Why do FC's vent oil tanks to frame rail?

Discussion in 'PSI Superchargers Tech Questions' started by Will Hanna, May 27, 2016.

  1. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
    Staff Member

    Joined:
    May 6, 2003
    Messages:
    6,706
    Likes Received:
    133
    In the process of engineering my FC.

    Something I have had issue with for a while is why in the hell do we still vent our oil tanks to the frame rail? I know that's just what we have done forever, but I can't see how the oil tank can vent once pan pressure gets into the frame rail.

    Now granted some run a one-way valve to prevent pressure from getting into the tank, and that is a great safety measure, but the only way the tank can vent is to have more pressure than the frame rail.

    The only good reason I can see is if you were running more oil capacity than what the tank would hold (some run tank oil plus a few in the engine. Not to mention volume added by fuel dillution). This is a real stretch because i think the oil pump would break the mag drive shaft first, but I guess if somehow if there was a restriction in the engine and it scavenged all the oil to the tank but didn't have nowhere to go...I guess it's also good if you overfill the tank, but that's more or less just less mess.

    Maybe I'm missing something here and someone can show me the light.
     
    #1
    Will Hanna, May 27, 2016
  2. blowntuner

    blowntuner New Member

    Joined:
    Sep 26, 2014
    Messages:
    23
    Likes Received:
    0
    The engine is building pressure en it's olso getting into the oil tank,pusshing the oil to the buttom preventing air bubbles in the suction tube
     
    #2
    blowntuner, May 27, 2016
  3. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    We vent our oil tank and the valve covers to the frame rails but then have a puke tank attached to the frame rails in the back of the car. You can't have a vent for the oil tank or the valve covers in the front of the car because then you have the danger of overflow or forgetting to drain the puke tank and in turn dumping oil on the track in front of your rear tires.
     
    #3
    Mike Canter, May 27, 2016
  4. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
    Staff Member

    Joined:
    May 6, 2003
    Messages:
    6,706
    Likes Received:
    133
    Obviously the FC has a puke tank connected to the frame rails.

    Mike - One way I have thought about doing it is having a line going to the chassis from the oil tank like normal, but putting a T in to a vent, along with a one way valve to prevent back flow. This would let the oil tank breathe, have somewhere for overflow and prevent back flow.

    A hemi oiling system needs all the help it can get on a 1/4 mile run to keep adequate oil flow and supply to the tank for when the chute hits.
     
    #4
    Will Hanna, May 27, 2016
  5. eagle1

    eagle1 Member

    Joined:
    Mar 25, 2007
    Messages:
    75
    Likes Received:
    4
    I struggled with this on the NTF car I had. It had a multi-stage dry sump. It basically did all its breathing through the oil tank vent. The oil tank was vented to the upper frame rail along with the engine. If you hurt a piston the engine blowby in the frame would not let the oil tank vent. It actually increased the oil pressure because of the accumulator effect of the added pressure.I removed the oil tank vent from the upper frame rail, put it on the lower rail, and added a second smaller punk tank for this. From that point on the "engine breather" puke tank never had anything in it. It was in the other tank. Frame rails are restrictive in breathing anyway. They can get oil in them that effectively blocks them. Look at the bigshow FC. Many have a large external breather line for the engine. I don't even vent the valve covers. Instead I vent the valley. If you have piston damage why have all the trash come up around your expensive valve train. You want the oil in the heads to drain back down. Why make it go down a drain back that has pressure coming from the wrong way.
     
    #5
    eagle1, May 27, 2016
    Will Hanna and ta455 like this.
  6. John Robinson

    John Robinson Member

    Joined:
    Mar 16, 2009
    Messages:
    112
    Likes Received:
    0
    We ran into this on the altered, we just ran separate tank to the rear & piped two dedicated hoses underneath .
     
    #6
    John Robinson, May 30, 2016
  7. tafc1445

    tafc1445 Member

    Joined:
    Nov 19, 2014
    Messages:
    35
    Likes Received:
    1
    I would've thought it was to get a slight head of pressure in the oil tank to help feed the oil pump, instead of just having atmospheric pressure trying to do the work.
     
    #7
    tafc1445, May 30, 2016
  8. TOL

    TOL Active Member

    Joined:
    May 18, 2005
    Messages:
    1,352
    Likes Received:
    18
    I tend to think it is just a matter of convenience and practice. You have tubes nearby, so why not use them, assuming they are not blanked off at intersections.

    In my thinking, you are better off to figure out how you want to properly vent the motor, and then run dedicated hard pipe plumbing to do so.

    With a decent volume catch can at the rear of the vehicle, with appropriate baffles, you should be able to puke & vent without drama at will.
     
    #8
    TOL, May 30, 2016
  9. Fuel Cars

    Fuel Cars AA/AM

    Joined:
    Aug 20, 2003
    Messages:
    306
    Likes Received:
    8
    Venting corrosive chemicals in to the frame rails to me is not good, just my .02 cents worth, keep the change.
     
    #9
    Fuel Cars, May 30, 2016
  10. Mark Leigh

    Mark Leigh Member

    Joined:
    Mar 9, 2010
    Messages:
    446
    Likes Received:
    2
    Will , Jim Head had a setup on his cars where the valve covers teed together an ran into a single 3 inch line which looked to tie into a 5 gal puke tank ------ I thought it was a great idea
     
    #10
    Mark Leigh, Jun 1, 2016
  11. crashly

    crashly Member

    Joined:
    Sep 2, 2006
    Messages:
    120
    Likes Received:
    1
    to take the fumes / waste oil back behind the drive wheels?
    we do it on mine
     
    #11
    crashly, Jun 17, 2016
  12. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
    Staff Member

    Joined:
    May 6, 2003
    Messages:
    6,706
    Likes Received:
    133
    I have decided to go with a round dry sump tank with an external vent that I will put an air filter on.

    What I would recommend to everyone else using a conventional vent is to make an aluminum "T" with a provision to put an inline air filter going to the frame rail. This will allow the tank to vent, while still using the frame rail for overflow. I also still highly recommend the one way valve.
     
    #12
    Will Hanna, Jun 21, 2016
  13. Randy G.

    Randy G. Top Alcohol

    Joined:
    Jun 9, 2003
    Messages:
    1,902
    Likes Received:
    37
    Will, I remember Newberry running an external vent with a filter on it on his S&W cars.
     
    #13
    Randy G., Jun 28, 2016
  14. NENE

    NENE Member

    Joined:
    Sep 19, 2010
    Messages:
    107
    Likes Received:
    1
    Will

    Wich 1 way valve would you choose ? I have both valve covers going both side of the chassis and I will need to weld a small tube to my chassis to accept my oil tank vent. So I presume the 1 way valve is only used on the oil tank vent line to prevent it to be blown in case of a torched piston ???

    Eric
     
    #14
    NENE, Jun 28, 2016
  15. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
    Staff Member

    Joined:
    May 6, 2003
    Messages:
    6,706
    Likes Received:
    133
    #15
    Will Hanna, Jun 28, 2016

Share This Page





XenPorta 2 PRO © Jason Axelrod from 8WAYRUN.COM