inlet and exhaust port sizes for mk 2 8v gti digifant,

[tomjaquesvolkswagen]

hello fellow 8v owners iam in the process of doing the 2litre conversion, iv got a short stroke audi block and a standered digifant head from a mates mk 2 8v engine, wat i need to no is, firstly what size are the original exhaust and inleat ports? and what would be the best size to port them out to? very much apreciated guys

[Simeon]

The size you can port them out to is pretty much dicated by the gasket size, unless you are going to get creative on the gasket. You can buy oversized exhaust gaskets, though only seen them on Bar-Teks website, but I'm sure you would be able to source them over here.

I just gasket matched my G60, inlet ports needed a lot more work than the exhaust ones.

[tomjaquesvolkswagen]

ok thanx i hadnt taken gasket size in to consideration so thanx for that, does any1 no the size of the valve ports (riginal size) im trying to get good bhp gains but i dnt want to loose the fuctionality of the car as its my everyday comuter , cheers

[danny_p]

shape is more inportant than size when it comes to ports.

a small well shaped port will flow a larger volume of air then a massive badly shaped port , a lot of ppl just hack metal out and wonder why it goes crap after and thats why.

to get an 8valve to go you need to open the ports as there are undersized for the valve

much work to the short side  radius   but don't ignore the back of the port tho.   chomp the valve guide stick out down but be carefull with the bump supporting it as there isn'tmuch metal there so can end up with insufficent support if you get to keen.

have the valves and seats tri cut.  blend the seats into the chamber.

don't port match the head to the exhaust manifold if you do open the head out open the manifold out more so there is a step all round the port