I buddy of mine metioned this when I was talking about getting heads P&P'd. What exactly does it do and what are it's advantages? I assume this would be somethig to do in conjuction with a porting and valve job, not in place of?

 

You can read about it www.extrudehone.com

I'm not an engineer, but I wouldn't suggest it in applications where you can reach with a die grinder. Wierdly shaped intake manifolds like a 300ZX Turbo on the other hand dont really have any other options other than fabbing up a complete custom unit.

 

Extrude honing is used to create a freer flowing exhaust manifold in the stock casing. Basically you shove some gritty stuff through the manifold at high pressure 'till it grinds down the rough spots and makes 'em flow better. But personally if I was gong to go to all the trouble of getting the manifolds off, I would just slap a pair of headers in there. Besides...who wants to look stock anyway???

 

This process is most often used on intake manifolds, although it can be used on heads, exhaust manifolds, or turbo housings.

-Chris

 

For intake manifolds, where you just want more runner volume (larger engines etc) the Extrude Hone process should be fine. If you're looking to raise runners etc., then it's a waste as you can't control where the honing actually takes place.
In a cylinder head, I'd never even think about it. The goal there should be to remove material in the correct areas, not just make the port larger. Areas of low flow shouldn't even be touched, the goal is to enhance the high flow areas and work the port to the correct size/taper/section-area for the application.

-Mindgame