Just curious why does tuner prefer to use doctile iron sleeve versus FRM. Isnt FRM harden carbon material suppose to be stronger than any metal, or is it just easier to produce piston for non FRM sleeve.

 

fiber reinforced material is just the lining used inside the cylinder. It is designed to be strong enough for oem specs, you cannot run aftermarket forged pistons/rings because the two similiar aluminums + higher heat expansion of the forged piston will wear each other out within a few thousand miles. Mahle makes forged pistons with a special coating that will work with frm sleeves w/out damaging anything. Iron sleeves with conventional forged pistons will be much stronger, it all depends on your power goals.

 

As Flex says, the reason aftermarket builds use iron is that the available pistons are incompatible with FRM.

FRM/MMC technology is not a simple process. It is a way of giving aluminium the strength and hardness required for a hi performance engine. So a light weight alloy block can have strength and longevity.

So another reason is availability. Ductile iron sleeves are freely available.

Also, the F20C is an open deck design. By using ductile iron sleeves with a wide top you convert the block to closed deck which is better for extremely high hp applications.

 

What I'd love to see is a closed deck Al sleeve with a FRM/MMC inner liner.

Not likely though.