Crank and Rod Innovations with Experts At Lunati - How it Works

Getting up to speed with the newest crank and rod innovations with the experts at Lunati

Stephen Kim Sep 27, 2012 0 Comment(s)
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Blower Cranks

Supercharged motors place stress on some very specific areas of a crankshaft that must be addressed for maximum durability. In high-horsepower motors, a supercharger can require several hundreds of horsepower to spin, which puts into perspective how much a blower can stress a crank. Lunati’s Pro Blower Series crankshafts for small- and big-block Chevys are designed specifically for supercharged motors. Since driving the blower with a belt puts lots of strain on the crank snout, the Pro Blower Series small-block Chevy cranks incorporate a larger big-block Chevy snout. All Pro Blower Series cranks also feature dual keyways and larger 3/4-inch threads for the crank bolt to ensure that the blower drive pulley doesn’t spin on the snout. Another benefit of the longer threads is that they allow the bolt to distribute clamping pressure to the front main cap. Furthermore, while Number 2, 3, and 4 rod journals still get gun-drilled like on all Lunati cranks, the Number 1 rod pin is not drilled. This strengthens the front end of the crank to deal with stress imparted by the blower. Lastly, to better endure the massive power capable with a blower motor, Lunati’s blower cranks have larger 1/2-inch flywheel bolts on the rear flange.

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Rod Lineup

Lunati offers three different lines of connecting rods. The Voodoo H-beam rods are our entry line and offer a great balance of strength and affordability. They’re forged from 4340 aircraft-grade steel, heat-treated, stress-relieved, and shot-peened. For the typical naturally aspirated, bracket race or street/strip combination, the Voodoo rods are a great choice. For power applications, Lunati recommend our Racer Series I-beam rods. They offer many of the same features as our Voodoo rods, but in a unique I-beam design that can easily handle well over 1,000 hp. The next step up is our Signature Series I-beam rods. They’re similar to the Racer Series rods, but come fully deburred and feature back-cut and radiused boltholes. Since the rods bolts are among the most highly stressed parts in an engine, Lunati includes premium ARP 2000 rod bolts with all of our connecting rods.

Rod Design

Some people say that H-beam rods are stronger than I-beams, while others say the exact opposite. Lunati manufactures both types of rods, so we’re very familiar with the pros and cons of each design. Generally, I-beams are lighter and stronger in compression, while H-beams are heavier and stronger when stretched. That said it’s not accurate to generalize that one design is stronger than the other. It really boils down to the overall design of the rod, and strength is independent of whether a rod is an I-beam or an H-beam in shape. A rod’s strength and durability comes from the material used, overall design, and the quality of the CNC program used to machine it.

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Stroker Kits

Some people don’t mind piecing together a rotating assembly, but Lunati offers convenient rotating assembly packages for both small-block Chevy, big-block Chevy, and LS applications. The kits are compromised of either Voodoo or Signature Series components, and include a crankshaft, connecting rods, pistons, rings, and bearings. A cam, timing set, and lifters can be added as optional items. Although we try to offer a diverse range of displacement options, piston compression heights, and compression ratio, we can also mix and match components to customize a package to a customer’s needs. Just call us and tell us what you need.




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