What was the first Schnuerle ported OS engine and when did it come out?

The 1973 OS 40SR...also the first normal CNC machined engine after they got the machinery to make the Wankel. The same crankcase was used when they went to the front induction which is the FSR and that's why the FSR's have SR moulded under the exhaust.

Yup that's the correct answer. The next one was the 60FSR followed by the 40FSR. Then the 10FSR and then They went nuts and brought out more FSR and RSR versions than you could keep up with. The FSR's were one of OS's best lines. Only draw back was the bolt on mufflers on some models. If you knocked the muffler off you also took a chunk out of the case. I have several od the 40, 45, 60, 61 and some of the others from 10 the 108.

Winner winner!

I too, love(d) the FSR's