History of the M3

BMW M3 Celebrating 20 Years of a Sporting Legend Text & photos courtesy BMW AG For 20 years the BMW M3 has been the by-word for race-bred on- road excellence in a compact car. Over three generations, the legend has gone from strength to strength, beginning as a four-cylinder two- door coupé and flowering into Powered by a 252 kW, 3.2-litre high- concerned, a sporty car had to do a mighty six-cylinder naturally technology, high-revving straight-six one thing: win. That was when the aspirated Coupé, Sedan and engine, now shared with the just M3 was born. Convertible, the envy of the world. launched Z4 M Roadster and the soon-to-arrive Z4 M Coupé, the Basic engine drawn from As popular with fast road drivers 2006 M3 celebrates its 20th birthday as it was successful on track, the Formula 1 in trade-mark understated style. However, the designers of the M3 legend was born of humble sports engine weren’t exactly beginnings but has grown to a How the legend was born standing there empty-handed. The position of majesty. The sentence has become a legend: right ingredients for the projected “Mr. Rosche”, said the BMW engine were available, the mission Much copied, never matched in its Chairman sometime around the was simply to put them together in purity of performance, function, beginning of the 1980s, almost as the right way. The crankcase of the and understated yet distinctive an aside to his engine designer, four-cylinder engine was available styling, the M3 today is as much in “we need a sporty engine for as a basis. This was being installed demand by enthusiasts as ever, as the Three Series”. Eberhard von as a solid two-litre engine in volume critically acclaimed as never before, Kuenheim knew exactly who he was production. Paul Rosche had long and undoubtedly the benchmark motivating to take action: since found out about the potential for a plethora of would-be rivals. Paul Rosche was not only the really contained in the grey cast-iron engineering housing. It was this block that was managing to form the foundation stone for director of M the champion engine of Formula GmbH, he was 1. Four cylinders didn’t simply also the father mean less weight and high torque of the turbo for blue riband performance, but engine which also offered ideal specifications for had powered the projected sports engine. BMW Nelson Piquet had already introduced the six- to victory in cylinder era in the 3 Series. But no the 1983 World matter how smooth and powerful Championship, the running of the in-line engine driving a was, it had one major disadvantage Brabham BMW. for racing given the technology And as far as available at the time. As the engine Rosche was speed increased, the length of the JANUARY 2007 crankshaft meant that it started to cut two vibrate much earlier than the short combustion four-cylinder shaft. The designers chambers off therefore designed the crankshaft the four- drive of the M3 as stiff as possible cylinder head so that it could achieve in excess of the M88 of 10,000 revolutions per minute. and bolted By comparison, at that time the a panel over four-cylinder of the 318i delivered the hole its maximum output at 5,500 rpm. on the rear The engineers were already aiming side.” for a rated speed of 6,750 rpm for the road version of the M3, i.e. they Potential left plenty of scope upwards. for developed in such a way that it records: The first engine could easily be supplemented by a Development goal: Group fires after just two weeks controlled catalytic converter. The A racing car development function was by no means a simple However, any plans for a The engineers then increased the task. In the mid-1980s, catalytic performance-enhancing capacity even further to 2.3 litres converters tended to reduce power supercharger had to be put to and the first prototype was now and make engines less fuel-efficient. one side. A turbo was out of the ready. Paul Rosche: “Whether you Another factor was that unleaded question on homologation grounds. believe it or not – we had created petrol didn’t exactly have the From the start, the fathers of the an outstanding four-cylinder reputation of being the ideal fuel M3 were also thinking in terms of engine for the 3 Series within the for high-performance engines. use as Group A racing cars, with space of two weeks. Under the The quality of the new fuel varied at least 5,000 units having to be development name S14, this engine too much in Europe to meet this manufactured within the space of was to generate specification. In order to err on headlines in the safe side, the team headed by sport and Paul Rosche adapted the engine in volume and reduced the compression from production 10.5:1 to 9.6:1. On the one hand, over the years this resulted in the engine not to come. One reacting to variations on the octane Sunday, I number with unpleasant knocking. drove to von On the other hand, the reduction Kuenheim’s flat in compression plus installation and gave him of the catalytic converter in the the car for a test exhaust system only resulted in a drive. When he loss of 5 of the standard 200 bhp. twelve consecutive months. This came back he said: ‘Good, I like it.’ meant that the M3 also had to be And that’s how the M3 came into Goal achieved: Full throttle capable of operating as an everyday being.” road vehicle. It was therefore ideal at Nardo Although the design engineers that the engineers had already Fast and clean: Adopting were pleased with the superior enjoyed many years of outstanding a catalyst barely slows the performance, they also spent some success with four-valve technology, sleepless nights. The north loop of most recently with the M1 that had M3 However, the engineers weren’t the Nürburgring was particularly only just been discontinued. Paul only working on performance. hard on materials and what was Rosche recalls: “We started work The emissions of the M3 engine blown into the manifold here by immediately. One advantage was were also supposed to be geared to the four-cylinder wasn’t digested so that the big six-cylinder originally future requirements. That’s why easily by the exhaust system – the had the same cylinder gap as the the four-cylinder was from the start pipes were continually fracturing. four-cylinder engine. We therefore JANUARY 2007 taper in order not to first pilot-production cars were interrupt the airflow ready and the M3 was launched over the edge of the to the press – appropriately on roof and at the same the racing track at Mugello. The time direct the airflow test drivers established that the more effectively onto aerodynamic profile of the M3 was the rear spoiler. Thick an understatement rather than an cheeks had sprouted overstatement – high-quality racing over the wide wheels of technology was housed under the the M3, the flared wheel beefy bodywork. Axle kinematics, arches came to an end suspension and damping had in a striking edge below changed. The braking system with the edges of the wings. ABS as standard comprised brake There was no question discs with ventilation at the front about it – the M3 looked and a high-pressure pump operated fast even when it was by the engine. This servo pump It transpired that the cause was perched on an exhibition stand. delivered power to the steering at unplanned growth in the exhaust the same time so that both systems system. High temperatures at were able to operate independently full load meant that the high- Plastic parts save weight Anyone who got that close was of the negative pressure of the performance system became so hot inclined to pat the new sports car engine. that it expanded by up to 25 mm on its chubby cheeks to see whether and became distorted within its the bulging wheel housings had mounting. A simple set of different 235 km/h top speed for simply been attached, or whether washers solved the problem. 58,000 marks they really had been pressed out The refined aerodynamic work The drivers from BMW Motorsport of sheet metal. And they were paid off with an outstanding GmbH immediately proved the impressed. The entire bodywork cW value of 0.35. The lift at the point. On the high-speed test track including the wings and the bonnet front axle was around half that of in Nardo, Italy, they drove an M3 were made of metal. A lightweight the other two-door 3 Series car. three times at full throttle over a plastic had been used for front The large rear wing reduced the distance of 50,000 km. The exhaust and rear bumpers, and side sills lift on the rear axle by some two system withstood the test just like and boot lid including spoilers in thirds. Bonded front and rear the rest of the car. order to keep weight down. The windscreens contributed to higher M3 weighed in at 1,165 kilograms bodywork stiffness that in turn M3 goes fast even without payload on the scales exerted a positive effect on driving standing still and hence remained a sporty performance. This was evident to On the BMW exhibition stand lightweight with only 5.8 kg for the driver in the form of increased at the Frankfurt Motor Show every 1 bhp.

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