Thoughts on Extrune and honing?
- Thread starter rudeone707
- Start date
Just so you know the process is called "extrude honing." I'm not sure what the difference is between extrude honing and porting. I've only heard of upper intake manifolds being extrude honed, but like I said I'm not exactly clear what it involves. Porting the stock heads is a great idea. Think about throwing on some bigger valves while you're at it. Also, if your friend can port your stock heads, maybe he can do your intake also. Otherwise, try an Edelbrock Performer or a Trick Flow Street Heat. All that along with the 1.7 rocker arms should give you some nice power for a fairly low price.
Extrude hone forces a material that looks like silly putty through the ports. The material has abrasives in it, so it removes some material and gives you a nice, almost polished surface.
The only problem I see besides cost is that air is compressible and that putty probably behaves like an incompressible liquid. There is a fundamental difference between compressible and incompressible flow. So extrude hone can optimize for incompressible flow, but that isn't always the best for air.
On another note, I saw an extrude honed fox intake at the Pleasanton hot rod show. It didn't have any takers at $300. I'm sure the porting cost more than that. Also at the show was a trick flow intake for $350, which would you rather have?
I don't think it's worth it unless it's really cheap, less than $150 for both. There are so many better aftermarket heads to port on, and the aluminum heads will save weight too. Also, ported aftermarket heads will hold some value. Ported stock heads will never be worth much more than stock, and stock is dirt cheap. If you can find a cheap set of GT40p's to port, that might hold a little more value and give you a bigger improvement.
The only problem I see besides cost is that air is compressible and that putty probably behaves like an incompressible liquid. There is a fundamental difference between compressible and incompressible flow. So extrude hone can optimize for incompressible flow, but that isn't always the best for air.
On another note, I saw an extrude honed fox intake at the Pleasanton hot rod show. It didn't have any takers at $300. I'm sure the porting cost more than that. Also at the show was a trick flow intake for $350, which would you rather have?
I don't think it's worth it unless it's really cheap, less than $150 for both. There are so many better aftermarket heads to port on, and the aluminum heads will save weight too. Also, ported aftermarket heads will hold some value. Ported stock heads will never be worth much more than stock, and stock is dirt cheap. If you can find a cheap set of GT40p's to port, that might hold a little more value and give you a bigger improvement.
As said above, extrude honing is a process that forces abrasive material through the ports of an object. It acts as a sanding agent which is supposed to make the ports smoother, thus letting air into them easier.
The problem I have with extrude honing is this: an exhaust port is supposed to be smooth, an intake port is supposed to be slightly rough to the touch, which is supposed to create a turbulent type affect going into the intake valve, which is better for velocity. I don't know about an extrude hone job on a pair of cylinder heads. On an intake manifold - maybe. On cylinder heads - probably not.
Joe
The problem I have with extrude honing is this: an exhaust port is supposed to be smooth, an intake port is supposed to be slightly rough to the touch, which is supposed to create a turbulent type affect going into the intake valve, which is better for velocity. I don't know about an extrude hone job on a pair of cylinder heads. On an intake manifold - maybe. On cylinder heads - probably not.
Joe
Zero Signal
Active Member
I've looked into the Extrude Honing aka Abrasive Flow Machining (AFM) and it will run you about $700 for the intake and about the same for each head. It's undoubtedly the coolest thing ever, but not worth the money.
GTJake
Founding Member
94tang said:
No it isn't. The injector sits in the lower manifold. It still has to travel out of the lower, into the intake port on the head, and past the intake valve. That's why you still want the intake port on the head to be a little rough.
Jake
The real solution to fuel atomization in fuel injected engines is the aim of the injectors. The ideal is to shoot the fuel directly at the back of the intake valve. The heat of combustion keeps the valve hot, so the fuel vaporizes on contact.
So, no, it does not matter what kind of surface your port has in an EFI engine, unless you are using the surface roughness as a vortex generator to attach a boundary layer of air, like on the short turn radius.
That is the sort of thing a top notch cylinder head porter might do, but the Extrude hone process will never do it.
So, no, it does not matter what kind of surface your port has in an EFI engine, unless you are using the surface roughness as a vortex generator to attach a boundary layer of air, like on the short turn radius.
That is the sort of thing a top notch cylinder head porter might do, but the Extrude hone process will never do it.
Ever seen a EH port? 331 Cobra is right - the putty cannot selctively remove material for best port shape and air flow.
Similar threads
