Rolls-Royce C range engines

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Rolls-Royce C6SFL
Manufacturer Rolls-Royce Limited
Configuration Six-cylinder, supercharged diesel
Displacement 12.17 litres (740 cu in)
Cylinder bore 5 1/8 inch (130 mm)
Piston stroke 6 inch (152 mm)
Fuel type Diesel
Oil system dry sump
Cooling system Water-cooled
Power output 190 brake horsepower (140 kW) at 1,800 rpm
Torque output 600 lb⋅ft (810 N⋅m) at 1,300 rpm

The Rolls-Royce C range was a series of in-line 4, 6 and 8 cylinder diesel engines used in small railway locomotives, construction vehicles, marine and similar applications. They were manufactured by the Rolls-Royce Oil Engine Division, initially at Derby and later at Shrewsbury, from the 1950s through to 1970s.[1]

Although officially termed the C range, they were best known for the most common C6SFL six-cylinder variant. Most had an output of around 200 bhp, with 233 bhp for the final models. Their construction was a conventional water-cooled vertical inline 6 four-stroke diesel engine of 12.17 litres (743 cu in). Most were supercharged by a Roots blower, but there were also variants with a turbocharger or normally aspirated.[2]

A later addition to the range was the SF65C model. This was a lower-rated version of the C range 6-cylinder engine and shared many of the advantages of the range's component rationalisation. It was available in normally aspirated or turbocharged variants, and both industrial and marine versions were available.[3]


Data from Version supplied for the Vickers-Armstrong crawler tractor [2]

General characteristics

  • Type: Six-cylinder, supercharged diesel
  • Bore: 5 1/8 inch (130 mm)
  • Stroke: 6 inch (152 mm)
  • Displacement: 12.17 litres (740 cu in)


  • Power output: 190 brake horsepower (140 kW) at 1,800 rpm
  • Torque: 600 pound-feet (810 N⋅m) at 1,300 rpm
C Range: comparison of available models[1]
Model Cylinders Aspiration Layout Power Application
C4NFL 4 Normal Vertical
C4SFL 4 Supercharged Vertical
C4TFL 4 Turbocharged Vertical
C4NFLM 4 Normal Vertical Marine
C4SFLM 4 Supercharged  Vertical Marine
C6NFL 6 Normal Vertical
C6SFL 6 Supercharged Vertical 190 bhp
C6TFL 6  Turbocharged Vertical
C6NFLH 6 Normal  Horizontal  180 bhp Railcar
C6SFLH 6 Supercharged Horizontal 233 bhp Railcar
C6TFLH 6 Turbocharged Vertical Railcar
C6NFLM 6 Normal Vertical Marine
C6SFLM 6 Supercharged Vertical Marine
C6TFLM 6 Turbocharged Vertical Marine
C8NFL 8 Normal Vertical
C8SFL 8 Supercharged Vertical  300 bhp 
C8TFL 8 Turbocharged Vertical
C8NFLH 8 Normal Horizontal Railcar
C8SFLH 8 Supercharged Horizontal  250 bhp  Railcar
C8TFLH 8 Turbocharged Vertical Railcar
C8NFLM 8 Normal Vertical Marine
C8SFLM 8 Supercharged Vertical Marine
C8TFLM 8 Turbocharged Vertical Marine


The engine was constructed around a monobloc cylinder and crankcase casting. Unusually, this was available in either cast iron or aluminium alloy. The cylinders were replaceable wet liners, with pumped water cooling. Valves were single OHV exhaust and inlet valves. Seven bearings with cross-bolted caps supported the nitrided crankshaft. The fuel injection system was direct, into a toroidal combustion chamber within the aluminium pistons. Supercharging was by a Roots blower driven at twice crankshaft speed, for a boost pressure of 8 psi.[2]

An unusual feature was the ability to build the engines with the flywheel and output drive arranged at either end. The supercharger, fuel injection pump, and other auxiliaries also changed sides. Although the crankshaft always rotated the same way within the block, this was the equivalent of offering left and right-handed rotation engines (the C6SFR variant).[2]

For a diesel at its introduction date of 1951, the engine operated at relatively high speed, up to 1,800 rpm. This was assisted by a viscous torsion damper at the opposite end to the flywheel.[2] High rotational speed made the engine an attractive choice in the developing market for small diesel-hydraulic locomotives.

Rolls-Royce Sentinel[edit]

"Sentinel" diesel locomotive, badged as "Powered by Rolls-Royce"

In 1957, Rolls-Royce acquired the Sentinel company of Shrewsbury, a builder of steam wagons and small steam locomotives.[4] Production of the C6 was relocated from Derby. Although Rolls-Royce had only intended to build prime movers, i.e. engines here, by the end of 1957 they had decided to continue with Sentinel's previously successful market for small shunting locomotives. This was initially the LB class, 0-4-0 with a typically Sentinel final chain drive, of 1959-1971.[4]

In the 1980s, the Shrewsbury diesel engine plant was acquired by Perkins.


C6SFL (supercharged by Roots blower), C6TFL (turbocharged), C6NFL (naturally aspirated), C6NFR (reverse rotation)

The C8SFL was a lengthened 8-cylinder variant, giving approximately 300 bhp. This was fitted to the MK3 Thornycroft Mighty Antar a British tank transporter

A C6SFLM (marinised) was also produced.

Horizontal railcar engines[edit]

Class 111 DMU with twin C6NFLH in each power car

Horizontal versions, such as the C6NFLH (H for horizontal), were also produced for railcars and mounted beneath the floor.[5] This engine was not completely horizontal, with the cylinders inclined slightly upwards at 17½°.[5] Wet sump lubrication was used.[5] Many of the ancillaries and servicing points were relocated to what were now the sides of the engine, so that they could be serviced from the sides of the railcar, rather than having to lift out floor panels.

The C6NFLH produced 180 bhp at 1,800 rpm. It was used by Metropolitan-Cammell in the Class 111 DMUs of the late 1950s and 1960s, rather than the 150 bhp BUT engines used in earlier classes. Two engines were used for each power car, marshalled into two or three car sets with a power car at each end, giving 720 bhp overall. This extra power was also used for the BRC&WC 'Calder Valley' sets.

An eight-cylinder version, C8NFLH, of 238 bhp at 1,880 rpm was also used. A single unit was used in each power car of the 112 and 113 classes. These were very similar, the 112 having a mechanical pre-selector transmission[6] and the 113 a Lysholm-Smith Twin-Disc torque converter (licence-built by Rolls-Royce) in a hydraulic transmission.[7] The high density 125 and 127 classes used twin engines.

Twin supercharged C8SFLH engies of 250 hp were used in some of the early New South Wales 620 Class railcars with licence built Twin Disc transmissions.[8] C8SFLH engines and licence built Twin Disc transmissions were also used to re-engine a number of Canadian National Railway and Canadian Pacific Railway's Budd railcars.[9]

Supercharged C6SFLH units of 230 bhp were trialled in a single British Rail Class 111[5] and were later retrofitted to the Norwegian Class 86 and 91 DMUs. The three South Maitland Railways Tulloch rail cars of the 1970s also used Supercharged C6SFLH units of 233 hp with a licence built Twin Disc transmission.[8]



The major railway uses of this engine were the horizontal versions used in many of the British Rail first generation DMUs. Norwegian State Railways also retrofitted them to their Class 86 and 91 multiple units.

Vertical engines were also used in a range of small shunting locomotives, sometimes in pairs for powers up to 600 bhp..


The marine variants of these engines were available in each of the 4, 6 and 8 cylinder models. These marine models were all of the vertical arrangement. Marine gearing options included M.R.F.10 3B, M.R.F.16B, M.R.F.16B/1B and M.R.F.21/B units from Self-Changing Gears Ltd, of Coventry and Thornycroft Type B units from Transport Equipment (Thornycroft) Ltd. of Reading.[1]

A pair of C6SFLM (marinised) were used for a speed of 20 knots.[13]

Construction vehicles[edit]

Fire appliances[edit]

See also[edit]


  1. ^ a b c Rolls-Royce Diesels Workshop Manual (4th ed.). Rolls-Royce Limited Oil Engine Division. c. 1960. 
  2. ^ a b c d e f Chapman, C.W. (1956). Modern High-Speed Oil Engines. Vol I (2nd ed.). Caxton. pp. 261–263. 
  3. ^ Rolls-Royce C Range Workshop Manual (11th ed.). Rolls-Royce Motors Limited, Diesel Division. 1983. 
  4. ^ a b c "DH16 Sentinel 0-4-0". 
  5. ^ a b c d Bolton, William F. (2006) [1956]. The Railwayman's Diesel Manual (4th ed.). Ian Allan. pp. 69–71, 91–92. ISBN 0-7110-3197-5. 
  6. ^ Bolton 1956, pp. 135–142
  7. ^ Bolton 1956, pp. 144–145
  8. ^ a b Cooke, David E. (1984). Railmotors and XPTs. Australian Railway Historical Society (NSW Division). ISBN 0-909650-23-3. 
  9. ^ Rolls-Royce Railway Traction Department Newsletter (14 ed.). Rolls-Royce Limited. April 1962. 
  10. ^ Gunzburg, Adrian (1989). The Midland Railway Company Locomotives of Western Australia. Melbourne: Light Railway Research Society of Australia. pp. 40–44, 49. ISBN 0909340277. 
  11. ^ Bjerke, Thor; Tovås, Ove (1989). Togbytte på Nelaug (in Norwegian). Norsk Jernbaneklubb. p. 200. ISBN 82-90286-10-4. 
  12. ^ "NSB Skd 220 194". Flickr. 
  13. ^ "RSL-1664: 43ft Range Safety Launch". British Military Powerboat Team.  External link in |publisher= (help)
  14. ^ "Rugged reliability: The Vickers VR180 Vigor". Archived from the original on 2008-10-14.