hops Posted April 28, 2004 Share Posted April 28, 2004 It seems to me that the combustion chamber of the ea82 engine is shaped very inefficient. Can anyone verify that? I'm in the process of rebuilding an engine. I just took off one of the heads tonight and noticed that the valves are very close to the combustion chamber wall or dome. It seems to me that if some material is removed around the valves it would help improve head flow! What are your thoughts? Klaus Quote Link to comment Share on other sites More sharing options...
hops Posted April 30, 2004 Author Share Posted April 30, 2004 well, bump...... Quote Link to comment Share on other sites More sharing options...
Tycho Posted April 30, 2004 Share Posted April 30, 2004 Based on the mediocre results I've seen here (even with high boost, different cams, etc)...I'd say it's shtty ****ty. When a turbo only buys you 18 HP it says something about your engine... Quote Link to comment Share on other sites More sharing options...
Nug Posted April 30, 2004 Share Posted April 30, 2004 I started doing something about it, but there were a few things I actually liked. Sooooo, what do you want to try? Unshrouding the valves? Changing the shape altogether? Gimmee some ideas. I have a pair of ea82T heads right here, for the sole purpose of modifying. Quote Link to comment Share on other sites More sharing options...
oddcomp Posted April 30, 2004 Share Posted April 30, 2004 first off .. clean up and polish the cylinder domes get rid of all casting marks get rid of any sharp edges <except the valves > find a spare motor tear it down and seperate it bolt the heads on to each half reach inside with a scribe <the use of machinists dye is recommended on the heads> and mark out with the scribe the exact position of the cylinder on heads <trace the cylinder on the heads> pull off the heads and look what you have it will tell you how much you can safely remove before interfering with the cyllinder sealing its as good a point as any to start with and much better than going all crazy with a die grinder as far as the intake and exhaust ports go port match the intake to the heads using the intake gaskets if your not sure what port matching is then before you trying it do alot of reading its how i learned <now if only i could learn to type so i can get my thoughts out better> if your fuel injected i would say polishing the intake side of the head ports when your done is good <no rough casting marks pretty much> if your carbed well then get rid of the nasty looking casting marks but leave the slightly bumpy surface there it will help improve the fuel and air mixing before it hits the cylinder i am sure there are many people here who can better explain this than me Quote Link to comment Share on other sites More sharing options...
The Scooby Posted April 30, 2004 Share Posted April 30, 2004 i would port the intake, smooth the sharp areas and such, then port and polish the exhaust, you want to keep intake rough so taht it keeps up turblance so the air/fuel mixture stays constant. then smooth out the complete combustion chamber, post a picture of the chamber it self and i will edit the areas and show you where the work should be done. Shean Quote Link to comment Share on other sites More sharing options...
hops Posted April 30, 2004 Author Share Posted April 30, 2004 OK, here's the deal. I'm rebuilding an EA82 engine, SPFI, non-turbo. I live at 7000 feet and the car seems way down on power...it needs to breathe. Cleaning up the ports, slightly reshaping them to cause a spiral flow into the combustion chamber is straight forward, done it many times on M/C engines. However I've never messed with the combustion chamber dome shape before. The valves seem to be very close to the chamber wall, so close in fact that I think it affects the flow. I will shoot some pics and further clarify what I'm talking about. Thanks for your input. Klaus Quote Link to comment Share on other sites More sharing options...
hops Posted May 3, 2004 Author Share Posted May 3, 2004 Here is a pic of my combustion chamber dome. My suggested mods are in the areas in red. Basically I'd like to make more room for the flow of gases near the valves. What do you guys think? Klaus Quote Link to comment Share on other sites More sharing options...
oddcomp Posted May 3, 2004 Share Posted May 3, 2004 those area's can be "cleaned up" but one thing it will do is lower your compression ratio.. so think about how much your going to remove Quote Link to comment Share on other sites More sharing options...
hops Posted May 3, 2004 Author Share Posted May 3, 2004 oddcomp, I'm also planning on getting the heads milled a bit to compensate for it. Klaus Quote Link to comment Share on other sites More sharing options...
Nug Posted May 3, 2004 Share Posted May 3, 2004 I guess I should have it done. I'd sort of lost interest, but if it ended up working, well, hey, that'd be cool! I have a pair of ea82T heads here, one with a pretty gnarly crack. Anyone wanna put them on an engine after I get them semi-hemi cut? Quote Link to comment Share on other sites More sharing options...
baccaruda Posted May 3, 2004 Share Posted May 3, 2004 details on that semihemi cut would be schweeeet. Quote Link to comment Share on other sites More sharing options...
oddcomp Posted May 4, 2004 Share Posted May 4, 2004 if you mill the heads to compensate for it what does milling do to the alignment of the intake ports. might cause leaks but then again it might not and will it affect the timing belts? i was thinking maybe some bigger pistons? maybe a set of custom one's? i don't know if any of the ea series had longer rods than the others i do know the n/a and turbo pistons are different Quote Link to comment Share on other sites More sharing options...
bushbasher Posted May 4, 2004 Share Posted May 4, 2004 yes milling the head any significant amount will cause the intake ports to not line up, and also the timing will be off. I would expect the intake to be easy to fix but not the timing belts. You would need to change the orientation of the cam pulleys to compensate for the different length. I would say the best idea would be to get some custom pistons made for a higher compression ratio with stock heads. Quote Link to comment Share on other sites More sharing options...
hops Posted May 5, 2004 Author Share Posted May 5, 2004 I'm only thinking about taking off 2-3mm on the shown areas in the combustion chamber. Milling to compensate for that would have to be minimal, I don't know, say about .2-.3mm. I believe I will also send the cams in to be reground. That could compensate for the change in cam timing. Then again, M/C racers slot the cam sprocket holes to allow for cam timing changes. I don't like the idea of custom pistons, they are never as durable as stock, most of them are forged and not cast. Forged pistons expand faster and expand more than cast pistons therefore the piston to cylinder clearance has to be larger to eliminate the chance of the piston seizing if it heats up to much. More cylinder clearance also means that the piston slaps more with the engine cold. Klaus Quote Link to comment Share on other sites More sharing options...
NoahDL88 Posted May 5, 2004 Share Posted May 5, 2004 true the forged may rattle when cold, but there much stronger than cast, so to me its worth it, and these subies warm up pretty quick. Quote Link to comment Share on other sites More sharing options...
hops Posted May 5, 2004 Author Share Posted May 5, 2004 Shadow, The inside intake valve seat diameter is 35.98 mm all cleaned up probly 36mm. The outside valve diameter is 42mm. Klaus Quote Link to comment Share on other sites More sharing options...
Guest taprackready Posted May 5, 2004 Share Posted May 5, 2004 yes milling the head any significant amount will cause the intake ports to not line up, and also the timing will be off. I would expect the intake to be easy to fix but not the timing belts. You would need to change the orientation of the cam pulleys to compensate for the different length. I would say the best idea would be to get some custom pistons made for a higher compression ratio with stock heads. Why not adjustable cam sprockets. There may be a version out there for the other imports that will fit a Suby. Take some measurments and look around. Bill Quote Link to comment Share on other sites More sharing options...
Snowman Posted May 5, 2004 Share Posted May 5, 2004 I think it would be easy to make some adjustable cam sprockets. Just turn the holes into slots and go. Quote Link to comment Share on other sites More sharing options...
hops Posted May 6, 2004 Author Share Posted May 6, 2004 I think it would be easy to make some adjustable cam sprockets. Just turn the holes into slots and go. I agree. KLAUS Quote Link to comment Share on other sites More sharing options...
RenaissanceMan Posted May 6, 2004 Share Posted May 6, 2004 I think it would be easy to make some adjustable cam sprockets. Just turn the holes into slots and go. I also agree with that one. I remember talking to a mechanic that had to get the heads surfaced on some subaru engine, and they took off so much that it wouldent idle properly anymore, so they had to find Thicker head gaskets?!, which apparently solved the problem. But anyway, for what you guys are thinking here, to advance the belt timing to compensate, you could also add an obstruction to the belt's path. Like an extra idler pulley that you could bolt down real tight so it wont move. Quote Link to comment Share on other sites More sharing options...
Hondasucks Posted May 6, 2004 Share Posted May 6, 2004 I read somewhere if you take off less than .030" off the head you don't have to worry about it. My Datsun's head was shaved .040" and it had shims in the cam towers, I suppose you could shim the cam tower with some shim stock if you were crafty lol... Also, the thing with forged pistons, use hypereutectic. They are cast, but are nearly as stong as forged. Call up United Engine Machine in Carson City, NV they might be able to make a set... Quote Link to comment Share on other sites More sharing options...
WJM Posted May 6, 2004 Share Posted May 6, 2004 why not have some DOHC 4V per cylider heads made.....and the EJ headers and intakes bolt up to the new heads. Quote Link to comment Share on other sites More sharing options...
hops Posted May 6, 2004 Author Share Posted May 6, 2004 why not have some DOHC 4V per cylider heads made.....and the EJ headers and intakes bolt up to the new heads. WJM, I'm doing this work to my wifes wagon (family wagon). If I was to go through all that expense and trouble I would not start with a Loyale Wagon, I'd get a WRX instead. It all started with a rebuilt. The engine overheated last year due to a clogged radiator and has been burning a quart of oil per 300 miles. After tearing down a spare engine I discovered the poor head design. I'm working on porting the heads right now, and thought it may be worth reshaping the combustion chamber a bit. I'm thinking about getting the cams reground to help it a bit too. We live near 7000' and the engine is very sluggish. Especially when we have the car loaded up to go camping with 3 people 2 dogs all the camping equipment (beer, etc.) and a trailer with my motorcycle on it. The most important thing is to keep the engine reliable while helping it up the mountains a bit. Klaus Quote Link to comment Share on other sites More sharing options...
WJM Posted May 6, 2004 Share Posted May 6, 2004 One word: TURBO. Quote Link to comment Share on other sites More sharing options...
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