just took mine off to port it as its the done thing. and my head ports are exactly the same size as the manifold ports so there is no step/edge/smaller runner than the exh port itself
?
can someone explain why the emphasis is on porting the entry to the manifold runners then?

 

wanting to bolt this back on soon. so should i port to the entrys to the runners on the mani?
i'm struggling to see why its a benefit as currently as stock the mani runner match the head exhaust port size

 

Your exhaust manifold did not need any porting at the turbo inlet ? I gained ~10 + whp throughout most of the powerband on my stock 9 turbo (this was ages ago but I'm sure I can find the before/after data). I did not port the manifold myself and just bought the Buschur ported and coated manifold - BR FTW ....

 

Current thought is to leave alone the side that mates to the exhaust manifold gasket. You yourself have just verified that it is pretty much a perfect match as is. Instead, direct your porting efforts to the side that mates to the turbine housing gasket.

 

Maybe it is already ported?

For reference, on my 2006 Evo 9 the ports were terrible. See pic below for reference. Those black rings are where there was carbon build up from different port sizes.

 

when i place the gasket on the manifold yes i have that huge lip.
but when i measured the exhaust port on the head its the same size as the manifold not the gasket ! ????

 

that makes sense to me looking at it from here.
just confused as to why i've seen many manifolds ported at the runner entry end for those guys that haven't head port work

 

turco i have the exact same soot/carbon build up on that lip however its not due to the ports being different sizes which i thought was the whole port of porting so there are no steps for the gas flow to go over

 

here is what i will have if i port but stock mani to stock head they are aligned except the gasket is larger and hence the soot/carbon line

 

It's not really limited to the diameter in most places but the overall transition and bends. It has terrible flow on the 1 runner. I once placed an air source to each runner to see, the #1 had more flow going out backwards through the #4 runner than to the scroll outlet! If you could somehow decrease this inferrence with a grinder, then porting will drastically help. But the opposite can happen too.

 

that is correct. when we port the exhaust manifold, we don't touch the side that makes to the head. except to clean out carbon buildup. the porting is extensive on the flange that mates up to the turbine housing though. there is easily an 1/8-1/4" all around to take out, and extensive material inside to smooth flow out.

 

yeah i could definately see areas that not only could be bigger but profiling and creating smooth transitions to smooth the flow into the turbo

 

Most people don't understand that it's not how large you make the runners when porting, it's how much you can increase and smooth out the flow within the runners. You don't have to enlarge the openings at the head at all, just at the Turbo side.

 

hopefully this thread will put other home d.i.yers on the right track