I've seen a lot of pictures of Ported and Polished heads but the surface finish seems to be somewhat rough... almost like bead-blasted. Shouldn't they be polished like a mirror? Or is the rough surface to aide turbulance?


Thanks

 

Yes, the rough surface you see is meant to enhance the mixture of the air and fuel. The polished portion is actually the chamber. Most people don't post pics of that since they're mostly the same, but check out the thread in the advanced tech section on grooves in heads and you'll see a couple pics. The chambers are polished to resist buildup of carbon and such. Someone feel free to correct me if I'm wrong.

 

You would want to see the exhaust port polished as well.



Kevin

 

Doesn't carbon build up in the ports too? If the ports were at a mirror like finish, it would seem that they would also resist carbon build up.

I'll check up on that article in the Advanced Section... thanks for the tip.

 

The exhaust ports are usually pretty smooth, but never the intake. The intake valve is closed when all the combustion/carbon is going on, excluding the overlap period.

 

There's got to be carbon in the intake since carbon can build up on the valves, manifold, and Throttle Body. About every 6 months I wipe down my TB. So, if the intake port was polished, then it would seem there would be less tendency for carbon build-up.

This is only a guess.

 

you have serious problems if you are getting carbon buildup in your plenum, intake runners, intake ports or intake valves.

 

In the "old days," the ports and the combustion chambers were polished... since then (I believe) the thinking has changed regarding high-speed air flow across a surface like that... ?? Maybe the old terminology of "polished" has hung on... ??

 

I think that's more likely oil coming from your pcv valve. You should definitely get that checked because it should not be necessary to clean it that often.

 

It could be the EGR / PCV. My last smog check was at the limit with NOx.

 

I believe the other reason for polishing the combustion chambers is to reduce hot spots and detonation. i am sure this is mainly with older small blocks with cast iron heads more than newer aluminum.

 

Now that you bring that up, I do recall reading about polishing the combustion chamber and piston heads. It was an article about "reflective heat". The point is to put more energy back into the combustion chamber for a more complete burn.