Cast vs. Steel Crankshaft

[njk53]

I would like an opinion from the engine builders on CR.

We run a BBC in a 4200 lb. car. One of our motors had a cast crank and the other had a forged steel crank. There are two schools of thought regarding cast vs. steel. The cast crank is lighter which in turn reduces the reciprocating mass of the engine producing more power. The other school of thought is to use a heavier steel crankshaft to keep the rotational momentum of the motor high due to the heavy weight of the car.

Anyone have experience on this subject?

[FireSale]

My school of thought is simple. Forged is stronger than cast - they are both steel - and my block is worth a lot to me. Crankshaft and rods are nothing but forged 4130 steel. I intend to leave nothing on the track but rubber.

Dale

[SSDiv6]

Originally Posted by njk53

I would like an opinion from the engine builders on CR.

We run a BBC in a 4200 lb. car. One of our motors had a cast crank and the other had a forged steel crank. There are two schools of thought regarding cast vs. steel. The cast crank is lighter which in turn reduces the reciprocating mass of the engine producing more power. The other school of thought is to use a heavier steel crankshaft to keep the rotational momentum of the motor high due to the heavy weight of the car.

Anyone have experience on this subject?

My experience and preference is for a lighter assembly.
The reduction of the reciprocating weight will allow the engine to accelerate quicker.
You can purchase a steel crankshaft that is as light as a cast iron piece.