The mandate with this Mercedes 190 SL vintage racing engine was to make as much power and torque as possible. The horsepower would be limited by the restrictive exhaust ports so the decision was made to increase the displacement by using a Mercedes 230 block and a Mercedes 220 crankshaft. This resulted in a 2.5-liter engine. Some porting was done to the head including lengthening the intake port dividers. Camshaft choice was critical so a profile was chosen with more exhaust duration.
On the dyno, the usual combination of carburetor and ignition tuning was done and the result was a strong, torquey and reliable vintage racing engine.
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Power: 165-hp @ 5,400-rpm, 175 lb-ft of torque @ 4,200-rpm
Type: M115, SOHC 2v, 4-cylinder
Bore: 93.75-mm Razzo Rosso forged pistons
Compression Ratio: 10.2:1
Heads: Mild porting
Cams: 244/246-degree duration (@.050") and 11/11-mm lift (in/exh)
Induction: Solex 44 PHH carbs with stock plenum
Exhaust: Stock headers
Ignition: Bosch distributor