Lunati Crankshafts

Lunati's big block and small block Chevy crankshafts are forged from the finest 4340 aircraft quality certified steel.   The 4340 alloy steel meets aircraft cleanliness and purity standards. Our exclusive non-twist design allows for continuous granular flow, producing a crankshaft with a higher cycle bending fatigue over the twisted forging version. The specifications during manufacturing are of the highest Lunati standards. For racing use, it is necessary that we improve on factory standards. We have done this with the material as well as the machining:

Design Specifications:
• All radii in the rod and main journals are .140".
• Roundness of each journal is within .0001" or less.
• Micro finishing of the journals are a grade 5 RMS or better.
• Crankshaft stroke is ±.001" maximum.
• A plasma gas nitrite heat treatment is used, which gives a case depth of .015"-.022".

Oiling Technology:
The oiling system is similar to GM's factory specification, however, we have developed more precise points where the oil enters the main and exits the rod journal. This exacting entrance and exit point improves the oil film thickness available at the rod journal. In addition, all oil holes have special attention given to the design for proper oil delivery.

The Lunati Coutoured Wing Design:
Lunati is proud to offer the Contoured Wing Design counterweights on all of its Pro Series crankshafts. The design of the leading edge of the counterweight is extremely important in directing the air and oil around the counterweights. This design allows the air and oil to be directed to the main, rather than the connecting rods, therefore keeping the air and oil away from the rotating connecting rods. Air and oil move around the Contour Wing Design without losing contact with the boundary layer. If the air and oil lose contact with the boundary layer, eddy currents will form, costing valuable horsepower through windage.