Exhaust manifold tweaking...

[A80Avant]

I had been told that there is a way to smooth out the roughness found on the inner side of the cast iron exhaust manifolds.i cannot say that i have found much over the net,as i would be probably not be using the correct terminology.I suppose that it must be some sort of sandblasting to be able to produce a smooth area on the inner side of the pipes.

This would give the ability to a cast EM to actually act as a tubular one(or at least reach at some point it's potential) in crack avoiding mechanism.I had read that the roughness of the tubes along with the heat are the reason of the cracking of EMs along with vibration etc.SO if there was a way to smooth those edges up,wouldnt it be good?Or is it too much of a hassle?

[twoqu]

Look for extrude honing. Hard to describe but its an abrasive putty forced under pressure into whatever needs the work. Its expensive!

[quattronutter]

exhaust manis can be ported in much the same way as a cylinder head

[dubmeister]

Try this:
http:/http://www.extrudehone.com/

[mcandmar]

I've seen intake manifolds that were etrude honed, leaves a smooth seamless finish. They can also enlarge the bore of intake manifolds using the same process.

[A80Avant]

but intake manifolds should be a bit rough,isnt that right?Isnt that why the porting on the inlet side of the cyl.head is done roughly?

Also the EVO EM or the RS2 EM cannot be ported the same way done in cyl.heads as the bends will definitelly leave untreated areas

thanks for the link!

[Jamo]

but intake manifolds should be a bit rough,isnt that right?Isnt that why the porting on the inlet side of the cyl.head is done roughly?

Also the EVO EM or the RS2 EM cannot be ported the same way done in cyl.heads as the bends will definitelly leave untreated areas

thanks for the link!

Err no, the putty is plyable it's not a rock hard substance, it bends to the internal shape of runners when forced through under pressure and it will leave no untreated areas

[mcandmar]

Intake manifold can be smooth finish, intake ports need to have a rough finish to prevent fuel from sticking to the walls. If it were a carburettor driven car then you are right, smooth intake manifold would be bad. But with fuel injection the fuel is added into the intake port, everything upto that point can be as smooth as you like.

The whole point of extrude honing is the ability to clean up areas you cant get access to with conventional porting methods. Think of an abrasive plaster scene pumped through the manifold under pressure, that rougly how it works.

[Greg_S]

I remember there being a discussion on this sometime ago, but could only find one thread on it at min