A couple of you guys may have seen my recent post about dilemma with my new engine that is going in soon. With my pistons and head chamber size, I'll be around 11.4:1 compression, and I want to lower it down into the 10's for driveability reasons. Here are the specs for my pistons at different combustion chamber sizes:

58cc -12.3
62cc - 11.7
64cc - 11.4
76cc - 10.1

Do you think it would be possible to have my combustion chambers on my AFR 190's opened up to around 70-72cc, and try to find a thicker head gasket to achieve my desired compression ratio? I dont remember the head gasket I'm runnig now, so I cant really compare gaskets yet. I'll find that out on Monday when I call Trick Flow.

 

What is your quench? You could use the .051 thick GM head gasket, but that would mess up your quench.

 

No idea. My builder may have it written down. This is my first engine so I was lax on the details when I was getting it built (a year ago...). I should have asked for everything writtin down so I knew what the heck I was getting.... Oh well, hindsight's 20/20....

 

Yes your AFR's combustion chambers can be opened up to
increase the cc size. Just don't take it all from one spot or do beyond the bore line. You'll have to get all the chambers the same too.

You'll need accurate specs on piston to deck clearance and valve notch cc's etc to accuratly calculate your measured compression ratio. Afr with there fast burn high swirl combustion chambers seem to tolerate a little more compression ratio but 11:1+ is a little high for pump gas. Aim for and honest 10.5:1. +/-

 

Thanks for the info. I'm definately not going to undertake this myself. Depending on how much the "operation" will cost, I may opt to have a little porting done as well. Any idea how much openeing the chambers should cost?