Intake Port Polishing DI engines - reduce carbon?

I was originally looking for information about the possibility of polishing the intake chambers while the head was still on the car, but that morphed into trying to find any correlation between polishing intake chambers and subsequent carbon build up.

While there were a number of articles talking about porting (making the passages larger) and polishing (making them smoother) I could not find a single one about the effect on carbon build up. The closest I got to the two concepts together was a question posted on VWVortex that was never answered.

So, I am uneasy about polishing the ports while the head is still on the engine due to the possibility of leaving metal in the ports, but the question still remains:

Will polishing the ports cut down on the build up of carbon?

Thought I would throw that out to see if anyone has any experience. I will continue to change my search terms around to see if I can find any information on the topic.


For the V10. I have not seen any data on this. But if we shift over to something in the same family like the S5 4.2. People have ported their cylinder heads and have reported no difference in cylinder carbon collection and that would be the same for the RS4.

If you’re looking to cut down on cylinder carbon build up while being able to help keep motor runinng well and making more power. I would suggest the JHM intake spacers. They have been shown on the V8 V10 and other apps to be one of the best mods for not just carbon but power.

Already have them and they will be going on soon. That is after I get my back out of traction cleaning these chambers.

I think I’ll do my next cleaning at 300,000 and not wait for 400,000 miles…


In theory a clean and well polished port with nothing for the gunk to grab on to, would do a lot better than the stock form.
At stock they are quite rough and nubby.

That’s the theory, sad to hear that it’s not so.

Yep, I was hopeful that smoothness would cut down on build up, however thinking about it, the valves are very smooth and they have the most build up, so…