Some guys come up with really interesting engine modifications and Bart Crauwels is one of those guys. Bart is currently working on a project that converts a Ducati 1000 DS, a 2 valve air cooled twin, into a supercharged single, using the rear cylinder as the blower. The 498cc single has 15 HP more than the original twin putting out 102 HP at the rear wheel, torque is increased and it runs fine to 10,000 rpm, 2500 rpm over stock. It's about 30 HP more than the well known Ducati Supermono. The Ducati V-One, as he calls it, is for racetrack use only and when things get sorted out he plans to build 40 of them for customers.
In recent years there have been some custom builders, Roger Goldammer comes to mind, who have replaced the rear cylinder on a V-Twin with a supercharger. Since the cylinder is already an air pump, Bart just used what was already there. Of course, the first question before doing this is whether the blown single will have more power than the twin it's derived from and the answer, in this case, is yes.
Another cool feature is the air tank under the seat, limited to 40 bars, which is good for a 10 second burst of compressed air when acceleration begins after which the blower's output kicks in. On deceleration, the tank is recharged. It's hard to see everything that Bart has done by looking at the photos, I notice an intercooler in the plumbing, too, but overall, I like this a lot.
Big thanks to Hugo for the tip!
More photos below: