There are gas engines and there are glow engines...a gas engine is usually found on larger modle aircraft and burn gasoline and oil mix like a weed wacker.....glow engines burn glow fuel a mixture of oil and methanol with nitro thrown as an oxidizer....</p>

for the same power out a 4 stroke will be bigger......a 52 4 stoke would be great on a 40 sized trainer....4 strokes sound good</p>

good flyin to ya</p>