Some people like it rough. Your car's intake/exhaust system do not. Make your car happy by porting or polishing some of your exhaust components! I'm using a header that I've got lying around for an example. You could do this to an uppipe, crossover pipe, or whatever you like, really. What you'll need: Dremel tool/Die grinder Some stone bits Gaskets (matching the ports to the gaskets) Time helps Step one: Take your gaskets and use them to mark out the material with a marker. This will give you an idea of what needs to be eliminated. Step two: Get to work porting the material. This can take some time. You might not even need to remove much. In the case of my header, I just want to smooth out the incoming area, so I'm trying to round off some edges and open the hole a little bit. Use a gasket to size it up and keep verifying it that way. Step three: Polishing. Basically, you just want to smooth out any rough patches. Use your finger to feel it out (beware of hot metal) and keep an eye out for any rough parts. Work on polishing these spots down. For this part, if you're looking for a very good polish, you'll want to polish down the barrel at least 1 to 2 inches or so. Basically, you're guiding the air into what it should be doing. Step four: Clean. Use compressed air to blow anything through. For some components, you'll want to fill holes with rags (intercoolers, for example) to prevent debris from getting in places you can't reach it. You do NOT want metal bits going through your heads, engine, or turbo. Step five: Install. Throw your shiny bits on and let your car appreciate your smoothness. Overall, I spent about an hour on my project. I was simply looking to smooth out the port and get a little gasket matching done. Ideally, you may want more material gone, and more polishing done down into the piping. I did not do this in my application however, it's just to put up for an example.
the deeper and more gradual of a transition from ported to the stock inner diameter you can go is the most beneficial. This changes the original step of the smaller port diameter into more of a taper or ramp which creates less turbulence. But that said, almost anything you can do to reduce the step from one different sized port to another is beneficial, the smoother the surface the less likely you will have carbon build up and also the the closer you can get it to a reflective surface the more heat will reflect and stay inside the exhaust manifold which in a turbo application will increase exhaust gas velocity.
its not the smartest thing to do on a tube manifold. you just ground down the weld on the flange. thats not something you want to do. and the gains you are talking about on that manifold you will never see. if you put that gasket on the head now you will see you made it a even bigger transition now because the head ports are smaller then the gasket. my 02. would be keep porting to the cast manifolds and not a tubing one like in the pic. cleaning up burrs is one thing but what you did was just weakens the manifold...
On mine I only cleaned off the burrs and rounded the edge. Being as my particular application was welded inside I didn't want to compromise the integrity of the piece (although I probably could weld the joints from the outside instead). I primarily just wanted to give some very simple examples. A stock manifold that is completely cast would benefit more from actual porting. This is very good supplemental information to take into account.
The hole on it is exactly the same, all I've done to it was make it shiny and rounded the edge off. My particular case was a polishing, but I figured porting would be a similar experience so I just included it in the instructions.
That's what I got from Clement's here in Roch, which wouldn't surprise me if they're wrong. It's basically a Chevy dealership with one Subaru Mechanic. That's it. I hate them so much...
