A Crankshaft manufactured from a solid steel billet is the top end range of any performance engine. Not only is the integrity uniform, it also allows the designer to achieve the optimal shape for performance as the final cranks start from a solid piece of material. PAR’s speciality in unique cranks for the unique extreme application does not fit well with the use of large quantities of sub standard material for forgings. OEM forgings or casting are usually made from material that is just enough for standard applications and power, so are not suitable for high horsepower and extreme applications.

All crankshafts are fully counterweighted to allow for maximum torque and high RPM levels to be achieved with minimal harmonics generated by resonant frequencies as a result from whirling which is a common problem with semi counterweighted cranks. OEM cranks are mainly semi counterweighted to allow for casting and forging with minimal costs and were never designed to take high hp levels.

Weight is a common query. Weight should be considered relative to the application, in some situations where there is a big difference between bore and stroke ratio and a turbocharger is introduced, weight cannot be compromised since there will be a reduction in torque and strength, whereas on the other hand in a naturally aspirated engine, weight needs to be kept to a minimum.

MATERIAL: 4340 High Tensile Alloy Steel (Hardened and Tempered)

MANUFACTURE PROCESS:

• CNC Rough Turning – Main journals and outside diameters of counterweights
• CNC Rough Milling – Big end journals and counterweights
• Stress Relief – Stresses due to machining are eliminated by heating the roughed crankshaft to a relatively low temperature of approximately 600~650deg C, then holding for 3 hours and allowing to cool slowly back to room temperature. This will allow for all movement to take place during this process and not inside the engine after machining
• Complete turning/machining of spout and flywheel flange detail
• Complete milling/machining of big ends and counterweights
• Machining of balancer bolt, flywheel bolts and any keyways and drive points
• Through hardening – use of a fluid bed to a hardness of 35~37Rc which allows the material to achieve maximum tensile strength of 1100~1200MPA
• Shot peening
• Grind all journals to size
• Vacuum nitriding to a hardness of 60~62Rc and a case depth of 0.5mm
• Final polishing of all journals

Crankshafts are manufactured to custom order so please contact us for more information and pricing.