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5th generation hood scoop question

Discussion in 'General 4Runner Talk' started by SCgman, Apr 18, 2019.

  1. Apr 18, 2019 at 6:14 AM
    #1
    SCgman

    SCgman [OP] New Member

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    Been visiting this site since mid 2017. Merely a SR5 guy, I've come to identify a scooped hood as the first indicator for TRD/Trail level 4wd system on a 4runner. I've seen several request to swap out scooped hoods with flush hoods due to glare issues. I'm noticing many pics of off-roading 5th generation runners with scoopless hoods and the TRD/Trail level rims.

    My question is, what functional or mechanical purpose is the reason behind a scooped hood? TIA.
     
  2. Apr 18, 2019 at 7:35 AM
    #2
    2016Pro

    2016Pro Why all of the Pro hate?

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    Zero function
     
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  3. Apr 18, 2019 at 8:20 AM
    #3
    SCgman

    SCgman [OP] New Member

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    Well, I'm devastated to hear that, but thanks anyhow.
     
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  4. Apr 18, 2019 at 8:25 AM
    #4
    Allaboutfamily

    Allaboutfamily Regular Hound Dog

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    Is the grille inside the scoop easy to remove?
     
  5. Apr 18, 2019 at 8:34 AM
    #5
    SCgman

    SCgman [OP] New Member

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    Form without function...…………gonna take me a while to accept.
     
  6. Apr 18, 2019 at 8:48 AM
    #6
    2016Pro

    2016Pro Why all of the Pro hate?

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    I dont believe that is a very good idea. The 4runner already has a factory cold air intake
     
  7. Apr 18, 2019 at 8:50 AM
    #7
    2016Pro

    2016Pro Why all of the Pro hate?

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    I dont think so. Will add zero value
     
  8. Apr 18, 2019 at 8:51 AM
    #8
    DGP1961

    DGP1961 New Member

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    Well got to remove it and re-route the air somehow. The air just blowing through even if you removed it wouldn't do much if anything.
     
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  9. Apr 18, 2019 at 8:57 AM
    #9
    Allaboutfamily

    Allaboutfamily Regular Hound Dog

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    I’m wanting to remove the grille in the scoop and paint it red. (The wife is wanting this done) Just wondered if it was easily removable.
     
  10. Apr 18, 2019 at 9:04 AM
    #10
    2016Pro

    2016Pro Why all of the Pro hate?

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    Do it! How many hp do you think it will increase?
     
  11. Apr 18, 2019 at 9:08 AM
    #11
    4X4Runner

    4X4Runner The Anti Pro, Pro! Staff Member

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    The left coast
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    Unfortunately I don’t think it would function very well as a intake. The first 1 1/2”-2” above the hood is a low pressure area that doesn’t see much air movement. If you watch water droplets dance along the hood you’ll notice they don’t move much with the air moving over the hood. I think it would actually be detrimental to engine performance due to the decrease in air pressure.

    With my snorkel on and a 1500 mile road trip I noticed no discernible improvement in fuel economy or performance.
     
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  12. Apr 18, 2019 at 9:11 AM
    #12
    4X4Runner

    4X4Runner The Anti Pro, Pro! Staff Member

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    The left coast
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    A ram air at the hood/grill would be a better option. Or cowl hood that scavenges the turbulent air at the base of the windshield
     
  13. Apr 18, 2019 at 9:16 AM
    #13
    4X4Runner

    4X4Runner The Anti Pro, Pro! Staff Member

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    The left coast
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    The hood scoop on the Subaru WRX is functional and you can see how large it is and the slope of the hood down to the front end. Now, the WRX scoop isn’t an air intake though, the intercooler is back up under the hood there.
    179D25B5-40B4-47A6-B700-AE23CBF2191A.png
     
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  14. Apr 18, 2019 at 9:40 AM
    #14
    2016Pro

    2016Pro Why all of the Pro hate?

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    The thing is it absolutely would not result in performance gains. You can take that to the bank.
     
  15. Apr 18, 2019 at 9:46 AM
    #15
    2016Pro

    2016Pro Why all of the Pro hate?

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    Just google some threads there is plenty of evidence that it wont provide any performance gains. Even then thread you quoted confirmed it.
     
  16. Apr 18, 2019 at 9:55 AM
    #16
    4X4Runner

    4X4Runner The Anti Pro, Pro! Staff Member

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    The left coast
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    I have a snorkel that’s plumbed directly into the air intake and at 60mph there’s a lot of force on the snorkel intake and I have yet to notice a improvement in fuel economy.
     
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  17. Apr 18, 2019 at 10:06 AM
    #17
    2016Pro

    2016Pro Why all of the Pro hate?

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    Here you go @Backslider Hey have a great day!
     
    Last edited: Apr 18, 2019
  18. Apr 18, 2019 at 10:26 AM
    #18
    4X4Runner

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    The left coast
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    That’s possible. I still think the hood scoop isn’t going to net any gain. Bernoulli’s principle states that the higher the velocity of air molecules the lower the pressure (airplane wing). As air hits the hood it slows down then as it moves over the hood it increases velocity and decreases pressure until it hits the windshield and slows down and increases pressure. By opening up the air scoop and plumbing it into the airbox, scientifically speaking is going to cause a pressure differential between the hood and the intake.

    You still have to contend with the boundary layer. Any object moving through the air is soon surrounded by a layer of slower-moving air known as the “boundary layer”. The boundary layer clings to the surface of the object, interfering with the flow of faster-moving air around or into the object. This can defeat the purpose of a scoop, particularly a ram scoop, by blocking air from entering the scoop inlet (except perhaps a small amount of the boundary layer air itself). To avoid that impediment, many scoops are raised or extended outside the body to place them above the boundary layer. This can increase the scoop’s effectiveness, although the scoop will then increase the vehicle’s aerodynamic drag.
     
  19. Apr 18, 2019 at 10:38 AM
    #19
    4X4Runner

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    The scoop would also have to be designed in such a way that any air entering it would be slowed down to increase pressure. Think smaller cross section opening and larger area at the back. Look at the channels designed into the floor of a modern race car. The “diffusers” start out small and widen/deepen as they go towards the rear of the car. Slow that air down and decrease air pressure to increase downforce.
     
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  20. Feb 4, 2020 at 10:54 AM
    #20
    Gyoaz

    Gyoaz Rex Kwon Do

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    Can anyone attest to any difference in glare with or without a scoop? I'm toying with the idea of a windshield mount light bar.
     
  21. Feb 7, 2020 at 6:15 AM
    #21
    Ak1m0to

    Ak1m0to New Member

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    The only thing I can see with the hood scoop is to help bring in cool air into the engine bay. Other than that, maybe if someone decides to go fi and fit a top mount intercooler like the subarus.
     
  22. Feb 7, 2020 at 8:02 AM
    #22
    4X4Runner

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    The left coast
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    It’s purely cosmetic. The 1.5-2” above the hood is a low pressure area and wouldn’t provide cooler air into the engine bay from the top and. This topic has been beat to death before.
     
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  23. Feb 7, 2020 at 8:05 AM
    #23
    Dillusion

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    No glare here. Maybe because I'm short.

    And yes the small scoop is pointless. But goes look better.
     
  24. Feb 7, 2020 at 12:28 PM
    #24
    snowruner

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    air in the engine bay will cause turbulence you'll see the hood flex under high speed if you cut the scoop for intake. the scoops are only on the trd offroad, trd pro, and trail trims. sr5 and limited trims do not have the scoop. its there for looks. same applies to Tacoma's and tundra's
     
  25. Feb 7, 2020 at 12:35 PM
    #25
    catus

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    I read on the interwebz that scoop'd Runners have better acceleration and get better gas mileage. The Barcelona Red Runners are the fastest too; Army Green are the slowest. It has to be true!</smartass'ery>
     
    Last edited: Feb 7, 2020
  26. May 21, 2021 at 12:15 PM
    #26
    Shnook718

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    Has anyone opened up this scoop? im thinking of just letting in some air to cool down the engine and my dual battery setup? Any arguments as to why i shouldnt?
     
  27. May 21, 2021 at 12:49 PM
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    Red_5

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    Water entering the engine compartment in heavy storms.

    And yes, I'm aware that the engine gets wet from beneath, but I wouldn't go adding more water to the mix for no reason.
     
  28. May 23, 2021 at 7:49 AM
    #28
    SlvrSlug

    SlvrSlug New Member

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    Being a low pressure area, it would help pull hot air out from the engine bay.
     
  29. May 29, 2021 at 10:24 PM
    #29
    Shnook718

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    very good point.
     
  30. May 30, 2021 at 12:06 AM
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    LandCruiser

    LandCruiser I have Toyotas

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    You can’t overheat this engine unless you punch a hole in the radiator.
     
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