Extrude Honing?

[Pete]

Originally Posted by Locobob

Bottom line: generally you'll get better results with properly done hand
porting.

Extrude Hone does not take off a whole lot of material, what you want is to make the holes bigger.
Basicly stock is 33mm and you want 35-36mm for best HP gains.

Pete

[Nacho_ZR1]

Originally Posted by XfireZ51

I used EH on the Xfire manifold of my 84. I think it worked there but it wasn't cheap. I understand the people at EH are reluctant to do LT5 plenums because runners may separate from plenum due to high pressure.

Yikes That wouldn't be good for business...

[SillyB]

Doug Rippie Motorsports sent their plenums and injector housings out to Extrude Hone in LA for porting. I know because Doug told me! I called up asking about the DRM 500/415 package, and they patched me in to the boss. He told me that since I was in LA and had all the other mods done already, I should just take the parts to Extrude Hone myself. (Doug was a really nice guy to talk to.)

When I went there the guy that runs the shop knew just what to do with the LT-5 parts. He showed me a few plenums he had in his shop that he had used to test different porting diameters on in the early days. He even had a siamesed plenum! Everything came out great, and I can definitely feel the seat of the pants improvement. I don't have dyno numbers to justify it, but I feel enough improvement that I'm happy with the money I spent.

- Sorry for the late post, but thought I'd throw in my $.02 for posterity!

[todesengel]

If you want bragging rights, and have done the big porting, go for it. Usually there is more hp to be picked up in other areas for the money spent.

When extrusion honing hit the import market I never bit, although I know a lot of people who did. It looks really nice, and certainly cannot hurt, but I met, or exceeded their hp with money applied elsewhere.

I am not saying that it does not hold value, or have a place, but for the majority I believe money is better spent elsewhere.

[FU]

Not knocking Doug at all , but try and understand.Extrude honing is very old school. It will get the porting better than stock BUT plenty of power WILL be left on the table. Why not do the porting job to the best of it's ability ? It pays off big time.
This is my opinion

[XfireZ51]

When I used EH some years ago on a Crossfire manifold, I did the porting first then finished it off with EH. I think they have different grits available for the compound and are now better able to remove a pre-determined amount of material. As I said previously, I spoke with the manager at EH in Pa. and was old they did not do LT-5 plenum due to the extreme pressure used and the possibility that the runners would separate from the plenum body.

[Kevin]

Originally Posted by XfireZ51

When I used EH some years ago on a Crossfire manifold, I did the porting first then finished it off with EH. I think they have different grits available for the compound and are now better able to remove a pre-determined amount of material. As I said previously, I spoke with the manager at EH in Pa. and was old they did not do LT-5 plenum due to the extreme pressure used and the possibility that the runners would separate from the plenum body.

i pass the shop every time i got back to my parents place, i should stop in one time

[Paul Workman]

What has been alluded to but not spelled out is EH cannot impart any particular shapes, e.g., the injector bosses, as Pete pointed out, or tapering the ports in the heads, or changing the (critical) shape of the runner/bowl junction, to name a few.

There's "better" and there's "best". The best comes from knowing where (and more importantly) where NOT to cut.



...my shameless brag rag...



You get what you settle for, I recon.

P.

[Nacho_ZR1]

Well for what it's worth, I will chime in to this topic seeing as how I was the originator of it. When I made this post, I was curious about it since I had been reading these forums and saw that everyone was getting their IH/plenums ported by hand. EH seemed like a better way since it was all computer controlled and consistent After i took a trip to Corey's and saw a plenum he was porting, I could see the amount of work that it takes and also how much material can really be taken out. The hand port method will be the route I take later this year

[Hog]

The 1997 LT4 SS Camaro(106 units) and 1997 LT4 Firehawk(29 units built) used the extrude honed stainless steel exhaust manifolds. These were "special" LT4's as they were balanced/blueprinted reassembled and dyno tested. The extra care was required in order to get the full 330hp out of the F-body LT4 as the stock 1997 F-body calibration was required to be used so the cars didnt need emissions recertification for the small vehicle run. These cars have the "normal" F-body 5800rpm fuel shut-off instead of normal 6412 rpm fuel shut-off the Y-body 96 LT4 cars had.
These cars will run 12's.

I saw some pricing for a TPI upper plenum and runners to get extrude honed, it was pretty pricey.

peace
Hog