A V8 engine is a V engine with eight cylinders mounted on the crankcase in two banks 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.
In its simplest form, it is basically two straight-4 engines sharing a common crankshaft. However, this simple configuration, with a single-plane crankshaft, has the same secondary dynamic imbalance problems as two straight-4s, resulting in vibrations in large engine displacements. As a result, 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 which 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.
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 as seen in a rear-wheel-drive vehicle
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. Industrial and marine V8 engines can be much larger.
V8s are generally only standard on more powerful muscle cars, pony cars, sports cars, luxury cars, pickup trucks, and SUVs. However they are often options in vehicles which have a V6 or straight-6 as standard engine. In some cases, V6 engines were derived from V8 designs by removing two cylinders maintaining the 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 is generally too wide and too long to fit easily 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.
V8s are common in purpose-designed engines for racing cars. 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 USA 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.
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 (120 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. Levavasseur eventually produced its own line of V-8 equipped aircraft, named Antoinette I to VIII. One of these aircraft, piloted by Hubert Latham, twice tried but failed to cross the English Channel in 1909 due to the engine's gasoline injection. However, in 1910, the same plane with the same engine and the same pilot was first in the world to reach an altitude of 3600 feet. 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. 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 American manufacturers to follow suit.
The first mass-production automobile V8 was introduced in the United States in 1914 by Cadillac, a division of General Motors which sold 13,000 of the 5,429 cc (331 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, but after merging with General Motors in 1918, discontinued the V8 to concentrate on economy cars.
In February 1915, Swiss automotive engineer Marc Birkigt designed the first example of the famous Hispano-Suiza V-8 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 are said to have powered roughly half of all Allied aircraft of the WW I era.[citation needed]
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. 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.
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.[15] Although Lancia stopped making the V8 design around World War II, the basic concept is used today in the Volkswagen VR6 engine.
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.
In its simplest form, it is basically two straight-4 engines sharing a common crankshaft. However, this simple configuration, with a single-plane crankshaft, has the same secondary dynamic imbalance problems as two straight-4s, resulting in vibrations in large engine displacements. As a result, 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 which 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.
Applications
V8s are generally only standard on more powerful muscle cars, pony cars, sports cars, luxury cars, pickup trucks, and SUVs. However they are often options in vehicles which have a V6 or straight-6 as standard engine. In some cases, V6 engines were derived from V8 designs by removing two cylinders maintaining the 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 is generally too wide and too long to fit easily 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.
V8s are common in purpose-designed engines for racing cars. 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 USA 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
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. 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 American manufacturers to follow suit.
The first mass-production automobile V8 was introduced in the United States in 1914 by Cadillac, a division of General Motors which sold 13,000 of the 5,429 cc (331 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, but after merging with General Motors in 1918, discontinued the V8 to concentrate on economy cars.
In February 1915, Swiss automotive engineer Marc Birkigt designed the first example of the famous Hispano-Suiza V-8 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 are said to have powered roughly half of all Allied aircraft of the WW I era.[citation needed]
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 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 is used by Volvo Cars as of 2005. 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. In 2010, GM introduced a 4.5 L Duramax diesel V8 with a 72° angle in which they state, "Considering manufacturing tolerances, a 72 V-8 engine can actually deliver better balance than a 90 engine." 72° V8 engines have been used in modern racing.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. 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.
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.[15] 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 classic types of 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 can achieve very good balance but requires heavy counterweights on the crankshaft. This makes the cross-plane V8 a slow-revving engine that cannot speed up or slow down very quickly compared to other designs because of the greater rotating mass. While the firing of the cross-plane V8 is regular overall, the firing of each bank is LRLLRLRR. In stock cars with dual exhausts, this results in 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 an exhaust system that resembles 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 tend to use flat-plane crankshafts instead.
- The flat-plane or single-plane crankshaft has crank pins at 180°. They are imperfectly balanced and thus produce vibrations unless balance shafts are used, with a counter rotating pair flanking the crankshaft to counter second order vibration transverse to the crankshaft centerline. As it does not require counterweights, the crankshaft has less mass and thus inertia, allowing higher rpm and quicker acceleration. The design was popularized in modern racing with the Coventry Climax 1.5 L (92 cu in) V8 that evolved from a cross-plane to a flat-plane configuration. Flat-plane V8s on road cars come from Ferrari (every V8 model they ever made, from the 1973 308 GT4, to the new 458), Lotus (the Esprit V8), TVR (the Speed Eight) and McLaren (the MP4-12C). This design is popular in racing engines, the most famous example being the Cosworth DFV.
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.
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