Eagle crank balance info

[Nick Micale]

As Eagle has stated, their Buick forged crank is internal balance.

To go with external balance like stock, about 100 grams would need to be removed each from front and rear counterweight.

If aftermarket rods [heavier than stock] are used, then weight will have to be added for internal balance.

The rod and main bearings need to be "fit" to the journals. The crank does not have rolled fillets, but a radius journal.

If all goes as planned, this motor will be installed and running next week for "field" testing! It is going into a 10 sec. GN so it will be a good first example for us.

 

[9SECVSIX]

Nick, Were you working with 36.6% or 50% ?
If you were going to use a 6.5" steel rod and a J&E piston would you try for 50% or would that require a great deal of heavy metal?

Thanks
9sec.

 

[tminer]

With stock block and rods; girdle; HRP&S poly mounts; piston/pin/ring weight around 725 gms; a dampener; internal balance; and 6400 rpm max, would the stock balance % be ill advised?

Thanks,
Tom

 

[norbs]

Crankshaft specialists reccomended me 52% ? should i let them do this?

 

[420]

Speaking of the Eagle crank, Nick, did you get my e-mail on Sunday?

 

[9SECVSIX]

Eagle Crank Bobweight?

Anyone know the bobweight amount used on the Eagle crank?
Eagle can't seem to find out for us

Thanks
9sec.

 

[Ormand]

The bobweight amount is a function of the weight of the piston, rings, pin, bearings and the rods. Has NOTHING to do with the crank.
Neither the 36% balance, or the 50% balance will really "balance" the rotating assembly, since a 90 degree V6 will never be in perfect balance. The 36% will balance better in the vertical, however, and the stock engine mounts take out the horizontal vibrations, so you don't feel them as much. The 50% is closer to a real dynamic balance, though, and is better for long engine life.
The Buick Power Source has a decent write-up on balancing.