Does the scavenging pump's flow rate max out at idle? | FerrariChat
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Does the scavenging pump's flow rate max out at idle?

Discussion in 'Technical Q&A' started by 911Fan, Feb 23, 2005.

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  1. 911Fan

    911Fan Formula 3

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    #1 911Fan, Feb 23, 2005
    I'm guessing that the oil level in the separator (which is the oil level which gets measured with the dipstick) is affected by the engine rpm as well as the oil temperature in a dry sump engine. But I've never seen any limits specified on the rpm for when to check the oil other that it be "at idle".

    Is the scavenging pump's flow rate already maxed out at idle?
     
  2. pma1010

    pma1010 F1 Rookie

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    #2 pma1010, Feb 23, 2005
    I don't believe so. My aftermarket pump achieves max flow at 5500 rpm. At idle is turns 500 - 600 rpm. The OEM scavenge pumps are gear driven. Expect same result. Pressure side shows same characteristics.
     
  3. 911Fan

    911Fan Formula 3

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    #3 911Fan, Feb 23, 2005
    Moments after posting my question, it occurred to me that the scavenging pump's flow rate has to closely match the main pump's flow rate. Otherwise there will be an imbalance somewhere.

    I hope this isn't one more thing I need to worry about!
     
  4. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #4 Rifledriver, Feb 23, 2005
    Since the typical scavange pump has 1 1/2 to 2 times the capacity of the supply pump at any engine speed the RPM should not make any difference to the level in the tank except of course at high RPM the oil that gets flung to places that slow its return to the sump where it can be returned to the tank. In theory the level should remain the same (or very close).
     
  5. 911Fan

    911Fan Formula 3

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    #5 911Fan, Feb 23, 2005
    I guess that's the critical requirement then -- the scavenging pump must always have a higher flow rate than the supply pump...
     
  6. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #6 Rifledriver, Feb 23, 2005
    Yes. They also do it to create a vacuum in the crankcase. Motor makes more power that way.
     
  7. pma1010

    pma1010 F1 Rookie

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    #7 pma1010, Feb 24, 2005
    This is exactly what the Pace Pumps engineer told me the other day. V cool.
    Philip
     
  8. mk e

    mk e F1 World Champ

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    #8 mk e, Feb 24, 2005
    They also set the return pump to flow about double the feed pump because in a turn, all the oil is on one sid of the engine and returning through only one stage of the pump...on a 2 stage pump each stage or the return pump needs to equal the flow of the feed pump or oil will build up in the crankcase.
     

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