BMW Advert 1986 - 635CSi, M6, E9 3.0 CSL, M1 - 'The latest in a short line of supercars...'

Another great advert from BMW, this time from 1986, promoting the benefits of their tuned straight-six power plants and their innovative (for the time!) use of four valves per cylinder. 24-valves were first seen in the E9 3.0 CSL 'Batmobile' in 1974, again in the M1 supercar in 1977 and finally making its way to the general consumer in the 1986 635CSi model E24 6er. 

As BMW discovered years ago, when you need extra power from an engine - on the race track for instance - just double the valves per cylinder.

The extra valves mean the the cylinders can take in more air and fuel on each stroke, burn it more efficiently and expel it quicker. So much so that 6 cylinders with 4 valves can produce more power than 12 cylinder with 2.

Take the three cars above, developed by BMW Motorsport.

The 3.5 litre CSL, affectionately known as the Batmobile, won the first of many races at the Saltzburgring in 1974, beating a 7 litre Camaro in the process.

A 192 mph version of the M1 won its class at Le Mans for the last 3 years. (At the Nurburgring in 1981 it won the race outright.)

The M635CSi, however, is merely a luxury road going coupe. Although it's capable of 158mph, it hasn't won a thing.

Except praise.

BMW UK Advertising Poster / Placard 1980 - M1, E21 320/6 + 6-cylinder engines

Nice 1980 placard from BMW UK advertising their family of 6-cylinder engines, from the later E21 320 to the M1's M88 and explaining the benefits of the. "Six cylinders where you'd expect to find four." in the compact 3-Series and "Six cylinders where you'd expect to find twelve." in the case of the supercar M1.

   BMW's dedication the six cylinder engine is not a recent phenomenon.

   It goes right back to BMW's original as a specialist engine-maker, rather than a car manufacturer.

   In fact, the first engines we ever built were six cylinder aircraft engines.

   Later, in the 1950's when conspicuous consumption was almost a status symbol, BMW preferred to stay with efficiency rather than extravagance and launched a six cylinder luxury car.

   Today, in the BMW 320, a car that's scarcely more than 14ft long, theres a sophisticated six cylinder power unit.

   And the BMW M1 on the right also needs no more than six cylinders. Even though in its most developed form, the engine can actually produce 800 bhp.

   It's not a blind dedication to six that makes us refuse the false economy of a four in the case of the 320. Or the wanton extravagence of a 12 in the case of the M1.

   Rather, we take our guidance from the laws of physics.

   According to those laws, it is not possible to build an engine that's perfectly balanced with less than six cylinders arranged in-line.

   Anything else, is a compromise that may help a car manufacturer balance its books. But won't help it balance its engines.

   Which is why every engine BMW make that's two litres or larger, is an in-line sic cylinder engine.

   Fortunately, there's no need for you to understand the laws of physics to discover the difference this makes.

   There's not a trace of roughness as you cruise. Or rawness as you accelerate.

   There's a smooth immediacy which motoring journalists normally describe as "turbine-like".

   And there's a flexibility which makes driving in traffic almost a pleasure. For with 85% of maximum torque at a mere 1900rpm you get a responsiveness in fourth gear that you might normally expect only in second gear.

   The BMW 320 costs £6,790.

   Which is scarcely more than cars whose manufacturers have chosen to compromise on their engines.

   And if they're prepared to compromise on the most important part of a car, where will those compromises stop?

BMW M10 Engine Family Tree

Interesting press release from BMW showing some derivatives of the much-loved 4-cylinder M10 engine, which I have covered in much detail before.

"With half the cylinders and half the power of todays V8 M3, the original 1986 car remains one of our all-time favourites. Its seemingly indestructible four-cylinder iron block, however, goes back to 1962 and the BMW 1500. This was also the block that formed the basis of the 1.5-litre turbo F1 engines that powered Brabham to many a race victory. That's not just the block type -- BMW Motorsport used actual 1500 blocks sourced from scrapyards, because the older the block, the fewer stresses remaining in it. Never has a production engine family been more versatile."

If I had the money...

Classic & Sports Car Magazine is full of things you'd give your right arm for, but this ex Spa prepared E12 530i touring car caught my eye. I've been hankering after an E12 for a good while now, but the engine swap / new turbo on my E60 means I don't have the 45k odd Euros lying around. Shame, as it has the M1 developed straight-six engine (M30) that made it into the M535i and would sure give a modern M5 a run for its money...

If you fancy it yourself and have deep pockets, here is the link to it on French auto-salon HistoricCars.fr - http://www.historiccars.fr/bmw-530-juma-bastos-24h-spa-francorchamp-1981.html.