How few cc's&psi on 93oct pump?

[stoneman]

I'am looking for a little more,safely out of my stock 98 260efi.
I figured the heads would be the best place to start.Was needing
to know how few cc's and max psi for good pump gas?
Thanks stoney!

[Firestarter]

36 cc = 145psi

[us1]

33cc at 145lbs.

[Talon2.5]

hey stoney!!


go to this thread for some good reading on this subject, click on the link below



http://forums.screamandfly.com/showthread.php?s=&threadid=12469

[Talon2.5]

and this one on the mathematics of cc's



http://forums.screamandfly.com/showthread.php?s=&threadid=12588

[Firestarter]

Us 1

I have 37-8cc stock heads, 36cc Champ heads (from merc), 34.5cc heads, 32cc heads, 26cc heads, and 21cc heads.
On my snap-on compression gauge, with a warm motor, flys open, and a good battery. The above yeild 130 (+/- 5), 140-142, 149-151, 155-160, 178-80. and 200. I can say that I know for sure that the measured (properly) 32cc heads with the thin gaskets 91 oct and 25% C-12 at 25 deg will detonate. With the 26cc heads you need VP-Red, and with the 21cc heads you need the C-12. Even the 34.5 cc heads are really close.
I am curious Y some say you can run 32cc ( I know others that agree), and other builders say 35cc is the min on pump gas.---which is my experiance. Now in all fairness, I also feel that that appliscation has a lot to do with how tight you can run, a drager with a 22 turning 10k freewheels his motor for a very short time, as compared to me who turns a 30 well into the 9's for a few miles.

Your thoughs.

Thanks

RT

[us1]

Its posable you motor has a low deck. Most all of my motors and guages read 145 with 33ccs.

[Firestarter]

3 undecked 260's, and 2 drag motors? ( I should also mention that the drags blow a few psi less 2psi).

Must be the cold Canadian air EH!.

RT

[Jay Smith]

Not to get into the middle of something BUT I have found that @ 33 to 34 cc will render 145-148 # compression. Firewalker seems your snap on gauge is a little low as the 21 cc heads render over 200# on our motors. Maybe I'm down in this thick muggy air which DOES make a difference. I used to run 200# compression with 4 gallons of 108 Phillips Racing with 1 gal of Exxon super unleaded at 10,000 rpms and have NEVER detonated a piston Maybe your altitude has made a difference in your numbers on your gauge and your detonation problems more apparent. Like I said don't want to start some stink just telling you what things are like for me.....


Just my observations !

Jay @ JSRE