changing pistons.. Balance the engine or not?

walmore · Jan 12, 2017

Hi there

I´m changing the pistons of the my engine 4.6 3V, the weigth of the stock pistons are 460gms and the weight of the new pistons are 466gms. The question is if I have to balance the engine?

thanks for your help

drive_55_not · Jan 12, 2017

I know the LS guys will simply throw new rods/pistons into their junkyard motors and run em', but they also don't turn the 7000+rpms the Mod motor can ..

IMVHO since it's apart, have it balanced.

.

RocketcarX · Jan 12, 2017

You'll be fine as is, 6 grams is essentially the weight of a nickel

RED09GT · Jan 12, 2017

Are the pins close in weight too?
If so, you'll be fine.

tjm73 · Jan 12, 2017

RocketcarX said:
You'll be fine as is, 6 grams is essentially the weight of a nickle

In total 8 nickles then.

If it's coming apart to have new pistons installed, balance it. It makes a difference. The piston pins also factor in to it. Did you account for the weight impact they will have? What about the ring pack? If you are spending several hundred dollars to do this swap, why not spend a little more to have it balanced correctly?

RocketcarX · Jan 12, 2017

tjm73 said:
In total 8 nickles then.

If it's coming apart to have new pistons installed, balance it. It makes a difference. The piston pins also factor in to it. Did you account for the weight impact they will have? What about the ring pack? If you are spending several hundred dollars to do this swap, why not spend a little more to have it balanced correctly?

The guy I learned to build engines from would say let it go, we saw this a lot messing with race engines, just my take on it though.
Ask the machine shop you use ands what they say.
You should weight the piston, pin and rings and then compare, its possible after that the weight difference is even less.

BruceH · Jan 12, 2017

Have it balanced. You have no way of knowing what the original balance specs were and/or how well it was done.

RocketcarX · Jan 12, 2017

BruceH said:
Have it balanced. You have no way of knowing what the original balance specs were and/or how well it was done.

This is true, I hadn't factored in the original balancing job being an unknown factor.

JeremyH · Jan 13, 2017

I would def balance again.

tjm73 · Jan 13, 2017

A friend of mine that has built a bunch of performance engines for other people I know says if you change something, balence it.

eighty6gt · Jan 13, 2017

You would be fine but with all of the bad karma from posting this in tech you should probably balance the engine to be safe.

wabirch · Jan 14, 2017

If you can add it to the budget knowing things could be pretty tense at home, it makes sense to add this to the list.

changing pistons.. Balance the engine or not?

walmore

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drive_55_not

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RocketcarX

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RED09GT

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tjm73

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RocketcarX

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BruceH

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RocketcarX

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JeremyH

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tjm73

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eighty6gt

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wabirch

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