The Triumph slant-four is an
inline four-cylinder petrol
car
A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods.
The year 1886 is regarded as ...
engine
An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy.
Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gen ...
developed by the
Triumph Motor Company
The Triumph Motor Company was a British car and motor manufacturing company in the 19th and 20th centuries. The marque had its origins in 1885 when Siegfried Bettmann of Nuremberg formed S. Bettmann & Co. and started importing bicycles from Eu ...
. It first appeared in 1968 in the
Saab 99
The Saab 99 is a car which was produced by Saab from 1968 to 1984; their first foray into a larger class than the 96. While considered a large family car in Scandinavia, it was marketed as a niche compact executive car in most other markets. It ...
. The first Triumph model to use the engine did not appear until 1972. With an original capacity of 1.7 L, displacement grew over time to 2.0 L. Triumph production ended in 1981.
History
In 1963 Triumph's Chief Engine Designer Lewis Dawtrey presented the results of his analysis of future engine technology trends and Triumph's anticipated needs.
After evaluating
rotary,
horizontally opposed
A flat engine is a piston engine where the cylinders are located on either side of a central crankshaft. Flat engines are also known as horizontally opposed engines, however this is distinct from the less common opposed-piston engine design, wh ...
,
V4 and
V6 configurations Dawtrey recommended an
OHC engine family composed of both
Inline-4
A straight-four engine (also called an inline-four) is a four-cylinder piston engine where cylinders are arranged in a line along a common crankshaft.
The vast majority of automotive four-cylinder engines use a straight-four layout (with the ...
and
V8 engines that could be built with the same tooling. The new range would be built in capacities of 1.5 L to 3.0 L, allowing it to replace both the four-cylinder
Standard SC and derivative
Triumph I6
The Triumph Six Cylinder or Triumph I6 engine is a cast-iron overhead valve straight-six engine produced by Standard Triumph. It is an evolution of the Standard Motor Company's inline-4 Standard Eight, with the addition of two cylinders and a ...
engines whose roots reached back to the
Standard Eight
The Standard Eight is a small car produced by the British Standard Motor Company from 1938 to 1959.
The car was originally launched in 1938 as the Flying Eight. After the Second World War the Flying range of Standards was dropped but an updat ...
of 1953. The recommendation was accepted and development began in-house at Triumph by a design team led by Dawtrey and
Harry Webster
Henry George Webster, CBE (27 May 1917 – 6 February 2007) was a British automotive engineer who worked on Triumph cars throughout the 1950s and 1960s.
Career
Harry Webster was born in Coventry in 1917, and educated at Welshpool County School ...
.
The initial model was to be a 1.5 L inline four.
At about the same time
Saab
Saab or SAAB may refer to:
Brands and enterprises
* Saab Group, a Swedish aerospace and defence company, formerly known as SAAB, and later as Saab AB
** Datasaab, a former computer company, started as spin off from Saab AB
* Saab Automobile, a fo ...
was working on a new 1.2 L inline four for their upcoming
99 model.
UK engineering and consultancy company
Ricardo
Ricardo is the Spanish and Portuguese cognate of the name Richard. It derived from Proto-Germanic ''*rīks'' 'king, ruler' + ''*harduz'' 'hard, brave'. It may be a given name, or a surname.
People Given name
*Ricardo de Araújo Pereira, Portugu ...
was involved in the Saab project and, while not directly involved in development of the slant-four, did have a general engine-development contract with Triumph and was aware of their progress. When Saab determined that developing their own engine would be too expensive and too risky, Ricardo put Saab into contact with Triumph.
Triumph agreed to supply Saab with 50,000 slant-four engines per year for the new 99.
Displacement had risen from 1.5 L to 1.7 L. Saab had exclusive use of the slant-four for the first several years of production.
Saab retained its existing
transaxle
A transaxle is a single mechanical device which combines the functions of an automobile's transmission, axle, and differential into one integrated assembly. It can be produced in both manual and automatic versions.
Engine and drive at the ...
, which was configured to be driven from the front of the engine. This required that the slant-four be turned 180° so that the clutch and flywheel were in the front.
A consequence of this is that the "front"-mounted water pump would be facing the firewall/bulkhead and be inaccessible, prompting it to be relocated to the top of the cylinder block.
The engine was used first by Triumph in the
Dolomite Dolomite may refer to:
*Dolomite (mineral), a carbonate mineral
*Dolomite (rock), also known as dolostone, a sedimentary carbonate rock
*Dolomite, Alabama, United States, an unincorporated community
*Dolomite, California, United States, an unincor ...
1850, which appeared in 1972. The regular Dolomite used the 1.85 L engine, while the sportier
Dolomite Sprint, unveiled in June 1973, got both a new cylinder head and an increase in displacement to 2.0 L. The slant-four was also used by
Panther
Panther may refer to:
Large cats
*Pantherinae, the cat subfamily that contains the genera ''Panthera'' and ''Neofelis''
**'' Panthera'', the cat genus that contains tigers, lions, jaguars and leopards.
*** Jaguar (''Panthera onca''), found in So ...
in the Dolomite-based
Rio
Rio or Río is the Portuguese, Spanish, Italian, and Maltese word for "river". When spoken on its own, the word often means Rio de Janeiro, a major city in Brazil.
Rio or Río may also refer to:
Geography Brazil
* Rio de Janeiro
* Rio do Sul, a ...
(1975–1977). The
TR7 debuted in 1975 with the 2.0 L engine and 8-valve cylinder head. A few pre-production
TR7 Sprint models received the sportier Sprint engine in 1977. Triumph stopped producing the slant-four when the TR7 was discontinued in 1981.
The V8 member of the engine family first appeared in a Triumph vehicle in 1970, fully two years before the slant-four. Development of the V8 had continued throughout the mid- to late-1960s, with early engines displacing 2.5 L. When
Charles Spencer (Spen) King took over as Head of Engineering from Webster, he authorized continued development of the
Triumph V8, and was also instrumental in getting the car it powered, the
Triumph Stag
The Triumph Stag is a 2+2 sports tourer which was sold between 1970 and 1978 by the Triumph Motor Company, styled by Italian designer Giovanni Michelotti.
Design and styling
Envisioned as a luxury sports car, the Stag was designed to compete ...
, into production.
The production V8 displaced 3.0 L.
Technical features
The slant-four's engine block is of cast iron (called ''chrome iron'' in some references). The cylinders are inclined at an angle of 45° from vertical.
This allowed the engine to be built with the same tooling needed for a V8, and reduced the overall engine height, permitting lower bonnets. The crankshaft ran in five main bearings. The pistons are aluminium with three rings. All slant-fours are
oversquare, with the larger capacity versions being even more so, as the increase in displacement came from increasing the bore diameter while holding the stroke length constant.
The cylinder head was cast from aluminium alloy. Combustion chambers were wedge-shaped. The
single overhead camshaft
An overhead camshaft (OHC) engine is a piston engine where the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion cha ...
was driven by a single-row ⅜" chain. The eight valves, two per cylinder, were inline and were operated on by the camshaft through bucket tappets with shims for adjustment.
Sprint 16-valve engine
![1974 Triumph Dolomite Sprint - Flickr - The Car Spy (21)](https://upload.wikimedia.org/wikipedia/commons/c/cf/1974_Triumph_Dolomite_Sprint_-_Flickr_-_The_Car_Spy_%2821%29.jpg)
Triumph added a unique
16-valve cylinder head
In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinders and forms the roof of the combustion chamber.
In sidevalve engines, the head is a simple sheet of metal; whereas in more modern ov ...
to the slant-four for the 1973
Dolomite Sprint. At the time there were at
British Leyland
British Leyland was an automotive engineering and manufacturing conglomerate formed in the United Kingdom in 1968 as British Leyland Motor Corporation Ltd (BLMC), following the merger of Leyland Motors and British Motor Holdings. It was partl ...
(BL) both
Harry Mundy, who worked on engine development at Jaguar, and
Walter Hassan
Walter Thomas Frederick Hassan OBE, C.Eng., M.I. Mech.E. (25 April 1905 – 12 July 1996) was a distinguished UK automotive engineer who took part in the design and development of three very successful engines: Jaguar XK, Coventry Climax and Ja ...
, also at Jaguar but in charge of engine technology development at BL as well. These two shared data on four-valve cylinder heads with King.
A team of engineers led by King and "with co-operation from
Harry Mundy and the engineers at
Coventry Climax
Coventry Climax was a British forklift truck, fire pump, racing, and other specialty engine manufacturer.
History
Pre WW1
The company was started in 1903 as Lee Stroyer, but two years later, following the departure of Stroyer, it was relocat ...
",
developed a 4-valve-per-
cylinder
A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base.
A cylinder may also be defined as an infin ...
head where all of the valves are actuated by a single
camshaft
A camshaft is a shaft that contains a row of pointed cams, in order to convert rotational motion to reciprocating motion. Camshafts are used in piston engines (to operate the intake and exhaust valves), mechanically controlled ignition systems ...
rather than the more conventional
DOHC
An overhead camshaft (OHC) engine is a piston engine where the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion c ...
arrangement. The valves are arranged in two rows of eight, inclined 27° from vertical. The inlet valves are in diameter and are operated by the camshaft lobes through bucket tappets, while the exhaust valves are in diameter and are operated through rocker arms.
The design of the cylinder head won a British
Design Council
The Design Council, formerly the Council of Industrial Design, is a United Kingdom charity incorporated by Royal Charter. Its stated mission is "to champion great design that improves lives and makes things better".
It was instrumental in the prom ...
award in 1974.
Capacity was increased to , and larger HS6
SU carburettor
SU carburettors were a British manufacturer of constant-depression carburettors. Their designs were in mass production during most of the twentieth century.
The S.U. Carburetter Company Limited also manufactured dual-choke updraught carburetto ...
s were fitted. Other changes to the Sprint engine included a duplex timing chain and alloy timing cover.
The big-end journals were also cross-drilled.
The engine was expected to make 135 bhp,
and King returned from holiday "to find an engine running on the bed giving 150 bhp at the first build."
Hence, it was initially intended to be named the 'Dolomite 135'. This was changed to 'Dolomite Sprint' and published reasons vary. One oft-repeated rumour is that production lines could not guarantee 135 bhp. However according to Matthew Vale,
it was during development that Triumph switched to measuring power from imperial (SAE) to metric (DIN), which calculated outputs approximately 5% lower. In this case 135 bhp SAE is 127 bhp DIN.
The Dolomite Sprint has been described as "the world's first mass-produced multi-valve car".
Multi-valve engines had first appeared in 1912, with the most recent prior to the release of the Sprint engine being the
Cosworth BDA
Cosworth is a British automotive engineering company founded in London in 1958, specialising in high-performance internal combustion engines, powertrain, and electronics for auto racing, automobile racing (motorsport) and mainstream Automotiv ...
(1969) and
Lotus 907 (1972), but they had not been not used in mass-production vehicles until after the introduction of the Dolomite Sprint.
The 16-valve 2.0 L engine was also used in a small number of prototype and pre-production
TR7 Sprints built at Triumph's plant in
Speke
Speke () is a suburb of Liverpool. It is southeast of the city centre. Located near the widest part of the River Mersey, it is bordered by the suburbs of Garston and Hunts Cross, and nearby to Halewood, Hale Village, and Widnes. The rural are ...
during 1977.
Saab B engine
In 1972 Saab brought production of the 1.85 L slant-four in-house to their
Scania
Scania, also known by its native name of Skåne (, ), is the southernmost of the historical provinces of Sweden, provinces (''landskap'') of Sweden. Located in the south tip of the geographical region of Götaland, the province is roughly conte ...
division at a facility in
Södertälje
Södertälje ( , ) is a Urban areas in Sweden, city in Södermanland and Stockholm County, Sweden and seat of Södertälje Municipality. As of 2017, it has 72,704 inhabitants. Södertälje is located at Mälarens confluence in to the Baltic Sea ...
. An uncorroborated letter to the editor of
Motor Sport magazine
''Motor Sport'' is a monthly motor racing magazine, founded in the United Kingdom in 1924
as the ''Brooklands Gazette''. The name was changed to ''Motor Sport'' for the August 1925 issue. The magazine covers motor sport in general, although from ...
references a Saab press release of July 1970 that indicates that this was planned from the outset.
Following the transfer Saab embarked on a redesign of the engine that resulted in the Saab B engine. Displacement increased to 2.0 L, but the bore diameter was smaller than the enlarged Triumph version, resulting in a swept volume of .
Saab's B engine shared much with the original Triumph design, including bore centres and bearings, but some previously problematic features, such as the water-pump and its seal, were redesigned.
Slant-four variants
Motorsports
The 16-valve Sprint engine was raced in
FIA
FIA is the Fédération Internationale de l'Automobile (English: International Automobile Federation), the world's governing body for all forms of motor sport where four or more wheels are used.
Fia or FIA may also refer to: People
* Fia Backst ...
Group 1 and Group 2 in Dolomite Sprints prepared by Leyland Special Tuning at Abingdon.
Their first season was 1974, but no finishes were achieved that year. In 1975 the engines received larger carburettors and a revised camshaft. With these changes they completed their first event at the Mintex Rally in 7th place. This was followed by a 2nd place in the Avon Tour of Britain and a 3rd at the Lindisfarne Rally. At the
Lombard RAC Rally
Wales Rally GB was the most recent iteration of the United Kingdom's premier international motor rally, which ran under various names since the first event held in 1932. It was consistently a round of the FIA World Rally Championship (WRC) calen ...
the Dolomite Sprint won the 2-litre class and Group 1 outright and placed 16th overall. For 1976 focus had shifted to the TR7, originally with the Sprint engine but by 1978 all efforts were focused on the TR8.
The private
Broadspeed
Broadspeed Engineering Ltd was a British automobile tuning and engineering company that operated from Sparkbrook, Birmingham, England, principally during the 1960s and 1970s. It was started and run by Ralph Broad, and first became well known for ...
team headed by Ralph Broad did extensive development on the Sprint engine, bringing power up to a claimed . Sprint-powered Broadspeed cars won the Manufacturer's Championship in 1974 and took the driver's title in 1975. In 1976 the cars took 2nd in the 2-litre class, and won again in 1978.
The Sprint engine also appeared in
Formula Three
Formula Three, also called Formula 3, abbreviated as F3, is a third-tier class of open-wheel formula racing. The various championships held in Europe, Australia, South America and Asia form an important step for many prospective Formula One driv ...
, in
Anson Cars
Anson Cars was a British racing car constructor.
In 1975, Formula One mechanics Gary Anderson (who worked for Brabham) and Bob Simpson (who worked for Tyrrell), built a Formula 3 car called the Anson SA1. It was based on the Brabham BT38 and ...
and
March Engineering
March Engineering was a Formula One constructor and manufacturer of customer racing cars from the United Kingdom. Although only moderately successful in Grand Prix competition, March racing cars enjoyed much better success in other categories ...
chassis. The Sprint-powered March placed 8th in the 1976 season. In 1979 two March cars driven by
Nigel Mansell
Nigel Ernest James Mansell, (; born 8 August 1953) is a British retired racing driver who won both the Formula One World Championship (1992) and the CART Indy Car World Series ( 1993). Mansell was the reigning F1 champion when he moved over ...
and Brett Riley finished 5th and 8th in the F3 championship and each driver won one race in the
Vandervell British F3 Championship.
References
{{DEFAULTSORT:Triumph Slant-4 Engine
Slant-4
Gasoline engines by model
Slant-four engines
Saab engines