Extrude Hone
 

Who has done the extrude honing or polishing of the intake runners? What is the procedure for doing this? Does anyone know if it is really worth it or not? I am going to be replaceing a broken 6th port actuator rod and figur I might as well do that mod as well while I have the upper and lower intakes off. Thanks :)

It is normally considered one of the last things you can do to extract all the power from your engine.&nbsp Keep in mind that it's going to cost you several hundreds of dollars to get your upper and lower intake manifolds done.&nbsp Gains would be 5%-15%...




-Ted

Last I checked I think ExtrudeHone got $75 a hole. I can see the potential for a small problem when honing below the secondary injectors. The rough surface help fuel atomization by causing turbulence in the air. An ice smooth surface can lead to poor atomization. Just a thought.

Chris

What to extrude hone?
 

I'm working on my new engine and wanted what I could/should extrude hone. Intake? Ports? What do you guys think?

Extrude hone is a great idea for any N/A motor. Forced induced motors need no smoother flow to extract more air through the intake as they are forcing all they need with Supercharger/Turbochargers. Until you reach the limits of capacity with a stock plenum on a Forced inducted engine there is little to no benefit. Anything under 15 to 16 psi would flow fine. More boost may want a bigger throttle body and a ported intake so more volume could be forced in. As it stands anyone running positive air pressure shouldnt waste thier money on Extrude hone.

Here is an idea to try. Just have the middle part of the intake Extrude Honed and then use a die grinder to port the lower intake manifold and port match the upper piece of the intake. By hand porting the lower intake you can smooth the intake tract up some while still leaving it roughed up some to help atomize the incoming air-fuel mixture. Somebody let me know if I'm crazy so I'll know not to try this.:)

IN theory the injectors themselves are what cause ATOMIZATION. Not the intake runners. that would be a substitute for poor flowing, and poor patterned injectors. Lisa Kubo uses extrude honed runners, yet she doesn't have that problem. Why? Because no matter how well you extrude hone everything, there will always exist turbulence. That's just the physics of the matter. This is especially true at every bend and flange and or connection. If your motor is ported then match the intake runners to the ports. Everyone can benefit from this. Not only will extrude honing increase the inside diameter but also polish it up a bit. This is not just beneficial on the intake side, but also be aware of the benefits that the exhaust can gain.
However this is money, and should be at the end of the "To Do" list.....But your money is your problem. Good Luck

In theory yes. What made me mention this in the first place is two-stroke porting and tuning experience. On a carburated (or injected for that matter) two-stroke you'll never see a polished intake port. It'll always have a rough, satin finish. Exhaust ports will always be polished for smooth laminar flow. Carburators and injectors do atomize the mixture but it has to flow a great distance to make it to the top of the piston (or rotor in our case). Polished intake tracts create less turbulence and fuel can puddle in corners or sharp bends. Extrude Honing the intake of most newer, 4-stroke piston motors makes sense because they have been designed with the injector very close to the intake valve and should have practically a straight shot at the valve. Little chance for the mixture to become saturated. The secondary injectors on an RX7 are a prime example of simply spraying fuel in the air and then letting it travel to the combustion chamber. I'm not saying I'm absolutely right, but if I were doing it I'd Extrude Hone the upper intake and just clean up the high spots of the short, lower, 90* section.


Chris