Slant Four
Encyclopedia
The Slant Four is a type of car
engine
manufactured by Vauxhall Motors
and in modified form by Lotus Cars
. Unveiled in 1966, it was one of the first production overhead camshaft
designs to use a rubber
toothed belt to drive the camshaft
from the crankshaft
(an honor shared with the 1966 Pontiac OHC Six), a method developed in 1956 by Bill Devin
.
s inclined at an angle of approximately 45 degrees (hence the name), and this is because Vauxhall had originally planned to develop a whole family of engines all built on the same production line. There was to be slant four and V8 versions in both petrol and diesel versions, designed under the guidance of Vauxhall's then chief engineer, John Alden. Although several diesel 4 cylinder and a V8 petrol engine prototypes were built only the 4 cylinder petrol made it to series production. There is a single overhead camshaft operating two valve
s per cylinder. An ingenious valve train design incorporating an inclined socket head cap screw
, allowed valve
clearances to be adjusted with a feeler gauge
and an Allen key. The block and crossflow
head are both of cast iron
. The layout makes good use of the cylinder inclination to lower the overall height of the engine, which allowed for more aerodynamic designs of cars to be achieved by lowering the bonnet
line. It also means most of the engine is very easy to access for maintenance, with the exception of the exhaust manifold
and spark plug
s, which are "underneath" the slanted cylinders.
Although prototype engines were fitted to the FC 101 Victor the first production car to use the engine was the 1967 Victor, at capacities of 1599 cc and 1975 cc. Later, for launch of the FE Victor in 1972, the smaller engine was increased to 1759 cc, and the larger, to 2279 cc. Bill Blydenstein racing developed a long stroke version with a capacity of 2600 cc, in which form it could produce almost 250 hp. Having originally been designed as the basis of a future V8
, the block is immensely strong and can handle huge increases in power without modification, also the crank was designed to be shared with the diesel version which meant in built strength was assured for the petrol versions. The larger capacities are renowned for their immense torque
(having such large pistons), but a downside of this is that they are not very smooth running or high-revving, and lack balance shaft
s. A fuel injection version of the 2.3 litre engine was planned for both the HP Firenza and VX4-90 and running prototypes were tested the project was abandoned due to cost and the impending merger of Vauxhall's design and engineering with that of Opel in Germany.
The engine was widely used in many models of car, and was also developed into a marine engine
for boat
s and was popular with amateurs due to its great strength, tunability and simplicity. The engine was still being manufactured well into the 1980s for the Bedford CF
van, and many of them are still in daily use.
Motor Show
its bore centers were exactly the same as those proposed by Lotus for their new all-alloy engine. Lotus boss Colin Chapman
immediately negotiated a deal with Vauxhall
to buy some of their cast-iron blocks so that development of Lotus’ own aluminum 907
engine could be sped up.
The design became the basis for the Lotus
2.0 and 2.2 engines used in a wide variety of sports car
s, but the basic block was cast in aluminium
alloy instead of iron, which made it considerably lighter. The Lotus engine also used a different cylinder head
of light alloy, featuring double overhead camshafts and four valves per cylinder. The engines were so close in design that, with a few modifications, the Lotus head can be fitted to the Vauxhall block; engines with Lotus heads were used in Vauxhall's dealer team race and rally programmes until the late 1970s.
one; in particular the cam carriers on the Vauxhall engine were angled upwards so that the covers were both horizontal (those on the Lotus engine were equal about the cylinder centreline).
The 16 valve engine was first used in the Chevette 2300 HS, but initially heads were in such short supply that road car production was delayed and the rally team continued to use the Lotus heads they were familiar with. This led to the cars being prevented from starting the 1978 Rally of Portugal
after protests from other teams. As a result all cars competing in international rallies were forced to use the Vauxhall head, and Blydenstein Racing, the company running the rally team, improved it to a point where it performed better than the Lotus head.
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
engine
Engine
An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines burn a fuel to create heat which is then used to create motion...
manufactured by Vauxhall Motors
Vauxhall Motors
Vauxhall Motors is a British automotive company owned by General Motors and headquartered in Luton. It was founded in 1857 as a pump and marine engine manufacturer, began manufacturing cars in 1903 and was acquired by GM in 1925. It has been the second-largest selling car brand in the UK for...
and in modified form by Lotus Cars
Lotus Cars
Lotus Cars is a British manufacturer of sports and racing cars based at the former site of RAF Hethel, a World War II airfield in Norfolk. The company designs and builds race and production automobiles of light weight and fine handling characteristics...
. Unveiled in 1966, it was one of the first production overhead camshaft
Overhead camshaft
Overhead cam valvetrain configurations place the engine camshaft within the cylinder heads, above the combustion chambers, and drive the valves or lifters in a more direct manner compared to overhead valves and pushrods...
designs to use a rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...
toothed belt to drive the camshaft
Camshaft
A camshaft is a shaft to which a cam is fastened or of which a cam forms an integral part.-History:An early cam was built into Hellenistic water-driven automata from the 3rd century BC. The camshaft was later described in Iraq by Al-Jazari in 1206. He employed it as part of his automata,...
from the crankshaft
Crankshaft
The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...
(an honor shared with the 1966 Pontiac OHC Six), a method developed in 1956 by Bill Devin
Bill Devin
Bill Devin was the founder of Devin Cars. He was a major influence on the automobile industry by demonstrating the world's first OHC driven by rubber toothed belt....
.
Vauxhall
The engine features four inline cylinderCylinder (engine)
A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before receiving precision machine work...
s inclined at an angle of approximately 45 degrees (hence the name), and this is because Vauxhall had originally planned to develop a whole family of engines all built on the same production line. There was to be slant four and V8 versions in both petrol and diesel versions, designed under the guidance of Vauxhall's then chief engineer, John Alden. Although several diesel 4 cylinder and a V8 petrol engine prototypes were built only the 4 cylinder petrol made it to series production. There is a single overhead camshaft operating two valve
Poppet valve
A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. The shaft guides the plug portion by sliding through a valve guide...
s per cylinder. An ingenious valve train design incorporating an inclined socket head cap screw
Screw
A screw, or bolt, is a type of fastener characterized by a helical ridge, known as an external thread or just thread, wrapped around a cylinder. Some screw threads are designed to mate with a complementary thread, known as an internal thread, often in the form of a nut or an object that has the...
, allowed valve
Valve
A valve is a device that regulates, directs or controls the flow of a fluid by opening, closing, or partially obstructing various passageways. Valves are technically pipe fittings, but are usually discussed as a separate category...
clearances to be adjusted with a feeler gauge
Feeler gauge
A feeler gauge is a tool used to measure gap widths. Feeler gauges are mostly used in engineering to measure the clearance between two parts.They consist of a number of small lengths of steel of different thicknesses with measurements marked on each piece...
and an Allen key. The block and crossflow
Crossflow cylinder head
A crossflow cylinder head is a cylinder head that features the intake and exhaust ports on opposite sides. The gases can be thought to flow across the head...
head are both of cast iron
Cast iron
Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...
. The layout makes good use of the cylinder inclination to lower the overall height of the engine, which allowed for more aerodynamic designs of cars to be achieved by lowering the bonnet
Hood (vehicle)
The hood or bonnet is the hinged cover over the engine of motor vehicles that allows access to the engine compartment for maintenance and repair. In British terminology, hood refers to a fabric cover over the passenger compartment of the car...
line. It also means most of the engine is very easy to access for maintenance, with the exception of the exhaust manifold
Exhaust manifold
In automotive engineering, an exhaust manifold collects the exhaust gases from multiple cylinders into one pipe. The word manifold comes from the Old English word manigfeald and refers to the folding together of multiple inputs and outputs.In contrast, an inlet manifold is the part of an engine...
and spark plug
Spark plug
A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed fuels such as aerosol, gasoline, ethanol, and liquefied petroleum gas by means of an electric spark.Spark plugs have an insulated central electrode which is connected by...
s, which are "underneath" the slanted cylinders.
Although prototype engines were fitted to the FC 101 Victor the first production car to use the engine was the 1967 Victor, at capacities of 1599 cc and 1975 cc. Later, for launch of the FE Victor in 1972, the smaller engine was increased to 1759 cc, and the larger, to 2279 cc. Bill Blydenstein racing developed a long stroke version with a capacity of 2600 cc, in which form it could produce almost 250 hp. Having originally been designed as the basis of a future V8
V8 engine
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....
, the block is immensely strong and can handle huge increases in power without modification, also the crank was designed to be shared with the diesel version which meant in built strength was assured for the petrol versions. The larger capacities are renowned for their immense torque
Torque
Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....
(having such large pistons), but a downside of this is that they are not very smooth running or high-revving, and lack balance shaft
Balance shaft
In piston engine engineering, a balance shaft is an eccentric weighted shaft which offsets vibrations in engine designs that are not inherently balanced...
s. A fuel injection version of the 2.3 litre engine was planned for both the HP Firenza and VX4-90 and running prototypes were tested the project was abandoned due to cost and the impending merger of Vauxhall's design and engineering with that of Opel in Germany.
The engine was widely used in many models of car, and was also developed into a marine engine
Marine engine
A marine engine is an engine that propels a ship or boat. Types of marine engine include:*Marine steam engine*Petrol engine or gasoline engine*Diesel engine*Steam turbine*Gas turbine-See also:*Marine propulsion*Engine room*Marine automobile engine...
for boat
Boat
A boat is a watercraft of any size designed to float or plane, to provide passage across water. Usually this water will be inland or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is a...
s and was popular with amateurs due to its great strength, tunability and simplicity. The engine was still being manufactured well into the 1980s for the Bedford CF
Bedford CF
The Bedford CF was a model of light commercial vehicle produced by Bedford Vehicles for almost twenty years from the late 1960s.In Germany and certain other continental markets, the CF was sold through Opel dealers as the Opel Bedford Blitz from 1973 on....
van, and many of them are still in daily use.
Lotus 900 series engines
It is said that when Vauxhall unveiled its new slant-four engine at the 1966 Earls CourtEarls Court Exhibition Centre
The Earls Court Exhibition Centre is an exhibition centre, conference and event venue located in west London, United Kingdom in the Royal Borough of Kensington and Chelsea . It is the largest exhibition venue in central London. It is served by two underground stations, Earl's Court and West...
Motor Show
British International Motor Show
The British International Motor Show is an automobile show held biennially in the United Kingdom. It is recognised as an international show by the Organisation Internationale des Constructeurs d'Automobiles. The 2008 was the last event with no news of a return of the British International Motor Show...
its bore centers were exactly the same as those proposed by Lotus for their new all-alloy engine. Lotus boss Colin Chapman
Colin Chapman
Anthony Colin Bruce Chapman CBE was an influential British designer, inventor, and builder in the automotive industry, and founder of Lotus Cars....
immediately negotiated a deal with Vauxhall
Vauxhall Motors
Vauxhall Motors is a British automotive company owned by General Motors and headquartered in Luton. It was founded in 1857 as a pump and marine engine manufacturer, began manufacturing cars in 1903 and was acquired by GM in 1925. It has been the second-largest selling car brand in the UK for...
to buy some of their cast-iron blocks so that development of Lotus’ own aluminum 907
Lotus 907
The Lotus 907 was an engine designed and manufactured for automotive applications by Lotus Cars. It was an original design, dual overhead cam, 16 valve all alloy powerplant. It displaced 1973 cc and developed approximately with dual sidedraft Dell'Orto carburetors...
engine could be sped up.
The design became the basis for the Lotus
Lotus Cars
Lotus Cars is a British manufacturer of sports and racing cars based at the former site of RAF Hethel, a World War II airfield in Norfolk. The company designs and builds race and production automobiles of light weight and fine handling characteristics...
2.0 and 2.2 engines used in a wide variety of sports car
Sports car
A sports car is a small, usually two seat, two door automobile designed for high speed driving and maneuverability....
s, but the basic block was cast in aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
alloy instead of iron, which made it considerably lighter. The Lotus engine also used a different cylinder head
Cylinder head
In an internal combustion engine, the cylinder head sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This joint is sealed by a head gasket...
of light alloy, featuring double overhead camshafts and four valves per cylinder. The engines were so close in design that, with a few modifications, the Lotus head can be fitted to the Vauxhall block; engines with Lotus heads were used in Vauxhall's dealer team race and rally programmes until the late 1970s.
Vauxhall 16 valve engines
Following experiments with an eight valve twin cam cylinder head for the Vauxhall Slant Four, the company developed a 16 valve, twin cam engine in the early 1970s; the first test engine, 'Old Number 1', was running by 1973. The cylinder head was similar in design but different in appearance to the LotusLotus Cars
Lotus Cars is a British manufacturer of sports and racing cars based at the former site of RAF Hethel, a World War II airfield in Norfolk. The company designs and builds race and production automobiles of light weight and fine handling characteristics...
one; in particular the cam carriers on the Vauxhall engine were angled upwards so that the covers were both horizontal (those on the Lotus engine were equal about the cylinder centreline).
The 16 valve engine was first used in the Chevette 2300 HS, but initially heads were in such short supply that road car production was delayed and the rally team continued to use the Lotus heads they were familiar with. This led to the cars being prevented from starting the 1978 Rally of Portugal
Rally de Portugal
The Rally de Portugal is a rally competition held in Portugal. First held in 1967, the seventh running of the race, the 7º TAP Rallye de Portugal was the third event in the inaugural FIA World Rally Championship in 1973...
after protests from other teams. As a result all cars competing in international rallies were forced to use the Vauxhall head, and Blydenstein Racing, the company running the rally team, improved it to a point where it performed better than the Lotus head.