Type 170 revisited

Does this look like a stationary engine or a boat motor to you? Despite common belief it seems as the supercharged type 170 was a stationary engine for high altitude rather than a Sturmboot motor.

Before continuing with Porsches post war development I want to go back in time to 1943 as new information has came to my attention.

A consultant at my workplace, and fellow vintage Porsche fan, did hand me a book a week ago. It was "Driving in its purest form" by Conradt. He had found an interview with Ferry Porsche from 1989 in the book that he wanted me to see.

In the interview Ferry mentions a project for a stationary engine for high altitude using a Roots compressor to compensate for the power loss due to the low air pressure. He also mentions that such an engine later was installed in his private kdf cabrio (as pictured in the "origin of the species" book by Ludwigsen).

As I see it, it's clearly the type 170 Ferry refers to. It all makes sense: The weight was too high for a Sturmboot application and the engine canopy (as seen above) did make it feel like a stationary engine.

Part of the document in which type 170 is (faulty?) categorized as a Sturmboot motor

If all this is true the 170 was not part of the Sturmboot program, despite what it's said on the typewrited copies I got (that originates from the Porsche archives). Or, could it be so that the first version, with the supercharger on top, was for the Sturmboot program? Perhaps when they realized it was too heavy they reused it for the high-altitude stationary motor request.

It's all goes to show that there are still things to discover in the early history of VW/kdf/Porsche engines and if something seems a bit strange you are probably missing a piece of the puzzle.