Featured Rear Diffuser

Discussion in 'Challenger Exterior Modifications Forum' started by SRT-Tom, Jan 22, 2019.

  1. SRT-Tom

    SRT-Tom Well-Known Member Super Moderator Article Writer

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    It's made for sports cars traveling at high speeds. Here is an explanation from a BMW website:

    "What is the purpose of a rear diffuser?
    The primary purpose of a rear diffuser is to efficiently increase the downforce of a vehicle. This helps increase grip and reduce aerodynamic drag.

    IMPORTANT PART TO UNDERSTAND?
    In order to fully understand the principles of how a diffuser works there is a simple rule of physics that must be understood. Air pressure naturally moves from high to low. Think of inflating a tire, high pressure exists in the air tank (100psi) and low pressure exists in the tire (30psi). Once the valve is open on the tire the pressure moves from high to low, the tank to the tire. This simple content must be understood when learning how a diffuser works.

    How does a rear diffuser work?
    As a vehicle drives down the road, high-speed air is passing underneath the vehicle at low pressure. As the air passes to the rear of the vehicle through the diffuser, the air expands through an expansion chamber (from high pressure to low). Through this expansion, airspeed reduces and pressure is increased (through what is called the Venturi effect). This pressure differential between the low-pressure air under the car and the high pressure at the rear creates a vacuum sucking the air out from under the car. With high-pressure air above the car and low pressure under the car, high downforce is present while reducing aerodynamic drag."
     
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  2. NC20RT

    NC20RT Full Access Member

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    It's actually similar to the Shaker hoods which I really enjoy as an appearance type thing. Even though a Shaker gives you actual cold air intake, I seriously doubt the horsepower changes. When the dealer installed the Shaker on my Mustang when the car was new back in '07, they said it makes really no increase in hp, it's just a cool appearance mod if you like that type of thing. It certainly works for me having grown up in the real shaker era. Now I own two. :cool:

    The original shaker was bolted on top of the carburetor and created a direct ram-air feed, unlike the new Shaker. Supposedly, the old shaker on the 1970-1971 Challenger and 'Cuda was good for up to 5 mph. in the 1/4 mile.

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    Last edited by a moderator: Apr 17, 2021
  3. 2017 Redline HC

    2017 Redline HC 2017 Redline HC

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    Shakers are my favourite hood design of all the Challengers.
     
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  4. TRCM

    TRCM Full Access Member

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    A real diffuser may work that way.,.....but what most (like the one in that pic) are nothing more than a bunch of vanes that straighten the air, which helps eliminate turbulence....which in turn reduces drag.....

    To have a true venturi effect, the vanes must be specifically shaped to have a convergent & divergent area and precisely installed & tuned................