Balancing a Crank

[LikeMy6]

- Has anyone here ever had or seen a production turbo crank internally balanced? Is it a PITA(expensive)?Reason I am asking is my father bought a Billet crank from Scat and it was Machined as a production replacement. when he had it internally balanced using billet rods and JE pistons, the machinist claims the crank was difficult to balance and that he had to use alot of Mallory! would this be common if balancing the production crank? If so I guess he would have been Better off leaving it externally Balanced. Would their need to be any difference in the couterweights(larger) if you wanted to internally balance this crank.Maybe Scat believed the crank was going to be externally balanced like the production crank. When buying a stroker crank say the 3.625" it IS usually internally balanced, does it come with larger counterweights for this reason?

Thanks for any help

Frank

 

[750H.P.V6]

Frank,

You hit the nail on the head. If you were to internally balance a stock crank it would take a lot of Mallory metal to balance it since there isn't enough counterweight material on the crankshaft.

Typically aftermarket forged/billet cranks have large counterweights since they are intended to be used in racing applications and internally balanced.

It sounds like your dad got a crank that was set up for external balance thus the need for all the Mallory metal. Mallory metal isn't cheap, how much did it cost to balance the crank?

Neal

 

[LikeMy6]

uh, you would have a SHIzniT if you knew! were Talkin over $1G I think its pretty bad that the machinist didnt see this and let my Dads engine builder know before he took it upon himself to just start drilling and packing Mallory. whats that crap(Mallory) sell for? the same as GOLD? I wonder now if all that drilling and filling has compromised the integrity of the crank! I dont think I would feel safe spinning it over 6000rpm. Neal what could he have told Scat to have them leave more Counterweight material,that he wanted it to be internally balanced?



Thanks

Frank