oil pressure

Discussion in 'PSI Superchargers Tech Questions' started by blownapex, Dec 17, 2006.

  1. blownapex

    blownapex Member

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    3/4 through 1/8 mile run our oil pressure goes from 90psi
    to 40 every run
    dan olson pan 11qt
    tried more oil 14qt
    kb stage 10 block and brad fuel heads
    no push rod problems
    do i install restrictor plugs in deck of block and
    what size hole should it have
    or is their another fix
    also we have twisted 2 mag shafts off cold oil
    pressure is about 160 till warm then idle is 60
    3000 rpm and up is 90 psi
    any experience would be helpfull
    thanks
    duane
     
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  2. Nathan Sitko - 625 TAD/TAFC

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    That sounds like a lot of variation...what kind of oil pump do you have? Is it a dry or wet sump?

    14qts of oil still isn't "lots" of oil, in our dry sump deal we run near 20 in the tank. We have a pleuger dry sump pump, 150psi cold and goes to about 110 when hot idling, usually 95-100psi after the burnout when staging dependant on how hot it is outside. The hottest weather we ran in was the Seattle national event, 105F outside, left the line with 85psi. Just would be curious to see why it's so low when idling. What does your car idle at??
     
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  3. blownapex

    blownapex Member

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    faria oil pump wet sump
    looks like system 1 also
    system 1 coarse screen oil filter
    idling at 1700
    during the run its at 90psi untill about 500 ft
    or about 3.5 second into run
     
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  4. Dave Germain

    Dave Germain New Member

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    I would be real careful about restricting oil up to the heads or you will eventually end up with pushrod problems which can be catastrophic. I know some of the top fuel guys run as much as 20 quarts of oil in a wet sump motor. I know that will probably be higher than the pan rail in the motor but it would help you to know if it is simply running out of oil. Another consideration would be clearances both in the bearings and the oil pump itself. Also what viscosity oil are you using. I don't know anyboy running less than 50 wt and on the hotter days lots of guys are running the 70wt nitro. How are you monitoring your oil pressure? I am assuming a racepak or something like that? Good luck with it. Dave Germain
     
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  5. Mike Canter

    Mike Canter Top Dragster
    Staff Member

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    As Dave said, I would not recommend oil restrictors. You will loose a pushrod end.

    One thing to try is to take you pan off and fill it with a measured amount to just at the ooil screen, then add one quart for the System One filter and add one or two quarts for oil lines and the block galleries and see how close that comes to what you are now putting in the car.

    It sounds to me like you are pumping all the oil into the top of the heads or lifter valley and leaving very little down below so you are sucking air with the oil and cavitating.

    Check all the oil drainback holes and make sure the head gasket hasn't blocked them or there is debris blocking the holes.

    We also always worm up the oil tank if the temps are low so we don't twist a pump shaft. They make heating pads which can attach to the bottom of the pan.

    Has this always down it or has it just started?
     
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  6. blownapex

    blownapex Member

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    we run 60 wt valvoline vr1 but we are switching to
    70w lucas or valvoline next year
    we monitor oil pressure with a computech computer
    this has done this from day one we want to run 1/4 mile
    but we cant with this problem
    1/2 inch drain holes are clear through block/headgasket/
    and heads
    their is threaded holes in the head surfaces for restrictors
    if i run restrictor what size hole .080/.100/.125 should i use
    17-20QTS is making sense
    THANKS
    NATHAN/DAVID/MIKE
    any help to do this one time is apreciated
    DUANE
     
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  7. Dave Germain

    Dave Germain New Member

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    It sounds like you are bound and determined to restrict the oil to the top of the motor. Restricting the oil to the heads is really restricting it to the pushrods. If you burn an intake adjuster to where it won't open the valve the next event is the motor goes lean because 7 cylinders are getting 8 cylinders worth of air. Unfortunately they are still only getting the amount of fuel that they were getting previous to the pushrod failure. That leans the motor and it eats a rod bearing and kicks the rods out the side of the block. So by restricting the oil to the top end you might boost the oil pressure to the expense of the rods, crankshaft, and block. Once that happens get in touch with me. I have a KB stage 15 block for sale. It's been windowed lots of times, that is how I figured this out. Dave Germain
     
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  8. john348

    john348 Top Alcohol

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    which heads are you running fuel or fat heads
    what crank are you using
    what main bearings and clearances
    and has the block ever been windowed???

    we used to run restrictors in our TFX bocks
    until we went to external oiling
    I went and dug up records
    we ran a .032 on right side and .045 on left side
    remember this was for a TFX block
    been way to many years to try to remember back when we ran KB's
    if we ran restrictors then or not, but i really think we did
    call up Keith Black's shop and ask
     
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  9. secondwindracing

    secondwindracing top alcohol

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    Restrictors...........(NO) I had the same similar problem.solved by preheating the oil and adding more oil16qts.The coolest idea I have heard is the one from mike, take off the pan and start filling it,ect. that will tell you how much oil is always in the motor not in the pan.and like dave said once you start having push rod probles look out...that can be devasting. Good luck.Dave Lowe
     
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  10. blownapex

    blownapex Member

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    when i called keith black they said .080 restrictor
    but do they really know my combination
    [stage 10 and bae fuel heads faria wet sump-
    dan olson pan bryant crank]
    looks like i will assemble and try more oil 16-20 qts
    then if i still have the problem ill remove heads and
    install the restrictors
    im thinking about gores fuel management and overboost richener
    any body had problems going this route on the fuel system
    THANKS EVERY ONE

    DUANE
     
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  11. BarryPaton

    BarryPaton New Member

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    I feel compelled to comment on this issue as we have run alcohol funny car, nitro funny car [Nitrofish], and now Top fuel dragster for nearly 30 years.First thing we must understand is that NO oil returns to the pickup until the engine stops! With crank windage, thick oil, small drain backs, how much 50 wt oil can you pour down a 1/2 in. hole in 4.5 - 9 seconds. Restricting the flow to the head with an .080 to .100 jet is quite aceptable because after a 90 second burnout and staging procedure the motor will have at least 8 -10 quarts in the top of the motor. On a dyno pull with the right side valvecover off, oil will shoot out of the drainback ??? holes 15 feet in the air! The motor requires 1.7 qts to operate! Having run wet and dry sump systems for quite a while put at least 20 qts. in the motor or tank, adjust the pump pressure to have at 100 psi runing hot and lastly forget about the oil pan, in this case size does not matter !!!
     
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  12. Dale Finch

    Dale Finch Member

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    Another idea and question. What is the condition of the Cam bearings? An internal leaker really shows up at idle. The pressure returns when the engine rpm comes up. It can mask this problem. It is very hard to change bearings on some raceblocks and this can become overlooked. You almost always see a dry sump on a TAFC with a screw. My experience is the engine oil capacity will make it on a roots but real problems show up when a screw is installed. Same pan and oil capacity. Won't make it. 18 quarts plus in a wetsump pan can start oil foaming and leaks.
    We have always run restrictors with external oiling to the head. Boats and cars. Helps stop oil leaking by the headgasket into the chambers beside the oil gallery that feeds the head. Careful with the silicon around the holes. .060 works great. Brad billet blocks come with this size restrictor.
     
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