E30 Zone

How much increase in power can one expect from an extruded hone intake manifold?

Care to add some details to your question?

What engine
What length
What diameter intake
What other modifications
What make manifold etc etc etc

Quote from Ireland engineering who sell them.

Due to the shape and casting method of the M20 intake manifold, extrude honing offers a significant performance increase. Up to 15 HP gains on modified engines can be expected. Although not cheap this modification offers a good bang for the buck. You can ship us your intake manifold or you can arrange for us to provide a core manifold. The procedure takes about 2-3 weeks. Core charge is $125.00.

i am looking into this with my stroker in the next few months.

I am looking for a spare manifold to clean up and paint black and polish the raised logo etc then i'll plan on doing a gasket match and clean up the raggedy stuff from the casting proces on the inside of the runners. Then i'll take it to a local guy who specialises in a similar process to extrude honing and see what he thinks.

The marketing ploy of these types of processes is that it only removes material at the points of restrictions but who knows for sure.
The key seems to be reduce the restriction without losing air velocity so you gain power at higher rpms and retain torque at low rpms.
For this reason i would probably only look to do it on a stroker or significantly modded engine.

From a practical point of view as it would be pretty easy to reduce the restriction of the runners but not without making them bigger, meaning you'll gain some but also also lose some. Its probably a bit like getting a good port job where it goes that anyone can enlarge the ports to make them flow better at high rpms but what about the flow at low rpm!!!

I have no idea what gains to expect.