Alex Martinez
Let's talk of the almost unknown BMW M8 E31 taking advantage of the recent celebration of the 24 Hours of Le Mans and the return to this brand competition. Although it may not seem like it, it was one of the most ambitious projects in the history of the Bavarian firm which was based on the Series 8 E31. In fact, a fully functional prototype even existed, but for reasons that we will now explain, never made it to production. Even for more than 20 years, the company reported that said prototype had been dismantled, although fortunately this was not the case.
We are referring to the BMW M8, the wildest Motorsport product ever made. Luckily for fans, this prototype served a lot despite its cancellation, since its heritage is enormous. We talk about technology for later models, from powering what is considered the best supercar in history, to victories in the 24 Hours of Le Mans.
Our readers will know well the BMW 850 CSI model, the sportiest version of the first 8 Series -with internal code E31-. It turns out that this model was nothing more than a “plan B” for BMW Motorsport, since its first option was the M8. As we said, The project was hidden for almost two decades, until the brand decided to rescue the prototype, for salons, events and fairs.
FOR ALL
In the late 80s, The Series 8 was having relative commercial success, especially in the American market and in Germany itself, so the Motorsport guys had already had their eye on this bodywork for a more performance version. At that time, BMW Motorsport Gmbh already had its own product range, with great reception among the public. Among them, stood out the M3 E30, the second generation of M5 and the last blows of the M635Csi.
It was time to go one step further. A blow on the table showing his true technical ability and his direct experience in competition. Treat certain Italian brands or those from neighboring Stuttgart on a one-on-one basis. That's how it started the M8 project that was internally called “Ferrari Killer”. The name was a statement of intent.
DEVELOPMENT OF THE BMW M8 E31
On an 850i, work began on two fundamental aspects: lightening the car as much as possible and providing the M8 with the necessary power to transform that comfortable and fast GT into a radical, high-flying sports car. Mechanically the work was intense. It was based on the V12 block of the 850i with internal code M70, the displacement was increased to 6 liters and multivalve cylinder heads were fitted with four valves per cylinder, although experiments were carried out with five per cylinder.
Work was also done on the exhaust and intake systems. This intake is made up of twelve independent butterflies, one for each cylinder, and connected to the accelerator by cable to give greater “feeling”. This represents a substantial difference with the rest of the E31, since they all have a “by wire” accelerator, that is, electronic. The intake ducts were made of carbon fiber., something unusual in those days.
The result of all this work was an engine with an impressive 640 HP of power, according to figures offered by BMW itself, associated with a 6-speed manual gearbox. This power would only be surpassed by other members of the M lineage decades later. The engine received the internal name S70..
ON A DIET
If the E31s were guilty of anything, it was that they were not exactly featherweights. No variant left the scale below 1.790 kilos, so lightening the set was essential. It began by eliminating all unnecessary equipment in a radical sports car.: audio equipment, rear seats, electric front seats, climate control, airbags, on-board computer and all kinds of luxurious extras.
In addition, new lighter materials were used: carbon fiber, composites, aluminum, etc. The glass windows, for their part, are replaced by lighter plexiglass ones, and some body components, such as doors, wings and hood, are made of carbon fiber. The huge, heavy front seats, They are replaced by a pair of baquets also made of carbon fiber. There is no concession to luxuries, just three small indicators, where the radio used to be. In this regard, the brand did not reveal its weight until its reappearance years later, and of course The weight reduction of the car was astonishing: 1.440 kg.
AN EXTERIOR TO THE HEIGHT
Aesthetically, the changes are very notable. To start, the characteristic retractable headlights disappear in order to house the new V12 intake and cooling under the hood. Its function is assumed by small headlights integrated into the front bumper, which also has a new design, with different brake cooling intakes.
Perhaps The most important novelty is the appearance of the B pillar between the windows, absent in the rest of E31. Such a brutal increase in performance makes it a necessity to increase the rigidity of the chassis. The wheel arches are wider to accommodate the new brakes and tires and In the rear fins there are separate cooling intakes that house two radiators, to cool other mechanical elements, such as the differential and gearbox.
Lastly, The mirrors are replaced by “howitzer type” ones., more aerodynamic, and the wheels are 17 inches, with a carbon fiber treatment, purely aesthetic we fear, although striking, yes. Of course, The suspension and steering settings were suitably modified., as you might guess.
THE ONLY BMW M8 E31
As we have been writing to you, the data on the unit is quite scarce, There is not even official data on the performance of the M8. Rumors place its top speed above 300 km/h, an acceleration from 0-100 km/h in just 3,5 seconds! With this data, he would have made things very difficult for his rivals of the time. So that we have some references, un Ferrari 456 GT, which would be its most direct rival in 1990, It delivered 426 HP and went from 0 to 100 in 5,2 seconds and a Porsche Turbo 911 At the moment, it was satisfied with 320 HP and 5 seconds to go from 0 to 100. Even the almighty Ferrari F40 It had less power and worse acceleration.
When the project was presented to the top management in Munich, they strongly rejected taking it to production: “We are not interested in putting our name on cars like this anymore,” was his response.. Memories of the adventure BMW M1 and its commercial and economic failure were still very present. Furthermore, managers did not believe that it was a salable model, not even in a short production run.
The “typical customer” of a BMW 8 Series would not look for such a radical concept and, in addition, the sales price would have to be taken into account. In those days, An 850Ci cost 12.500.000 pesetas in Spain, extras aside, which would be equivalent to about 180.000 euros today. How much would a car like the M8 cost then, with all that technology and exotic materials? It is very difficult to calculate, but a lot, a lot of money. Available to very few in 1992. After all this, Motorsport opted for its Plan B, launching the 1992CSi on the market in 850., with a version of the S70 engine with “only” 380 HP, and maintaining the GT essence that the E31 exuded.
A GREAT LEGACY
After the BMW board of directors refused to market the M8, all the time and money invested in the project was considered lost. The board forced to cancel the entire project, to hide any evidence of its existence, and it was even publicly stated that the prototype had been destroyed. Many rumors circulate about the latter, starting with the one that says there were several units that were dismantled and later reassembled.
Even before that order to destroy the prototype, someone from Motorsport decided to ignore it and hide the unit in some lost corner from the brand's garages. On the other hand, engineers continued working on the S70 engine. And that is where one of those magical coincidences of life comes into play, which caused one of the great milestones in the history of the automotive industry: the call of McLaren.
In those days, in Woking they had been working on a street supercar for some time. The sporting successes in F1 They had launched the project that started from the head of the design genius, Gordon Murray, while waiting for his flight at an airport. For the younger ones, we can say that Murray was the design guru in F1 in the 80s, the Adrian Newey of the time.
BMW COMES TO THE RESCUE
Starting from an unlimited budget, the entire project was going at a good pace, but there were some problems finding an engine block that fulfilled Murray's premises. He wanted a naturally aspirated engine to give a faster response and increase reliability, powerful -500 HP minimum- and light -no more than 250 kg-. McLaren was allied with the Japanese Honda to motorize their F1 cars, but when asked for an engine for the project, Honda refused.
The Japanese did not want to motorize any car that did not have their logo on the hood, and even less if it overshadowed their brand new one. NSX. Isuzu was also contacted, which was testing a 12-liter V3,5 to enter F1., but it was rejected because they were looking for a proven and reliable design. Panic was beginning to appear due to the possible failure of the project due to not having an engine.
Casually, Gordon Murray met his friend Paul Rosche, genius of BMW Motorsport engines, at the 1990 Hockenheim GP. Both had worked together in the team F1 Brabham in the early 80s. Murray was the designer of the Brabham BT52, which won the 1983 world championship with Nelson Piquet and the BMW M10 Turbo engine. They both talked about the McLaren project, and Rosche was forceful: “Gordon, maybe we have an engine for you.”.
A KNOWN BLOCK
An engine already tested and fully functional. With the continuous work of engineers on the block derived from the original M70 They had improved their numbers even more, but McLaren asked for some more modifications. The engine had to be usable comfortably on a daily basis and comply with current emissions regulations. Finally, They offered McLaren a 12 cm V6.0643, which produced 627 hp at 7.400 rpm with 651 Nm of torque at 5.600 rpm, thanks to the new variable distribution system (VANOS).
The weight of the block was only 266 kg. A complex system was also designed for the accelerator, so that, in the first part of the pedal stroke, the response was more measured and, in the last part of the stroke, the response was more brutal. All this to facilitate the driving of the McLaren F1. This is the S70/2 internal code engine that Gordon Murray was understandably delighted with.
The McLaren F1 was officially presented in Monaco in 1992 with the S70/2 engine under the hood. From the first minute, the international press raved about it, especially dynamically. At that precise moment, all the time and money invested by BMW in the M8 prototype began to pay off. The publicity and success that came with motorizing the F1 was incalculable, and sporting successes were immediate.
THE BMW S70/2 IN COMPETITION
In 1995, in his first participation, A McLaren F1 won the 24 Hours of Le Mans, with a BMW S70/2 engine absolutely standard, except for the programming of the control unit. To provide greater reliability, the power was reduced to 600 HP. And not only did they win, of the top five finishers, four were McLaren F1. resounding success.
Following that path of success, at Le Mans, with good classifications in subsequent years, the Bavarian brand created the BMW V12 LMR, a competition prototype destined to win the 24 1999 Hours of Le Mans. And, of course, with an S70/2 under the hood. They achieved victory again that year, which was the definitive boost to the brand's sports program to fulfill the desires of maestro Paul Rosche and enter F1 again as engine supplier for Williams, in the year 2000. But that is another story, which perhaps we will tell another day. Meanwhile we are left with the BMW M8 E31, a car that seemed doomed to oblivion to bequeath two victories at Le Mans to the Bavarian firm.
