Forged vs Billet: Callies Explains Crankshaft Choices

When we began our conversation with Brook Piper at Callies Performance Products, our conversation humorously compared crankshafts and baking cookies. When you consider the metallurgy and machining processes involved with a racing crank, there are many variables to create a good cookie… er, crankshaft.

The left is a Callies Performance Products billet steel crankshaft, while a Ford forged 4340 Magnum crank from Callies is on the right.

4340 Crankshafts

The Forged 4340 crank is created with a process that matches its title. The “4340” references the alloy of metals, while “forging” describes the heating and compressing of the metal into forging dies on a multi-ton press.

“What qualifies as 4340 steel is a broad term,” Piper describes. “Many parts of the world struggle with material cleanliness, but it still reaches the parameters as a 4340 material. Callies acquires different raw materials from all over the world to create what we think is the purest SAE 4340 billet that goes into our forged Magnum crankshaft line.”

High heat and tons of pressure stamp the 4340 metal in a mold into its general shape, while a billet crankshaft begins as a cylinder of high-strength alloy with massive amounts of material machined away.

The Compstar line of forged 4340 crankshafts is a more affordable option; these cranks are forged overseas in Callies-owned dies, rough machined to pre-finish dimensions, and completed in Ohio.

“One key difference between Callies in-house and overseas materials is that they can’t get as much nickel in the 4340 material as we can stateside. They also have energy restrictions there which limit heat treating and nitriding processes. We can achieve more surface hardness here,” Piper describes.

Everything that makes a crank’s alloy strong is there for a reason. Nickel makes it tough, silicone provides machinability, and carbon makes it better to harden. There’s a real recipe to it. – Brook Piper, Callies Performance Products

That said, the Compstar line still has cost-effective value as a racing crank to limit at approximately 1,000 horsepower. “We are approximating our horsepower claims because we want to talk to our customers,” Piper says. ‘Many variables like car weight, drivetrain, normally aspirated/nitrous/boosted parameters may alter our recommendations.”

Side-by-side cutaways between a billet and forged crankshaft illustrate the difference between the alloys' grain structure. The forged crankshaft (left) shows how it achieves its strength by compressing the material, and the tighter grain flows along the length. The billet grain (right) flows straight, but the material is far stronger in this condition.

Piper continues, “Let’s say an enthusiast wants a big-block crank for 800 horsepower. Our Compstar will do that all day long. If they want American-made with a longer life, they will be spending 3,000 dollars for a billet crank, but that’s what we do. We sit down and try to cater to a customer’s needs.”

Billet Crankshafts

Production of a billet crank is very different from a 4340 forging — the process will quickly explain why there is a higher price point.

Callies' precision CNC and lathe centers do all of the machining processed by their Ohio craftsmen on their Billet and Magnum line cranks, while the Compstar line arrives rough machined and finished in-house.

Compared to a forging shaped with presses and dies, the Callies Ultra and Magnum billet cranks are machined from a solid bar of high-strength steel alloy. That is a lot of machining and wear on equipment. In Callies’ case, the billet material is typically a 4330 material. This alloy may sound close to a 4340 number, but it is a highly different alloy with more premium steel.

“We also use an EN30 steel that offers additional strength for huge cubic inches, longer spread bore blocks and nitro applications,” Piper explains.

Callies, crankshaft, crankshafts, billet, forged

Another variable is life expectancy. The Callies team can’t stress enough that they want to help enthusiasts decide between a billet crank’s life and strength option, or possibly replace your 4340 crank in less time. It’s all in the alloy “recipe.” If you’re in the market for a new crankshaft, give them the team at Callies a call to discuss the best choice for your application.

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About the author

Todd Silvey

Todd has been a hardcore drag racing journalist since 1987. He is constantly on both sides of the guardwall from racing photography and editorship to drag racing cars of every shape and class.
Read My Articles

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