DJ_Kuehn Posted June 30, 2006 Share Posted June 30, 2006 Hey guys, I race hovercraft and have an ea-81 powerplant. The motor is all stock except for a holley 5200 carb and tuned exhaust headers. It WAS a low milage motor with only 27,000 when I put it in, but that's shot now. Here's the short version of what happened: I was racing, doing quite well actually, and was really putting the heat on the first place guy trying to pass. Well, he had to turn to avoid hitting someone, which caused me to turn to avoid hitting him, but it didn't work so well. We hit hard, but when youre racing and everything is still running, you keep going and hope for the best :cool:. Turns out, my radiator got punctured in that accident. I went about 4 more laps (this is non-stop full throttle, btw) at about 1:45 per lap, finally passed and got into first place then my engine started sounding wierd and went to idle. About 30 seconds later it backfired a couple times and died. I then turned around and found out that I had no coolant whatsoever. SO, I have what was a great running ea-81 that went around 5-7 minutes at full throttle with no coolant. I've tested the compression and here's what I found. Cylinder 2 had 150psi and 4 has 135psi (drivers side) Cylinders 1 and 3 have nothing. Here's my question... I know these are very tough motors and I might not need to do a full rebuild. What is your suggestion for fixing this up? Could it just be a head gasket issue since both right side cylinders have no compression, or did I burn my valves up? I haven't had time to tear it all down yet, but would prefer to have parts ordered so that I can put it back together right away (that way I'm less likely to forget how it came apart!). How should I proceed? Thanks guys! And, since I know someone will ask, here are the pictures of race. I'm the orange #23. http://prophotoproductions.exposuremanager.com/g/Sunday5&gallery_page=&gallery_all=&view=1&photo_page=3 Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted June 30, 2006 Share Posted June 30, 2006 Just need a head gasket - but do them both, and have the heads milled. You almost certainly warped them, and the milling will give you higher comp. anyway. I doubt you did any other damage - unless you lose oil or oil pressure, the insides will be fine. GD Quote Link to comment Share on other sites More sharing options...
DJ_Kuehn Posted June 30, 2006 Author Share Posted June 30, 2006 Awesome, I hope that's all it is. If I do mill it down, how much can come off? Also, I've considered doing that before, but I've been told that increasing compression doesn't do any good unless you change cam profiles. Is that true? Quote Link to comment Share on other sites More sharing options...
baccaruda Posted June 30, 2006 Share Posted June 30, 2006 it won't do a whole lot of good, call it a "technical improvement." You can only mill them so much before it affects the alignments of mounting the intake manifold (bolts andports) so keep that in mind. best of luck! hovercrafts are cool is that a hydraulic lifter motor (better of the two, has stickers on the valve covers) or do you have to adjust the lifters? Quote Link to comment Share on other sites More sharing options...
Sonicfrog Posted July 1, 2006 Share Posted July 1, 2006 Wow! How do you get into Hovercrafting!!! E-mail me and I'll post it on my blog:grin:!!! Given the comp readings you posted, I second the motion on the head gasket. I had an EA81 and they are very easy to fix. Quote Link to comment Share on other sites More sharing options...
()__1337_CRAYOLA__()> Posted July 1, 2006 Share Posted July 1, 2006 Well I Guess It's True Then... Subarus And Thier Motors Can Do ANYTHING Quote Link to comment Share on other sites More sharing options...
ccrinc Posted July 1, 2006 Share Posted July 1, 2006 Actually, if you have ZERO compression on one side, and ran it like that, you probably had at least one cylinder sleeve turn. In which case, the engine is toast. The valves on these engines don't burn: they're enormous for the size of the engine. Emily http://www.ccrengines.com ps: do you know the Zangs? Quote Link to comment Share on other sites More sharing options...
dxrflyboy Posted July 1, 2006 Share Posted July 1, 2006 Actually, if you have ZERO compression on one side, and ran it like that, you probably had at least one cylinder sleeve turn. In which case, the engine is toast.The valves on these engines don't burn: they're enormous for the size of the engine. Emily http://www.ccrengines.com ps: do you know the Zangs? You'll know for sure once you pull the head...keep your fingers crossed! Quote Link to comment Share on other sites More sharing options...
4x4_Welder Posted July 1, 2006 Share Posted July 1, 2006 To get past the head planing issue, you just need to be a little creative. Custom intake, throttle body, an injector over each port, and a seperate water tube with thermostat........ Quote Link to comment Share on other sites More sharing options...
DJ_Kuehn Posted July 2, 2006 Author Share Posted July 2, 2006 Thanks for all the help guys! I'll try to respond to each of you here. Barracuda: I don't know if it's got hydraulic lifters or not. It's a 1980 motor, the first year for the ea-81, so probably not. I'll probably only mill off what's necessary to get things flat again. Crayola: Soobs are actually VERY common in hovercraft and aircraft. They can do anything CCRinc: When I say zero compression, I mean I can turn it over with my finger over the plug hole and feel some compression, but it's not enough to blow my finger off. It's probably like 15psi or so. Does that make any difference? And yeah, I know both bobby and billy very well, I'm friends with both of them. Are they getting motors from you now? I know they have some bad feelings towards another subaru rebuilder so I figure they've found a new source by now. If they're buying off you, I'm sure you got to hear a good story about a timing gear. 4x4 welder: Thanks, but that's a bit more creative than I plan on getting LOL I REALLY REALLY hope its the head gasket. I'm glad to hear that the valves are as tough as everyone claims, I was afraid I'd be buying new heads and valves. HOwever, I never thought of the sleeve issue. I'll probably cry if those came loose. I may have to send some money CCRinc's way It will probably be a couple weeks before I can tear it down and I really hate not knowing! If anyone else has any suggestions or ideas, please feel free to jump in. Thanks, Jason Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 2, 2006 Share Posted July 2, 2006 I wouldn't worry about the cylinder liner - they can spin if the engine has been bored (more likely if it's been done without a bore plate), but generally they do not. I've seen my share of blown head gaskets, and I've yet to come across a spun sleeve. Usually they blow, and as you are describing they still have about 15 - 30 psi of compression. Likely you'll be fine with just some new gaskets. Take .020" off the heads for a bit more compression (your manifold will still fit fine). I would also reccomend the Fel-Pro perma-torque gaskets. They don't need to be retorqued, and I've personally put mine through a complete coolant loss and severe overheat (I mean SEVERE - a lot like your scenario) with no ill effects. Also - you would benefit in the power and torque department from getting your hands on some 83+ heads. They have larger intake valves (2mm larger in diameter) and are good for several HP. Wouldn't be any more work, just have to get a set. I have a few sets, but shipping might be a little steep. GD Quote Link to comment Share on other sites More sharing options...
TheSubaruJunkie Posted July 2, 2006 Share Posted July 2, 2006 He's right about the 83 heads. Your motor being a '80 is a non hydro lifter with smaller valves. You'll know once you pull the heads what your in for. Sounds like an awesome hobby, you running a weber on the engine or stock intake/carb? -Brian Quote Link to comment Share on other sites More sharing options...
SuBrat84 Posted July 2, 2006 Share Posted July 2, 2006 . The motor is all stock except for a holley 5200 carb and tuned exhaust headers. Brian Quote Link to comment Share on other sites More sharing options...
TheSubaruJunkie Posted July 2, 2006 Share Posted July 2, 2006 Oh duh! Thanks E. -Brian Quote Link to comment Share on other sites More sharing options...
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