In 1966, Formula One regulations doubled the permitted engine size, now up to 3 litres. They also allowed for up to 1.5 litres for turbocharged engines. So off went racing teams, making use of this larger engine size limit. For 10 years, no one thought of exploring turbocharging for their engines. That was until Renault brought the RS01 to the 1977 British Grand Prix. Renault didn’t win the race, but it put turbocharging forward as a viable method of power. By 1979, Renault had developed their turbo charging technology to the point of winning races. Turbocharging was to now be taken seriously.
Jumping to the 1980s, BMW struck a deal that appointed them as the engine supplier for future F1 owner Bernie Ecclestone’s Brabham team. Witnessing Renault’s success using turbocharged engines, BMW began developing this themselves.
As stated, Formula One regulations limited turbocharged engines to 1.5 litres in size. Luckily, BMW had plenty of 1.5 litre blocks already in production for their M10 engine.
The M10 was an inline four cylinder engine that BMW used in their road cars at the time. The block, designed in the 1950s by an engineer who also raced cars, was unique because it had been designed to allow its 1.5 litre displacement to be bored out and increased to up to 2 litres if needed. This versatility was incredibly useful for manufacturing, for-filling many roles for BMW. This block over its life would be finished in 1.5, 1.6, 1.8 and 2 litre versions to suit different needs.
There’s a lot of stories regarding how BMW would select and prepare the M10 blocks to be used in F1. It is said only blocks with 100,000 kilometres or more on the clock were used. This was because this long service life would have highlighted any existing defects from the casting process.
To ensure even more durability, it’s claimed the block then had to be left outside for several months. When left to the elements, the constant changes in temperature caused the metal to expand and contract constantly, hardening the metal and increasing its durability.
While the block sat exposed to the weather, it also is said that the engineers would urinate onto the metal, as it was long believed since ancient times that metal strengthening properties are found in urine.
With the M10 block, BMW used gear driven camshafts, electronic injection, and a large Garrett turbocharger to name a few features. In this F1 ready form, the engine was known as the M12/13. The engine revved up to 11,500 rpm, and pumped out approximately 850 bhp in qualifying trim, and 650 bhp in race trim. Nelson Piquet used this power plant to win the Canadian Grand Prix in 1982.
This engine’s competition used V6 engines, but because of the fewer cylinders, the M12/13 had less components and therefore less friction and thermal energy being produced. This allowed the vehicle to have less radiators for cooling the engine, meaning a smaller size and therefore reduced the cars drag; great for top speed on straight portions of track.
BMW continued developing the engine and cranking up the boost pressures from the turbo, and by 1986 had the M12/13 producing a staggering 1,300 bhp in qualifying trim. This is a conservative estimate too, as dynamometers of the time could only accurately test up to 1,000 bhp. It’s believed the actual horsepower was closer to 1500. These figures meant the engine was the most powerful F1 engine ever built, a record that still stands today.
To achieve this power out of 1.5 litres of displacement, the turbocharger forced up to 80psi (5.5bar) of air into the cylinders. The level of performance this engine provided doesn’t come for free however. The draw back of all this power meant the lifetime of this engine was incredibly short, needing to be rebuilt after every race, if it even lasted the entire race. The amount of raw power being produced often caused engines to retire early in an explosive fashion due to the extreme pressures and forces involved in such a small engine being pushed this hard.
Along with all this, without having two turbos like the competition to even out lag, having one giant turbo also comes with giant lag. The boost would kick in almost all at once, rapidly surging horsepower and torque. The power delivery on this engine was described by multiple drivers as coming on like a light switch. During this point, the car would apparently become very lively, needing a skilled driver to tame. The turbo would take up to two seconds to kick in and this meant during a race, drivers would begin accelerating while coming through the apex of a corner.
The engine required massive amounts of skill and experience to keep up with, but when one could reign it in and control this force of nature, it would delightfully reward the driver with some of the fastest straight line speed in all of F1. It would drop behind in the tighter areas of the track while the driver battled huge amounts of over steer and turbo lag, but when the track opened up into a straight and the rear wheels dug into the tarmac, the engine would remind the competition what 1,500 bhp looks like.
By 1987, BMW had pulled out of F1 but continued to supply Brabham with the M12/13 engines. The British racing team Arrows continued to use the engines too. As BMW had stopped official support of the engine, Arrows re-branded the M12/13 engine as Megatron.
Other teams flocked to buy the engine but it was Piquet for the Brabham team that saw the most success. During Brabham’s run with the engine Piquet won 7 times, including the 1985 French Grand Prix, and also had 9 fastest laps.
The anarchy and glory was not to last forever though. 1988 was to be the last season that turbochargers could be used in competition when Formula One regulations banned their use. Many teams went back to V6 and V8 naturally aspirated engines, and the Megatron and the M12/13 were rendered obsolete.