I'm about to have a 16v head ported and polished for my 16v track day engine. I have a 051 casting head which came off a 9A that I stripped that has the thicker inlet tract divider with the water way in it. I Also have an early KR 027 casting that has the much thinner solid port divider. I know there is alot of talk on vortex about which is better but I was wondering what people are running (in Polished and ported form) and what kind of figures they have. I know Gary has qwite a few plots on his site so it would be interesting to know what casting code people like Ian B, Chrismc, GVK, Tub, Ian (white Mk1 16v), Infinity, Dex, Graham Scott and anyone else with a modified valver with headwork. If anyone has done any flow bench testing with either heads in standard or modified state I would be very interested in some CFM figures for comparison.
I 'think' mine is an 051 Ray, I think the man in the shed said that although the early 027 head looks like it's got massive inlet ports the exhaust ports are smaller than the 051s Martin (hotgolf) posted up a load of differences of the heads in a thread recently too. http://www.clubgti.com/forum/forum_posts.asp?TID=94126 If it's the best possible top end power you're after, shed man can work a bit more magic to gain this, but it costs a lot more than the 'normal' head. Edited by: GVK
I've got pictures from a guy in the states who cut a 051 and a 027 to compare the ports. http://i7.photobucket.com/albums/y261/dubnutta/18vs2016vhead cut3.jpg (big pic) As mine is going to be a 1.8 still it's gona make it's power from revs mainly but still need a nice spread of torque from around 3k but that is going to be largley dependant on the cam profiles. I've had a prity indepth conversation with "shed man" about the final spec and he said the 027 flows better but people still get good figures with the 051. I'm 90% decided on the spec, ther's not much point going mad untill I get some forged rods and uprate the full valvetrain.
I need to get my finger out and cut the 051 I have here. The pics from vortex are good, but I need one cut through the divider and bot through the port itself. Thjis way we can see how far you can machine it out without hitting the water jacket that goes through there. From experince. it's easier to port an early head as the larger divider of the 051 is more difficult to get to further down the throat, where as the larger divider on the exhaust side is easier to work on. Comparing the 2 after proper headwork then there's not going to be alot in it.
this link you posted shows a before and after ported head doesnt it? here it is: you can see where they have taken the lip off behind the valve, and where the valve guide fits (is this a god idea? would have thought it made the valve guide insecure?) or is this just the difference between a 2.0l 16v head and a KR head. i say this as i can see casting marks in the inlet of the right hand side pic. wouldnt they have been taken off when porting?
I had the choice & went later KR head (051 i think) , as man in the shed thought it would be a good idea as I was trying for cooler running/less pink risk & it would then run a tad cooler with the water jacket in the inlet, also for the same reason i had an extra 1cc larger combustion chamber machined than normal spec too.
How long would you reckon valve guides/valves would last if you were to grind them out completely from the port? I am thinking about doing so to mine to see any power difference - not bothered if they only last 30k or so, but if they're going to die off after about 5k miles then I won't bother.....
I took them right out and after 15k there doesn't seem to be any more oil burn or noise than usual so far. You could remove the guide, take away the cast support and the have the new guides machined so theres a nice taper on them for when they come through the head.
i had a 16v head done by a local guy who does mini and nova heads, very cheap. he cut the guides short on the exhaust side, but left the inlet. its been running ok so far in my mates mk2 2.0l 16v. not many miles use though. should be ok, will just ware out a bit quicker. probably be good for 50k miles plus. you dont usually see standard uncut guides that need replacing in engines that have done 80k plus miles.
If your gonna remove any, remove the inlets. The exhausts wear far quicker than the inlets. If you've ever measured guide wear its always the exhausts that go.
