'Flowing' an exhaust manifold

[martinjs]

Received RS2 ex manifold today (cheers marco/vagparts) and am wondering if it is worth me polishing the inside? even though my head is stock!
give me something interesting to do at work tonight:wacked:

[Lee]

Extrude honing is probably one of the best things you can do to a cast iron manifoldIt onvolves umping an abrasive slurry through the manifold until smooth. Smoother bores reduce the tendancy for carbon build up. If you are bored at work, look ot up on the web (extrude hone) and price it up.

Lee

[RSCoupe]

This topic came up on the S-car forum here in the states a couple of months ago. It was widely agreed that extrude honing the exhaust manifold was a waste of money. After a couple of thousand miles, the carbon will have coated the interior of the manifold taking away the smooth finish. The best place to extrude hone is the head and intake manifold (after porting).

[Pisobiker]

Re: 'Flowing' an exhaust manifold

Originally posted by martinjs
Received RS2 ex manifold today (cheers marco/vagparts)....

Marco

[Audi Parts Guru]

In my opinion it's worth doing, but only if you've got loads of spare cash and you're after max BHP. Otherwise i'd spend the money elsewhere

[martinjs]

ahh sod it, ill just clean all the carbon off and get it slapped on at the w/end

[Audi Parts Guru]

Martin, go and get yourself one of those Dremel drill thingys and just take off the high spots and generally smooth the inside of the manifold where you can

[martinjs]

suppose it wont hurt will it, ok then ill do that

[Pisobiker]

Another small tip, Martin:

make exhaust ducts match perfectly the new head to header gasket. Then put the gasket over the manifold and do the same with it.
Be carefull to center gasket to manifold; there should be 2 or 3 holes on the manifold that go thight on the studs, so that there is no fixing play between header and head. use those same holes to center the gasket on the header.

This way you'll not have any step or sharp edge and flow will appreciate


Marco

[desmo888]

Originally posted by Pisobiker
Another small tip, Martin:

make exhaust ducts match perfectly the new head to header gasket. Then put the gasket over the manifold and do the same with it.
Be carefull to center gasket to manifold; there should be 2 or 3 holes on the manifold that go thight on the studs, so that there is no fixing play between header and head. use those same holes to center the gasket on the header.

This way you'll not have any step or sharp edge and flow will appreciate


Marco

the "gasket match"

a must for exhaust AND intake to extract all available hp...

[desmo888]

Originally posted by Pisobiker
Another small tip, Martin:

make exhaust ducts match perfectly the new head to header gasket. Then put the gasket over the manifold and do the same with it.
Be carefull to center gasket to manifold; there should be 2 or 3 holes on the manifold that go thight on the studs, so that there is no fixing play between header and head. use those same holes to center the gasket on the header.

This way you'll not have any step or sharp edge and flow will appreciate


Marco

the "gasket match"

a must for extracting all available hp...