max0 5 Posted April 18, 2007 (edited) Can anyone tell me why the valves are Exhaust inlet inlet Exhaust Exhaust inlet inlet Exhasust in order rather than Exhaust inlet Exhaust inlet Exhaust inlet Exhaust inlet or vise visa? Bit of head blagging question so the picture might help I was woundering if it was pug been tight and allowing the two middle exhausts valves to share the same exhaust manifold hole? Or is there some thing else? Such as heat / flow involved? Also are most 8's the same? Cheers Andy Edited April 18, 2007 by max0 Share this post Link to post Share on other sites
pug_ham 244 3 Cars Posted April 18, 2007 No honest idea why but the valve order is probably like that to make it easier & cheaper to manufacture the manifolds but it does seem a fairly common practice on 8v heads. The exhausts don't strictly share a port on the exhaust manifold but they do use the same branch. They have a dividing wall between them for approx 2" inside the manifold. If you want cheap, check the Mini cylinder head. Only two inlet ports & three exhaust but these are well know for having poor manifold designs & a three branch downpipe & alloy inlet can make a whopping difference. Graham. Share this post Link to post Share on other sites
max0 5 Posted April 18, 2007 (edited) The exhausts don't strictly share a port on the exhaust manifold but they do use the same branch. They have a dividing wall between them for approx 2" inside the manifold. Cheers Graham, I did already know that was just been blonde for a moment but on the head pictured from my turbo engine it has less studs on the middle ports (4 for 2 ports as instead of 3 for the end ones) so wounder if its just cheaper. If you want cheap, check the Mini cylinder head. I used to be really into minis after my dad stuck a stage 2 head / k&n / 3in1 manifold on a metro gta. it claimed to give it some thing daft like 25% power upgrade... Just dug out a old mini sport catalog and been on there website and found the kit he got http://www.minisport.com/classic-mini-shop...or-product.html claims 30% more torque. If only pugs where that easy to tune Edited April 18, 2007 by max0 Share this post Link to post Share on other sites
max0 5 Posted April 18, 2007 I also just noticed the mini head is a "reverse-flow cylinder head" - had to google for that term eg all the ports are on one side. As oppose to the cross flow head of the pug - intake and exhaust ports on opposite sides. Could it be the exhaust gases leaving the cylinder helps to aspirate the intake gases and this valve sequence aids that? Answers on a post card to the usual addres! Share this post Link to post Share on other sites
veloce200 3 Posted April 18, 2007 (edited) for starters it would look odd as you'd have an inlet on far left and exhaust on far right which would make it assymetrical. also it makes sense as you have two inlets nestled together rather than to hot exhaust pipes on either side. not seen an 8v laid out any other way correction apart from hemi heads and twin cams...! its a bathtub thing! Edited April 18, 2007 by veloce200 Share this post Link to post Share on other sites
M_R_205 5 1 Cars Posted April 19, 2007 id agree wirth veloce it would keep the inlets much cooler having two together rather than 1 between 2 exhaust ports Share this post Link to post Share on other sites
