They say that the heart of the engine is the camshaft, since it is one of the key components that dictates the engine's power level, power band, idle quality, and other characteristics. If the cam is the heart, then the crankshaft is the spine. The crankshaft also dictates power and powerband, but in a much more ambivalent way (through its stroke which, along with the bore size, dictates the engine's cubic-inch displacement). The crank is what transfers the up and down reciprocating movement of the piston and rod into the rotating motion required to drive the transmission. It carries the weight of all eight rods and pistons, and must deal with the shock loads of the combustion process. A stock crank does this fine...in a stock engine. But when power levels start to climb, that stock crank will eventually give under the tremendous loads imposed upon it.
Cast Nodular Iron
Tensile strength 95,000 Psi
Speedmaster&ulade; cast nodular iron crankshafts are perfect for mildly built street engines or just to replace stock crankshafts that have seen better days. These Speedmaster&ulade; crankshafts are precision-ground to exacting tolerances.
5140 Forged Steel
Tensile strength 115,000 Psi
Speedmaster&ulade; 5140 forged steel crankshafts are perfect for high compression or blown street applications as well as most race cars. Horsepower ratings should be limited to the 700HP range for maximum efficiency. For the most serious street and racing applications look to the 4340 Series crankshafts.Speedmaster&ulade; crankshafts are precision-ground, heat-treated and inspected for superior tolerance control. Speedmaster&ulade; crankshafts also have straight-shot and chamfered oil holes, and feature lightening holes in all rod throws. These crankshafts also have a large radius on all journals for improved strength and wear resistance.
4340 Forged Steel
Tensile strength 145,000 Psi
For absolutely serious street and racing applications, a 4340 forged steel Speedmaster&ulade; crankshaft is the only choice. They are perfect for high horsepower, torque and RPM’s and work great for all levels of power adders. Horsepower ratings are good for 1000 HP. Speedmaster&ulade; crankshafts are precision-ground, heat-treated, shot-peened and inspected for superior tolerance control. Speedmaster&ulade; crankshafts are also nitride-hardened for superior wear resistance, have straight-shot and chamfered oil holes, and feature lightening holes in all rod throws. These crankshafts also have a large radius on all journals for improved strength and wear resistance
** Feature available in some items within product line
Tensile strength 162,000 Psi
Billet crankshafts are at the top end of the high-performance crankshaft scale, They are precision CNC-machined from a solid chunk of forged steel on state-of-the-art equipment by master craftsmen for precise indexing and throw-to-throw consistency. The grain structure is not stretched or deformed; This makes for a stronger, stiffer, more durable finished product. Most Pro Race categories run billet cranks. Choose a better made billet crankshaft from Speedmaster&ulade; and choose peace of mind.
Main Journals − Machined surfaces located at the center of the crankshaft; rotation axis of the crankshaft runs through the center point of the main journals; main journals rotate in the main bearing bore created by the engine block and main caps.Connecting Rod Journals − Surface to which the connecting rods attach. They circle around the crank’s axis of rotation.Counterweights − Balance the crankshaft to eliminate harmful vibrations. (Check the internal or external balance specifications of the particular crank)Snout − Extends through the front end of the engine block; the camshaft timing assembly is connected to the snout, as well as the damper/balancer.Flange − Mounting structure for the flywheel or flexplate.
The tensile strength is the maximum amount of tensile stress that it can take before failure, for example braking.