ok, so im hopefully going to be picking up a ecotec head this week and i am going to have access to a machine shop this weekend. what should i do with it while im there. granted i dont really have any experiance in this kind of work.

i guess that may be the wrong question to ask...i mean im gonna try to port and polish it...but maybe some tips on how to do it would be great. thanks!

there are a million and one online articles on how to self-port heads, so i'd suggest googling a few of those to get the basic concepts first. As for the eco head in particular, the exhaust side is REALLY weak so I'd focus a lot there, but the intake can be hogged out quite a bit with good results also. Just remember that typically, the biggest gains are had from smoothing out the area in the valve pocket, and not by opening up the port entrances. FOr the intake side, just try and match the port entrance to the exit of the intake manifold, and for the exhaust side, I've read of it being recommended to leave a little smaller than the entrance to the header/manifold because match porting it basically makes a bubble which causes turbulence. Don't know how much truth their is to that but it made sense enough to me when I read it. Wish I still had the link...




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ok cool, that helps. ill do a little googleing lol thanks!

Scarab (Jersey Jay 1.8T) wrote:I've read of it being recommended to leave a little smaller than the entrance to the header/manifold because match porting it basically makes a bubble which causes turbulence. Don't know how much truth their is to that but it made sense enough to me when I read it. Wish I still had the link...

I've always heard the reason you leave it smaller is to help combat gas reversion. Generally, it is only done on one edge though (the bottom IIRC, because exhaust gases primarily flow along the top edge, but don't quote that).




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