420motorsport. Crankshafts – billet and forged for engine builds

What does a crankshaft do, and why replace it?

The crankshaft converts the up-and-down motion of the pistons into rotation and determines the engine's stroke. A crank with a longer stroke increases displacement, e.g. 96 mm for Toyota 2JZGTE/2JZGE or 100.6 mm for BMW S58B30T0. A crank with stock stroke is typically chosen for its strength. Brands in this category include Brian Crower, Wiseco and HKS, and you can see all crankshafts in one place.

How to choose a crankshaft

Engine code: The crank must fit your specific engine. The product name states the engine, e.g. 3SGTE or Ford 5.0L Coyote.

Stroke: A new stroke typically requires pistons with a different compression height and matching connecting rods, so the whole project needs to be calculated.

Material: Billet 4340 steel cranks are machined from a solid blank, while forged cranks are formed under pressure. What suits you best depends on power goals and use.

Weight: A lightweight crank can make the engine rev more quickly, but it also affects rotating mass and balance.

Journals: Some cranks have Honda-size journals, as stated in the product name, and this determines your choice of connecting rods.

Installation and maintenance

Bearing clearance and end play should be measured during assembly, and the rotating assembly is typically balanced together. You'll find bolts and other parts under crankshaft hardware and accessories. Clean oil with the correct viscosity and a well-functioning lubrication system are crucial for bearing life.

Frequently asked questions

What is the difference between a billet and a forged crankshaft?

A billet crank is machined from a solid steel blank, e.g. 4340. A forged crank is formed under pressure and then machined. Both can be very strong, and the choice depends on power goals, use and what is available for your engine.

Can I install a longer-stroke crank without changing other parts?

Typically not. A longer stroke changes the piston's position at the top of the cylinder, so pistons, connecting rods and block clearance must suit the new geometry. Check the dimensions for the specific part number before you order.

Does the car need an inspection after a crankshaft swap?

It depends on the car and the modification. If displacement or power is increased, it may require registration of the modification or an inspection. Check the rules for your specific project before the car goes back on the road.