If you have your intake; heads; whatever extrude honed the process is akin to porting, correct? My question lies in the area where gasket mating is concerned.

Suppose you have already gasket matched an intake manifold, and the opeing is perfectly matched to the gasket. During the extrude hone process, is that area unchanged? Or does it get opened up in the process? If so, wouldn't that create a sealing problem? Or does the extrude hone process only make changes internally, past the gasket mating areas?

 

I looked into this a while back and didn;t have it done because it is really expensive. It is my impression that it enlarges the port opening as well as the interior of the runner. The pictures at their web site show the abrasive putty flowing right out of the ports. The abrasive is pumped through there until all the interior casting irregularities are removed, so this could easily be 1/16" minimum. It seems like they changed their web site, so I can't substantiate my info and I'm going from memory. It seems like a very good process and I may still have it done in the future, but like you, I have port-matched LT4 heads and manifold and this might wreck my work unless I was willing to redo the head intakes to a larger size. One benefit to the LT4 manifold is the extra thick ports compared to LT1s. They also have a GM LT4 gasket with bigger ports specifically for ported manifolds. Maybe someone who actually had it done will chime in...

 

i was under the impression that extrude honing is for the areas where the typical grinder wont reach. doesnt have any other real benefits, i wouldnt think.
jeremy

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'93 z28 m6 (Purple Pearl Metallic)
stock shortblock, 230/236 cam, mildly ported heads, hooker longtubes, csi waterpump, all the usual bolton stuff.....
7.98 @ 88.7mph 1.84 60' (1/8mi)

 

I did it on my SHO taurus intake system and heads..It did open the ports a little but i told them that i already did my port match..They can control the pressure and flow of the putty if need be to lessen the mateirial removed..
It is very pricey and id only do it again if i really really had to waste money..I gained 12cfm average and spent over $900 when i was done..probally cheaper on a lt1 intake when compared to a SHO's 3.2 DOHC V6..24 intake runners on the intake..

Possibly it would be great if you were just gonna do bowl work and a port match on heads..But it still costs a lot..

 

$900

woah.

There was a GMHTP article about AS&M building a LT4 about a year ago, that had the intake extrude honed then ceramic-coated. I called out of curiosity and I think they quoted ~$400 for the intake and coating. The extrude honing was only about a ~$200 option... but don't quote me on it (might have been $400... can't remember).

 

One of the main uses for extrude honing is to keep stock manifolds looking stock but to make them perform better. Some people with older all-original muscle cars do this instead of adding headers. However the gain is very slight, i've seen only 1-5hp gains.