Piston/comp confusion

Anonymous · Post by **Anonymous** » Sun Mar 06, 05 10:44 am

Ok guys, please bear with me on this one!
I need 360 pistons. I would like to increase the comp rate from approx. 8.4/8.6 std to 9.3/9.6. I appreciate that a number of exact measurements are required to calculate exact comp rates.
That aside, my difficulty is trying to interpret sellers info into approx. comp ratios
e.g would these pistons be appropriate for daily use with mild cam, 3.23 gears etc
http://store.summitracing.com/
cylinder head cc for my motor suggests 65-73cc (big variance!)
If anyone is happy to get their hungover(?) heads onto this on a Sunday morning i'd appreciate it!

Dave-R · Post by **Dave-R** » Sun Mar 06, 05 12:17 pm

Give us the right link to the summit part no.

What year heads are these? I might have the chamber cc listed.

Dave-R · Post by **Dave-R** » Sun Mar 06, 05 12:19 pm

Here are some more pistons for you to look at.

http://www.hughesengines.com/general/pi ... istons.asp

Anonymous · Post by **Anonymous** » Sun Mar 06, 05 1:10 pm

Dave, heads are 79/80 ( I think) ..596 castings. My book has them at somewhere between 66-73 cc.
The Hughes pistons appear to be same spec as the ones in the link i tried to post ecept for Summit are selling them at the clearence price of $10 each!
Got to take wife to lunch, i'll be back in a while1 cheers

Anonymous · Post by **Anonymous** » Sun Mar 06, 05 1:15 pm

The url doesnt help. The part number is STL -H405P30
and lists the piston spec and application.

Dave-R · Post by **Dave-R** » Sun Mar 06, 05 7:35 pm

Your heads are listed as having either 65.5cc or 68.4cc chamber volume so with those pistons (-10cc dome volume) you are going to end up with something around 9:1 compression ratio.

Anonymous · Post by **Anonymous** » Sun Mar 06, 05 8:33 pm

Thanks for looking it up Dave, as Mancini havent answered any of my e-mails i may still go with Hughes as they have selected pistons that they think are suitable. Summit provide a bewildering range (to the less well informed) which puts the onus on the buyer to know what he needs