gas flowed/ported cylinder head

i want to have the cylinder head on my gti ported and i mite go for bigger valves, can anybody recommend anywhere decent? i'm looking for a cylinder head that performs properly rather than one that is shiney and pretty. i had grant motorsport in mind, but i've heard bad things about them recently and the phone number doesn't work, had a look at the tsr pack c, but that seems a bit pricey for what it is.

i've come to the conclusion that if i have the work done at a 'vw specialist' i'll be paying over the odds for the fact they are 'vw specialists'. not that cash is the issue, i just don't like being ripped off!

any recommendations will b much appreciated

(excuse the dodgy english, 2 many sunday evening pints!)

There's a group buy on clubgti. The man in a shed thread.

Youre unlikely to need bigger valves on an otherwise stock engine and youre more likely to lose power as a result because the bore shrouding figure will go up as larger valves are installed.
Plus youd need to lift them higher to get a benefit which means a naff idle and narrow power band  with all its grunt up top, just where you use it least.
I could probably do the portwork/flowtest stuff but ive no idea what the stock gti heads ports currently make in stock form or how much extra youd likely get.
Heres a few photos of some portwork i did a few weeks ago.

http://i82.photobucket…eads/v6finishedintake.jpg

http://i82.photobucket…6/4v6/heads/v6closeup.jpg

http://i82.photobucket…/surfacefinishcloseup.jpg

Not polished or shiny, as its a pointless exercise and does nothing ecept cost a lot.

I too have been looking into this for a few weeks now as i am building a track car for next year.

from what i have read untill you are looking at a 1.9 overbored engine and a metal cam etc you dont need a bigger inlet valve just a slightly larger exhaust valve, then open up the ports to 33mm iirc and clean up the throats too to 33mm (again some one my tell me im wrong on this..) then open up and balance the chambers but theres no need to mad here just a small clean up to remove some shrouding. I looked at the tsr web site but their pack c head seems a bit steep.

the engine is lightly modified, i suppose i should have listed the spec first!
its a 2.0 AGG tall block with the original dx head,audi throttle body and WUR,i have a cam on order from america (taking advantage of the exchange rate!) the cam has a duration of 286 degrees and a max lift of 11.2mm, i also plan on fitting a 4 branch manifold to the jetex exhaust system thats already fitted, oh and i have a volvo metering head base thingy that allows the fitment of an induction kit (have a bmc kit in mind)

i was under the impression that i needed larger exhaust valves because of the extra displacement of the engine.

i'm not too fussed about shifting the powerband a little bit further up the rev-range as i do like to rev it

i also don't mind the idle being a bit 'burbly' i think it sounds quite purposeful, but i don't want it to sound like its going to cut out and die every time i stop at the lights. previous owner of the car fitted a piper 270 cam,it feels and idles like a standard cam….although i suppose no benefits will be felt with a standard head

your portwork looks good,what engine is that from?

Since we now know the lift (11.2mm) we need to work out the curtain areas of the valves and thatll help us find out if theres any benefit from going larger, but i doubt itll make any real difference unless going turbo.
Once i know the curtain areas i can work out discharge coefficients and see how much air they could flow theoretically vs what a 2.0 litre will move at max rpm's.
Port sizes may/may not be close to optimum already, dunno without measuring them, but i wouldnt make them larger unless they need to be. Big ports can flow lots of gas, but they flow slowly like a wide lazy river.
iirc the intakes are around 38mm. Optimum port size is 80% (0.8 times) the valve diameter so the intake port sizes need to be no bigger than 30.5mm.
From that we can work out the exhaust valve diameters needed.
Again iirc thats 0.8 to 0.9 times intake valve size so 0.9 would be around 34mm. Std size is 33 so very close.

Ports in the pictures are a toyota head or two.

exhaust 85% of intake ideally. so 40mm intake suggests 34mm ex. valve sizing is also dependent on where you want your power. lower down requires smaller valves. higher up, bigger ones. the valves are not really the problem on the 8v head. it's the exhaust throats that are the biggest restriction. some tuners never used larger valves on their heads. some suggest the heads need bigger exhaust valves. personally, i'd not bother with bigger valves, just find some one who knows how to flow the head properly.
 the cam you have on order is quite a wild one and will want to produce it'ss power quite high up. i'd imagine 7000rpm. this will want good headwork to help it and a strong belly. lightening and balancing may be needed. don't think the 2.0 tall block would like 7,000rpm too much.

Thanks for that wooders i wasnt sure on the valve sizes and was going on the 1.8 gti heads as a baseline hence 38/33.
Cant see the point of putting in a wild cam when the engine spends most of its time at other points in the rev range other than max, ie accelerating up.
Going on the intake valve size, port shouldnt need to be any bigger than 32mm to be optimal.

Nothing else to add beyond whats been said as its all good stuff.

Overboost said

Nothing else to add beyond whats been said as its all good stuff.

apart from gti heads having 40mm in/33mmex valves on the 1.8

i don't think i'll go for bigger exhaust valves as i can't see an extra 1mm in diameter making much (if any) noticeable difference.

with regards to the cam, if i'm honest,i only ordered it because it was on sale for a bargain price! the specs look fairly similar to the specs of the kent gs2,which a friend of a friend has in his car,and that doesn't seem to be massively flat lower down. the cam only cost me $100 so if its no good for what i need,i haven't lost too much cash

i noticed when i changed to the tall block that the engine wasn't as free revving as it used to be,i've had the flywheel lightened since, which has made the engine a bit more keen to rev, i thought about having the crank and rods lightened and balanced but my budget can't really stretch to it at the moment

the cam and head will help the engine breath better up top and rev a bit more.

You sure about those intake sizes wooders? Haynes ( prolly wrong) has 1.6 and 1.8 from 1984 to 1990 8valves as being 38 mm intakes, exhaust as stated at 33mm.  :dontknow:

i've just measured the valves in my head and the inlets are 40mm and the exhaust valves are 33mm

1.6 38in 33ex. 1.8 40in 33ex. that's for the gti engines. the 2.0 8v also has 40in 33ex. 1.8 carb has 38in 33ex.

Thank you!