Engine M44/07 150hp, M44/05 163hp??
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Tom
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Some people have been able to 're-ring' existing pistons/blocks with success, but there is a risk that the new rings won't seat well -- leading to poor compression, high oil use, smoking, etc.944year83 wrote: Fri Apr 17, 2026 9:44 am Can I change piston rings without doing anything to the aluminum block? Has anyone done this?
Why do you want to do that?
I understand, now. You're thinking of replacing the pistons in the 924S engine before having it installed in your 944. As you said the 924S has only 70 000 kilometers, it should be in good condition with fairly fresh bores, so fitting new rings to the 10:1 pistons and installing them ought to work fine. It will be a total strip down of the motor, so, you should probably replace all of the seals and the rod bearings in any case, since that won't add much to the bill, and you'll get a fresh, leak free motor. If the old rod bearings don't show signs of scratches, you can probably skip replacing the main bearings and the balance shaft bearings.944year83 wrote: Fri Apr 17, 2026 9:44 am Can I change piston rings without doing anything to the aluminum block? Has anyone done this?
It will be a lot of labor time, so if you're paying someone to do it, you will have to ask yourself if the 10-13hp gain will be worth the money. If you're doing the work yourself, it could be a fun project, though. You could also look into other power upgrades, like a camshaft, more modern ignition, AFM delete, ECU, injectors etc. but then, all of that wise advice about keeping things stock go out the window...