Mercedes-Benz W154 #12 – Spark

1939 Mercedes-Benz W154
Pilot: Rudolf Caracciola Team: Mercedes-Benz Race: 1st place in the 1939 Germany GP Spark - B66040439 (diecast)

Published 08/08/18

Maybe the only thing that never changes in motorsports is that rules always change. So following that commandment, in October of 1936 the rules for Grand Prix racing for the 1938-1940 seasons changed. Engines without superchargers could displace 1000 to 4500 cm³, and engines with superchargers could displace 666 to 3000 cm³. The cars (without fluids) should weigh from 400 to 850 kg on a sliding scale depending on the engine capacity. With that, Mercedes’ W125 became illegal. So they needed a new car, and the engineering team started working on it in early 1937. Chassis designer Max Wagner used a chassis and suspension that followed closely the W125. The body was also lower and much more streamlined. And to add novelty, from the cockpit the pilot could control the hydraulic rear dampers.

The new M154 engine, developed by Albert Heess, was a 60° V12 with DOHC that displaced  2962 cm³. Supercharged by two single-stage Roots compressors it produced around 430 hp. However, with some improvements, by the end of the season engineers managed 480 hp. But the M154 consumed a lot of oil, to the point that engineers installed a hatch for adding oil during pit stops. And since fuel also cooled the high revving engine, fuel consumption was high, so the new car had two fuel tanks. It carried an insane 340 liters (!) of fuel.

W154 #12
Just look at those louvers on the hood. That’s Spark being awesome.

The W154 proved to be a successful car, giving Rudolf Caracciola his third European Championship. But the M154 was oil-thirsty and proved to be fragile if pushed over its limits. It also had a recurring issue at pit stops – it was hard to restart. For the 1939 season the car needed to be revised, so the W154 was rebodied and the engine improved. In essence it was the same car from 1938, and not a new car. Even so, it’s erroneously referred to as the “W163” because of the different body.

To correct the engine issues the M154 was rebuilt, and this new engine was called M163. It had the same displacement and was also supercharged, but had a higher compression ratio and didn’t have fuel injection. Basically, it was the same M154 but with a few improvements. This improved W154 also had a better designed radiator, reducing the frontal area of the car. And to allow a whole GP race without refueling, the fuel tank could now hold 420 liters (!!) of fuel. An absurd feature that would cost Richard Seaman’s life at Spa, in June.

W154 #12
From a distance those numbers looked as if they were painted on. But no, they’re decals.

The most important GP race for the German teams in 1939 was undoubtedly the XII Großer Preis Von Deutschland on June 23rd, at Nürburgring. Not wanting to take chances, Auto Union fielded five Typ Ds against Mercedes four W154. The German teams were up against four Maseratis, two Delahayes and a lone Alfa. On race day there were around 300,000 spectators to witness what would be the last German GP for a long time, watched by two huge Zeppelins overhead.

Hermann Lang took the lead and was basically flying low, but on the 3rd lap had to retire with engine troubles. Tazio Nuvolari’s Typ D assumed first place, followed by Rudi Caracciola in the W154 #12. Nuvolari led for 5 laps, until he dropped back with mechanical issues. It started to rain, and that was Caracciola’s element. With the rain beating down on the track, he led the race all the way to the checkered flag. It was Caracciola’s 6th win at the German GP, and the last win of the Rain Master.

W154 #12
The same W154, but quite different from one another.

Though the W154 won five GP races in 1939, because of the war, that season didn’t have an official winner, so maybe it’s not a very important Silberpfeil. However, in my eyes it was the last of the (true) Silberpfeile from Mercedes, therefore it was a must buy. The thing is that Spark doesn’t offer the 1939 version of this car with war paint, only the W154 from 1938. What they do offer is a superb plain version of the car, and that’s what I bought.

W154 #12
The model stock as I got it, without war paint.

This is a Mercedes-Benz dealership exclusive edition, and interestingly, it’s not a resin model, but a diecast one. So it was just a matter of getting the right decals to transform it into Caracciola’s winning W154 #12. The decals were super easy to obtain and apply, and even close up it’s hard to say if they are decals or tamp prints. In the end I now have a very nice diecast model from Spark with the correct war paint. And, of course, this W154 #12 is a custom job, so another bonus 🙂

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