The diesel car markets are the same ones who pioneered various developments (Mercedes-Benz, BMW, Peugeot/Citroën, Fiat, Alfa Romeo, Volkswagen Group). There were also small diesel engines produced in England by British Leyland and Perkins. For reasons of economy the petrol BMC "B" series engine was converted to diesel and produced in capacities of 1.5 and 1.8 litres. Perkins produced the 4.99, 4.107 and 4.108 engines all of which were extremely reliable. Later BL produced the five main bearing "O" series engine which was extremely strong. Petrol turbo variants could make 200HP and the engine was ideal for converting to a diesel. In fact, the 1988 Austin-Rover MDi unit (also known as the 'Perkins Prima') was developed by Perkins Engines of Peterborough, who have designed and built high-speed diesels since the 1930s. It is not easy to make a lightweight and powerful top class diesel engine owing to the immense pressures and heat produced within the engine. These problems were solved by VM Motori and the engines were apparently so good that Rover, Ford and Jeep bought them. The interesting features of the engines were the tunnel-bore block and separate cylinder heads to allow for expansion.
