Milling down the head?

[Thesil]

I recently purchased 10.5 to 1 pistons, I would like to know how I can increase the compression ratio from there. I would like to have 11.1 CR. My thought was to either have a thinner headgasket, or mill down the head? any suggestions?

[TBreu007]

You could do both.It's recommended to shave the head anyway to get a nice smooth mating surface to curb leaks.

A good auto machine shop or shop that spacializes in heads can do it no problem. You should at least get a match port or maybe a full head port too since you have the head off.

[SSS]

Don't shave the head too much, 8 thou would be MY limit. You could also do what i did, and have an additional 5-6cc of material welded into the combustion chamber, bringing compression up by about 0.5:1 to approx. 11.0:1-11.1:1.

[TomsMR2]

the difference in power between 10.5:1 and 11:1 is very marginal... plus it'll knock easier. leave it where it is man.

[TrunkMonkey]

the difference in power between 10.5:1 and 11:1 is very marginal...

right on the money.

you won't notice any gains by switching from 10.5:1 to 11:1 (maybe 1 hp). at this point, 11:1 will only gain you bragging rights.

-demetrius

[Aries]

right on the money.

you won't notice any gains by switching from 10.5:1 to 11:1 (maybe 1 hp). at this point, 11:1 will only gain you bragging rights.

-demetrius

bragging rights, and a motor that will only run on 104 octane...

[Thesil]

ah wise 240 owners you are... thanks a lot