I'm planning on boosting my JDM H22 and am very interested in the Mahle Gold Series pistons (MFR). Finally a piston designed for my sleeveless block!! If my cylinders are in good shape can these just go in, or does my block need to be honed to take the 9:1 slugs? And if anyone has heard of or had any experience w/them, are there any specific rods that they work best with?

 

Not to sound like a jerk or anything, but there was about a 14 page thread on that topic alone. Search and you'll find it. Off the top of my head, yes the Mahle's are compatible with the frm sleeve, and some bore out the cylinder walls .25, but I think the main question was how long do they hold up.

 

Mahle has a sweet piston setup for the h22's now. In the old days for h22s with the FRM cylinders you had to go with sleeves if you wanted to run forged because of expansion and what not. I reccomend going witha .25 overbore piston from Mahle to get a fresh surface to seat the rings with.