i understand how to port my original headers but i dont quite understand the term "ported and POLISHED" can someone explain to a thicko please

 

bttt

 

usually thats used in the heads, polishing the surfaces of the heads to smooth the airflow out i guess....

dont think you can polish your "headers"

 

Before



After



The exhaust ports are missed matched to the headers, you need to remove all the metal out to the soot mark, and also split them and do the same with the joints etc. you don't need to polish just grind out the ports to match gasket.

 

You can port them which most people do, like the pictures show but you can also polish them too for a much smoother surface then just a port, this aids further in gas flow and reduces the chance of carbon build up. I've just done my heads this way

 

would just a correct size gasket work better/as good as porting?

as the ports (head + manifold) are the same size

 

heres what the headers look like after ive ported and polished them..

http://i16.photobucket.com/albums/b4...n/100_0682.jpg

 

will exhaust gases 'swirl' now as engine port is smaller than exhaust port?

 

rentone
they look good! did you use a rotary file for that? thinking of doing mine but still have cat downpipe. would there be any noticable gain??

 

How far down are you guys actually porting them?

 

With the headers i go as far as i can

 

which is?

 

Hmm, well the short one on the LH bank i can get all the way through with the right tools, the collector on the other side i just do down to the bend.

 

Bob, I know where you're going with this..!

Strictly speaking gas flowing is probably more accurate a description. Basically all your trying to achieve with the cast oem headers is to reduce any restrictions in the direction the gas flow (ie hitting a big step at a joint). Actually making the bores bigger will slow the gas flow down and reduce low down response (as well as weakening the design).

One thing that needs to be done is ensuring that the gaskets are in the correct position on replacement as they can move and partially block flow. IIRC someone in projects got around this by 'tacking the gaskets in place with some gasket paste before reassembly..?

 

Not going anywhere with this.

Was just curious how far down the headers people were able to port.

 

The porting also has to be done in such a way that the exhaust gases are accelerated.

 

How is that done Harvey ? (not too sure what porting involves even though i understand the results !)

 

dont want to put a spanner in the works guys, but make sure 100% that you have cleaned your headers thouroughly, any swarf left in there will end up wearing the turbo extreemly quickly!

 

after porting, i polish them up as much as possible so i suppose this should accelerate the gases a bit but you can only get so far down.

http://i16.photobucket.com/albums/b4...n/100_0682.jpg

 

i just used some grinding bits in a 240v drill and then polished it up with a wire bit and it comes out really smooth.

 

Yeah i air line and jet wash mine out proper!!

 

I am not sure that a highly polished surface is desirable or necessary.
Because of the arduous nature of the work involved, removing quite a lot of cast steel, I find powerful air tools are essential. As is a variety of tools to get as far in as possible and reach otherwise inaccessible areas.
A flexidrive is essential.

 

I read in one porting and polishing guide that the inlets should be left slightly rough/course to the touch and the exhausts should be polished as much as poss, to stop carbon build up i presume..

 

I use a 415v die grinder that gets in about 4" to quickly eat away metal on entrances, runner joiners, cast marks and seams, then go in afterwards with a Dremel and flexi extension, which is quite a bit slower. This combo gets into virtualy all parts of the cast headers.
Its all finished off with a grinding cone down to 200 grit.
I can't even contemplate polishing the things up, the time spent would be far longer than doing the useful part of porting.

Oh and don't do it near a car

 

The worst bit IMO is removing the original brackets for the heat sheilds, a real PITA and made more mess than all the porting..!

Obvioulsly you don't need to do this but it makes wrapping a fair bit easier..!