I am currenly in the proccess of buying new pistons for my AP1 and everywhere i turn for new pistons (JE, CP, weisco) they all say i need to put in new sleeves. Why? they are the stock or standard bore, so why would i need to resleeve my block. would i need to resleeve the block for new OEM pistons as well or is this just for aftermarket / high performance pistons. i have a brand new block due to a wrist pin going bad in my other motor, and i really dont want to have to resleeve it. Thanks

 

If you have a new block you probably don't need to. They are assuming you're putting the pistons in a used motor, which means the cylinder walls could have varying degrees of wear. Also they don't always wear evenly, you can have an oblong cylinder or scoring.

If you really want to know, call up the manufacturer and ask them. Let them know its a brand new block, then see what they say.

 

I have heard (so may or may not be fact...so buyer beware): the oem piston material is a special alloy for use with fiber reinforced cylinder walls. Other pistons will be damaged by the fiber reinforced cylinder walls.

I believe the H22 in the Prelude had the same problem.

You might do some internet searching on fiber reinforced cylinder walls and pistons to see what kind of hits you get to see if you can verify.

 

the f20 has fiber reinfoced metal sleeves FRM and the pistons are made specially for these sleeves and when you get aftermarket pistons they will expand faster than the FRM material and tear up the cylinders.

if your cylinder walls arent too scorned/scuffed you can have them honed but there is only a certain amount they can be: before you tear through the FRM material. and a special machine/ machinist should do it as they're require differnet procedures than regular sleeves.

but since you have a new block you may be okay.

 

Thanks for all the info, this helps. i should be good with OEM pistons for sure. i just need to do some phone calling to find out if the Aftermarket pistons will be good on a new block.

 

Aftermarket pistons will not work in stock sleeves, unless they are frm friendly. Looking at the mgf site will tell you. Mahle makes frm pistons for h22a's but not for f20's to my knowledge. Unless you want to have your new block resleeved, you will need to use oem pistons which btw you can get in overbore specs.

What was said above is true, if you put forged aftermarket pistons in your oem frm bores the pistons will gouge your cylinder walls. This usually happens in a matter of minutes.