Heat shield or not?

Discussion in 'Fuel Economy' started by Gageraid, Feb 25, 2015.

  1. Gageraid

    Gageraid Well-Known Member

    Should I use the heat shield that is on my K&N CAI or not for mpgs. Without the heat shield, it may be able to act as a WAI.

    Last edited: Feb 25, 2015
  2. Gageraid

    Gageraid Well-Known Member

    Bump. I know there are some great people that would have some solid advice for me. :stickshift:
  3. ALS

    ALS Super Moderator Staff Member

    Personally I don't think it would matter much with modern engines.
  4. Gageraid

    Gageraid Well-Known Member

    I've done 40 miles so far without the heat shield.
    I'll keep ya'll posted if anything positive comes from it.
  5. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    My first thought when you posted: what car is this?

    Also, assume:

    CAI = Cold Air Intake


    WAI = Warm Air Intake
  6. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    I kinda think you are the only one here who has installed a CAI.
  7. some_other_dave

    some_other_dave Well-Known Member

    In general, warmer air will be better for MPG. We know people who have run their intakes from right next to the exhaust header to get warm air quickly. That does seem to help, especially in winter.

    In practice, your setup may not make enough difference to notice.

  8. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    The pictures posted are without heat shield?

    I would think the chromed pipe as shown would be pretty good reflector of heat.
  9. 08EscapeHybrid

    08EscapeHybrid Moderator

    I would never install one of those monstrosities in any of my vehicles, but if a friend insisted on doing it, and wanted to make it work for economy, then not installing the shield would be the way to go.
  10. Gageraid

    Gageraid Well-Known Member

    I appreciate your input.
    I did it along with the exhaust when I first got the Jeep. Did it for the sound. :stickshift:
    We'll see if my fuel economy changes at all with the heat shield removed.
  11. Gageraid

    Gageraid Well-Known Member

    First picture is without, second picture is with.
    The heat shield is plastic and black shaped like the letter L.
    Last edited: Mar 1, 2015
  12. Gageraid

    Gageraid Well-Known Member

    2008 Jeep Liberty 3.7L.
  13. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    Ahh: SECOND picture is with the heat shield, am I right?
  14. Gageraid

    Gageraid Well-Known Member

    Correct. I see I needed to edit that post lol. :p
  15. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    Ok. I was looking at that first pic till my eyes bled, searching for elusive black, L-shaped heat shield, LOL.

    Anyway: the whole object of the large diameter, chromed pipe, filter off in the corner, and the plastic box surrounding the filter is to isolate the filter from the hot environment typical in the engine bay, is it not?

    If you leave the heat shield off, you're partially defeating/diluting the purpose of the design. Not saying that's a bad thing, but I mean, you could take it further, remove the chromed pipe and connect directly to throttle intake. If it was practical.

    Ultimately, if the object of the package is to cool the intake air, why not run it as provided, with the heat shield, for a few tanks? Then maybe pull it all out and do a few more tanks stock, see how that goes.
  16. Gageraid

    Gageraid Well-Known Member

    I've had the cold air intake and heat shield on for two years now lol. I guess I forgot that detail.
  17. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    I doubt you'll see much difference either way with the intake being so far from the engine. Maybe a couple degrees. As for what effect those couple degrees might make, even harder to say for sure. You would think warmer makes for faster warmup, but the air in the engine bay will only warm up after the engine is warm enough to radiate heat out, so it can't warm you up *much* faster unless you're pulling air straight off the exhaust header.

    Warm air intake should help with economy. Warmer air is less dense, so for a given intake volume, there's less oxygen and then a matching lower amount of fuel. You'll still need to make power, though, so you'll press the throttle slightly more to make it up. The end result is ever so slightly better because there's less vacuum resistance at the throttle, but that's about it.
  18. Gageraid

    Gageraid Well-Known Member

    I'm very aware this is something that is going to be so minor. I just really like to fiddle around with variables.
  19. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    So maybe this is more of a performance mod? Aiming for colder denser air.

    If the object is mpg, just pull it, go back to stock, and maybe sell?
  20. Gageraid

    Gageraid Well-Known Member

    Performance and sound it what it is used for. I care that it makes the engine sound good.
    I love hypermiling with the cool engine audio to go with it.

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