oil pressure concerns

Discussion in 'PSI Superchargers Tech Questions' started by promodracer, Oct 29, 2013.

  1. promodracer

    promodracer Member

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    Well i tightened up mains and am now pulling off both valve covers with a single line at rear of each. Still loosing pressure when warm. When crusing at 2000 rpms it drops to 35lbs.
    Do i pull a second line on each head? Im thinking it would max out existing lines in valve covers going to one suction section of pump.
    What do you guys think?
    Buy the way drain holes in the head are two 1/2" holes per side.
     
    #21
  2. blown375

    blown375 New Member

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    Guys are saying that the clearance on the mains is opening up and allowing the oil to flow too freely .
    What do you think is happening to the clearances in the oil pump when it gets hot ?
    Back when I had hot rod street cars , I had a smallblock Chevy that carried 15 psi at a hot idle but when you rev'd the engine the oil pressure guage jumped up like a tach !
    How high does the pressure go when you throttle it ?

    P.S. I use 70w bradpenn with no snake oils added and have never had an oil related problem !
     
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  3. Mark Leigh

    Mark Leigh Member

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    Just a suggestion here , you have a hemi with race setup clearances that you are running on the street --------- My move would be to close up the main bearing clearance to .003 and the rods I assume are aluminum ? I would go to .003 there also ,

    I know someone here will yell--- you'll shoot your eye out ! Your dilemma is the street driving and wanting to race it some , the clearances are just too big for more than 3 minutes of drag racing - street racing --

    No oil or additive is going to solve this -- I still haven't read what fuel you are running ? Also are the posters running their car as a street vehicle also ?

    If you are running Alky , it will break the oil down soon too ---------in a street mode ------
     
    #23
  4. jeffj

    jeffj Member

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    Wow, old thread! What I was referring to was the amount of growth in an aluminum block from room temp to 300 degrees. The rise adds .003 to what main bearing clearance you see at room temp. That amount of growth would be ok to drive on the street with decent oil pressure with a good pump. Problem would be that you cannot start off with zero clearance and let it grow to .003 when hot..... Very tricky but if you had a really straight line bore and perfect crank and about .001 cold it could work but don't start it cold in cold weather and for sure, let it warm up at idle before you drive it or put any load on it.
    On the oil subject, everybody has their pet dog that is so wonderful and has never bitten anybody, the kids all jump all over him and he likes it when they kick him in the head and we cannot believe that he bit you! What did you do to him?
    Jeff Johnsen
     
    #24
  5. promodracer

    promodracer Member

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    I had .006 on mains tightened .001 but as you all know Bryant turns them down more than street pieces. I have 130 lbs cold. drops quickly with heat. don't think its return issue now. solution is to turn crank down so can tighten up more, unless its possible to get bearings that will tighten it more. is this possible.
    yes I run methanol and no its not washing down oil. and heat is cooking things off well. temp stays around 180 degrees or so. pressure is 35- 40lbs at 2000rpms down the freeway.
    i'm thinking tighter main clearance's are my only option. what does everyone think now?
     
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  6. Mark Leigh

    Mark Leigh Member

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    That's what I am trying to tell you --- tighten the mains ----- I know with a Nitro motor on a hot day --- I can see a 40 lbs loss of oil pressure if you do a quick turn around between rounds -- because the block is warm already for the second round -
     
    #26
  7. promodracer

    promodracer Member

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    Is there enough bearing options out there to accomplish this without turning the crank down?
     
    #27
  8. Mark Leigh

    Mark Leigh Member

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    NO------------ your post about turning it down to close to .010 under to achieve a .003 main clearance is the best way at this point , unless you call a crank manufacture and order a new crank with journal sizes to do the same and use std. bearings -
     
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  9. Sandracer695

    Sandracer695 Member

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    You can also align hone the block to the small side of the housing bore. Rule of thumb is 10lbs of oil pressure per 1000 rpm. If you rev motor to 6000 rpm does it stay at 35-40psi or go up?
     
    #29
  10. promodracer

    promodracer Member

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    oil pressure concernes

    I will have to look again
     
    #30
  11. promodracer

    promodracer Member

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    oil pressure concernes

    that's what I was afraid of.
     
    #31
  12. blown375

    blown375 New Member

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    You need to go buy a big bottle of reality!
    You need to make a decision whether you want to streetcar or ProMod,
    If you're trying to build a Promod to drive on the street , you're going to wind up with a car that's not very drive able or reliable on the street and not reliable or competitive at the racetrack.
    Odds are your going to hurt your self or someone else.
    A promod on the street isn't going to handle and will easily get out of control and a promod with the wrong bearing clearances is going to kick the rods out and potentially get crossed up and hit the person on the other lane.
     
    #32
  13. promodracer

    promodracer Member

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    oil pressure concernes

    The car has been very manageable on the street at one to one. great to drive. yes tune up for track would differ. going to live with pressure where it is. bearings are good so far. I have driven it a few times now. max 20 mile range.
     
    #33

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