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BMC A-series engine

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The Austin Motor Company A-series is a British small straight-4 automobile engine. Launched in 1951 with the Austin A30, production lasted until 2000 in the Mini. It used a cast-iron block and cylinder head, and a steel crankshaft with three main bearings. The camshaft ran in the cylinder block, driven by a single-row chain for most applications, and with tappets sliding in the block, accessible through pressed steel side covers for most applications, and with overhead valves operated through rockers. The cylinder blocks are not interchangeable between versions intended for conventional end-on mounted gearboxes and the 'in-sump' transaxle used on British Motor Corporation/British Leyland front wheel drive models such as the Mini. The cylinder head for the overhead-valve version of the A-series engine was designed by Harry Weslake – a cylinder head specialist famed for his involvement in SS (Jaguar) engines and several Formula One-title winning engines. Although a "clean sheet" design, the A-series owed much to established Austin engine design practise, resembling in general design (including the Weslake head) and overall appearance a scaled-down version of the 1200cc overhead-valve engine first seen in the Austin A40 Devon which would form the basis of the later B-series engine.

BMC A series
Overview
ManufacturerAustin Motor Company
British Motor Corporation
British Leyland Motor Corporation
Rover Group
MG Rover Group
DesignerLeonard Lord, Bill Appleby, Eric Bareham
ProductionLongbridge, Cowley in UK between 1951 - 2000;

Pamplona in Spain, NMQ (Nueva Montaña Quijano) between 1966 - 1975;

Blackheath, Gauteng in South Africa between 1960 - 1980
Layout
ConfigurationInline-four engine, (Straight-three engine and Straight-twin in Prototype)
Displacement803–1,275 cc (49.0–77.8 cu in)
Cylinder bore
  • 57.92 mm (2.280 in)
  • 62.43 mm (2.458 in)
  • 62.9 mm (2.48 in)
  • 64.58 mm (2.543 in)
  • 70.6 mm (2.78 in)
Piston stroke
  • 61.95 mm (2.439 in)
  • 68.26 mm (2.687 in)
  • 68.4 mm (2.69 in)
  • 76.2 mm (3.00 in)
  • 81.4 mm (3.20 in)
Cylinder block materialCast iron
Cylinder head materialCast iron, Aluminium
ValvetrainOHV 2 valves/ cyl. in OEM versions, OHC 4 valves/cyl prototype and in racing.
Compression ratio7.5:1, 8.3:1, 8.5:1, 8.8:1, 9.4:1, 10.5:1, 23.6:1 (Diesel)
Combustion
SuperchargerShorrock and Eaton supercharger (racing only)
TurbochargerGarrett T3 (1275 Turbo only)
Fuel systemSU carburettor or fuel injection
ManagementRover MEMS, Lucas, AE Brico, T.J Fuel Injection, Lucas CAV (Diesel Version)
Fuel typePetrol, Diesel
Cooling systemWater-cooled
Output
Power output28 to 96 bhp (21 to 72 kW; 28 to 97 PS)
Torque output40 to 85 lb⋅ft (54 to 115 N⋅m)
Emissions
Emissions _target standardEuro 3 (MPi engine).
Chronology
SuccessorRover K-series engine, Tritec engine

Engine family list

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All engines had a cast iron head and block, two valves per cylinder in an OHV configuration and sidedraft SU carburettor. Engines were available in diesel in the BMC tractor.

All A-series engines up until mid-1970 were painted in British Standard (381c) 223 "Middle Bronze Green".[1] This does not include overseas production models such as Australian manufacture. "Factory/dealer warranty replacement" units were painted black, these were primarily distributed for the failures common to the "wet crank" primary gear system in early Minis.

Petrol
ID Displacement Years Bore Stroke Compression
ratio		 Fuel system Horsepower @rpm Torque @rpm
A 803 cc (49.0 cu in) 1951-1956 57.92 mm (2.280 in) 76.2 mm (3.00 in) 7.5:1 Single H2 / Zenith 26JS or 26VME 28 PS (21 kW; 28 hp) 4800 40 lb⋅ft (54 N⋅m) 2400
848 cc (51.7 cu in) 1959-1980 62.9 mm (2.48 in) 68.26 mm (2.687 in) 8.3:1 34 PS (25 kW; 34 hp) 5500 44 lb⋅ft (60 N⋅m) 2900
948 cc (57.9 cu in) 1956-1964 76.2 mm (3.00 in) 8.3:1 37 PS (27 kW; 36 hp) 4750 50 lb⋅ft (68 N⋅m) 2500
970 cc (59 cu in) 1964-1967 70.6 mm (2.78 in) 61.91 mm (2.437 in) - Twin HS2 65 PS (48 kW; 64 hp) 6500 55 lb⋅ft (75 N⋅m) 3500
997 cc (60.8 cu in) 1961-1964 62.43 mm (2.458 in) 81.28 mm (3.200 in) 8.3:1 55 PS (40 kW; 54 hp) 6000 54 lb⋅ft (73 N⋅m) 3600
998 cc (60.9 cu in) 1962-1980 64.58 mm (2.543 in) 76.2 mm (3.00 in) 8.3:1 Single HS2 39 PS (29 kW; 38 hp) 4750 52 lb⋅ft (71 N⋅m) 2700
998 cc (60.9 cu in) 1964-1971 64.58 mm (2.543 in) 76.2 mm (3.00 in) - Twin HS2 55 PS (40 kW; 54 hp) 5800 57 lb.ft (77 N.m) 3000
1,070 cc (65 cu in) 1963-1967 70.6 mm (2.78 in) 68.26 mm (2.687 in) 8.5:1 Twin HS2 70 PS (51 kW; 69 hp) 6000 62 lb⋅ft (84 N⋅m) 4500
1,098 cc (67.0 cu in) 1962-1980 64.58 mm (2.543 in) 83.8 mm (3.30 in) Single HS2 47 PS (35 kW; 46 hp) 5200 60 lb⋅ft (81 N⋅m) 2450
1,098 cc (67.0 cu in) 1962-1968 64.58 mm (2.543 in) 83.8 mm (3.30 in) - Twin HS2 55 PS (40 kW; 54 hp) 5500 61 lb⋅ft (83 N⋅m) 2500
1,097 cc (66.9 cu in) 1971-1980 70.6 mm (2.78 in) 69.85 mm (2.750 in) - - 54 PS (40 kW; 53 hp) - - -
1,275 cc (77.8 cu in) 1964-1971 70.6 mm (2.78 in) 81.28 mm (3.200 in) 8.8:1 Twin HS2 76 PS (56 kW; 75 hp) 5300 79 lb⋅ft (107 N⋅m) 3000
1,275 cc (77.8 cu in) 1967-1980 70.6 mm (2.78 in) 81.28 mm (3.200 in) - Single HS4 57 PS (42 kW; 56 hp) 5300 69 lb⋅ft (94 N⋅m) 3000
1,275 cc (77.8 cu in) 1968-1974 70.6 mm (2.78 in) 81.28 mm (3.200 in) - Twin HS2 70 PS (51 kW; 69 hp) 6000 77 lb⋅ft (104 N⋅m) 3000
A+ 998 cc (60.9 cu in) 1980-1992 64.58 mm (2.543 in) 76.2 mm (3.00 in) 9.4:1 Single HIF38 44 PS (32 kW; 43 hp) 5250 52 lb⋅ft (71 N⋅m) 3000
1,275 cc (77.8 cu in) 1980-1992 70.6 mm (2.78 in) 81.28 mm (3.200 in) 9.75:1 Single HIF44 62 PS (46 kW; 61 hp) 5600 72 lb⋅ft (98 N⋅m) 3200
1,275 cc (77.8 cu in) 1983-1990 70.6 mm (2.78 in) 81.28 mm (3.200 in) 9.4:1 Single HIF44 / Turbo 96 PS (71 kW; 95 hp) 6130 85 lb⋅ft (115 N⋅m) 2650
1,275 cc (77.8 cu in) 1992-1996 70.6 mm (2.78 in) 81.28 mm (3.200 in) 10.1:1 SPi 63 PS (46 kW; 62 hp) 5500 70 lb⋅ft (95 N⋅m) 3000
1,275 cc (77.8 cu in) 1996-2000 70.6 mm (2.78 in) 81.28 mm (3.200 in) 10.1:1 MPi 62 PS (46 kW; 61 hp) 5500 72 lb⋅ft (98 N⋅m) 3000
1,275 cc (77.8 cu in) 1992-2000 70.6 mm (2.78 in) 81.28 mm (3.200 in) 10.1:1 SPi / MPi 77 PS (57 kW; 76 hp) 5800 80 lb⋅ft (110 N⋅m) 3000
Diesel
A 947 cc (51.7 cu in) 1962-1969 62.9 mm (2.48 in) 76.2 mm (3.00 in) 23.6:1 Lucas CAV 15 PS (11 kW; 15 hp) 2500 38 lb⋅ft (52 N⋅m) 1750

A versions

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803

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Austin A35 van engines, original 948cc left, replacement 803cc right

The original A-series engine displaced just 803 cc (49.0 cu in) and was used in the A30 and Morris Minor. It had an undersquare 57.92 mm × 76.2 mm (2.280 in × 3.000 in) bore and stroke. This engine was produced from 1952 to 1956.

Applications:

  • 1952–56 Austin A30, 28 hp (21 kW) at 4400 rpm and 40 lb⋅ft (54 N⋅m) at 2200 rpm
  • 1952–56 Morris Minor Series II, 30 hp (22 kW) at 4800 rpm and 40 lb⋅ft (54 N⋅m) at 2400 rpm

948

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1956 saw a displacement increase, to 948 cc (57.9 cu in). This was accomplished by increasing the bore to 62.9 mm (2.48 in) while retaining the original 76.2 mm (3.00 in) stroke. It was produced until 1964.

Applications
Model Power output Torque
Austin A35 34 hp (25 kW) at 4,750 rpm 50 lb⋅ft (68 N⋅m) at 2,000 rpm
Morris Minor 1000 37 hp (28 kW) at 4,750 rpm 50 lb⋅ft (68 N⋅m) at 2,500 rpm
Austin A40 Farina 34 hp (25 kW) at 4,750 rpm 50 lb⋅ft (68 N⋅m) at 2,000 rpm
Austin-Healey Sprite 43 hp (32 kW) at 5,200 rpm 52 lb⋅ft (71 N⋅m) at 3,300 rpm
Austin A40 Farina MkII 37 hp (28 kW) at 5,000 rpm 50 lb⋅ft (68 N⋅m) at 2,500 rpm
Austin-Healey Sprite MkII MG Midget 46 hp (34 kW) at 5,500 rpm 53 lb⋅ft (72 N⋅m) at 3,000 rpm

848

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An 848 cc A-series engine in a 1963 Austin Mini

The 62.9 mm (2.48 in) bore was retained for 1959s 848 cc (51.7 cu in) Mini version. This displacement was reached by dropping the stroke to 68.26 mm (2.687 in). This engine was produced through to 1980 for the Mini, when the 998 A-Plus version supplanted it.


Applications
Model Years Power output Torque
Austin Seven/Austin/Morris Mini[a] 1959–69 34 hp (25 kW) at 5500 rpm 44 lb⋅ft (60 N⋅m) at 2900 rpm
Riley Elf/Wolseley Hornet[a] 1961–62
Austin A35 Van 1963–68
Mini Moke 1964–68
Mini 850/City 1969–80 33 hp (25 kW) at 5300 rpm

997

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The one-off 997 cc (60.8 cu in) version for the Mini Cooper used a smaller 62.43 mm (2.458 in) bore and longer 81.4 mm (3.20 in) stroke. It was produced from 1961 to 1964.

Applications:

998

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The Mini also got a 998 cc (60.9 cu in) version. This was similar to the 948 in that it had the same 76.2 mm (3.00 in) stroke but the bore was increased slightly to 64.58 mm (2.543 in). It was produced from 1962 to 1992. This engine was first introduced into the Mk II versions of the Riley Elf and Wolseley Hornet, before becoming common fitment in the mainstream Minis.


Model Years Power output Torque
Riley Elf/Wolseley Hornet 1962–69 38 hp (28 kW) at 5250 rpm 52 lb⋅ft (71 N⋅m) at 2700 rpm
Mini Moke, Australian Mokes. 1966–82
Mini Moke, Portuguese Mokes. 1983–93
Austin/Morris Mini Cooper 1964–69 55 hp (41 kW) at 5800 rpm 57 lb⋅ft (77 N⋅m) at 3000 rpm
Austin/Morris Mini 1967–80 38 hp (28 kW) at 5250 rpm 52 lb⋅ft (71 N⋅m) at 2700 rpm
Mini Clubman 1969–75
Mini (automatic) 1969–80 41 hp (31 kW) at 4850 rpm 52 lb⋅ft (71 N⋅m) at 2750 rpm

1098

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The 1.1 L; 67.0 cu in (1,098 cc) version was fitted to:

  • MG Midget Mk1 1098cc from Oct 62- 64
  • MG Midget Mk2 1098cc of 1964- 66
  • Austin A35 Van 1098cc of 1962- 68
  • Austin A40 Farina Mk2 - From Oct 62- 68
  • Morris Minor from Oct 62- 71.
  • Austin / Morris BMC Saloon from 1962.
  • Mini and its derivatives, the 1098cc engine mounted transversely.

It was a stroked (to 83.8 mm (3.30 in)) version of the 998 previously used in the Riley Elf and Wolseley Hornet. It was produced from 1962 to 1980.

Applications:
Years Model Power output Torque
1962–66 Austin A35 Van 48 hp (36 kW) at 5100 rpm 60 lb⋅ft (81 N⋅m) at 2500 rpm
1962–67 Austin A40 Farina
1962–71 Morris 1100/Morris Minor 1000
1962–68 MG 1100 55 hp (41 kW) at 5500 rpm 61 lb⋅ft (83 N⋅m) at 2500 rpm
1962–64 Austin-Healey Sprite MkII 56 hp (42 kW) at 5500 rpm 62 lb⋅ft (84 N⋅m) at 3250 rpm
1962–64 MG Midget
1963–74 Austin 1100 48 hp (36 kW) at 5100 rpm 60 lb⋅ft (81 N⋅m) at 2500 rpm
1963–67 Vanden Plas Princess 1100 55 hp (41 kW) at 5500 rpm 61 lb⋅ft (83 N⋅m) at 2500 rpm
1964–66 Austin-Healey Sprite MkIII 59 hp (44 kW) at 5750 rpm 65 lb⋅ft (88 N⋅m) at 3500 rpm
1964–66 MG Midget MkII
1965–68 Riley Kestrel/Wolseley 1100 55 hp (41 kW) at 5500 rpm 61 lb⋅ft (83 N⋅m) at 2500 rpm
1973–75 Austin Allegro 49 hp (37 kW) at 5250 rpm 60 lb⋅ft (81 N⋅m) at 2450 rpm
1975–80 Austin Allegro 45 hp (34 kW) at 5250 rpm 55 lb⋅ft (75 N⋅m) at 2900 rpm
1968–82 Mini Moke (Australia only)
1969–71 Morris Mini 1100/Morris Mini K (Australia only)
1971–75 Morris Mini Clubman/Leyland Mini (Australia only)
1975–80 Mini Clubman 45 hp (34 kW) at 5250 rpm 56 lb⋅ft (76 N⋅m) at 2700 rpm
1976–80 Mini 1100 Special

1070

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The 1,070 cc (65 cu in) version was another one-off, this time for the Mini Cooper S. It used a new 70.6 mm (2.78 in) bore size and the 68.26 mm (2.687 in) stroke from the 848. It was only produced in 1963–1964. Paired with the even rarer 970 cc (59 cu in) version, below, it became that rarest of things: an oversquare A-series engine.

Applications:

970

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The Mini Cooper S next moved on to a 970 cc (59 cu in) version. It had the same 70.6 mm (2.78 in) bore as the 1071 cc Cooper S but used a shorter 61.95 mm (2.439 in) stroke. It was produced from 1964 to 1965.

Applications:

1275

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The largest A-series engine displaced 1.3 L; 77.8 cu in (1,275 cc). It used the 70.6 mm (2.78 in) bore from the Mini Cooper S versions but the 81.4 mm (3.20 in) stroke from the plain Mini Cooper. It was produced from 1964 until 1980, when it was replaced by an A-Plus version. The bore size was around the maximum possible in the block, with very little separation between the middle cylinders, which often contributed to head gasket failures.

Applications:
Years Model Power output Torque
1964–71 Austin/Morris Mini Cooper S 76 hp (57 kW) at 5800 rpm 79 lb⋅ft (107 N⋅m) at 3000 rpm
1965-74 Mini Marcos 76 hp (57 kW) at 5900 rpm
1966–70 Austin-Healey Sprite MkIV 65 hp (48 kW) at 6000 rpm 72 lb⋅ft (98 N⋅m) at 3000 rpm
1966–74 MG Midget MkIII
1967–68 MG 1300/Wolseley 1300 58 hp (43 kW) at 5250 rpm 69 lb⋅ft (94 N⋅m) at 3000 rpm
1967–68 Riley Kestrel 1300
1967–68 Vanden Plas Princess 1300
1967–73 Morris 1300
1967–74 Austin 1300
1967 MG 1275/Riley 1275 69 lb⋅ft (94 N⋅m) at 3500 rpm
1967 Wolseley 1275
1967 Vanden Plas Princess 1275
1968–69 Riley Kestrel 1300/Riley 1300 70 hp (52 kW) at 6000 rpm 77 lb⋅ft (104 N⋅m) at 3000 rpm
1968–71 Austin America (automatic) 60 hp (45 kW) at 5250 rpm 69 lb⋅ft (94 N⋅m) at 2500 rpm
1968–73 Wolseley 1300 (manual) 65 hp (48 kW) at 5750 rpm 71 lb⋅ft (96 N⋅m) at 3000 rpm
1968–73 MG 1300 MkII 70 hp (52 kW) at 6000 rpm 77 lb⋅ft (104 N⋅m) at 3000 rpm
1968–74 Vanden Plas Princess 1300 (manual) 65 hp (48 kW) at 5750 rpm 71 lb⋅ft (96 N⋅m) at 3000 rpm
1968 MG 1300/Riley Kestrel 1300
1969–71 Morris 1300GT 70 hp (52 kW) at 6000 rpm 74 lb⋅ft (100 N⋅m) at 3250 rpm
1971–82 Mini Moke Californian Australian only.
1969–74 Mini 1275GT 59 hp (44 kW) at 5300 rpm 65 lb⋅ft (88 N⋅m) at 2550 rpm
1969–74 Austin 1300GT 70 hp (52 kW) at 6000 rpm 74 lb⋅ft (100 N⋅m) at 3250 rpm
1971–80 Morris Marina 60 hp (45 kW) at 5250 rpm 69 lb⋅ft (94 N⋅m) at 2500 rpm
1971 Austin Sprite 65 hp (48 kW) at 6000 rpm 72 lb⋅ft (98 N⋅m) at 3000 rpm
1973–80 Austin Allegro 59 hp (44 kW) at 5300 rpm 69 lb⋅ft (94 N⋅m) at 3000 rpm
1974–80 Mini 1275GT 54 hp (40 kW) at 5300 rpm 65 lb⋅ft (88 N⋅m) at 2550 rpm

A-Plus versions

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British Leyland was keen to update the old A-series design in the 1970s. However, attempts at replacement, including an aborted early-70s British Leyland 'K engine' (unrelated to the later Rover K series) and an OHC version of the A series, ended in failure. During the development of what was to become the Austin Metro, engineers tested the A series against its more modern rivals and found that it still offered competitive (or even class-leading) fuel economy and torque for its size. While in the 1970s the A series had begun to seem dated against a new generation of high-revving overhead cam engines, by the end of the decade a new emphasis on good economy and high torque outputs at low speeds meant that the A series's inherent design was still well up to market demands.

Given this, and the lack of funds to develop an all-new power unit, it was decided to upgrade the A-series unit at a cost of £30 million. The result was the 'A-Plus' Series of engines. Available in 998 and 1,275 cc (60.9 and 77.8 cu in), the A-Plus had stronger engine blocks and cranks, lighter pistons and improved piston rings, Spring loaded tensioner units for the timing chain and other detail changes to increase the service interval of the engine (from 6,000 to 12,000 miles (9,700 to 19,300 km)). More modern SU Carburettors and revised manifold designs allowed for small improvements in power without any decrease in torque or fuel economy. Many of the improvements learnt from the Cooper-tuned units were also incorporated, with A-Plus engines having a generally higher standard of metallurgy on all units, where previously only the highest-tuned engines were upgraded in this way. This made the A-Plus engines generally longer-lived than the standard A series, which had a life between major rebuilds of around 80,000 to 100,000 miles (130,000 to 160,000 km) in normal service. Studies were made into upgrading the engine to use five main crankshaft bearings but the standard three-bearing crank had proven reliable even in high states of tune and at high engine speeds, so it was not deemed worth the extra funding.

The new engines received distinctive 'A+' branding on their rocker covers and the blocks and heads were colour-coded for the different capacities: yellow for 998 cc (60.9 cu in) and red for 1,275 cc (77.8 cu in) engines.

998 Plus

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The A-Plus version of the 998 cc (60.9 cu in) motor was produced from 1980 to 1992.

Applications:

Years Model Power output Torque
1980–82 Mini 1000/City/HL 39 hp (29 kW) at 4750 rpm 52 lb⋅ft (71 N⋅m) at 2000 rpm
1980–82 Austin Allegro 44 hp (33 kW) at 5250 rpm 52 lb⋅ft (71 N⋅m) at 3000 rpm
1980–90 Austin Metro 41 hp (31 kW) at 5400 rpm 51 lb⋅ft (69 N⋅m) at 2700 rpm
1982–88 Mini HLE/City E/Mayfair 40 hp (30 kW) at 5000 rpm 50 lb⋅ft (68 N⋅m) at 2500 rpm
1981–86 Austin Metro HLE 46 bhp (34 kW) 52 lb⋅ft (71 N⋅m)
1988–92 Mini City/Mayfair 42 hp (31 kW) at 5250 rpm 58 lb⋅ft (79 N⋅m) at 2600 rpm

1275 Plus

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The larger 1.3 L; 77.8 cu in (1,275 cc) engine was also given the "A-Plus" treatment. This lasted from 1980 to 2000, making it the last of the A-series line.


Applications
Years Model Power output Torque
1980–82 Austin Allegro 62 hp (46 kW) at 5600 rpm 72 lb⋅ft (98 N⋅m) at 3200 rpm
1980–84 Morris Ital 61 hp (45 kW) at 5300 rpm 69 lb⋅ft (94 N⋅m) at 2950 rpm
1980–90 Austin Metro 63 hp (47 kW) at 5650 rpm 72 lb⋅ft (98 N⋅m) at 3100 rpm
1982–89 MG Metro 72 hp (54 kW) at 6000 rpm 75 lb⋅ft (102 N⋅m) at 4000 rpm
1983–85 Austin Maestro HLE 64 hp (48 kW) at 5500 rpm 73 lb⋅ft (99 N⋅m) at 3500 rpm
1983–93 Austin Maestro 68 hp (51 kW) at 5800 rpm 75 lb⋅ft (102 N⋅m) at 3500 rpm
1984–89 Austin Montego 68 hp (51 kW) at 5600 rpm 75 lb⋅ft (102 N⋅m) at 3500 rpm
1989–90 Austin Metro GTa 72 hp (54 kW) at 6000 rpm 75 lb⋅ft (102 N⋅m) at 4000 rpm
1990–91 Mini Cooper 60 hp (45 kW; 61 PS) at 5500 rpm 71 lb⋅ft (96 N⋅m) at 3900 rpm
1990–91 Mini Cooper S 78 hp (58 kW) at 6000 rpm 78 lb⋅ft (106 N⋅m) at 3250 rpm
1991–96 Mini Cooper 1.3i/Cabriolet 62 hp (46 kW; 63 PS) at 5700 rpm 70 lb⋅ft (95 N⋅m) at 3900 rpm
1991–96 Mini Cooper S 1.3i 77 hp (57 kW) at 5800 rpm 80 lb⋅ft (110 N⋅m) at 3000 rpm
1992–96 Mini Sprite/Mayfair 50 hp (37 kW) at 5000 rpm 66 lb⋅ft (89 N⋅m) at 2600 rpm

1275 Turbo

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To allow the MG Metro to compete with larger, more powerful hot hatchbacks a turbocharged version of the 1,275 cc (77.8 cu in) A-Plus was developed with the assistance of Lotus Engineering. A Garrett T3 turbocharger was fitted along with a unique SU carburettor with an automatic pressure-regulated fuel system. The engine block, cylinder head, pistons, crankshaft and valves were all modified from the standard A-Plus engines. The turbocharger was fitted with an advanced two-stage boost control system which only allowed full boost to be achieved at engine speeds above 4000 rpm - this was to prevent damage to the sump-mounted four-speed gearbox, the design of which dated back to the early 1950s and could not reliably cope with the high torque output of the Turbo engine at low speeds. The quoted power for the 1,275 cc (77.8 cu in) A-Plus Turbo was 94 bhp (70 kW) although in practice the tune could vary from car to car and, because the engine was not intercooled power varied significantly depending on the weather. The MG Metro Turbo was entered in the British Touring Car Championship in 1983 and 1984, with the tuned engines producing in excess of 200 bhp (150 kW). Turbo versions lasted from 1983 to 1990.

Applications:

  • 1983–89 MG Metro Turbo, 94 hp (70 kW) at 6130 rpm and 85 lb⋅ft (115 N⋅m) at 2650 rpm
  • 1989–90 Mini ERA Turbo, 94 hp (70 kW) at 6130 rpm and 85 lb⋅ft (115 N⋅m) at 3600 rpm

1275 MPi

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Japanese Mini Paul Smith engine, notice the side radiator
 
MPi A-Series

A special "twin-port injection" version of the 1.3 L; 77.8 cu in (1,275 cc) engine was developed by Rover engineer, Mike Theaker. It was the last A-series variant, produced from 1997 to 2000. Few changes were made to ensure the engine complies with Euro 2 (later Euro 3) emission standard, such as adding a 3-way catalytic converter and making it twin-point injection, the engine also receive changes with ignition system by having a wasted spark instead of the distributor. For the Japanese domestic market. the engine maintained the single-point injection version of the engine and the radiator is still on the side due to the space constraint for the air conditioner component.

Applications

JOHN COOPER GARAGES

During the 1990s Mini Cooper revival, John Cooper Garages offered a number of factory-approved "Cooper S" and "Cooper Si" upgrades to the standard Coopers. The conversions came with a full Rover warranty, and could initially be fitted by any franchised Rover dealer.

  • S pack (carb) 77 bhp (57 kW)
  • 1st Si pack (Spi) 77 bhp (57 kW)
  • 2nd Si pack (Spi) 82 bhp (61 kW)
  • 3rd Si pack (Spi) 86 bhp (64 kW)
  • 1997 Si pack (Mpi) 85 bhp (63 kW) @ 5500rpm
  • 1999 Si pack (Mpi) 90 bhp (67 kW) @ 6000rpm[2]

Diesel version

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The diesel version appeared in 1962, on the BMC Mini tractor. It was developed with the help of Ricardo Consulting Engineers. It was redesign of existing 948 cc version, new purpose-designed cylinder head, with Lucas CAV fuel injection. This engine has dry liners. The block is almost identical to the petrol engine. The oil pump has been removed from the camshaft and is driven by an extension to what would have been the distributor drive. It uses Ricardo-patented "Comet V" combustion chambers, with a compression ratio of 23.6:1. Produced 15 hp at 2500rpm and 38 lb⋅ft (52 N⋅m) torque at 1,750 rpm. A petrol version of this modified engine was 'reverse-engineered' for use in the Mini Tractor whilst retaining parts commonality with the diesel variant, rather than using a standard petrol A-series unit. The diesel A series was also sold as a marine engine under the BMC name alongside the diesel B-series engines. Production ceased in 1969.

South African engines

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At the end of 1965, BMC South Africa started a new program, with the aim of using more components manufactured in the country (using less imported components from U.K.). They decided to develop and manufacture their own version of the engine. Two versions were made with 1.1 and 1.3 litres, using the same cylinder block. The block was redesigned, new oil circulation arrangements and redesigned main bearing (bigger dimensions) and stronger/biffers camshafts. Both versions use the same connecting rods, but different crankshaft and pistons. Prototypes versions were made by 1969. Production began in 1971, ending in 1980.

South African engines[3][page needed]
Displacement Bore Stroke Horsepower
1,098 cc (67.0 cu in) 70.6 mm (2.78 in) 69.85 mm (2.750 in) 54 PS (40 kW; 53 hp)
1,275 cc (77.8 cu in) 70.6 mm (2.78 in) 81.3 mm (3.20 in) 62 PS (46 kW; 61 hp)

Nissan production

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The A-series design, along with particularly the B-Series, was licensed by Nissan of Japan. Many changes were made for the initial OHV Nissan C engine and the succeeding E and E-1. An early change was to incorporate a five-bearing crankshaft. The cylinder head was modified by swapping plugs and ports, plugs fitted between pushrods and eight ports eliminated the Siamesed inlet and exhaust ports. Nissan modified the design into the later Nissan A engine that was launched in 1966 with an aluminium head and wedge combustion chambers. It formed the basis for many of their following engines, notably the later OHC Nissan E engine]], was scaled up into the Nissan CA engine which culminated in the DOHC 169 PS (124 kW; 167 bhp) CA18DET. The basic design was also scaled down into the Nissan MA engine. All these engines show their lineage by the characteristic un-skirted crankcase block of the BMC A-series, but with the A and E having the camshaft moved to the right side allowing greater port areas, and a mounting on the right wall of the crankcase for the oil pump, whereas the BMC A-series had the oil pump at the back end of the left-side camshaft.[citation needed]

OHC version

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With the intention of updating the current engine, for use in the new Mini Clubman (ADO20), and current ADO16, Leyland developed an OHC version. It appeared in a prototype version in 1971, with single overhead camshaft. It featured redesigned cylinder block, new aluminium cylinder head and twin SU carburetors. Eleven prototypes units were built, in three different capacities, 970, 1070 and 1275 cc. All engines use the same cylinder bore dimension of 70.6 mm, to reduce the number of engine parts, reducing production costs. It uses a modular approach, making it possible to produce the three versions with the same engine block. The lack of investment and the turmoil and chaos in British Leyland, meant the engine never reached production. In 1975 the plan was abandoned in favour of the "A+" version that reached production in 1980.

OHC A-Series[3][page needed]
Displacement Bore Stroke Horsepower @rpm Torque @rpm
970 cc (59 cu in) 70.6 mm (2.78 in) 61.91 mm (2.437 in) 59.8 PS (44 kW; 59 hp) 6750 51 lb⋅ft (69 N⋅m) 5250
1,097 cc (66.9 cu in) 70.6 mm (2.78 in) 69.85 mm (2.750 in) 73 PS (54 kW; 72 hp) 6500 64 lb⋅ft (87 N⋅m) 5000
1,275 cc (77.8 cu in) 70.6 mm (2.78 in) 81.3 mm (3.20 in) 85.2 PS (63 kW; 84 hp) 6750 80 lb⋅ft (110 N⋅m) 4500

Twin cylinder A-series

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Under the code ADO11, a 474cc twin cylinder with a single H2 SU carburetor based on the 948cc unit was built with the intention to be used in ADO15 (Mini) with an in-sump gearbox.[4] In May 1957, the engine was tested in one Austin A35, alongside a 20 hp 500cc air-cooled later 670cc water-cooled 2-cylinder two-stroke engine developed by Dr Joe Ehrlich of EMC Motorcycles[5] that was tested in one Austin A30 before being used in an experimental Austin A30 based prototype with weight reduced to 584 kg (by way of a special lightweight body in steel that was a couple of gauges lighter than normal with altered panels to keep weight at a minimum) known as the Austin A20 or the "Lightweight Austin 7".[6]

In 2021 retired racing driver and Bugatti specialist Ivan Dutton rebuilt an example of the 4 stroke engine from an original head and cylinder block and documented the work on Youtube. He also has the EMC 2-cylinder two-stroke engine which he plans to return to running condition.

Current use

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This engine continues to be improved, it has a very large and wide market, whether in the classic car industry or the racing industry. It has a wide OEM manufacturer support. Almost every part of the engine is still made, whether in original specification or improved versions, pistons, camshafts, crankshafts, cylinder heads. Cylinder heads are available in 8v or 16v, made in aluminium with 5, 7 or 8 ports. Additionally over the past few decades it has not been unusual to see the A-Series stretched beyond 1275cc with capacities ranging from as low as 1293cc up to 1479cc, although it is commonly enlarged to 1380cc while retaining its reliability so long it is serviced regularly and well looked after. [7]

The A series engine is currently used in David Brown Mini Remastered. The engine is totally rebuilt, with new internals to an improved specification. The engine used is based in 1275cc MPi version, with larger capacity versions including the 1330cc Monte Carlo [8] as well as the 1380cc and 1450cc Oselli Edition. [9]

Mini Remastered updated version
Displacement Bore Stroke Compression
ratio 		Carburation Horsepower @rpm Torque @rpm
1,275 cc (77.8 cu in) 70.6 mm (2.78 in) 81.28 mm (3.200 in) 10.1:1 MPi 72 PS (53 kW; 71 hp) 4600 88 lb⋅ft (119 N⋅m) 3100
1,330 cc (81 cu in) 72.19 mm (2.842 in) 81.28 mm (3.200 in) 10.1:1 MPi 84 PS (62 kW; 83 hp) - - -
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998cc "A" version in 1977 Mini Clubman.
 
1275cc "A+" Turbo version in 1990 Mini Turbo.
 
1098cc "A" version with Automatic Gearbox (by Automotive Products, "AP" ) in sump, used between 1964 - 1992.
 
1275cc "A+" MPi version, with Air conditioning.
 
Rover MEMS ECU used in SPi and MPi versions.

See also

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Notes

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  1. ^ a b Riley and Wolseley were brands of BMC. The Mini, Elf and Hornet were built on the same wheelbase and suspension with differences in the bodywork and trim

References

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  1. ^ Austin Morris (BL) internal documents archives.
  2. ^ Adams, Keith (12 November 2017). "Engines: A-series". AROnline: Best of British Cars. Keith Adams. Retrieved 1 December 2019.
  3. ^ a b Robson, Graham (2011). The A-Series Engine, Its first sixty years. Haynes Publishing. ISBN 9780857330833.
  4. ^ Pressnell, Jon (2009). Mini : the definitive history. Sparkford: Haynes Pub. pp. 19–21. ISBN 978-1844254750.
  5. ^ "Vintage Thing No.77 - 1947 EMC 350".
  6. ^ Sharratt, Barney (1988). Post-war baby Austins. Osprey. pp. 143–152. ISBN 0850457106.
  7. ^ Vizard, David (1999). Tuning the A-series engine : the definitive manual on tuning for performance or economy (3rd ed.). Sparkford: Haynes. ISBN 978-1859606209.
  8. ^ "Inspired by Monte Carlo". David Brown Automotive.
  9. ^ "Mini Remastered, Oselli Edition launches in full". David Brown Automotive.

Further reading

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  • Northey, Tom (1974). World of Automobiles. Orbis Publishing. p. 1054.
  • Robson, Graham (2011). The A-Series Engine: Its First Sixty Years. Haynes. ISBN 978-0-85733-083-3.
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Wikimedia Commons has media related to BMC A engine.
  • "A-series engine". The Unofficial Austin-Rover Web Resource. Archived from the original on 27 September 2007. Retrieved 13 April 2005.
  • "Turbo Minis". The No.1 Turbocharged A-series resource. Archived from the original on 9 April 2005. Retrieved 13 April 2005.
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