A V8 engine is an eight-cylinder piston engine in which two banks of four cylinders share a common crankshaft and are arranged in a V configuration.
Origins
The first known V8 was the Antoinette 8V, designed by Léon Levavasseur, and built since 1904 by the French Antoinette company for use in speedboat racing, cars, and later, airplanes.
Also in 1904, V8 engines began small-scale production by Renault and Buchet for use in race cars. The Curtiss V-8 motorcycle motorcycle set an unofficial motorcycle land-speed record of 219.45 km/h (136.36 mph) on January 24, 1907.
Design
V-angle
Most engines use a V-angle (the angle between the two banks of cylinders) of 90 degrees. This angle results in good engine balance, which results in low vibrations. However, the downside is the greater width of the engine compared to those that use a smaller V-angle. V8 engines with a 60-degree V-angle were used in the 1996–1999 Ford Taurus SHO, the 2005–2011 Volvo XC90, and the 2006–2009 Volvo S80. The Ford engine used a 60-degree V-angle because it was based on a V6 engine with a 60-degree V-angle. Both the Ford and Volvo engines were used in transverse engine chassis, which were designed for a front-wheel-drive layout (with an on-demand all-wheel drive system in the case of the Volvos). To reduce the vibrations caused by the unbalanced 60-degree V-angle, the Volvo engines used a balance shaft and offset split crankpins. The Rolls-Royce Meteorite tank engine also used a 60-degree V-angle, since it was derived from the 60 degree V12 Rolls-Royce Meteor which in turn was based on the Rolls-Royce Merlin V12 engine. Other V-angles have been used occasionally. The Lancia Trikappa, Lancia Dilambda, and Lancia Astura, produced 1922–1939, used narrow angle V8 engines (based on the Lancia V4 engine) with V-angles of 14–24 degrees. The 1932 Miller four-wheel drive racing cars used a V8 engine with a V-angle of 45 degrees. The 8-cylinder versions of the 1945 through 1966 EMD 567 diesel locomotive engine also used a V-angle of 45 degrees.
Crankshaft configuration
Cross-plane crankshaft
Most V8 engines fitted to road cars use a cross-plane crankshaft since this configuration produces less vibration due to the perfect primary balance and secondary balance. The cross-plane crankshaft has the four crank pins (numbered from the front) at angles of 0, 90, 270, and 180 degrees, which results in a cross shape for the crankshaft when it is viewed from one end. The rumbling exhaust sound produced by a typical cross-plane V8 engine is partly due to the uneven firing order within each of the two banks of four cylinders. A usual firing order of L-R-L-L-R-L-R-R (or R-L-R-R-L-R-L-L) results in uneven intake and exhaust pulse spacing for each bank. When separate exhaust systems are used for each bank of cylinders, this uneven pulsing results in the rumbling sound typically associated with V8 engines. However, racing engines seek to avoid these uneven exhaust pressure pulses to maximize the power output. The 1960s cross-plane V8 racing engines used long primary exhaust pipes (such as the Ford GT40 endurance racing car) or located the exhaust ports on the inside of the V-angle (such as the Lotus 38 IndyCar) to link the exhaust systems from each bank and provide even exhaust gas pulses.
Flat-plane crankshaft A flat-plane crankshaft configuration provides two benefits. Mechanically, the crankshaft can be machined from a flat billet and does not require counterweights so it is lighter. However, it produces more vibration due to a secondary imbalance. Most early V8 road car engines also used a flat-plane crankshaft since this was simpler to design and build than a cross-plane crankshaft. Early flat-plane V8 engines included the 1910 De Dion-Bouton engine, the 1915 Peerless engine, and the 1915 Cadillac engine. A flat-plane crankshaft is used by many V8 engines fitted to racing cars. From the gas dynamics aspect, the flat-plane crankshaft allows for even exhaust gas pulses to be achieved with a simple exhaust system. The design was popularized in motor racing by the 1961–1965 Coventry Climax FWMV Formula One engine, and the 1967–1985 Cosworth DFV engine was highly successful in Formula One. Several production sports cars have used flat-plane V8 engines, such as every Ferrari V8 model (from the 1973 Ferrari 308 GT4 to the 2019–present Ferrari F8 Tributo), the Lotus Esprit V8, the Porsche 918 Spyder, and the McLaren 720S.
Automobile use The first V8 engine used in a road-going car was the 1905 Rolls-Royce built in the United Kingdom. This model was initially equipped with a 3.5 L (214 cu in) V8 engine. However, only three cars were made before Rolls-Royce reverted to using straight-six engines for their cars. In 1907, the Hewitt Touring Car became the first car built in the United States with a V8 engine. The engine was designed and built by Edward R. Hewitt who emphasized the V8's superiority to the typical I4 and I6 and six-cylinder engines of the time because of its lower weight and easier to make crankshaft compared to the I6s of equal power as well as the V8 not taking much more space than a I4. The 1910 De Dion-Bouton— built in France— is considered to be the first V8 engine produced in significant quantities. The 1914 Cadillac L-head V8 engine is considered the first road-going V8 engine to be mass-produced in significant quantities, with 13,000 sold the first year. This engine was built in the United States and was greatly assisted by Cadillac's pioneering use of electric starter motors. The popularity of V8 engines in cars was significantly increased following the 1932 introduction of the Ford Flathead V8. By the early 21st century, the use of V8 engines in passenger vehicles declined as automobile manufacturers opted for more fuel efficient, lower capacity engines, or hybrid and electric drivetrains.
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