balancing & piston weight

Seight-V8 · Post by **Seight-V8** » Sat May 27, 2017 1:37 pm

hello all,

how much material in weight removed a piston would constitute a engine re-balance?.

If I was to remove the same amount if material from each piston, and then make sure they all weighed the same afterwards.

just I thought I have about resolving a problem.

thanks

scott

stevieturbo · Post by **stevieturbo** » Sat May 27, 2017 7:04 pm

Aluminium is light...I'd think you'd need to go pretty nuts before it would become a concern.

Seight-V8 · Post by **Seight-V8** » Mon May 29, 2017 10:00 am

so I've tried to look at this problem with a little bit of scientific thinking.

so the weight of aluminium is 15g per 25mm cube....so google tells me...

I've made a cad model of a piston I have......and applied material mass to the model.

I've then worked out how much material I will remove to fix the problem I have.

The cad program tells me I will remove 0.605g from each piston, x8 piston gives a total removal of 4.84g for all pistons.

Info from the web tells me engines are balanced to 56g....

So is this material removal still inside a rebalance tolerance?....before I do more damage than good.....

thanks

scott

stevieturbo · Post by **stevieturbo** » Mon May 29, 2017 10:18 am

They'll soon build up 0.5g of carbon on top....and the weight of oil etc etc.

DEVONMAN · Post by **DEVONMAN** » Mon May 29, 2017 12:14 pm

When I had my engine balanced they adjusted the weight of each item to within 0.5 grms of each other.

What ever you do to the piston weight has less effect than say changing the weight of the big end of the con rod because reciprocating weight has only 50% effect compared to rotating mass.

Given that you have changed things like the flywheel and clutch the original balance is probably off a little anyway.

I wouldn't worry about 0.605 grms taken off each piston.

I have run an engine with pistons that were 19 grams lighter than the originals and only minor vibration could be felt compared to before.

Seight-V8 · Post by **Seight-V8** » Tue May 30, 2017 7:57 am

cheers all,

I need to get this engine moving, as I've now chosen to ignore it for over 4 months.....which doesn't help solve anything.

there's bound them be another problem along in a minute anyway, just my luck with this build....

regards

scott