BMC A-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
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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.