Bent conrod

Discussion in 'PSI Superchargers Tech Questions' started by Matt, Jan 15, 2008.

  1. Matt

    Matt Member

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    Found a bent conrod in my motor, crank trigger wire came apart at 1200 ft, data is the same from all previous runs, is it possible that the motor could have hydrauliced from no mag or is it more likely from massive detination from a temparary blocked nozzle?
     
    #1
    Matt, Jan 15, 2008
  2. blwnaway

    blwnaway Member

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    Did it kill the motor or just make a very weak connection?
     
    #2
    blwnaway, Jan 15, 2008
  3. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    nozzle

    i would be inclined to say blocked nozzle, because i've seen numerous runs where a cylinder dropped for whatever reason (blown alky application) and it had no damage whatsoever other than to the time slip. alot of drivers like myself will instantly hit the kill switch at the end of the run after the chutes hit.

    i have seen a/fuelers bend rods on dropped holes, but they have a significantly higher fuel volume.
     
    #3
    Will Hanna, Jan 15, 2008
  4. Matt

    Matt Member

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    Lead came off and killed motor at wide open throttle, I hit the the kill switch at the stripe but the butterflys are closed.
     
    #4
    Matt, Jan 15, 2008
  5. lucky2wd

    lucky2wd Member

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    I had a nozzle plug once for a little while and the egt really showed it, the piston even started to cave in but it bend a rod in a different hole....
     
    #5
    lucky2wd, Jan 15, 2008
  6. Bob Meyer

    Bob Meyer Comp Eliminator

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    One of my England cars were running a NGK plug that was supposed to be the "same" as our 6061-10. The electrode itself was about .050 wire. Any plug in the motor would just up and die, (the hole would go cold) and sure enough the GRP would bend in that hole. Happened about 4-5 times, and the last time I was there, saw it with my own eyes. Went over to that "Grumpy OLD guy" and borrowed 6061's and problem solved. NGK Europe now finally brings them in.
    I doubt it has anything to do with clogged nozzles.
    Bob
     
    #6
    Bob Meyer, Jan 15, 2008
  7. Matt

    Matt Member

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    I have plenty of runs logged and the egt is the same or very little difference in that cylinder, the fuel system is spotless and have a filter in front of the barrel valve that is 10 times smaller that my smallest nozzel and the nozzel wasn't blocked, run 6061-11 plugs and the plug showed no real difference between other runs, is it possible when the motor stopped the fuel in the manifold ran forward into no 1 cylinder the intake valve was open at the time and filled the cylinder with raw fuel and as the ran down on the tyres it hydrauliced the cylinder and bent the rod, there was no other damage to any other cylinders at all. I was hoping that this may have happened to some other guy's who maybe able to confirm something one way or another.
     
    #7
    Matt, Jan 15, 2008
  8. Mike Canter

    Mike Canter Top Dragster
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    Was the rod so bent that the motor wouldn't run or did you find it during a tear down? If you found it during a tear down then the rod might have been bent during a different run for some totally different reason. Since you say that you are running a crank trigger then the question is if you are running a shielded and grounded crank trigger cable. The reason I say this is that if the motor fired randomly because of false trigger from the crank trigger then it sure will bend a rod.

    MSD crank triggers and ignition boxes are very sensitive to interference from sparkplugs firing, electric fans or even solenoids turning on or off. This type of interference is called Electro Magnetic Interference or EMI. When crank triggers are used the cable running from the crank trigger back to the MSD box becomes an antenna for picking up all the EMI being generated by anything electrical on the motors and causes the ignition box to randomly fire. This random firing can cause serious damage to a motor or may just cause it to backfire or just pop through the exhaust or just not run right. Sometimes this EMI will cause the ignition box to fire at a time that will take out one or more pistons or rod and will appear like detonation. These problems may just take out a piston every 20 to 30 races or every other race.

    To fix this problem MSD has made a special new crank trigger cable. This new cable is shielded internally and has a separate ground wire for the shield. The new shielded cable has a separate black wire with a lug on it to be attached to chassis ground. If you do not have this new shielded cable then I highly recommend that you get one. If you have this new cable but have not attached the ground wire to chassis ground then you should do that as soon as possible.
     
    #8
    Mike Canter, Jan 16, 2008
  9. wildride boy

    wildride boy Top Sportsman Racer

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    MSD P/N is 8164
     
    #9
    wildride boy, Jan 16, 2008
  10. Randy G.

    Randy G. Top Alcohol

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    Back in the olden days a friend of mine claimed he knew a guy (sounds like Ocean's 11) that bent a rod by missusing the squirt bottle starting the engine.
     
    #10
    Randy G., Jan 16, 2008
  11. eli

    eli Banned

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    Matt, you should be happy that you caught it and you didn't put the rod trough the block. :eek: :D
     
    #11
    eli, Jan 16, 2008
  12. Matt

    Matt Member

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    I run the sheilded cable, lehaye trigger, I go thru rod bearing every three runs and the bearing was crushed 020, crank was not blackened and oil pressure wasn't affected, and Eli I'm buying a lotto ticket.
     
    #12
    Matt, Jan 16, 2008
  13. egghead

    egghead New Member

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    If this is the case, the CTI pickup should be done with an inexpensive LED, photocell, and fiber optic cable. The trigger pulse would be gated with a tiny mirror on the flywheel. This system would be almost completely immune to EMI. The only complication I can imagine is dirt getting on the optics, but this system could probably be engineered to have much higher reliability than anything anything involving electrical cable. If it's important to maintain the magnetic pickup (not sure why that would be the case), the trigger signal could still be relayed into an LED or laser diode adjacent to the sensor and then propagated down an optical fiber to the spark generator.
     
    #13
    egghead, Jan 16, 2008

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