Air cooled vs water cooled - highest power potential?

Hi all,

My project engine is a Zip 50 2 stroke air cooled engine, its going to be pretty basic and in stock form I think it puts out around 4.5bhp, my 37cc Blata B1 liquid cooled engine puts out around 8bhp as standard, why is the power difference so much even with a smaller displacement? Its the same with the 49cc air cooled pocket bike engines, surely the power output should be closer?

Anyhow, back to my question, the engine will be run at full throttle for about 25 seconds at a time, there will be plenty of air flow to the engine due to the layout of where the engine will be. Would air cooling be sufficient for higher power or should I look at sorting out a water cooling system.

On the question of water cooling, are the air cooling and water cooling heads be interchangable? Ie is the casing the same with the same bolt pattern etc? I am aware that there will be a water pump in the casing but this can easily be resolved with the use of an electric water pump, I also have spare radiators from my Blata B1 bikes and the frame is ment for water cooling so has all the brackets needed etc.

I will be going with air cooling initially as its simple and thats how the engine comes, in future I will look at upgrading further to a 70cc kit and then maybe higher but thats a while off.

I know that the cylinder can overheat and cause the oil to thin out causing a seizure, which is why liquid cooling is better for continuous power but the engine will be run at full power for a short time.

My basic question is - would a tuned liquid cooled engine allow for more power than a air cooled engine?

 

Thats the perfect answer I was looking for, I kinda figured that the cylinders would be interchangable, I think I will run with the air cooled setup intially, see what I can do drivetrain wise to maximise the potential of the stock setup, then upgrade the cylinder and exhaust further - ie start with carbs, reeds, weights and general maintainence plus the brake and then go from there.

There is plenty of space in the frame for a few extra parts due to my project bike's layout, just having a look at your Vespa project it looks exactly what I am looking at doing, the difference being is that my bike will be much lighter!