Triumph I6

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Triumph I6
Triumph Straight-6 engine.jpg
Overview
Manufacturer
Also called Triumph Six Cylinder
Production 1960–1977
Chronology
Successor Leyland PE166 engine

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 larger displacement.

Introduced in their Standard Vanguard Six in 1960, it was used in a wide range of Triumph vehicles, including the Triumph TR5, TR250, and TR6.

Origin[edit]

Standard Eight engine[edit]

The Triumph six is based on the 4 cylinder engine first used in the Standard Eight in 1953. Displacement of the engine in the Eight was 803 cc.

The engine was modified a number of times for use in the Standard Ten, Triumph Herald, and Triumph Spitfire. First for the 948 cc Herald, and again for the 1147 cc Herald 1200, the cylinders were re-aligned[clarification needed] to give better clearance for the head studs and allow the bore to be enlarged. The engine was further developed and bored from 69.3 mm (2.7 in) in the 1147 cc version to 73.7 mm (2.9 in) giving 1296 cc for the Herald 13/60, the stroke was also increased from 76 mm (3.0 in) to 86.5 mm (3.4 in) providing 1493 cc for the Spitfire 1500.

Inline 6[edit]

The six cylinder engine was developed from the four used in the Eight and the Ten.[citation needed] It was first used in 1960 in the Standard Vanguard Six, in which it had a 74.6 mm (2.9 in) bore and a 76 mm (3.0 in) stroke, giving a capacity of 1998 cc.[1][2]

The engine was next used in the Triumph Vitesse, a sports saloon based on the Herald, in 1962.[1][3] In this application, the engine had a 66.75 mm (2.6 in) bore, reducing displacement to 1596 cc.[1][4] The Vitesse was given the two-litre engine with the 74.6 mm bore in 1966.[4]

The Triumph 2000 replaced the Vanguard Six in 1963 when Leyland discontinued the Standard marque.[5] The two-litre six was later used in the Spitfire-based GT6 coupé from 1966 to 1974.[6]

Beginning in 1967, the engine was used in the Triumph TR5 and TR250 sports cars, replacing the Standard inline-four engine used in TRs from the TR2 to the TR4A. For this application, the stroke was increased to 95 mm (3.7 in), giving 2498 cc. When equipped with the Lucas mechanical fuel injection system in the TR5, this new 2.5-litre version gave a claimed 150 bhp (112 kW; 152 PS) at 5500 rpm[4][7]. When tested on dynamometers, 110 to 130bhp at the crankshaft is more usual, and may explain Triumph's decision to fit the TR7 with a 2-litre slant-four engine, whose power output and hence performance were in fact similar to those of the earlier and ostensibly more powerful engine. The TR250 was sold in the US with Stromberg carburettors to avoid the need for additional emissions control systems; this reduced the power to 105 bhp (78 kW; 106 PS) at 4500 rpm.[7] The TR6, made from 1969 to 1975, used the TR5's engine,[4] detuned to 125 bhp (93 kW; 127 PS) in 1973.[7] with a 106 hp version of the TR250's engine in the United States.[7]

The fuel-injected 2.5 litre engine became available in the 2000 unit body as the 2.5 PI in 1968;[8] this was supplanted by the twin-carburettor 2500 TC in 1974.[4] The 2000 and 2500 TC were discontinued in 1977.[4]

Technical[edit]

A partial chart of Triumph engine numbers is posted on the "Spitfire & GT6 magazine" site.[9] However the capacity appears not to match the bore/stroke, or that published on other sites including the GT6 Ezine,[10] hence the corrections in the tables below.

Engine Applications Chart

Engine No. Prefix Capacity Car
HB 1596 cc Vitesse 6
HC 1998 cc Vitesse 2 Litre
KC 1998 cc GT6 Mk1/2
KD 1998 cc GT6 Mk1/2 (Anti Smog) (US?)
KE 1998 cc GT6 Mk3
KF 1998 cc GT6 Mk3 (US)
KG 1998 cc GT6 Mk3 (Sweden)
MB 1998 cc 2000 Mk1
MB 1998 cc 2000 Mk1
MG, MM, MN 2498 cc 2500
ME, ML 1998 cc 2000 Mk2
CC 2498 cc TR250 & TR6
CF 2498 cc TR6
CP, CR 2498 cc TR6(injection) and TR5PI

Factory Quoted Power Chart

Model Quoted power @rpm Quoted torque @rpm Capacity
TR5 150 bhp (112 kW; 152 PS) @5500 164 lb·ft (222 N·m) @3500 2498 cc
TR250 104 bhp (78 kW; 105 PS) @4500 143 lb·ft (194 N·m) @3000 2498 cc
TR6 (69-72) 150 bhp (112 kW; 152 PS) @5500 164 lb·ft (222 N·m) @3500 2498 cc
TR6 (73...) 124 bhp (92 kW; 126 PS) @5000 143 lb·ft (194 N·m) @3500 2498 cc
TR6 (USA) 104 bhp (78 kW; 105 PS) @4500 143 lb·ft (194 N·m) @3000 2498 cc
2.5 PI Mk1 & Mk2 132 bhp (98 kW; 134 PS) @5500 153 lb·ft (207 N·m) @2000 2498 cc
2500 Mk2 99 bhp (74 kW; 100 PS) @4700 133 lb·ft (180 N·m) @3000 2498 cc
2500 TC 106 bhp (79 kW; 107 PS) @4700 139 lb·ft (188 N·m) @3000 2498 cc
2000 Mk1 90 bhp (67 kW; 91 PS) @5000 117 lb·ft (159 N·m) @2900 1998 cc
2000 Mk2 84 bhp (63 kW; 85 PS) @5000 100 lb·ft (140 N·m) @2900 1998 cc
2000 TC 91 bhp (68 kW; 92 PS) @4750 110 lb·ft (150 N·m) @3300 1998 cc
GT6 Mk1 95 bhp (71 kW; 96 PS) @5000 117 lb·ft (159 N·m) @3000 1998 cc
GT6 Mk2 104 bhp (78 kW; 105 PS) @5300 117 lb·ft (159 N·m) @3000 1998 cc
GT6+ 95 bhp (71 kW; 96 PS) @4700 117 lb·ft (159 N·m) @3400 1998 cc
Vitesse 6 70 bhp (52 kW; 71 PS) @5000 92 lb·ft (125 N·m) @2800 1596 cc
Vitesse 2L 95 bhp (71 kW; 96 PS) @5000 117 lb·ft (159 N·m) @3000 1998 cc
Vitesse Mk2 104 bhp (78 kW; 105 PS) @5300 117 lb·ft (159 N·m) @3000 1998 cc

Racing[edit]

Triumph raced Spitfires, and some early GT6 prototypes at Le Mans, with some good success, and later at Sebring but due to rule changes and the takeover by Leyland, this was not continued.

Replacement[edit]

After Triumph, and later Rover, were absorbed into Leyland Motors in 1960, and 1967 respectively, work began on a successor to both the Triumph 2000 and the Rover P6 which would also use a new straight six engine design. The engine, known internally as the Leyland PE166 was originally intended to be a development of the Triumph I6, but ended up becoming an entirely new design, with almost no interchangeable parts with the original. The Rover SD1 was the only recipient of this engine in both 2.3L and 2.6L capacities.

Notes[edit]

  1. ^ a b c Robson 2011, p. 199.
  2. ^ Culshaw & Horrobin 2013, pp. 286–287.
  3. ^ Culshaw & Horrobin 2013, p. 320.
  4. ^ a b c d e f Culshaw & Horrobin 2013, p. 322.
  5. ^ Culshaw & Horrobin 2013, pp. 287, 320.
  6. ^ Culshaw & Horrobin 2013, pp. 321–322.
  7. ^ a b c d Elliott 2007, p. 105.
  8. ^ Culshaw & Horrobin 2013, p. 320, 322.
  9. ^ "Triumph Spitfire and GT6 Engine Numbers". Archived from the original on 18 November 2013. Retrieved 4 April 2010. 
  10. ^ "GT6 Ezine, Reference Section". Archived from the original on 5 March 2012. Retrieved 4 April 2010. 

References[edit]

  • Culshaw, David; Horrobin, Peter (2013) [1974]. The Complete Catalogue of British Cars 1895 - 1975 (e-book ed.). Poundbury, Dorchester, UK: Veloce Publishing. ISBN 978-1-845845-83-4. 
  • Elliott, James (March 2007). Elliott, James, ed. "The Magic Numbers". Classic & Sports Car. Haymarket Publishing. 25 (12): 100–109. ISSN 0263-3183. 
  • Robson, Graham (May 2011). The Book of the Standard Motor Company. Poundbury, Dorchester, UK: Veloce Publishing. ISBN 978-1-845843-43-4. Retrieved 19 October 2014.