MG began offering the MGB GT V8 in 1973 powered by the aluminium block 3,528 cc Rover V8 engine, first fitted to the Rover P5B. This engine had been used in the unibody GM 1961–1963 A-body platform Buick Special/Skylark and Oldsmobile F-85 and 1961–1962 Pontiac Tempest and was the lightest mass-production V8 in the world. The Buick version had a dry, undressed weight of and the 1963 Skylark with optional four-barrel Rochester carburettor and 10:1 compression ratio produced 200 hp (150 kW) at 5,000 rpm. By the time Rover had made webbing modifications to strengthen the block, the engine was considerably heavier (over 170 kg). Some changes were made by MG-Rover and the engine found a long-lived niche in the British motor industry. These cars were similar to those already being produced in significant volume by tuner Ken Costello. MG even contracted Costello to build them a prototype MGB GT V8. However, the powerful engine used by Costello for his conversions was replaced for production by MG with a more modestly tuned version producing only 137 bhp (102 kW) at 5,000 rpm. Nonetheless, of torque helped it hit in 7.7 seconds and go on to a top speed. Fuel consumption was just under 20 mpg.