In a shock announcement in September of 1938 the Italian motorsport association declared that during the following season all single seater races on Italian soil would be run for Voiturettes instead of Grand Prix cars. In retrospect the decision was understandable as the Italian manufacturers had played second fiddle in Grand Prix racing to the German Mercedes-Benz and Auto Union teams. For the smaller Voiturette class both Maserati and Alfa Romeo had just developed brand new and highly advance cars. A shift to the Voiturette class for all events would greatly increase the chance of national glory in Italy's premier events, including the prestigious Tripoli Grand Prix in May.
Despite having just six months to design, build and test a brand new car, Mercedes-Benz team director Max Sailer gave the green light in November of 1938; the 'Silver Arrows' would defend their title in the 1939 Tripoli Grand Prix. Although some design elements from the existing W154 Grand Prix car could be carried over, the new Voiturette most certainly needed a bespoke engine. French for small car, the name of the class could be taken very literally as the cars featured engines half the size as those found in the 'big' Grand Prix cars. To be exact, the displacement limit was set at 1.5 litre for the Voiturette class.
Although no parts were interchangeable, the new M165 engine owed much to the M154 3-litre Grand Prix engine. Apart from the displacement, the biggest difference was the number of cylinders; a V8 for the Voiturette compared to the original V12. What was carried over was the valvetrain with twin gear-driven camshafts per bank and four valves per cylinder. Designed for high revs, the cylinders were 'oversquare' with a bore of 64.0 mm and a stroke of 58.0 mm. Two Roots-Type Superchargers were fitted, boosting the power to a hefty 254 bhp. To cope with all this power the engine was constructed mainly from steel with the blocks and heads welded together.
The W165 chassis and suspension was pure W154 but at about 4/5 scale. The frame consisted of two large oval-tube side-members reinforced by five cross-members. Suspension was by double wishbones and coil springs at the front and a DeDion axle with torsion bars at the rear. The V8 engine was mounted in the chassis at a six degree angle to help the propellor shaft clear the driver's seat on the left. The seat itself was mounted off-set to the right. The power was fed to rear wheels by a five-speed gearbox that was mounted transversely behind the final drive. The tiny package was tightly wrapped in an aluminium body, again similar to that of the latest W154.
Little over four months after the project started the first of the three proposed W165s was completed. On April 10th, less than a month before the Tripoli race, the testing commenced at Hockenheim. Chief engineer Rudolf Uhlenhaut and Works drivers Rudolf Caracciola and Hermann Lang all tried the new Voiturette racer. Amazingly it was Uhlenhaut who set the fastest lap of the day. After the successful first test, Mercedes-Benz confirmed the entry of two W165s for the Tripoli Grand Prix for team-leader Caracciola and 1938 winner Lang. It was still very much a race against the clock for the Germans; the second car was completed on the boat to the Italian colony.
During the practice sessions the two drivers tried both cars and Lang set the faster time, closely followed by his team-mate. However, it was not the fastest time. Luigi Villoresi set that in his streamlined Maserati. Lang was told to set a blistering pace in the early stages and come in for tires and fuel halfway through the race. In what was considered the better of the two chassis, Caracciola started with a more conservative pace and picked up places as the competition, pushed beyond their limits by Lang, retired. Despite his lengthy tire change, Lang managed to keep Caracciola well behind him to clinch a spectacular one-two debut victory for the W165. Mercedes-Benz had driven their point home; nothing could stop the Stuttgart steamroller.
Apart from some demonstrations and further testing, the W165s were not seen again in 1939. However development continued as it looked likely that the 1.5 litre formula could be adopted for Grand Prix racing in the very near future. The third chassis was completed and it appears a fourth car was also built. Special streamlined bodies were also constructed with an eye on both the 1940 Tripoli Grand Prix and the various 1.5 litre World Records held at the time by MG. The engines were fitted with a two-stage Supercharger system that lifted the power to 278 bhp and also improved the low end performance. All this preparation work came to nothing as the German government tragically decided to drive their, altogether more violent point, home.
At least two examples, presumed to be both Tripoli cars, survived the War at the Mercedes-Benz representative in Zurich. They were held by the Swiss government until 1950. By this time 1.5 litre had indeed become the displacement limit for Grands Prix, which are part of the newly created Formula 1 World Championship. The W165's rivals of old, Maserati and Alfa Romeo, were still running strong and a return to Grand Prix racing by Mercedes-Benz was the subject of heavy speculation. Eventually, in the summer of 1951, the green light was given to build a further five W165s. It proved to be too late as for 1952 the regulations were heavily revised, rendering all 'Voiturette' style racing cars obsolete. In the end the W165 raced just once but can still be considered one of the old time great single seater racers as the final development of the pre-War 'Silver Arrows.'
The two surviving Tripoli racers were retained by Mercedes-Benz and lingered in the company's massive collection until 1995. Upon receiving an invitation from Lord March for that year's Goodwood Festival of Speed, the Tripoli winning car was carefully reconditioned. It missed most of its bodywork, which was carefully recreated by Joachim Ohlinger. The fruits of the labour came in June that year when the beautifully prepared W165 was piloted up the hill first by the then Mercedes Museum director and later by racing legend John Surtees and McLaren principle Ron Dennis. It was the first time in over fifty years that the car had been driven in public. Since then, it has only made very few public appearances. The ex-Caracciola car is on permanent display in the new Museum.
Article by Wouter Melissen, last updated on July 07, 2011
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