Ported Headers - Open to the idea?

[sluggish94]

I saw a thread on another forum where a gentleman spoke about getting his headers ported by a professional porter. The porter showed videos of a header's CFM increase on a flow bench before and after his port job.

From my understanding, the idea behind porting something is to maximize the CFM an inlet/outlet is able to "allow". If a header has excess slag from the welds, irregular port shape, lumpy bends, or a smaller than advertised collector, one could come to the conclusion that these "restrictions" could potentially be worked out, right?

On the other hand, I saw an Engine Masters video where they put a bunch of dents in the headers up and down the primaries and lost nothing on the engine dyno. So this makes me think, was that porter onto something or was he backing a bogus service? Could a 1 5/8 short tube header flow as much CFM as a 1 3/4 short tuber header with a "port job"? Is there a possible CFM gain going from a 2in to 2.5in collector or is it marginal at that level?

Just something to ponder over.

 

[Werecow]

From what I've been able to gather there's not much gain in doing a port match on headers because most of the gain you get from them is the scavenging effect from having the exaust ports tied in further down the exaust path, or even as Ford and Chrysler engineers found out back in the 60's the old style "Tri Y" style headers. Now if you wanted to port cast manifolds, that's a different story. There are some, albeit small gains that might be gained by doing some port matching on cast manifolds. I've actually been looking into that as options for headers on my foxbody are pretty slim to none. Nobody makes a set of headers to fit a 351M for a 90 mustang... Even Cleveland headers won't fit because of the increased deck height of my engine. I've tt someone who has a set of the Cleveland headers and he said I'd have to do a lot of chopping and welding to make em fit...

 

[OLD H2S]

Easy to do and it works. A great place to learn and get the tools you need for doing heads. It is long and slow but still better than video games.
The part that is hard to grasp is how a small change in diameter makes a big change in flow, just going up 1 jet size makes a big difference in carb tuning and the same in port flow and on a header mistakes do not count, heads are touchier. Tools are cheap but a mask and face shield are MANDATORY. Ask me how I know..

 

[Werecow]

Considering cast manifolds are probably all I'm gnna be limited to I think I'm gnna have a go at porting mine. Can't hurt eh??

 

[PinkieT]

Maybe you can find a local shop to use the extrude hone process.

. My buddy used to run a race class requiring all factory stock parts, and this sure helped on his restrictive cast intake and exhaust manifolds where grinders couldn't reach.

 

[evilcw311]

Not many places left doing that. I just sold a fox 5.0 intake that had been extrude honed.


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[OLD H2S]

They have gone commercial only, they do not deal wither hobbyist any more. The set up and wear a tear on their set up is big and they charge too much to make it fast and cheap to us. Most of the companies that had the machine would not pay for a new one when they found out how fast they wore out and that each manifold job needed a custom jig and fixture to hold it correctly, it is not universal plug and play. Finding one that did Ford parts was few and far between compared to doing Chevy parts. I almost bought one back in the day to polish plastic injection mold runner systems.