Supercharger Calculators: W165 Silver Arrows Still A Beauty After 70 Years

The picture you see here shows one of four cars that were made, of which only two survive. Built to compete in the 1939 Tripoli Grand Prix, the W165 was Mercedes’ response to a radical rule change by Italian racing authorities, which tried to “balance” the regulations in favor of Italian machinery. At the time, Mercedes’ W154 was the dominant Grand Prix car, and the rule change in favor of smaller cars was meant to exclude the W154.So, what Mercedes did was to use its considerable talent and resources to produce the W165. This feat of engineering was developed in just a six month time frame. To make the smaller car, the W165 was essentially a four-fifths version of the W154. Although the engine basically used the same design from the 3-liter V12 found in the larger Grand Prix car, the smaller displacement (1.5 liters) engine was a V8 using the valvetrain design of twin cam heads and 4 valves per cylinder. Two Roots superchargers were fitted to each bank of cylinders, giving an output of around 254 horsepower. By today’s standards, it’s a trivial output, but bear in mind that this is the pinnacle of 1930s racing technology.

Development time was so short that the second car was reportedly finished on the boat to Italy. In the practice sessions for the race, the new W165 racers were fast, but were not fast enough to match the initial pace of the streamlined racers from Maserati. So, of the two race cars that were entered, one was instructed to go all out from the start of the race as a sacrificial lamb while the other was driven more conservatively. This strategy worked perfectly as the rest of the field tried to chase down the rabbit and fell down the wayside as the pace destroyed machines one by one. The conservatively driven car picked up places as it went and in the end, it was a Mercedes one-two finish.