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Old 02-19-2021, 11:52 AM   #9 (permalink)
Isaac Zachary
High Altitude Hybrid
Join Date: Dec 2020
Location: Gunnison, CO
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Avalon - '13 Toyota Avalon HV
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Originally Posted by jakobnev View Post
Wouldn't other moving parts need to shed some weight too to keep the engine balanced?
Pistons are usually balanced by other pistons, at least in 4, 6 and 8 cylinder engines. Usually one piston goes up and another goes down at the same time canceling each other out. This is why you're supposed to try to keep all your pistons the same weight. I put my pistons on a scale accurate to the tenth of a gram when rebuilding. And some sets are much heavier or lighter than other sets already, with no change in engine balance in the end.

But depending on the engine yes, this could be true. Any engine that has an inherent primary imbalance, like a 3 cylinder engine, will usually have some sort of weights on the flywheel and pulley to counteract the imbalance. But you wouldn't have to lighten everything in the engine to restore balance. You'd just have to take off a little at those weights.

Originally Posted by Piotrsko View Post
I thought Mahle custom pistons were lost wax style of casting with machining to tolerance. So no great leap to sinter cast them then machine and I can see where they can be made thinner that the lost wax process.

With lighter pistons, you just remove metal from the rotating mass counterweights, NBD.
3D printed pistons are still in the test phase. Apparently this can make then significantly lighter than other methods like with the gyroid design freebeard mentioned.
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