Near the end of the run in 1931, a lightweight SSK made its appearance, not as a production item but as a special, reserved for the factory racing team. Only six of these cars, known as the SSKL, were built. The "L" stood for leight or "light," because the frame and many other components were drilled to remove excess metal. Chassis weight accordingly went down to about 2,640 pounds. At the same time, horsepower went up-way up.
The major modification was adoption of an "elephant" compressor delivering 12-psi boost, but the SSKL also had a lighter crankshaft and flywheel, special valves, high-lift camshaft, and high-compression pistons. The factory recommended using a fifty/fifty mixture of gasoline and benzol to avoid local overheating in the cylinder head. Maximum output was 300 horsepower at 3,300 rpm.
A special streamlined single-seater was built on the SSKL chassis in 1931 for Manfred von Brauchitsch to drive at Avus. It was the fastest car present, completing the race at an average speed of 121.6 mph. Its top speed was not far short of 150.
One measure of the SSKL's performance was provided in 1960 by Road & Track magazine. Geared with a 2.76:1 rear axle, the test car's top speed was 120 mph. Out of deference to its age, acceleration was calculated on the basis of power/weight ratio: 9.5 seconds for 0-60 mph, 41 seconds from 0-100. That was quite a performance for a 30-year-old veteran-and there wasn't a car of its era that could have touched it.
Keep reading for specifications on the Mercedes S, SS, SSK and SSKL.