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1G What went wrong? Bearing Failure

Posted by 97egl, Apr 17, 2019

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  1. 97egl

    97egl Proven Member

    60
    4
    Joined Feb 6, 2014
    Indianapolis, Indiana
    I destroyed an engine in my 93 N/A car I had built it for enduro racing. Mostly stock other than I eliminated the balance shafts and ran ACL race bearings. I only made it 24 laps and the engine locked up solid. It did get hot, I hit 240 degrees so I started making my way to the top of the track to pit. It reached 250 before I got off and thats when it stopped running and locked solid. Oil pressure never dropped below 20 at idle and always 40+ while racing. I also never heard any rod knock. Once it cooled off it actually turned over and started again. i had 80PSI of oil pressure but it didnt want to stay running. Strangely enough still didnt hear a rod knock.

    Tore it down and the #4 spun. I have parts to build another engine but before I put it together I want to make sure the same thing doesn't happen and I'm not really able to figure out why it spun. All the other bearings are scored up too. But I think that is from the bearing debris running thru the engine. #4 is the only one that spun. Got so bad the crank turned black from being hot and its bent as well.

    I have a few things I've thought it could be but really have no definitive answers and I REALLY don't want to build another engine just to have it blow up. This isn't the first engine I've built by far but it is the first 4g63 so I'm hoping someone on here has some experience with building them to last on circle tracks. Enduro is different than drag. 300 laps of wide open throttle for the most part so it's pretty grueling on an engine, lots of heat, possible oil starvation in the corners and tons of windage in the crank case from oil splashing around.
     

    Attached Files:

  2. dustyboner

    dustyboner DSM Wiseman

    952
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    Joined Mar 13, 2016
    abq, New Mexico
  3. stillrunning

    stillrunning Proven Member

    97
    43
    Joined Oct 10, 2013
    brandon, Florida
    There's really allot of variables, this is a good reason to blueprint engines operating in adverse conditions, so when something happens we have a good idea what wasn't directly related to failure.
    Bearing clearances changing at sustained higher oil temps
    Oil viscosity lost at sustained higher oil temps
    High rpm can put allot of stress on rod bolts allowing the bearings to loose some preload
    I would be more inclined to relate it to the elevated temps and operation conditions at the the time but again tough to say
     

    Street Build 394  3

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
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  4. motomattx

    motomattx Proven Member

    1,688
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    Joined Dec 9, 2010
    wampum, Pennsylvania
    What kind of rpm was it running? if your running any car engine at 7500 rpm for 300 laps wide open its not likely going to last long unless its made of top notch materials and has a really really great oil supply system and cooling system.
     

    Drag Race Build 2K  16

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  5. ThunderChild

    ThunderChild Supporting VIP

    2,523
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    Joined Jan 5, 2012
    Rathdrum, Idaho
    All of the above.
    I'd also say do some cooling system mods so you can keep the temp down. Maybe run a restrictor instead of a thermostat, higher pressure cap, bigger radiator, proper dual fans. That's alot of temp for an engine running on the ragged edge constantly.

    Also curious is the crank oil channel balls were removed and the channels cleaned out really well? I don't think this is what caused the failure, but it may have contributed by depositing debris on that journal and exacerbating the damage.
     

    Street Build 166  3

    1990 Plymouth Laser N/T
    fwd · manual · 1G DSM

    266  8

    1987 Toyota Pickup/Hilux
    awd · manual · Misc Vehicles

    Street Build 793  7

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM

    Street Build 1K  1

    1992 Eagle Talon TSi AWD
    manual · 1G DSM

    Street Build 2K  10

    1992 Eagle Talon TSi AWD
    awd · manual · 1G DSM
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  6. DSMPT

    DSMPT Proven Member

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    Joined Jun 12, 2014
    Japan / Mexico, Arizona
    As everyone above already mentioned about the oiling and cooling, other opinion here.
    IMO, Eliminated the balance shafts was not a good idea. An unbalanced engine + balance shafts eliminated + heavy rods/pistons + WOT for long time = A lot of stress on the bearings.
    If I were you, I would balance the next engine, re-install the balance shafts and use a ATI damper or fluidampr. Also shave off some weight from the rods/pistons or use lighter rods/pistons/pins. This would make the bearing's life significantly longer, compared to unbalanced engine with heavier rods/pistons. Coating on bearings and longer rods would be beneficial, too. Depending on the budget though..
    And of course, building the engine properly is the most important.
     

    Drag Race Build 1K  2

    1990 Mitsubishi Eclipse GSX
    awd · manual · 1G DSM

    Street Build 1K  4

    1998 Mitsubishi Eclipse GSX
    awd · automatic · 2G DSM
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  7. 97egl

    97egl Proven Member

    60
    4
    Joined Feb 6, 2014
    Indianapolis, Indiana
    I was only hitting about 6500 going into the corners. At the beginning theres 100+ cars on the track so it's not a really fast track until after about laps 40. About 25% are dropped out of the race by then.

    There are several other 4g63 powered cars out there so there's gotta be some way to make them last. I know most the guys are running against the rev limiter going into the corners and it's entry level racing so if you place 1st or 2nd you loose your car so these guys are building these in a garage on a budget. I don't mind changing the rod bearings out every other race and the mains once a season which is what I do with my 2.5 Dodge Shadow. But this type of failure in 24 laps just baffles me

    I did not remove anything to clean the crank oil channels. Just blew thru them with compressed air to try and clean out any debris. I'll look into what to remove to clean those. Thanks for that advice. I do know i need to figure out how to get the temp down. Normally I try to keep the temp 200 or under in my other cars. I have both fans wired to run constantly when the engine is on but still under red flags when the car was sitting the temp would climb. I am only able to run pure water since it is asphalt and it was pretty brown and had a bit of rust in it, not sure if rusty water can cause cooling issues but not good either way. New block will have to be cleaned out good before I put it together.

    Budget is a huge factor due to the fact that they claim the top 2 cars. You get 2500 and loose your car so you want to have minimal investment in it. I may try running balance shafts in the new rebuild. I always thought they where mostly to smooth out idle. I have always eliminated them in my other cars with no issue but every engine platform is different. My concern was the little belt coming off under high RPM and taking the timing belt out but not sure if that would really be an issue
     
  8. bastarddsm

    bastarddsm Supporting Vendor

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    Mendota, Illinois
    What way does the oil go in the pan on a corner.....
     

    Showcar Build 5K  1

    1991 Eagle Talon N/T
    9.805 @ 144.00 · 1G DSM
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  9. 97egl

    97egl Proven Member

    60
    4
    Joined Feb 6, 2014
    Indianapolis, Indiana
    Its being pushed towards the rear main seal on the engine away from the pickup. However my low oil psi light never came on and i never noticed it dropping pressure in the corners. In prior experience with other cars if there was an issue with the oil moving away from the pickup the light would always come on half way thru the corner and adding simple baffles solved this. Since the 4g63 already has a baffle I didnt add any. Maybe this was a mistake not baffling but without oil psi loss i wouldn't think that the bearing should spin that quick especially at lower speeds in the first laps. It is something to lool at tho. Maybe a combination of heat drawing air into the pump and removing the balance shafts took it out that quick. I just wish i had a sure answer. Really dont want to cook another engine. I appreciate all the feedback so far tho guys!
     
  10. bastarddsm

    bastarddsm Supporting Vendor

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    Mendota, Illinois
    The gauge tells you the pressure, not the quality, could be full of air and still show that's its good. Switches and sensors are pretty slow responding.
     

    Showcar Build 5K  1

    1991 Eagle Talon N/T
    9.805 @ 144.00 · 1G DSM
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  11. 97egl

    97egl Proven Member

    60
    4
    Joined Feb 6, 2014
    Indianapolis, Indiana
    Good point. I'll have to look at maybe adding more baffles or changing the factory set up. Thanks!
     
  12. motomattx

    motomattx Proven Member

    1,688
    496
    Joined Dec 9, 2010
    wampum, Pennsylvania
    Balance shafts are going to cause a failure at those sustained rpm's for sure, I would flash an ecu to run a lower max rpm and take a lot of timing out the higher the load for both cooling and for knock control, at those temps and rpm's it might have spun from knock.
     

    Drag Race Build 2K  16

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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