New Piston Heavier Than Original Piston

[FTTSHO]

You ideally want all pistons to be the same weight. All pistons need to be within 5 gram of weight difference, if you want everything to last as long as possible. The weight limits are different based on the engine, but ideally you want all of them to be as close as possible, within 5 grams.

Some engines are fine with upto 10-15 grams of difference, but some specify 5 grams. Also, conrod weight differences matter too, and there are specific limits to that too. I would not just go for “good enough”, I would try to get it as close as possible.

Just imagine the engine spinning at 4,000 rpm, and one piston causes things to be out of balance. It’s not good for the longevity of bearings.

 

[MaximumMini]

I ended up bringing the new piston down to 439g which is well within factory specs and so it should now be well within the factory specs for piston weight deviation.

The piston and new rings have since been installed and I'm driving the vehicle. At this time I'm doing hard acceleration runs to help seat the rings. It may take a while for full compression to develop. So far so good.