I would thing a smaller motor running at 100% woudl be better than a big moter running at 40-50%. I would start with figuring out how much fuel a 20 mm restrictor would flow. FInding a motoor for that size and starting there. Maybe an old 350X Honda.

Smitty

 

If you make the restrictor a huge venturi, this joker is going to make some torque! What about using a turbo charged wankel engine? might just give em the smack down x10. IF you end up using a piston engine though, your going to need some big compression numbers!

 

are you aloud to mod the engines?

 

The Jr dragster thing is a great ide...
also a small 4 stroke like the xr70/xr100 is light yet can easily be modded to produce much more hp....and even full tilt air restriction won't play into effect

I'd also look into a Kaw ninja 250 motor...they make almost no torque, but they rev to the moon and can take more compression than stock


What are fuel restrictions? Oxygenated...high octane?

 

I still say rotary. Has better efficency than piston motor so it should be able to make more power with less air. Although they dont have much compression so they really like turbos.