Aftermarket Cranks

[Larry Hill]

When you grind a 3.980 FE crank to 2.200 the crank is lighten about 1.625 pounds. I said pounds not ounces. The big gain is the change in polar moment of inertia. The weight reduction and where it occured is a big reason why the engine will accelerate faster. Multiply that times three if an automatic and four if its a stick and Ta-dah the car is faster.

And why does the 390/ 427get to use these rods?

[SSDiv6]

Originally Posted by Larry Hill

When you grind a 3.980 FE crank to 2.200 the crank is lighten about 1.625 pounds. I said pounds not ounces. The big gain is the change in polar moment of inertia. The weight reduction and where it occured is a big reason why the engine will accelerate faster. Multiply that times three if an automatic and four if its a stick and Ta-dah the car is faster.

And why does the 390/ 427get to use these rods?

Just 1.625 pounds?
I know of many that have removed a lot more by just using a different year crankshaft; there are OEM crankshafts for alter model car that have the crankpins and main journals drilled from the factory...and yes, the rules say no parts crossbreeding, however, how they can know?

As an example, you can get the "Stock Plus" GM forging crank fro Crower that is around 4 ~ 5 pounds lighter than OEM.

The rods were approved because at the time, it was the only rod that was close to the actual FE rod length. The same with the Oldsmobile small block rod; the first approved rods were 6" Chevy rods. It was the time of the advent of many new rod brands and makes, using forgings made in China.