Nitromethane

Hey guys. haven't posted in a while, but converting my 383 nitrous motor to a turbo motor project which means new pistons - my current flat top's weigh around 415g (according to the manufacturer) - my JE turbo pistons weigh "430g" (in actuality they are around 428/429g after weighing them myself) - someone told me that if the new pistons are within 5% of the weight of the old pistons, I don't "NEED" to balance the motor, is this true? I know I SHOULD rebalance - but if I'm not gonna notice any vibrations and there's gonna be no damage to the motor if I don't rebalance, I'd rather just put the new pistons in and get on with life. I'm willing to sacrifice a few hp.

So you guys with the machining experience, should I re-balance over a <15g weight difference?

chevyguy3

i wouldnt worry about it. normal carbon buildup and oil can add up to that much of a difference in weight (though some builders will account for that and take a guess at adding wieght for those factors when balancing)

personally though if it was my motor, i would get a good scale and grind your new pistons to the weight of the old ones (or as close as you can get if there isnt much material to play with)