i.e.., 4032, etc. get the weight per cc and go from there. For instance, 4032 alloy weighs 2.8 grams/cc. So, if 2cc was needed to be removed from a 4032 alloy piston, you would weigh the piston, shave off a bit, say .001"-.002", reweight the piston; keep shaving until you have removed 5.6 grams (2cc x 2.8gms=5.6gms)

I don't know any easier way to do it.

 

Plus 1 hear on your input
This is a good way to remove excess dome without having to re-cc piston: Mill a small amount and re-weight piston until total reduction is reached.




First and most time consuming is to actually mock up, with top ring and some grease to seal the chambe, install the head wtihout gasket and, using a buretee and ATF measure the chamber volume. The before/after chamber volume will verify the actual dome volume; they do vary from the manufacturers spec. Then, mill off .001", re-measure and you will know how much to mill to hit your target.

Easier way is to determin the alloy, i.e.., 4032, etc. get the weight per cc and go from there. For instance, 4032 alloy weighs 2.8 grams/cc. So, if 2cc was needed to be removed from a 4032 alloy piston, you would weigh the piston, shave off a bit, say .001"-.002", reweight the piston; keep shaving until you have removed 5.6 grams (2cc x 2.8gms=5.6gms)

I don't know any easier way to do it.[/quote]

 

Jack,
Call the shop and I can give you the dedicated gram weight per cc for them.
Scott