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  1. #1
    Senior Member Array painlessauto's Avatar
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    Default Whipple noise

    I've previously owned gen2 2.3 & 3.4 Whipple superchargers. Both spun quiet and smooth.

    I have a brand new Gen4 2.9 right from Whipple. Just unboxed it.

    Take a listen to this
    https://youtu.be/fi_RQfty1Sg

    Normal?

    Whipple is closed until Monday. I know the gen4 rotors use an abradable coating that "wears" in with use. This noise seems more than that, I can feel the noise in the pulley as I spin it. Noise originates from the rear of the rotors/case.

    What do you think?

    Matt

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  3. #2

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    That does not sound right, Matt.

    The abradable coating is supposed to provide a way to improve the efficiency of the compressor by fine-tuning the operational fit of the rotors to the case. I believe Line 2 Line Coatings provided the original coatings for Whipple. I don't know if Whipple changed their service provider or brought the process in house. In any event, I would not expect to hear the sound your video is demonstrating. That sounds like a mechanical contact between rotor and case and, as you already know, that should not occur in a screw design compressor.

    I think I would let discretion be the better part of valor and wait until Monday to talk to the Whipple guys. It may well be that they assemble them that tightly with the coated rotors and case but my instincts tell me something is amiss.


    Ed
    Last edited by eschaider; 03-01-2020 at 09:13 AM. Reason: Spelling and Grammar

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    We'll, sounds like we are on the same page Ed. I'll post Whipple's answer when I have one.

    Matt

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    Response from whipple


    All good. The is the rotor coating scraping each other. You will also hear it at start up once installed and takes about 300-400 miles of normal driving to wear in.*


    Looks like I'm going to run it and see what we get. The noise sure had me nervous but Whipple knows their product. Can't wait to spin this thing!

    Matt

  6. #5

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    Good news, Matt! Keep us posted on the differences between this performance of the new style compressor and it's predecessor.


    Ed

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    Quote Originally Posted by eschaider View Post
    Good news, Matt! Keep us posted on the differences between this performance of the new style compressor and it's predecessor.


    Ed
    I'm hoping for a win win with this setup. Gen4 2.9 vs gen2 3.4

    Less rotational mass, more efficient rotor design, better discharge. Hoping my IAT2 drop to prevent timing from being pulled. Running 25-26# boost through both setups so we'll see

    Matt

  8. #7

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    Matt, I don't recall if you are using the OEM inter cooling system or if you have modified yours. If you still have the OEM system any improvements in the the heat transfer capabilities will show immediate results in terms of power.

    Whenever we compress air (lets assume a 100% efficient compressor) the process of compressing the air has a baseline amount of heat that is imparted to the compressed volume. In addition to this baseline increase in air temp their are adders for compressor efficiency (actually it is the lack of efficiency) that further raise the compressed air temps.

    In the mid to late 1600's a guy by the name of Robert Boyle discovered the relationship between the pressure and volume of a gas as it changes either pressure or volume. He reduced the pysical phenomena he observed to a mathematical formula and it was subsequently christened with the moniker Boyle's Law.

    The law stated that a volume of a gas at pressure #1 would be equivalent to a smaller volume of the same gas but at pressure #2 (which would be a higher pressure). Boyle made no attempt to incorporate temperature. His law boiled down to

    P1 * V1 = P2 * V2

    Graphically Boyles Law looked like this;

    Name:  BoylesLaw.1.jpg
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    Boyles Law while a good start was not sufficient to solve our version of the heat from compression problem. We need to incorporate the elements of heat and molar volume to determine how much the compressed mixture has been raised in temperature. To do this, the work from a French Physicist, Jacques Charles, in the late 1700's was needed. Charles measured the relationship of changes in temperature and volume. His contribution said that increasing temperature increased volume and vice versa. Grphically his contribution looked like this;

    Name:  CharlesLaw_(2).1.jpg
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    At this point we have almost everything we need to predict charge temperature from compression except one item, molar volume — mass. The process must maintain the same molar volume of the gas through the compression process in order for the next enhancement to the calculation to provide the correct answer.

    In the early 1800's a man named Amedeo Avogadro solved the problem by finding the correlation between the Amount of gas(n) and Volume(V) (assuming Temperature(T) and Pressure(P) remain constant) per molar volume (n) of the gas. This "n" in the relationship came about because of the work that Avagadro did in determining what a molar volume was and contained. The contents numbered in the millions of millions of millions and the actual number became known as Avagadro's number or 6.0223 x1023. With a little algebraic soft shoe the Natural Gas Law was born as

    PV = nRT.

    Where,

    • P = the absolute pressure of the gas
    • V = the volume of ideal gas
    • n = the amount of gas in moles
    • R = the universal gas constant
    • T = the absolute temperature.


    When we want to calculate the temp between a gas at atmospheric pressure and a gas at boost pressure in an intake manifold the equation becomes two equations describing the pre and post compressor environment and the two reduce to

    (P1*V1) / T1 = (P2 * V2) / T2

    Where,

    P = Absolute pressure of the gas; Ambient (P1), Post Compressor (P2)
    V = Compressor volume (V1) or engine displacement (V2)
    T= Gas Temperature pre compression (T1) or post compression (T2)

    That means the charge temperature at the outlet of the compressor will be described by;


    T2 = (P2 * V2 * T1) / (P1* V1)



    Increases above these temperatures are attributable to lower compressor efficiency. The closer you get to these outlet temperatures the more efficient the compressor is.

    When the temperature number is high the intercooler heat transfer capacity needs to be equally high to sink away the heat of compression. If the heat does not get bled off by the IC then the ECU will either pull timing or the engine will begin a destructive detonation process. Either way power suffers.

    Because the IC on an 03 Cobra has a finite heat transfer capability, heating the intake charge by going to higher manifold pressures can quickly become an exercise in diminishing returns because once the IC can not sink away the additional heat energy, the ECU will either pull timing to protect the engine or the engine will begin to detonate. Either way, the anticipated horsepower increase becomes unavailable.

    Interesting dilemma ...


    Ed


    p.s. For those intrepid individuals who want to actually crank out the numbers, the number system you want to use is the SI system not the Imperial System and always use absolute temperatures and pressures..
    Last edited by eschaider; 03-03-2020 at 05:35 PM. Reason: Fixed Broken Pic Link

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