How much oil pressure

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by taf122, Apr 16, 2010.

  1. taf122

    taf122 New Member

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    526 tfx, bae fat head, 1471 hhr, 8000 rpm max. Looking at 180 psi at idle, 60 wt. valvoline,75 degree weather. Is this too much!!! Please help, able to lower pressure. Thanks Tony
     
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  2. secondwindracing

    secondwindracing top alcohol

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    sounds like a bunch to me..Dave
     
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  3. nmro2114

    nmro2114 Member

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    It has been discussed here before. I think the rule of thumb is 10 psi per 1000 rpm.
     
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  4. hemi altered 378

    hemi altered 378 Blown Altered

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    there are a couple different opinions on this one that i have heard, when i asked the very same question years ago. some people run 175-200, and some people run 80-120. we like a little more pressure, and have ran it that way for the last 12 years. we run a hemi with a wet sump, KB billet pump, deep dragster pan, 60 wt oil. our car idles on 185, then drops to 150 when warm. just make sure that you have enough oil in it, we use a Dan Olsen dragster pan and 16 quarts. if i can help, give me a call
    Darren
    937-776-7542
     
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  5. jim phillips

    jim phillips ta/fc

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    i like to leave with a 120lbs thats what i was told to leave with when i started running the hemi are bad things could happen i dont know if for sure BUT i dont leave without a 120lbs not sure what it is on a run
     
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  6. blown375

    blown375 New Member

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    I'm making 200 psi at the hit of the throttle and thru the run ... I have had no problems !
     
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  7. Moparious Crewcheif

    Moparious Crewcheif New Member

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    Not sure too much is a issue. Not enough would be a worry. We run around 125 with no problems. We may even up that some. Just be sure you don't pump all your oil reserve up into the motor and start pumping air. Oil pressure is a good thing air is not.
     
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  8. Bob69

    Bob69 Member

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    When I run fresh mineral based 60wt, oil pressure is around 160psi at idle and go's through the traps 180 odd.
    Switched to synthetic pressure dropped to 120 at idle and gos through through at 120.
    I have the bypass screwed in as far as it can with synthetic.
    I also have big big-end clearances which dictates higher volume of oil requirements.

    I believe that more power you should have more oil pressure to keep crank journals and bearings apart. If I could get more pressure out of my pump I would be happy.

    PSI screw in pro-mod
     
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  9. Bottlefed

    Bottlefed New to Blowers

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    Here is my long winded feeling on oil pressure,

    On a conventional racing engine, N/A or Nitrous the parts do not suffer from a lot of flexion so there is no need to run big bearing clearances to prevent mechanical contact. On these engines the 10 psi per thousand rpm works fine, it allows plenty of oil to be supplied to each bearing in the engine and also provides sufficient flow in the "work area" ( the clearance between the crank pin and the bearing shell) to keep the temperature of the oil within its operating range.

    Maintaining separation of bearing from crankpin (under load) is not a function of oil pressure but rather as the crank rotates the oil that is trapped between the crankpin and the bearing shell forms a "wedge" of oil between the parts and the oils lubricating properties keep this wedge of oil in tact so as long as you have enough pressure to supply adequate oil to the clearance then it will be fine.

    So on the engines above, the only thing extra oil pressure will do is to rob horsepower from the engine due to pumping losses as well as windage losses created by all of the oil that is forced between the bearings flying around inside the motor.

    Now on the other hand on roots or screw blown alky or nitro motors where component flex is a hard fact, extra clearance is needed to keep the parts out of mechanical contact. In addition by running lots of pressure and large clearances you force a lot of oil through the "work area" allowing additional cooling of the parts by the oil, since the oil is often mineral and is also often diluted with large amounts of fuel its ability to work at elevated temps is far lower than the oil in a conventional racing engine. Where on a non blown engine you worry about HP loss from the pump and windage, on a blown engine you generally have plenty of power as long as you don't hurt things so instead you worry about having plenty of oil pressure. In addition all the oil flying around in the crankcase cools the pistons crowns and rings which get very hot since the ability of the rings to transfer heat to the cylinder walls is not as great as on an engine with coolant. Add to that the fact that to ensure you always have enough oil present in the bearing to supply a good wedge during tire shake etc. generally the more pressure the merrier.

    That’s my 2 cent’s and you may have been overcharged :rolleyes:
     
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    Last edited: Apr 18, 2010

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