Crossplane

The crossplane or cross-plane is a crankshaft design for piston engines with a 90° angle (phase in crank rotation) between the crank throws. The crossplane crankshaft is the most popular configuration used in V8 road cars.

Crossplane crankshafts could be used in many cylinder configurations that have evenly-spaced firing, as long as the number of cylinders is a multiple of four in two-stroke engines, or a multiple of eight in 4 stroke engines. Unless the crank pins have big-end phase-offset, the V-angle requirement must be met for evenly-spaced firing in V configurations as listed below.

2 cycle: L4, L8, L12, L16, V4 (V-angle of 90°), V8 (45°,90° or 135°), V12 (30°,60°,90°,120° or 150°), V16 (22.5°,45°,67.5°,90°,112.5°,135° or 157.5°), flat4, flat8, flat12, flat16, etc.

4 cycle: L8, L16, V8 (V-angle of 90°), V16 (45°,90° or 135°), flat8, flat16, etc.

However, crossplane crankshafts have been used on other 4 stroke configurations like L2, L4, V2 and V4 engines with unevenly-spaced firing where its prominent advantage of smaller secondary (non-sinusoidal) vibration, which increases exponentially with crankshaft rotational speed, out-weighs the disadvantages like the imbalance in firing spacing and the increase in rocking vibration.

The most common crossplane crankshaft for a 90° V8 engine has four crankpins, each serving two cylinders on opposing banks, offset at 90° from the adjacent crankpins. The first and last of the four crank pins are at 180° with respect to each other as are the second and third, with each pair at 90° to the other, so that viewed from the end the crankshaft forms a cross. The crankpins are therefore in two planes crossed at 90°, hence the name crossplane. A crossplane V8 crankshaft may have up to nine main bearings in the case of an eight throw design, and usually has five bearings supporting four throws each with a shared crank pin.

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Wikipedia