RE: Engine tuning
I cannot say how much is lost, although I have been told 2-3,000 RPM. I purchased a couple of engines from e-bay when the change was made 2 years ago and get about 18,500 on an 8.75 X 7.75NN prop. Others with newer engines seem to do better. It appears, in my opinion, that the engine out performs initial expectations and there is a speed creep occurring as people experiment with various propeller combinations and I am sure different head shimming and timing.
The initial idea for the engine was to have a setup that would replace the previously preferred Webra Speed 40 with an ultrathrust muffler, Roy Andrassy experimented with the Nelson SS engine to see how it could be detuned so it could compete but not dominate the series. Since the Webra was long in the tooth and there were some incentives put n place for people to switch most in the district quickly moved over to the Nelson / detuned pipe combination. Some of the selling points were;
-The Nelson is a design for purpose racing engine and was robust enough to be a reliable performer, the detuning even made a better case for this.
-The Webra was no longer in production and new engines were not available to new entrants.
-The Nelson could easily be converted with a tuned pipe to compete in the NMPRA 428 event.
Since the engine has been in use for 2 years most appear to like the trouble free operation and the new LS has made them more plentiful for people starting out. The intro of the LS version however may take away from the argument of using this engine in the 428 class competitively but this is only of interest for a small group anyways.
Airplanes used range quite a bit from Vipers to Seekers, Neme-Q, Vortex, Slingshots, Kase and the like and some of the better built woodies are doing well. I cannot say I have seen any Q500 airplane fail under flying stresses. In the end I think the engine is a good fit for this district, since the flyer numbers are not large enough to hold a 424 and 428 event regularly but the Nelson configuration seems reliable and affordable and at the same time people can start out with an engine other than the Nelson if they wish (although not many do).
KM