1971 Porsche 917K “Schnörkel” Spark - S1899 (resin)
Though introduced in 1969, the Porsche 917 was not a winner from the get go. It was a difficult car to drive. In fact, it was downright dangerous. It took almost a year for Porsche’s engineering department to figure what was wrong with it. And that only happened with the invaluable input from John Weyer Automotive’s (JWA) engineers. After a lot of practical testing they finally figured out that the tail section of the car was all wrong. When they swapped the original long tail for a shorter tail section, the car finally delivered. To the point that in 1970 Porsche had its first overall victory in the 24 Heures du Mans.
What never was a problem for the 917 was the engine. The Type 912 was a brilliant piece of engineering. A flat-12 (180º V-12), it displaced 4494 cm³, and with DOHC and 24 valves it produced 580 hp. Though very complex, it was reliable and sturdy. Even so, for 1971 the engine gained size (4907 cm³) and power output went over 600 hp. Still, with the aerodynamics of the car totally sorted out, engineers felt that there was room for improvement in the engine bay.
The science behind ram-air intake is quite simple, and in the 70’s it was a proven concept. Basically, it consists of forcing more air into the engine through the sheer speed of the car. The faster the car goes, more air is rammed into the engine. It makes the engine volumetrically more efficient, and consequently increases power output. So there’s an increase in power without the need to increase displacement or to use turbo or supercharging. Thus, it was only natural that Porsche tested the principle on their race cars. And they tried it in three* different cars. Chassis #917-016, 020 and 032 all received a big double air scoop over the engine at some time and became a 917K Schnörkel. However, the principle didn’t work very well on the 917.
Along with other modifications, JWA tested the idea at different race tracks. To generate enough ram air pressure the 917 needed two ram boxes and air scoops. But the “periscopes” above the engine increased drag by about 5%. Furthermore, the increased air flow also created excessive disturbance to the fuel mixture strength. In the end, adding everything up, they concluded that the power gain was not enough to justify the losses. With that, both Porsche and JWA dropped the ram air project. That was the end of the Schnörkel.
Probably because the idea didn’t work, info on the real 917K Schnörkel is scarce. It seems that Porsche tested #917-032 at Weissach. JWA ran #917-016 in the test sessions of the 1000 Km of Monza and Le Mans. The only car that actually raced was #917-020, at Brands Hatch, sporting Martini colors. From what I gathered, Spark’s model is probably chassis #917-032 as tested at Weissach. It’s a beauty of a model, and the first “weathered model” that I actually like. In general I think weathering should be reserved for a diorama, but in this case I really liked the effect. And this model is even more special. It was a gift from that stinker (and great) friend of mine, the Earl of Northumberland. Because, you know, karma 🙂
*Chassis #917-30 also had the scoops, but was only used for wind tunnel testing, and not on a track. However, there may be more chassis that used the ram air setup. Unfortunately though I couldn’t find solid information on other Schnörkel 917s.