The Porsche engine pictured above came in 60 HP ("N" engine), 75 HP ("SC" engine), and a Roller Crankshaft version rated 90 HP in the "Super-90". The Industrials were generally the 60 HP version. They have a special prefix by the serial number. It was mostly done by changing the compression ratios. All the Porsche 1600's had an extra main bearing, and were factory balanced to Much, Much higher RPM's. VW engines of the same era were balanced to 4500 RPM's, the Porsches were balanced to close to 10,000 RPM's using a Westinghouse automated balancing machine. The engine would not withstand that high a speed, but it ran inordinately smoothly. In addition they sport a form of "Hemi-heads", with angled valves, ( rectangular ports), and much bigger intake as well as exhaust ports. They continued making the 90 HP model for 912's without the Roller bearing crankshaft.
They had an entirely different sound from a VW engine. That improvement came from the tuned exhaust. Instead of a pulsating Rum, rum, rum sound they had a steady Swish sound that did not pulse. Besides having RPM ranges up to 7500 RPM, their Torque band started sooner and went thru a higher RPM range than a VW.
Thus the moniker from the first Vintage ST4 Owners Club: "Dedicated to the preservation of the Rare Swedish Snow Porsche"
A Snow Trac with one of these is a real "Champion-of-the-snow".
Nice engines!