cylinder head porting and polishing?

[chancha]

guys, having been an avid reader on here for the last few months and now in a position to finally get started on my urq 20v to rs2 upgrade I would like to ask everyone on here what their take is on the merits of porting and gas flowing the 20v head. I ask because I will be getting the head skimmed soon and was up in Dundee at Agra engineering for a look around and they can do it quite easily. It seems a shame that whilst the head is off that not doing it would be a chance missed. Any thoughts appreciated........

[Doug_RS2]

They are a good bunch of guys there - have you asked them what they can do?

I thnk the older guy on the desk is Jim? Did you see my head and block there?

[chancha]

yes, Doug, the older guy on the desk showed me around. They seemed quite chuffed when I mentioned your name and that you had recommended them. BTW I was up to see if anything could be done with the cracked rs2 manifold that I have. Unfortunately they seem to think that metal stitching would not work, si I suppose I'll have to take my chance with it the way it is..........any news on when your own engine will be ready?

[Doug_RS2]

Was it a special weld that was needed? It might be worth finding a specialist and sending it to them?

My car is basically waiting on rod and pistons before the final rebore/hone of the block, and balance of all the spinning bits. Probably be middle of may if I am realistic.

[audiman]

Cast iron manifold are very hard to weld up and seal, in the long term. They cant be mig or tig welded. If you drill a small hole at the end of the crack and them brase the manifold, this will normally hold it back for a while. Only cure really is to buy a new one £457+VAT!!!!!!!! BTDT

[Mark Halligan]

Chancha,

I'm no expert but IMHO its worth getting the head ported and and polished (polish exhaust ports only), a proper gas flowing job done on a flow bench would be best, but that would probably cost you a kidney or two .
Along with the usual checks on the guides to see if they are within specs....they may need replacing, so might as well get them checked out too while the head is out.


Cheers,

Mark.

[Stick Insect]

Chancha, have a chat with these people,

http://www.slinden.co.uk/

their website shows work done on old car stuff.

Putting on a leaking manifold is a waste of time, it will let you down when you least want it.

When you say polishing I assume that you mean gas flowing, getting a nice polish won't help the air flow, On Minis a highly polished surface is detrimental to laminar airflow.

I used to work for a company in Dunfermaline called Fortronic many years ago.

David

[chancha]

I bought the em on this site. I was told and have no reason to disbelieve that the manifold was not leaking, however, the cracks are a worry for later on.........yes, I meant gas flowing the head and not just a spit and polish-)-)

Rgds Kevin

[Stick Insect]

Kevin,
It's worth sorting it out, £100 quid or so for peace of mind. If the crack carried on and you had to take the exhaust etc. off you would not be happy. Think of it as if someone offered you £100 to take your exhaust off, you'd tell them to sling their hook.

The old adage comes into play: A stitch in time saves nine...

David

[desmo888]

Originally posted by Stick Insect

When you say polishing I assume that you mean gas flowing, getting a nice polish won't help the air flow, On Minis a highly polished surface is detrimental to laminar airflow.

David

But it is helpful to enlarge the ports a bit and do a gasket match. This insures the ports are more efficient. The sides need not be perfectly smooth.

What do you think Stick?

[Mark Halligan]

I couldnt afford to have my cylinder head proffesionally gas flowed on a bench so I took a chance and did it myself, I followed advice from a few people who know more than I do about the subject, and followed these instructions , thanks to Mihnea for that link.
If you decide to DIY, the Standard Abrasives kit is sold by Demon Tweeks, its a lot of work though.

Mark.