Hi there,
I think I have finally decided what engine I am going to have a go at building. I was thinking about designing my own from scratch, and even had thoughts about a DKM type engine, but I have come up with a better idea. I am going to basically build the SW92, BUT with a few changes to the design.
The biggest difference will be that my engine will use a proper epitrochoid rather than 2 circles. The porting may have to be adjusted slightly to suit the epitrochoid. I am going to keep an eccentricity of 3.5mm, however I am going to decrease the rotor radius from 28mm to 25.5mm. 28mm seems too big for this engine. I'm not sure if this has something to do with the housing that was used. The rotor width will stay at 18mm. After these changes have been made, the capacity of the 'new' engine is 8.4cc. I will therefore be making an SW84, not an SW92 (I may as well change the name slightly while I'm at it...). The only other change I'm going to make is to the cooling fins. I prefer the look of the OS style fins to the ones on the plans. Oh, I'll also replace the homemade venturi with a commercially available carburettor.
This should save a lot of time, as the basic design is already in place, so I can concentrate on the more important parts.
Mark, maybe you can help me here on some detail. I was looking at the plans for the SW92 and it looks like the internal gear is cut into the rotor. It seems like quite a good idea to do this. Am I correct in thinking this? Finally, does the author give any detail on how he actually cut that internal gear in any of the text? It's at times like this that I wish I could read German...
Thanks
Warren