exhaust manifold porting Q

[redamnavit]

I'm doing a mild bit of porting (more removing internal casting flaws and polishing it up) of the exhaust manifold before I send it and my turbo's exhaust housing off for thermal coating.

I'm looking at the dividing wall in the collector, right where it joins to the turbo. Does that thing serve a purpose? Is it structural, or can I knife-edge it to give myself a smoother, larger flow path?

(As I side note, when I took off the manifold I noticed two of the gaskets had been put on the "opposite" ports than they were meant for; as a result half the gasket surface was in the way of the exhaust flow and the other half was barely covering the surface of the manifold. I need to go nuts with the flap wheels tomorrow to clean out all the layered carbon that built up from interrupted exhaust flow. Damn monday engine. )

[paul_s13]

I was warned against knife edging the exhaust divider by a race engine builder, he said that if you make it too thin then there isn't much metal to dissapate the heat quickly enough, melty melty!

[redamnavit]

I was warned against knife edging the exhaust divider by a race engine builder, he said that if you make it too thin then there isn't much metal to dissapate the heat quickly enough, melty melty!

Thanks for the advice. I ended up just rounding the sharp edges on the divider, grinding out all of the casting roughness and defects I could find inside the runners, very mildly cleaning up the port openings and generally polished the interior as close to mirror as possible. Four and a half hours; I hope I get one or two HP from it.

I'll post a pic or two when the manifold and turbo housing come back from Swaintech.

[Rookie_ca18]

Quote »Four and a half hours; I hope I get one or two HP from it. [/quote]

Man the things we do for horse power...

[SSSCA18DET]

I'd agree, I would go to nuts on the divider, if this fatigues due to lack of stregth (ie thinner wall) and cracks, say by by turbo...

[paul_s13]

The quickest and most effective head porting you can do is to match the ports and the inlet manifold, I found I got v high torque figures after I did that - 282flb @ 16psi ain't bad

[redamnavit]

I'm looking for spare head to work on in my spare time; I'm somewhat paranoid about modifying anything when its my only one.

[SSSCA18DET]

You need to live in Australia, I've got a couple laying about....

[redamnavit]

You need to live in Australia, I've got a couple laying about....

Well I'll be in NZ for about a week and a half come October. Its closer than the US...