Crankshaft design

V8 engine

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Experimental Liberty V8 aircraft engine shows the V-shaped configuration when looking at it from the front or back. Automotive versions usually use a wider, 90° block angle.

Short block of an American Motors V8 engine showing the four cylinders on each side of the V configuration

A V8 engine is an eight-cylinder V engine with the cylinders mounted on the crankcase in two sets of four cylinders, in most cases set at a right angle to each other, but sometimes at a narrower angle, with all eight pistons driving a common crankshaft.^[1]

In its simplest form, it is basically two inline-four engines sharing a common crankshaft. However, this simple configuration, with a flat- or single-plane crankshaft, has the same secondary dynamic imbalance problems as two straight-4s, resulting in vibrations in large engine displacements.^[2] Since the 1920s most V8s have used the somewhat more complex crossplane crankshaft with heavy counterweights to eliminate the vibrations. This results in an engine that is smoother than a V6, while being considerably less expensive than a V12 engine. Most racing V8s continue to use the single plane crankshaft because it allows faster acceleration and more efficient exhaust system designs.^[3]

Contents

• 1 Applications
• 2 History
• 3 V angles
• 4 Crankshaft design
• 5 American V8 engines
• 6 Australian V8 engines
• 7 British V8 engines
• 8 Chinese V8 engines
• 9 Czech V8 engines
• 10 French V8 engines
• 11 German V8 engines
• 12 Italian V8 engines
• 13 Japanese V8 engines
• 14 Korean V8 engines
• 15 Swedish V8 engines
• 16 Russian V8 engines
• 17 Spanish V8 engines
• 18 Other V8 applications
• 18.1 In motorcycles
• 18.2 In motorsport
• 19 See also
• 20 Notes
• 21 References
• 22 External links

Applications

Assembled Oldsmobile 400 CID overhead valve engine with heads and complete valve train but without manifolds, rocker covers, timing chain cover or oil pan

Assembled Ford 460 and installed with all components

A modern V8 seen in a 2006 Chevrolet Impala

The V8 with a crossplane crankshaft (see below) is a common configuration for large automobile engines. V8 engines are rarely less than 3.0 L (183 cu in) in displacement and in automobile use have exceeded 8.2 L (500 cu in) in production vehicles, such as the American Cadillac Eldorado for instance. In some applications, e.g. industrial and marine V8 engines, displacement can be even larger.

In automobiles V8 engines are used in a wide variety of cars, mostly they are utilized in more powerful segments and types of vehicles, such as for example the American muscle cars, and also in sports cars, luxury cars, pickup trucks, and sport utility vehicles. Many car manufacturers offer a V8 as an option in vehicles which have a V6 or straight-6 as standard engine. Hence V8-engined cars in many countries are a symbol of exclusivity and prestige, as they are only found in upscale, high-performance premium/luxuy vehicles. In some cases, V6 engines were derived from V8 designs by removing two cylinders while maintaining the same V-angle so they can be built on the same assembly lines as the V8s and installed in the same engine compartments with few modifications. Some of these employed offset crankpins driving connecting rod pairs, enabling a regular firing sequence.

The traditional 90° big-bore V8 engine, as found on many American makes, is generally too wide and too long to fit in vehicles with a transverse engine front-wheel drive layout, so its applications are limited to rear-wheel drive sports cars, muscle cars, pony cars, luxury cars and light trucks. The shorter and occasionally narrower V6 engine is easier to fit in small engine compartments, but a few compact V8 engines are used in transverse FWD and transverse AWD engine configurations in larger cars, such as Cadillacs and Volvos. These engines often have tighter cylinder bore spacings, narrower cylinder bank angles, and other modifications to reduce their space requirements.^[4]

In motorsports V8s are common and have been a popular engine choice in purpose-designed engines for race-cars in many different types and classes of automotive racing, with use for example in the Formula-1 or the American NASCAR-racing league. They usually have flat-plane crankshafts, since a crossplane crankshaft results in uneven firing into the exhaust manifolds which interferes with engine tuning, and the crossplane's heavy crankshaft counterweights prevent the engine from accelerating rapidly. They are a common engine configuration in the highest echelons of motorsport, especially in the U.S. where it is required in IRL, ChampCar and NASCAR. V8 engines are also used in Australian motorsport, most notably in the V8 Supercars. Formula One began the 2006 season using naturally aspirated 2.4 L (146 cu in) V8 engines, which replaced the 3.0 L (183 cu in) V10 in a move to reduce costs and power.

Medium-weight trucks tend to use the straight-6 configuration since it is simpler and easier to maintain, and because the straight-6 is an inherently balanced layout which can be scaled up to any size necessary. Large V8s are found in the larger truck and industrial equipment lines.

Although it was the early choice for aircraft engines, the V8 engine is seldom used in modern aircraft engine as the typically heavy crankshaft counterweights are a liability. Modern light planes commonly use the flat-8 configuration instead as it is lighter and easier to air cool. In addition it can be manufactured in modular designs sharing components with flat-4 and flat-6 engines. One of the few V8 engines used for aircraft propulsion in the World War II years was the German inverted V8 configuration, air-cooled Argus As 10 powerplant.

History

1909 Antoinette VII aircraft with Antoinette V8 engine

V8 Vulcan engine, about 1919

Marc Birkigt's Hispano-Suiza 8A aviation V8 engine of World War I

In 1902, Léon Levavasseur took out a patent on a light but quite powerful gasoline injected V8 engine. He called it the 'Antoinette' after the young daughter of his financial backer. From 1904 he installed this engine in a number of competition speedboats and early aircraft. The aviation pioneer Alberto Santos-Dumont saw one of these boats in Côte d'Azur and decided to try it on his 14-bis aircraft. Its early 24 hp (18 kW) at 1400 rpm version with only 55 kg (121 lb) of weight was interesting, but proved to be underpowered. Santos-Dumont ordered a larger and more powerful version from Levavasseur. He changed its dimensions from the original 80 mm stroke and 80 mm bore to 105 mm stroke and 110 mm bore, obtaining 50 hp (37 kW) with 86 kg (190 lb) of weight, including cooling water. Its power-to-weight ratio was not surpassed for 25 years.^[5] Levavasseur eventually produced its own line of V8 equipped aircraft, named Antoinette I to VIII. Hubert Latham piloted the V8 powered Antoinette IV and Antoinette VII in July 1909 on two failed attempts to cross the English Channel.^[6][7] However, in 1910, Latham used the VII with the same engine to become the first in the world to reach an altitude of 3600 feet.^[8] Voisin constructed pusher biplanes with Antoinette engines, also, notably the one first flown successfully by Henry Farman in 1908.

The V8 engine configuration became popular in France from 1904 onward, and was used in a number of aircraft engines introduced by Renault, and Buchet among others. Some of these engines found their way into automobiles in small quantities. In 1905, Darracq built a special car to beat the world speed record. They came up with two racing car engines built on a common crankcase and camshaft. The result was monstrous engine with a displacement of 1,551 cu in (25,416 cc), good for 200 bhp (150 kW). Victor Hemery fixed that record on 30 December 1905 with a speed of 109.65 mph (176.46 km/h). This car still exists.

Rolls-Royce built a 3,535 cc (216 cu in) V8 car from 1905 to 1906, but only 3 copies were made and Rolls-Royce reverted to a straight-6 design.

In 1907 The Hewitt Motor Company built a large 5 passenger Touring Car. It was equipped with a hefty V8 engine that developed 50/60 horsepower and had a bore of 4 inches and a stroke of 4 1/2 inches. The Hewitt was the first American Automobile to be equipped with a V8 engine.^[9]

De Dion-Bouton introduced a 7,773 cc (474 cu in) automobile V8 in 1910 and displayed it in New York in 1912. It was produced only in small quantities, but inspired a number of manufacturers to follow suit.^[10]

One of the first production automobile V8s was introduced in the United States in 1914 by Cadillac, a division of General Motors which sold 13,000 of the 5.4 L (330 cu in) L-head engines in its first year of production. Cadillac has been primarily a V8 company ever since. Oldsmobile, another division of General Motors, introduced its own 4 L (244 cu in) V8 engine in 1916. Chevrolet introduced a 288 cu in (4.7 L) V8 engine in 1917 and installed in the Chevrolet Series D. In February 1915, Swiss automotive engineer Marc Birkigt designed the first example of the famous Hispano-Suiza V8 single overhead cam aviation engines, in differing displacements, using dual ignition systems and in power levels from 150 horsepower to some 300 horsepower, in both direct-drive and geared output shaft versions. Almost 50,000 "Hisso" V8 powerplants in total, as the engines became nicknamed, were built in Spain, France, the United Kingdom, Italy and even by Wright Aeronautical in the United States during World War I, and from their almost-exclusive use to power the important French SPAD S.VII (about 6,000 produced) and SPAD S.XIII (nearly 8,500 produced) fighter aircraft, and the Royal Air Force's Royal Aircraft Factory S.E.5 fighters (some 5,200 built) and Sopwith Dolphin (nearly 2,100 built) fighters, the H.S. 8-series overhead cam valvetrain vee-eight aviation engines are said to have powered roughly half of all Allied aircraft of the WW I era.

By 1932, Henry Ford introduced one of his last great personal engineering triumphs: his "en block", or one piece, V8 engine. The production was the largest commercially available V8 to the masses. Offered as an option to an improved 4-cylinder Model "B" engine in a low priced car, this compact V8 power plant, with its down draft carburettor, enabled 1932 Ford to outperform all other popular competitors and was conceived as years ahead of its time. The Ford flathead V8 is still heralded today as one of the first pioneers in 'hot rod' engines.^[11]

V angles

The most prevalent V angle for a V8 is 90°. This configuration features a wide, low engine with optimal firing and vibration characteristics. Many V6 and V10 engine configurations are derived from production V8 designs, they often use the 90° angle; however, balance shafts are incorporated to reduce vibration and/or more complex cranks to even the firing cycle. V8s can use different angles. One notable example is the Ford/Yamaha V8 used in the Ford Taurus SHO. It was based on Ford's Duratec V6 and shares that engine's 60° vee angle. A similar Yamaha-built engine was used by Volvo Cars between 2005 and 2010. These engines were designed for transverse front-wheel-drive installation and are narrower than usual for efficient use of space. Because they are not at the ideal 90° angle for a V8, they require a counter-rotating balance shaft and offset split crankpins for complete smoothness.^[12] 72° V8 engines have been used in modern racing.^[13]

The Rover Meteorite V8 engine was derived from the Rover Meteor tank engine (hence derived from the Merlin aero engine), so shared the Meteor's 60° vee angle.^[14] In years past, Electro-Motive produced an 8-cylinder version of their model 567 Diesel locomotive engine, with a 45° cylinder angle. The 1932 Miller four-wheel drive race cars also featured a 45° V8.^[15]

An extremely narrow-angle V8 was introduced by Lancia in 1922, which had an angle between cylinder banks of only 14°. This created an engine that was shorter than a straight-6, but much narrower than a conventional V8. It was based on a Lancia V4 engine design that was almost completely "square" in the length and width of its layout. Because of their compact design and overhead camshafts, these engines were lighter and more powerful than comparable engines of the time.^[16] Although Lancia stopped making the V8 design around World War II, the basic concept is used today in the Volkswagen VR6 engine.

Crankshaft design

Main article: Crossplane

There are two types of 90 degree V8s which differ by crankshaft:

• The cross-plane or two-plane crankshaft is the configuration used in most V8 road cars. 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 cross-plane have half as strong (and twice as frequent) secondary vibration than flat-plane, but requires heavy counterweights on the crankshaft to counter Rocking Vibration caused by plane imbalances (See Engine balance for details). With the Secondary Vibration advantage, the cross-plane V8 can be scaled up to large displacements without causing destructive vibration. However, the use of heavy counterweights makes the cross-plane V8 a slow-revving engine that cannot speed up or slow down quickly compared to flat-plane because of the greater rotating mass. While the firing of the cross-plane V8 is evenly spaced overall, the firings on the 'L'eft and 'R'ight banks are LRLLRLRR or RLRRLRLL, resulting in uneven intake and exhaust pulse spacing for each bank. In stock cars with exhaust manifolds merging four exhaust ports into one exit, this results in uneven filling/scavenging of intake/exhaust gas in the cylinders (that prevents combustion to be uniform across cylinders) causing the typical V8 burble sound that many people have come to associate with American V8s. In all-out racing cars it leads to the need to connect exhaust pipes between the two banks to design an optimal exhaust system, resulting in the long exhaust pipes that resemble a bundle of snakes as in the Ford GT40. This complex and encumbering exhaust system has been a major problem for single-seater racing car designers, so they tended to use stub exhaust pipes in the 1950s, or place exhaust ports on the inside of the V angle as on the 4.2 L (256 cu in) Ford Indy engine in Lotus 38.

• The flat-plane or single-plane crankshaft has crank pins at 180°. As they always move two pistons together, the Secondary Vibration is twice as strong (and half as frequent) as cross-plane, unless balance shafts are used, with a counter rotating pair flanking the crankshaft transverse to the crankshaft centreline. As it has nearly perfect plane balance,^[17] it does not normally require counterweights. The crankshaft with less mass and thus inertia allows quicker revving up and down, in addition to the firing being LRLRLRLR or RLRLRLRL with regular overall and per-bank pulse spacings for uniform combustion without requiring a complicated exhaust system. The design was popularized in modern racing by the Coventry Climax FWMV 1.5 L (92 cu in) V8 that evolved from a cross-plane to a flat-plane configuration (with longer conrods). Flat-plane V8s on road cars come from Ferrari (every V8 model they have ever made, from the 1973 308 GT4, to the new 458), Lotus (the Esprit V8), TVR (the Speed Eight), Porsche 918 Spyder, McLaren (the MP4-12C), as well as Ford (the Mustang Shelby GT350). This design is popular in racing engines, the most famous example being the Cosworth DFV.^[18]

In 1992, Audi left the German DTM racing series after a controversy around the crankshaft design of their Audi V8 DTM. After using the road car's cross-plane 90° crankshaft for several years, they switched to a flat-plane 180° version which they claimed was made by "twisting" a stock part. The scrutineers decided that this would stretch the rules too far.

The cross-plane design was neither obvious nor simple to design. For this reason, most early V8 engines, including those from De Dion-Bouton, Peerless, and Cadillac, were flat-plane designs. In 1915, the cross-plane design was proposed at an automotive engineering conference in the United States, but it took another eight years to bring it to production. Cadillac and Peerless (who had hired an ex-Cadillac mathematician for the job) applied for a patent on the cross-plane design simultaneously, and the two agreed to share the idea. Cadillac introduced their "Compensated Crankshaft" V8 in 1923, with the "Equipoised Eight" from Peerless appearing in November 1924.^[19]

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