Piston:
SE Pro Twin Cam Forged Piston FOR the ACR Performance 10 110+ Cylinder Heads -3-7/8"

Query:

When paired with an appropriate cam, and everything else is in place, does anyone have any factual information about the pistons not producing a 10:5:1 compression ratio?

Any doubts at all whether they are factual, or not?

Are the Wiseco domed 10:5:1+5 Domed Pistons more reliable and of better quality than the SE or are they rated the same?

Is their a better brand?
BD

 

A compression ratio has nothing to do with the cam choice. Your choice of head gasket will have more effect on CR than minute manufacturing tolerances on pistons. Now cam choice will effect cranking pressure and what alot of guys like to call corrected compression ratio but a true CR is nothing more than Displacement + Head volume divided by Head Volume. Factoring into the displacement is also the piston dome cc + or -

 

The compression is dictated buy the combustion chamber size and amount of dome on the given piston. The ACR heads have a combustion chamber of 95cc so the SE piston dome is approximately +14cc which will give you approximately 10.5:1 with a stock gasket. The SE stuff is petty close so the compression ratio will be right around 10.5:1.
Now the wiseco piston you are speaking of is only +5cc dome. With the stock head that had a 85cc chamber, would give you 10.5:1. But, if you combine it with a 95cc chamber head like the ACR you will only have about 9.6:1.
Harley and wiseco make quality pistons.

 

Thanks just tryin to decide whetether I want to use my old SE's with new stock heads or invest in Wiseco. Either way the pstons are going to Baisley's along with the heads to match things up. Thanks guys.

 

There is more to it than just dome vs chamber, you have to factor in the displacement of the cylinder , ie roughly 800cc per cyl into 80cc dome, roughly 10-1! With +cc domes you lose those cc in disp value but also lose those cc's in dome volume, it is actually more of a flame travel/squish thing, dome shape that is ,when designing pistons and heads together in a package as some of the SE products are. There are problems when mixing up products from diff mfg's with no prior experience on how they will work together , not just CR numbers. Having the pistons sent along with the heads to your head guy is the correct thing to do.

 

Thanks, good information, I'll lay it all out to Dan, I'm sure it will all come togther, as a result of input from all.