bgd73 Posted October 21, 2006 Share Posted October 21, 2006 I took intake off and found a "nub" on cylinder head it is in the "oem view" part of photo at the bottom of intake hole. Can this be ground away, down into the port about an inch or so, making a circle out of it? I also found it for intake manifold itself. I am willing to guess the whole opening can be ground by at least 1 mm for intake and head, along with the "nub" being ground away.Thats 2 mm total for diameter.It is no doubt a squeeze tighter there in comparison to the spfi barrell and intakes main tunnel. Of course anyone who has done this knows what "only" 2mm can do to a circumference on intake paths If a worry exists about superheated coolant, it is getting more cool air to counteract the missing strength (if it can even be said to be structurally important). How very conservative these things are oem. Anyone done this mod? Link to comment Share on other sites More sharing options...
idosubaru Posted October 21, 2006 Share Posted October 21, 2006 yes i've done this to XT6 heads. XT6 heads are exactly like EA82 heads except with one extra cylinder slapped on the end. same mold basically, same valves, vavle seats, springs, etc. anyway, yes they are rather imperfect but i did not have that lump that you see in yours, nor do i recall any lumps like that in the EA82 heads that i've pulled. i'd grind them away myself. remove all the casting flash, there should be a nice line of it running down into the runners. also set the intake manifold gasket on the head without the intake. you'll also notice the gaskets protrude quite far (at least the Subaru and Fel-Pro gaskets i tried both did) into the intake stream. i'd cut those down to match. and the intake linkely won't match perfect either. cut the gasket to match the head then grind the intake to match the gasket so they all line up. bolt the gasket to the head so you know exactly how it will set. get a good grinder to save yourself some time. cheap grinders will take you forever. the goal is to smooth it out and take off as little material as possible. you're not aiming for a complete redesign and bench flow test of the head, but just smoothing them out as much as possible. Link to comment Share on other sites More sharing options...
Hodaka Rider Posted October 21, 2006 Share Posted October 21, 2006 The 'nub' is actually a fin, and it helps split the flow into the two runners in the head itself that run to the two separate intake valves. I would guess that it helps more at low engine speeds than high, so getting rid of it will probably lose you a bit of response at lower rpm's. EA-81's and EA-82's both had these fins. (not sure about turbo variants, though) Link to comment Share on other sites More sharing options...
operose Posted October 21, 2006 Share Posted October 21, 2006 do I see blood right next to the "intake port" picture? Link to comment Share on other sites More sharing options...
idosubaru Posted October 21, 2006 Share Posted October 21, 2006 here are some pictures of some work i did on the heads, gaskets and intake. http://www.xt6.net/forum/viewtopic.php?t=4169&highlight=intake+runner never noticed those fins on the XT6 - but they have dedicated ports for each intake, so that explains that. Link to comment Share on other sites More sharing options...
bgd73 Posted October 21, 2006 Author Share Posted October 21, 2006 yes i've done this to XT6 heads. XT6 heads are exactly like EA82 heads except with one extra cylinder slapped on the end. same mold basically, same valves, vavle seats, springs, etc. anyway, yes they are rather imperfect but i did not have that lump that you see in yours, nor do i recall any lumps like that in the EA82 heads that i've pulled. i'd grind them away myself. remove all the casting flash, there should be a nice line of it running down into the runners. also set the intake manifold gasket on the head without the intake. you'll also notice the gaskets protrude quite far (at least the Subaru and Fel-Pro gaskets i tried both did) into the intake stream. i'd cut those down to match. and the intake linkely won't match perfect either. cut the gasket to match the head then grind the intake to match the gasket so they all line up. bolt the gasket to the head so you know exactly how it will set. get a good grinder to save yourself some time. cheap grinders will take you forever. the goal is to smooth it out and take off as little material as possible. you're not aiming for a complete redesign and bench flow test of the head, but just smoothing them out as much as possible. Thanks. I was surprised to see how imperfect that really was, in lining up gaskets and ports. Will have heads off and take them all apart to get the spots indicated. The cfm is so tight, with heat expansion as well, these nubs make no sense. Like running coolant just after the heads into an spfi unit (very hot).Or the spfi unit not even lined up to intake. I am going back to a carb version soon, will check below intake and get gaskets right on that one too. the carb has a big opening, to go to same squeeze as spfi heads is even stranger.It would explain the constant vaccum troubles on my old DL. I am glad someone has done this, I will go ahead and clean them up. That is blood near the intake port! You spoke it and I just looked at my fingers. Sure enough... I guess I go numb and partially blind while working. Link to comment Share on other sites More sharing options...
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