16v205 9 Posted August 23, 2006 Hi Im looking for a replacement head for my gti-6 engine and have been offered a 1.8 xu7j4 head. Just waiting for the guy to get back to me about the exhaust port shape. Does anyone know if there would be any real world differences between running this head compared to a gti-6 head with the same cams in? Ive read that the valves are a similar enough size? Are the inlet ports adequate or should I just continue to look for a gti-6 head? Cheers Rich Share this post Link to post Share on other sites
pug_ham 244 3 Cars Posted August 23, 2006 First (& only main) difference I can think of is that the XU7 head will have 83mm chambers not 86mm like the GTi-6 head. Graham. Share this post Link to post Share on other sites
Miles 331 1 Cars Posted August 23, 2006 I'm pretty sure the ports are the same, I know the XU10J4R is as I;ve got a brand new head with me, The main differance is that it doesn't have the oil spray bar's, Have to check the valves but I;m sure I've tried this and they fitted. Share this post Link to post Share on other sites
Kev-G 1 Posted August 23, 2006 I'm sure that when we looked @ a 1.8 head the ports looked smaller than a Mi....Overall design was the same only restricted... Share this post Link to post Share on other sites
jochem 0 Posted August 23, 2006 The RS head is a slighty ported version in comparisen to the 1.8 head. Cams are 1 mm milder. Would need to ask about the valves, but think they were the same. Share this post Link to post Share on other sites
16v205 9 Posted August 23, 2006 I'm sure that when we looked @ a 1.8 head the ports looked smaller than a Mi....Overall design was the same only restricted... Cheers, see thats what I heard but ive yet to measure one. The oil spray bars not being there only aid's the installation of the cams as they got in the way on a normal gti-6 head. I think ill buy it and see if theres a measurable difference, Rich Share this post Link to post Share on other sites
Sandy 191 Posted August 24, 2006 (edited) 1.8 inlet ports are a fair bit smaller with a sort of lotus flower section towards the throat, different to both the 10J4R and 10J4RS. But the smaller ports are better suited to re-wokring, because the extra material allows the ports to be formed exactly how the head man wants them. (Assuming he's that good and doesn't just smooth and polish ) I'm running the 1.8 standard head on my 1.8 with GTi6 cams at the moment, and it does feel a bit held back at higher rpm, but it's very strong low down and part throttle. Edited August 24, 2006 by sandy309 Share this post Link to post Share on other sites
