Cutting hundreds of set of heads a year I find that 34 CC's with a 1 MM head gasket at seal level will yield 138-145 psi cranking compression IF motor is healthy, the highest I suggest on pump gas premium..
High performance heads that stock come in at 38 CC's ( 260 HP ) I find can be cut successfully by this formula :
For each .010" of metal removed you reduce the CC's by .7
Example if you cut .030" off you have reduced the CC by 2.1
so a safe/sensible route for Sean to take with his newly aquired 2.5 200 powerhead would be to buy some std 260 heads ............ or do you think that will not make sufficient difference?
I have no idea what his exisiting heads should be in cc
Cheers, i didnt think the xr2 heads would be to good an idea, heads are coming off anyway to replace headgaskets so il get the heads cut by 40- 50 thou, dont want to go too far,
chhers