The crazy thing is that the bigger motors don't give much of a usable
performance gain. We are currently running a Ninco Classic class at Bolwextric and after six rounds it is very obvious that the NC1 powered cars can be "driven" using the full power band of the motor, whereas those using NC2 Healeys and Cobras are having to use the "point & squirt" method. The track is hardly what you would call a tight twisty circuit either, where a lower powered car would generally shine. Admittedly the NC2 cars briefly come into their own on the longer straights, but are soon caught up by the NC1s being "driven" round the bends.
Oddly, the three NC1 cars dominating the racing are all yellow TR250s.
It's not just the classics either! We recently had a 3-meeting Ninco McLaren GTR class and the most successful car was NC1 powered. And we are currently running a Gumball Rally class with cars eligible from many different manufacturers in which the best cars at the first meeting were NC1 Ferrari F50s. A while back we had a hot hatch class and the only "big" engined car that could give the NC1s a race was the Clio with suspension.
It seems to be a case of getting every last drop of available power out of the NC1 as opposed to trying to hang on to the first 50% of the NC2.
Still, at least brackets are available, so it's not the end of the world and all those NC2/5 motors make pretty coloured track banking wedges!