thebull

ive seen that people have tihs down as a mod. what exactly does this do,and what type of hp gains does it give. also how difficult is this to do by yourself?

got rice?

iTrader: (2)

This is not something the average Joe Schmoe can do in the garage. It's a time consuming and difficult job that can easily do more damage than harm. Most head jobs start out with a machinist that does one port, then the rest is done by CNC machining.

PiotrC70

That what you are seeing is people saying, polished intake manifold meaning... The have it chromed out...so to say...I don't believe anybody here has actually DONE a port & polish on the heads itself, maybe though.. who knows.

thebull

i just watched Trucks today on TNT and coincidently they are going to show how to port and polish heads on next weeks program. i cant wait to see it, although i will probably be too afraid to actually do it myself.

PiotrC70

and that's where I got my inspiration.

brubenstein

This is a non-trivial thing to do. It requires pulling the heads and removing the valves just to start doing something. A very basic porting involves matching the port in the intake manifold to the intake port of the head, removing any casting flaws in the intake port and getting the valve seats recut (usually a multi angle cut for the intake). Reshaping the intake port (for a significant power increase) takes the right tools, experience and a flow bench. A simple clean-up port job is probably good for a 10% increase in power and won't make the engine any peakier. A more extensive port job will tend to trade off some lowend for high end power. And oh yes, the flow of all six intake and six exhaust ports have to match. Polishing is just smoothing things out with 240 grit paper. You really don't want a high polish in the port, because it will create a thicker boundary layer between the fuel air mixture and the wall. A good race port/polish would probably be good for 50 HP. If anyone thinks this is easy to do right, they haven't done it.
It's the kind of mod that is most appropriate for real racing, where you have to do mods within rules. For instance, if you're running in a street stock class, you may not be able to change the intake or exhaust, but you can do a "clean up" port and good valve job. Since it's probably cheaper to put on a supercharger, than have an experienced race shop prepare your heads, it's not very cost effective for street racing. Another difference between streep prep and real race prep.

Keven97SE

I checked out the intake ports on our heads when I had my intake manifold off. The ports are really good. I saw no notable casting flaws, the surface isn't that rough, and the port divider (splits the one intake into two ports) is pretty smooth. Of course, I couldn't see the seats, but I really don't think there's much point in doing a port job...pretty good already.

Also, Ford SHOs can make lots and lots of high rpm torque (HP) without doing any port work, and those engines use 1mm SMALLER intake ports and either the same or smaller size exhaust ports. Leads me to believe that our heads perform similarly.