Ian Oddie has been working on this spectacular engine for a 1/5 scale:
Even though i've been into racing Rc car racing quite seriously for many many years, i didn't know there were any organised top speed trials until Mr Lovering contacted me a few weeks ago and made me aware of it all!!
All very very interesting, but i don't see many 1/5th large scale cars attempting it??
I would have thought they're ideal, despite being bigger/heavier we use a 2 stroke petrol engines which are relatively strong and can be made to produce as much power as can be controlled with.....nitrous!.
A standard 23cc zenoah has about 4 bhp with good racing pipe fitted, a 26cc has around 4.3, again with a good tuned pipe fitted. Tuned they have around 5.9bhp and 6.7bhp respectively, but with nitrous the 26cc in the picture was tested up to 8.9 bhp and that limit was only set by the nitrous/fuel jets in the solenoids. The compression and ignition timing were all set-up with nitrous use in mind, plus the piston was tapered to prevent it nipping in the cylinder with the extra heat/pressure from the use of nitrous.
I'm sure with suitable gearing (2 or 3 speed box) and nitrous a 1/5th scale will be able to go very very quick.