[QUOTE=Northern.dj;5268232you see the top drivers with all the top engines but they get them cheep from sponsors the off road comunity have been using cheap engines for age's so engine manufactur's get the prices down[/QUOTE]
Be sure about one thing, you can never be a toplevel driver with offroad engines, the total performance of such an engine is less.
Beside that, if you tune up an offroad engine to get onroad specs there is a high chance the conrod and/or piston will explode due the higer forces on higher rpm. There is a different choice on materials for an offroad engine what will make the engine cheaper, the choice for weaker materials is not only cheaper on the materials itself but there is also also in a shorter machinetime for making the parts and less maintenance on the machinery.