What should the finish be on the inside of an exhaust port?
I know that polishing the port reduces carbon buildup because it can't stick to a smooth surface, but does it hurt preformance?
Airplane wings actually have a rough surface to increase the flow of air over the wings.
I believe that polishing ports makes air stick to the port by increasing friction. Just think of trying to drag one piece of sheet glass over another.
Discuss...
Well, polishing reduces the small bumps in the aluminum port, which should reduce friction.
i think 2 pieces of glass sticking together has more to do with the molecular properties of glass and the structure of the molecules.
dittp what jon-o said about the glass....really no discussion needed about the exhaust port either, read any literature on two strokes or on gas flow and it will say the smooth is better
all the planes i have worked on are usually polished aluminum?
mirror finish. that's what i shoot for
Haha. This is te most discussed subject in Holland.
It seems very logic that a polish't surface is the best.
Butt probably it isn't.
Take the plane thing. Throu that it's as smooth as possible to reduce friction.
But with a moped engine there is more than just air!
There is also gas and oil. When you sand (not polishing) the transfer-ports. The oil that is in the mixture wil stick to the transfer-ports wall. This tiny oil surface is much smoother than that you can ever polish it. So? probably sanding the transfers is better than polishing.
yeh, transfers=smooth but not polished because its not a gas flow, its actually a suspension of liquid droplets....exhaust=polished because it is now a gas (hopefully, depending on how good the combustion is)
Like this pic polishing helps reduces carbon build up to.
Fast bat out
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