head work

bengie · 13-11-2006, 19:42

any idea on what it will cost for porting, polishing, new valve stem seals and a new head gasket on a 1.8T anyone?

just wondering like

TeflonTom · 13-11-2006, 20:02

the 20v turbo head is a very well deisgned head to start with! in many ways it's not dissimilar to the yamaha 5 valve motorcyle cylinder heads, having 3 inlet valves, and 2 exhaust valves on each cylinder..... because they are so good it is quite difficult to get any sort of gains out of porting work without spending a fortune on specialist porting work, also the frequent mistake people make is making the ports too big on, because they are working on the theory that big ports equals big flow numbers, in my experience, i've allways found that smaller ports give a much better turbo/throttle response...

my advice also is not to waste too much time polishing the intake ports either becuase this allows fuel vapour condensation on the port walls which can lead to fuel metering problems and genral rough running. the other common misconception made by many is making the exhaust ports match the size of the headers on the exhaust manifold by drawing round the gasket then grinding it out to match... having the 'lip' there discourages reversion and helps to reduce charge robbing... but to be fair, with the camshaft profiles you'll be running all these little pointers i've made are a little circumstantial and i doubt if you'll notice any difference at all with the standard oe cam profiles....

the one place you may pick up some power is by trying to equalize the flow in the manifold so that each cylinder is filled the same amount..it's surprising how much the flow to each cylinder can vary......

in regards to cost, i would say about £600 plus for the porting work alone (i certainly wouldn't touch one for less!) and a head gasket is about £40, plus you need a few other seals and gaskets too, plus a set of cylinder head bolts, you would also change the cambelt while you had it all apart too, the rest is labour...... 8-9 hours is my estimate

bengie · 13-11-2006, 20:06

feck, i already had the cambelt done this year. might stick to just the selas for now

TeflonTom · 13-11-2006, 20:09

i do get hold of some decend ported 20v heads sometimes.... next time one comes along i'll let you know!

bengie · 13-11-2006, 20:14

does depend on cost really but thanks mate

bengie · 15-11-2006, 17:41

a mate of mine, who's mate runs a garage has suggested just getting a re-con head on exchange and changing the whole lot including vlaves etc. yet to get a pice on that though.

TeflonTom · 16-11-2006, 18:12

unless, there's a problem with your existing one ,it's not worth it...

however, if yours is burning oil a re-con one is a good investment

13-11-2006, 19:42	#1
bengie splash!!!! Join Date: Feb 2004 Location: planet earth Posts: 15,219 Thanks: 17 Thanked 144 Times in 125 Posts	head work any idea on what it will cost for porting, polishing, new valve stem seals and a new head gasket on a 1.8T anyone? just wondering like __________________ owner of a skoda octavia 4xvrs3

13-11-2006, 20:02	#2
TeflonTom Briskodiodion Join Date: May 2006 Location: Hayling Island, Hampshire Posts: 8,214 Thanks: 47 Thanked 231 Times in 203 Posts	Re: head work the 20v turbo head is a very well deisgned head to start with! in many ways it's not dissimilar to the yamaha 5 valve motorcyle cylinder heads, having 3 inlet valves, and 2 exhaust valves on each cylinder..... because they are so good it is quite difficult to get any sort of gains out of porting work without spending a fortune on specialist porting work, also the frequent mistake people make is making the ports too big on, because they are working on the theory that big ports equals big flow numbers, in my experience, i've allways found that smaller ports give a much better turbo/throttle response... my advice also is not to waste too much time polishing the intake ports either becuase this allows fuel vapour condensation on the port walls which can lead to fuel metering problems and genral rough running. the other common misconception made by many is making the exhaust ports match the size of the headers on the exhaust manifold by drawing round the gasket then grinding it out to match... having the 'lip' there discourages reversion and helps to reduce charge robbing... but to be fair, with the camshaft profiles you'll be running all these little pointers i've made are a little circumstantial and i doubt if you'll notice any difference at all with the standard oe cam profiles.... the one place you may pick up some power is by trying to equalize the flow in the manifold so that each cylinder is filled the same amount..it's surprising how much the flow to each cylinder can vary...... in regards to cost, i would say about £600 plus for the porting work alone (i certainly wouldn't touch one for less!) and a head gasket is about £40, plus you need a few other seals and gaskets too, plus a set of cylinder head bolts, you would also change the cambelt while you had it all apart too, the rest is labour...... 8-9 hours is my estimate

13-11-2006, 20:06	#3
bengie splash!!!! Join Date: Feb 2004 Location: planet earth Posts: 15,219 Thanks: 17 Thanked 144 Times in 125 Posts	Re: head work feck, i already had the cambelt done this year. might stick to just the selas for now __________________ owner of a skoda octavia 4xvrs3

13-11-2006, 20:09	#4
TeflonTom Briskodiodion Join Date: May 2006 Location: Hayling Island, Hampshire Posts: 8,214 Thanks: 47 Thanked 231 Times in 203 Posts	Re: head work i do get hold of some decend ported 20v heads sometimes.... next time one comes along i'll let you know!

13-11-2006, 20:14	#5
bengie splash!!!! Join Date: Feb 2004 Location: planet earth Posts: 15,219 Thanks: 17 Thanked 144 Times in 125 Posts	Re: head work does depend on cost really but thanks mate __________________ owner of a skoda octavia 4xvrs3

15-11-2006, 17:41	#6
bengie splash!!!! Join Date: Feb 2004 Location: planet earth Posts: 15,219 Thanks: 17 Thanked 144 Times in 125 Posts	Re: head work a mate of mine, who's mate runs a garage has suggested just getting a re-con head on exchange and changing the whole lot including vlaves etc. yet to get a pice on that though. __________________ owner of a skoda octavia 4xvrs3

16-11-2006, 18:12	#7
TeflonTom Briskodiodion Join Date: May 2006 Location: Hayling Island, Hampshire Posts: 8,214 Thanks: 47 Thanked 231 Times in 203 Posts	Re: head work unless, there's a problem with your existing one ,it's not worth it... however, if yours is burning oil a re-con one is a good investment

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