Whats porous?

That's never been proved that they won't.

They have thicker valve stems and can accept +1mm larger valves with minor mods.
They are cast from a better grade alloy and the had finishing on them is very good around the valve seat. (early ones)
They were cast by cosworth, hence coscast

coscast wont go porous

Whats the difference... to be thick??

cos 'bad news sells'

i dont know why people worry :lol:
coscast or not
you hear maybe 50 storys of a non coscast head going, how many your think vauxhall made, add a few 00's on the end :D
its all horror storys like the old XE corsa Snap shafts and stuff.....

u hear the odd story of the bad time but you never here " my non coscast head is on 130,000 miles and still going strong" as no one cares :lol:

my last xe i had was a coscast

just read abit of this (second picture down)
Looks like it is a coscast mate

http://www.max-boost.co.uk/max-boost/internet_articles/Astra-mk2_com%20-%2020XE%20Coscast%20Cylinder%20head%20dossier.htm

to make 100%

best way to tell look under the exhaust manifold think its neaer cyl 2 and itll say coscast

[Edited on 02-04-2005 by BeArDy]

infact i dont think it is (reason for edit)
looks like the face has been flatted to make it look like it is

[Edited on 02-04-2005 by BeArDy]

just wondered, iirc it is but just wanna make sure, any other way of telling?