Flat-plane Crankshaft for Cobra Engine

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Ferraris opinion


FLAT-PLANE CRANKSHAFT
The engine’s flat-plane crank (with 180° between throws) epitomises Ferrari’s uncompromising design approach.
Eight-cylinder engines with a 90 degree angle between their cylinder banks are a relatively recent addition to Ferrari history.
Apart from the engine sported by the 1956 World Championship-wining F1 car, which Ferrari inherited from Lancia after the latter pulled out competition, and the one mounted to the 248 sports prototype in the early 1960s, it was 1973 before a Ferrari would be powered by an engine with this specific architecture.
Characteristically flat-plane crankshaft engines have a crankshaft with crankpins angled at 180 degrees to each other or “flat” i.e. on the same plane.
Ferrari_F430_Crankshaft
Ferrari_F430_Crankshaft
Generally speaking V8 engines have a 90 degree angle between the cylinder banks with each crank pin offset at 90 degrees from the adjacent ones i.e. they are “crossed” at 90 degrees. Hence the cross-plane name. Whether a flat or cross-plane crankshaft is chosen depends on what kind of performance is required. To get maximum performance from the engine, the flat-plane must be used but for all-round functioning the cross-plane is best. This why all Ferrari V8s engines (from the 308 to the 328, the 348 to the 355,the 360 to the 430,and the special high performance GTO series, the F40 and the recent California, our first front V8) use a flat-plane crankshaft.
The advantages of the flat-plane crankshaft over the cross-plane one can be summarised as follows:
A flat-plane crankshaft is lighter than a 90-degree, or cross-plane crankshaft, and, having a lower rotating mass than the latter, provides sharper response as well as allowing higher maximum revs, useful when seeking higher power outputs. Another advantage of the flat-plane crank is that it allows more efficient exhaust manifold design.
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