Porsche 904 Carrera GTS Fuhrmann Engine

 Produced from 1953 to 1964, the Type 547 engine was one of Porsche’s greatest motors.  The motor came out of the desire for more revs and more power, something the Beetle derived pushrod motors could not deliver on.  Going from the agricultural Beetle motor to the four cam seemed about as big as a jump as the Wright Flyer to the Saturn V rocket.  

By utilizing overhead camshafts, valvetrain mass is lowered, this allows the engine to rev higher before reaching valve float.  As well, flow through the heads can be better optimized as there is no pushrod impeding air flow.

What else makes the Fuhrmann engine so legendary? Part of it comes down to its vertical shafts. While conventional dual overhead cam engines rely on either belts or chains to drive their camshafts, the Fuhrmann engine uses a complex system of bevel gears to turn them. With bevel gears, the correct backlash is required so the gears do not bind. Backlash is the amount by which a tooth space exceeds the thickness of a gear tooth engaged in mesh.

Along with its four camshafts, the engine also has two spark plugs per cylinder.  With the raised redline allowed by the dual overhead camshafts, the actual combustion process must be expedited.  By having two flame fronts, combustion is both faster and more complete, resulting in more power.   

During its tenure, the Type 547 racked up wins all across the globe.  Five Targa Florio wins and sixteen class wins at Le Mans. It powered the 550 Spyder that James Dean tragically lost his life in.  Dan Gurney, Graham Hill, Stirling Moss, and Hans Herrmann all cut their teeth in the 718. The Fuhrmann engine last performed its service in the 904 Carrera GTS, Butzi’s favorite vehicle.  

The example shown here was fitted in the 904 Carrera GTS in its largest capacity  at two liters. Producing approximately 180 horsepower in road going form, it produced ample power to push the lightweight fiberglass bonded body. 

By using one piece bearings for the camshaft, the camshaft must be disassembled and rebuilt.