Term and meaning: port and "polish" question

[SUPERJET-113]

Of course porting is porting, but where does the term polish come from? Does that mostly apply to 4 stroke engines? and why?

I know on all the 2 strokes I've seen(including mine) the cases/intake manifold,etc are roughed up or I've seen sand blasted parts too. I heard and thought this was for better fuel atomization going through the motor.
My friend is telling me that he is polishing the inside of his B pipe, intake manifold, inside of B head pipe/manifold.
I told him I thought he was wasting his time..lol

Can someone please explain some of this?

Also I meant to put this in general or driveline, so if a mod wants to move it, that would be fine.

 

[snowxr]

Yes, the polishing is for 4-stroke heads. Engine builders will reshape the combustion chamber and then polish the dome of the chamber, which will reduce the chances of having hot spots and carbon build up. They do this to the intake and exhaust runners, too.

If I had a penny for every time I had a guy tell me his jet ski or snowmobile HEADS were bored/ ported and polished.... I'd be rich ( well, dollar menu rich)

 

[sflsurfrider]

polishing, on 2strokes, is for the exhaust ports, and manifold, for better flow.

 

[keefer]

Yep, I took the time to polish the exh runners on my cyl and smooth out as much of the B pipe mani as possible. I media blasted the intake areas and some of the case area to promote atomization. IMO little things like this add up to better performance.

 

[Idok]

Of course porting is porting, but where does the term polish come from? Does that mostly apply to 4 stroke engines? and why?

I know on all the 2 strokes I've seen(including mine) the cases/intake manifold,etc are roughed up or I've seen sand blasted parts too. I heard and thought this was for better fuel atomization going through the motor.
My friend is telling me that he is polishing the inside of his B pipe, intake manifold, inside of B head pipe/manifold.
I told him I thought he was wasting his time..lol

Can someone please explain some of this?

Also I meant to put this in general or driveline, so if a mod wants to move it, that would be fine.

that will cause a loss of power....dont know if it'd be noticeable or not, but you want a rough intake for better fuel atomization and smooth exhaust....

 

[SUPERJET-113]

polishing, on 2strokes, is for the exhaust ports, and manifold, for better flow.

Now that makes sense. Thats why some guys get their exhaust systems extrudehoned, especially the cast parts..

 

[cambo au]

that will cause a loss of power....dont know if it'd be noticeable or not, but you want a rough intake for better fuel atomization and smooth exhaust....

x2 i was also taught that the intake should be rough and exhaust polished it was explained to me that if you polish the intake area it is like when you get water on your windscreen when it runs of you still get like a fine layer of water on the glass when it is flowing over a sandblasted aluminiumi think it also helps with atomisation
it made sence to me anyway but i think it is still one of those great debates

 

[stanton]

polish doesnt necessarily mean to a shiny smooth finish.