RE: West .50V1 bench run
That head is mostly air, it's kind of a helicopter-ish cooling head. If you trimmed it down on the lathe it would probably look normal.
mkI: revs are good, but if the porting and timing of the engine result in the volumetric efficiency going downhill past the point where the increasing rpm times the diminishing torque no longer results in a power gain - then you have exceeded the design potential of the motor as is. This engine's horsepower peak is apparently in the 21k area. If I ran it at 25k I expect the motor would hold up fine, but I also would expect to find that 25k/21k rpm increase times the (torque at 25k)/(torque at 21k) decrease would result in less power output. Unless I modified the motor to breath at those rpm. Power = speed.
The idea is to burn as much fuel/air mixture per second as you can, so revving higher does of course increase that potential courtesy of repetition, but if the engine can maintain some breathing efficiency. The design parameters that allow it to do so make it more and more of a special purpose engine as you climb in performance potential. The old rule of never getting something for nothing applies once more. The MB40 for example ingests and burns enormous amounts of fuel/air mixture at 30-33k or whereever it runs, but try to run it at what, 16k?, and see what happens. One day we'll have the universal .40. Oh wait, that's a hipo electric ([X(]).
MJD