Fuel into crankcase Incident

Discussion in 'InsideTopAlcohol.com Tech Questions' started by GottaGoFaster, Apr 7, 2019.

  1. GottaGoFaster

    GottaGoFaster Member

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    Hi ITA--

    Hoping for some advice on what to look for after an incident that occurred during late staging/while on trans-brake (grid limited rpm). Engine is KB hemi, conventional roots blown alcohol setup.

    Right_Turn small.jpg

    Burnout/staging was normal, creeped into 2nd bulb, got on trans-brake, released button--car immediately took a hard fast right turn. Car tried to roll over, zoomies on driver side kept it from going over. Just missed tree and my opponent (I was in left lane). Was able to keep it off the wall(s), pure luck.

    Turns out i launched through my own oil slick which was a result of dry sump tank overflowing with alcohol (overflowed tank, then vented out the breather tank).

    When i returned to pit, inspected check valves, return lines, even pulled fuel pump to look at seal around drive shaft. Nothing obviously wrong.

    Any ideas? I haven't launched car since that last run.

    [Pro mod car, dry sump tank up front by fuel cell]
     
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  2. Mike Canter

    Mike Canter Top Dragster
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    Look and see what your fuel pressure is at idle and make sure your port nozzle Check Valve is set higher than the fuel pressure. Normally a port check valve is set to 18 lbs crack pressure. What is yours set at? You want the port nozzles off at idle.

    Do you have drains on your overflow tank/puke tank and if so when was it drained. That has happened before for me if the tanks were not drained?

    Have you checked your barrel valve leakdown and made sure it has changed and gone rich at idle?

    Also check that your idle return check valve is not in backwards.
     
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    Last edited: Apr 7, 2019
  3. rb0804

    rb0804 Active Member

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    which pass of the day was this? 1st, 2nd, 3rd? I’d also like to know when was the last time it was drained and also what the circumstances were before the run? Is it possible you have a hurt hole recently you thought was ok? Were you on the twostep longer than usual? Do you use a leanout on the two step?
     
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  4. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    I would think this is well outside the confines of tune up related issues. As Mike stated, the idle check could be backwards or stuck. Fuel lines could be swapped between the idle check and pump saver. Multiple main jets in the barrel valve could be blocking return passage (I have seen 3 jets do that- I didn't do that one, I'm only guilty of 2 jets once.)

    It's also been my experience when we start looking for shooters on the grassy knoll, we're usually over complicating things.

    I'm not trying to call you or anyone on your crew out, but the most logical explanation is the oil tank was filled without draining the motor. Couple a tune up a little on the rich side (they are this time of year) and the capacity is far exceeded.

    Let's say you have a 14-16 quart dry sump deal. That's 4 gallons capacity in the tank alone. By the time you did a burnout, backed up and got to stage, close to half of that is in the motor. That means you would roughly need to put 2 gallons of fuel just to overfill the tank. It's going to take more than that when you figure in half the oil is in the motor. I doubt you have enough fuel capacity and pump to put that much fuel through it at idle. That would also be assuming that all unburned fuel went past the rings to the crank case, which we know quite a bit of it would be coming out of the pipes. It would be very obvious what the problem was. Plus the math doesn't add up.

    Depending on your vent set up, could it be that the tank was overfilled and filled up the overflow while filling it.

    Glad you saved the car and get a chance to chase down the problem. I'm not trying to be a dick, but the grassy knoll theories are rarely correct. "The simplest explanation is usually the correct one."
     
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  5. GottaGoFaster

    GottaGoFaster Member

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    Thanks as always ITA. Great amount of veteran advice here for sure.

    I have fought a very rich condition from day 1 with my setup, have not been able to pin it down. (Fuel sys has been flowed twice, with mostly similar setup resulting). Slowly been creeping toward correct burn--but huge changes on main jet (like 20 numbers) have made only small changes in how rich it runs. Definitely points toward something significant that I have put together incorrectly--like backward checks, incorrect plumbing, etc.

    Whatever had been causing it to run rich seems to not be the reason for "the bad event", as while I have run rich, filling the oil tank had not been even a remote issue. I am a small crew--2 of us, and the driver/owner (me) is the only guy that gets to put oil in. Not that i couldnt screw that up--but i dont think extra oil was the situation. Plus the oil was so milky, it seems to be all fuel and not extra oil.

    i will definitely check how many main jets are in the barrel valve. I could see that happening (but might be too embarrassed to admit it if I find that is the case).

    I am wondering if debris could have wedged into the port check during start/burnout and then was pumping fuel past rings during back-up and staging. I have about 1-1/2 gallons of reserve capacity in the dry sump/catch tank--maybe that was enough time to pump it all full?

    Like so many things done during the heat of racing, i took everything apart and now the motor has even been freshened since. Didn't find a single thing yet that would have caused it. Putting it all back together this week, will fire over the weekend and see where i am at.
     
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  6. lucky devil

    lucky devil Member

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    I know its going off Topic Will...... But do you really think Oswald did it ;-)
     
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  7. Bjs344

    Bjs344 Member

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    Can you move things around so that you don’t puke oil on the tires? I would have wrecked every car I ever put a blower motor in if my puke tank dumped in front of my tires.
     
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  8. Mike Canter

    Mike Canter Top Dragster
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    A lot of cars run either a hose or use a frame tube to connect to a puke tank in the middle of the trunk with a vent pipe that comes up through the trunk lid.
     
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