In 1986, the turbocharged BMW M12 engine for F1 could produce an amazing 1,500hp for qualifying trim. Not bad for a 1,500cc engine. Even more amazing was that they used stock blocks from their road cars to manufacture the engines.
BMW used M10 blocks that were from cars that had high miles. The theory was that a seasoned block had all the stresses from casting relieved during its thousands of heat cycles. This practice traces its roots back 70 years to the Flathead Ford V8 used by some sprint cars of the day. In 1980, Roger Rage pulled a seasoned small-block Chevy from a school bus and managed to qualify, and even lead (while in the pits), the Indy 500.
The BMW M12 engine’s Achilles heel was fuel management. The massive turbocharger could force huge amounts of air into the engine once the compressor got up to speed. Making sure there was enough fuel at the right moment was critical for the life of the engine. If the engine ran too rich or lean, piston and turbocharger damage could quickly occur.
