why are watercooled so much more powerful

[Glen]

was thinking this on the way home the other night,

what is it about a watercooled engine that makes it so much more powerful than their air cooled siblings. obviously they can operate at the higher power levels longer because of the water cooling, but how do they get this 3-4hp more when they have the same bore (and from what i can see, nearly the same stroke)

all i can think of is that the watercooleds have a 4 pedal reed cage and much bigger carb. but i would think theres more to it than that

cheers

[SIKKO_X2]

yeah ive been wondering why aswell.

[greeny]

There are a multitude of reasons behind the surplus power of the watercooled engines.

Firstly, water cooled motors are designed specifically for racing. This means they have a comparitively large transfer area. The more oxygen you can pump into the cylinder, the more power you make. Thus you can see a full blown 6-port bizeta producing upwards of 18hp. (they have 6-transfers)

Secondly, the exhaust port size, shape and hight determine outright power, and the power characteristics of the engine. Most water cooled engines have very large exhaust ports. The 5-port polini and 6-port bizeta have three exhaust ports if you include the small auxillary exhaust ports set to the sides and high of the main exhaust port. These increase power throughout the rev range, and due to the hight of the ports, when combined with exhaust tuning, allow W/C engines to rev harder than their A/C counterparts (16000-18000 rpm).

Thirdly, the crank case and crank shaft itself are full circle items designed to increase crankcase compression and flow more efficiently than those in air-cooled motors. Once again, more air=more power. The crankshaft in italian engines are steel and are massively strong, allowing far more revs. The cases are stiffer to put up with the stresses 16+hp demands.

Hope that goes some way to explaining the basics. If you want more detail on anything, feel free to contact me. Cheers

[SIKKO_X2]

so are you saying that if you machine your own aircooled engine, it will be as quick as an A/C?

[Robbie]

Originally Posted by SIKKO_X2

so are you saying that if you machine your own aircooled engine, it will be as quick as an A/C?

I hope that is a typo.

[SIKKO_X2]

i meant if you machined an aircooled engine exactly like a watercooled, would it be quicker than a usual reed inducted engine?

[GLEN #159]

Originally Posted by SIKKO_X2

so are you saying that if you machine your own aircooled engine, it will be as quick as an A/C?

ROFL !!!!!

Double quoted for the record .....

[SIKKO_X2]

well he didnt mention that the coolant does anything, so i just assumed and thought i would ask

[sharp_lines]

Yeah good question for sure.
I think its physically not just the water cooled being the same except for machining but the physical position of galleys allows for more physical space than the air cooled

[Dazza]

A watercooled engine and a aircooled engine made the exactly the same way.
i.e Elite 14R and the Elite 14WR
Have the same power.
But the more power you produce the more heat you produce.
So this is where a watercooled engine can get rid of the heat better.
Optimal temp for a pocket bike to run is around 65 to 75 degrees.
An aircooled bike will not get rid of the heat as quickly as a watercooled.

So a watercooled will produce more power due to it being able to get rid of the heat much more quickly and will be able to continue to run at optimal temperature.