V4 (engine)

A V4 engine is a type of four-cylinder engine, a V engine with four cylinders. A V4 engine typically has three main bearings. Usually one bank of cylinders will comprise cylinders # 1&3, and the other bank # 2&4. For reasons of packaging, the Honda VFR1200 has a 1&4, and 2&3 layout.

Compared to an inline-four, the advantages of the V4 engine include compactness, short length along the crankshaft, and, with a 90° V-angle, perfect primary balance giving a smooth and nearly vibration-free operation.

A disadvantage is that, as with a V-twin, it is more difficult to locate ancillaries, inlet systems, and exhaust systems. A V4 is usually more expensive to produce than an equivalent in-line four, having two cylinder heads and exhaust manifolds, and thus four distinct parts where an inline engine would have two. Also, while a V4 is essentially two V-twins side-by-side, a V4 can have a rocking couple that is not present in a V-twin. The compact 60° V4 is not perfectly smooth and needs a balance shaft.

In modern times, the V4's advantages have made it particularly suitable for motorcycles and outboard motors; but the advantages in a car have been found not to be worth the expense, especially as access for maintenance can become more difficult.

One of the earliest V4 internal combustion engines was that designed by Émile Mors of Paris to power his motor-car of 1897. The 90 degree V-angle with central camshaft and spark ignition meant its layout is much like more modern engines, though in this case the inlet valves were operated by suction alone. At the time the lack of vibration from this layout was a key selling point.

The V4 engine has not been widely used in cars. AMC, Ford, Lancia and ZAZ were the only companies to manufacture such an engine.

Lancia produced several narrow-angle V4 engines from the 1920s through 1960s for cars like the Lambda, Augusta, Artena, Aprilia, Ardea, Appia, and Fulvia.

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