Anybody remember Extrude Honing?

[harrisonm]

I was reading an old Mopar Muscle Magazine the other day, and I came across an article about how someone had their iron exhaust manifolds extrude honed and picked op 10 HP. As I remember, extrude honing forced a thick, abrasive liquid though the inside of a part like a cast iron exhaust manifold and it not only smoothed things up, but it removed some material. I would think it would be useful for more than iron exhaust manifolds. Does anyone do it anymore. I haven't heard about it being done for quite a while.

 

[Matts440]

I remember it, also works great supposedly for plastic manifolds as well. Not sure if its done anymore, think it was pretty expensive to have done, but it sure smoothed out the aluminum runners. Heres a place here in Ca

Extrude Hone AFM
8800 Somerset Blvd.
Paramount, CA 90723

 

[crackedback]

Huge waste of money for the gains.

 

[64DartGTinAZ]

Yeah - I remember reading about that 20 or 25 years ago...nearly forgot about it

Extrude Honing | Bonehead Performance

This book excerpt renders an opinion based on experience on the dyno with Extrude Honed parts:

Practical Engine Airflow

 

[abodyjoe]

Huge waste of money for the gains.

i agree...

i was talking to one of the F.A.S.T guys years ago that had just had it done to his manifolds. it didn't help at all he said..

 

[Killer6]

Probably more accurate in that instance was that it didn't help enough, F.A.S.T. guys are running equip designed to maximize output with the choke of stock components.
I believe IIRC there was an intake test on a 440 motivated RR/Satellite body in one mag that went from mid-12's to .20's-.30's with an Extrude Honed intake, not bad.
It is a slow & $$$$$ job tho', so as noted, not usually cost effective. The main issue with the process is that it doesn't always address form & transition problems, it just
makes them larger, so it is up to the owner to work out any porting/changes on their own before having the piece done.

 

[plymman]

Extrusion honing is usually used as a last step in performance mod. The media is silicon carbide grit in a polymer similar to silly putty, the harder you compress it the firmer it gets. It does work in some cases, flow bench testing has proven that. Extrude Hone is expensive because it is slow and it is a monopoly even decades after it was invented.

 

[harrisonm]

Thanks for the posts. I had never heard any of the negative stuff. Isn't it funny how all e heard was good things about it in the car Mags at the time?