fatjoe10

Hi all,

I have an f22 block in good condition that only needs a rehone to restore the wall surface. I was thinking of using some f20 pistons with the f22 rods and crank to increase compression, as I've read on some forums. If I understand correctly the resulting CR is in the 11.7 neighborhood.

My question is, How much would I have to mill off the head/block, if possible, to achieve a CR between 12.7-13?

Another option I have is to use some 12.5 CR Woessner pistons, however I'd like to work with what I already have here sitting at home.... Your help is appreciated. Thanks!

Terror

What do you plan on doing that will require the compression to be at 12.7-13:1?

scors2

don't quote me on this but 1mm will take off a point of compression. I think when guys put a 2mm head gasket it reduces the compression by 1 point and i think the stock head gasket is 1.2mm but again don't quote me. but to raise compression that way is not a good idea. your bringing the valves closer to the piston i don't think it will work the way you want it to. and im pretty sure that anything over 12.5 you should go with race gas.

scors2

You should just use those 12.5 CR Woessner pistons.

fatjoe10

This will be more like an experimental engine... no real reason to do it other than I want to

Also, Inlinepro is able to tune a 12.5 cr engine to run on 93 without problems, as I've seen both in real life and from online research. In fact, there's an user here who has a stroker kit very near 13.0 if my memory serves me correctly running on 93 without issues..

So 1mm looks like so far? I will be claying this engine to be sure of no piston/valve contact.

scors2

I live in a place where fuel quality is not very good. I just don't feel comfortable running more that 12.5 on pump gas. Sure you can pull the timing back a whole bunch, but whats fun about that. But good luck to you I hope you figure something different out.

CrazyPhuD

JDM AP1 11.7 pistons in a 2.2L should put you right around 12.5

Requiem

^^^^Took the words right out of my mouth.

fatjoe10

CrazyPhuD: Wow I didn't even think of that. So no way to make with work with USDM ap1 pistons? I mean, I have everything I need. I'll look into the jdm ap1 pistons as well, thanks ppl

LostMotion

I think 1mm would take 7 CCs out of the chamber.

I would get a pro engine builder to do the calc, or do the calc yourself to make sure it's right. Don't take my back of the envelope calc as gospel.