july7543

Due to a recent failure, I have been investigating a rebuild of my short block. I had a few questions that I wasn't able to find answers to by searching.

1. Does anyone have a feel for what the safe limits of boost are with stock compression and meth injections. I'm looking to push 12psi in the short term with more boost likely in the future.

2. Can the CP 9.0:1 or 9.6:1 pistons be used with the S2K's FRM sleeves? They actually seem to be cheaper than OEM and I may give due consideration to using these if it is required to have higher boost in the future. (So as to avoid tearing the head off again to add a 2 or 3mm head gasket.

3. Is sleeving the block needed if I don't intend to ever exceed 450whp?

[Edit] 01/03/09 To Update Subtitle

PsykotiK

if you have low CP pistons.. no need to use head gasket.. and you should use all oe parts if youre not going more then 450

m R g S r

check in to coating options for the CP's. CP's out of the box will not work, they need a special coating. there was just a thread on here about a company that makes pistons to work with the FRM sleeves, the company is wosner.

inline pro also makes a set of pistons to work with the FRM sleeves, but if i remember correctly, they wanted around $900 for a set of pistons. IMO that is insane, i got a complete mint f20 shortblock for $700. and i made 500whp on pump gas stock compression.

july7543

So I've stripped down the short block and it looks like I'm going to need a hone and at one new piston. As a result, I have a few questions.

1. Must the engine rotating assembly be rebalanced if one or all pistons are replaced.
2. Is it reasonable to replace only one piston and get four new sets of rings.
3. Is it worth changing over to f22c crank and rods to gain some extra displacement? Perhaps using either AP1 or AP2 pistons. I'm running an AEM EMS and am looking to use the 3.0" pulley I have with the Novi1000.

july7543

After reading a little about f22c vs. f20c. It seems like I should pickup about 5% torque across much of the rev range using the f22c. With the EMS, I would consider setting the redline at 8500 which would help negate some the loss in performance associated with a lower redline on a centrifugal sc setup. I don't track my car often so the extra torque is appreciated and the torque curve should still have that fun shape.

wadzii

mahle will makes pistons that will work w/o sleeving, they are made on a custom basis and run around 800bux.

i always recommend replacing the pistons as a set. If you are using OE pistons its not really necessary, just make sure they all weight about the same.

in your case, something blew up a piston, that means the others are probably damaged and will break sooner than later.. replace them all.

Replace all the rings.

If you are boosting use the ap2 pistons with ap2 crank and rods. Ap1 pistons will raise the compression to approximately 12:1. You will need a bigger pulley to reach the same boost if you add displacement.