Heat transfer in the engine bay

  1. Saxperience Forum Bum Joined: Oct 2007 Spalding-ish Posts: 2512 Mk4 Anniversary golf. 106 Quiksallye
    #1
    Right. Im thick and need help.

    I can just remember school and some lessons on heat transfer with colours etc.

    Things you want to keep hot, you paint dark matt colours to absorb the heat yes?

    Things you want to keep cool, you get them as shiney as poss to reflect the heat?

    So what is the best thing to do with cam covers?

    Thermos flasks are reflective so they hold the heat in. If you buff up the cam covers, wont it make them hotter?

    Told you i was thick.

    Help
  2. Established Member Joined: Apr 2009 just aroon the corner Posts: 1509 Audi S5, Corsa, Defender 90 CSW
    #2
    looking into it mate, wayy too much, get a wrap on the manifold, that makes the biggest different,

    thermo's dont keep stuff warm inside cos its shiney, hence why u get plastic ones and all sorts, its the properties and the design of the inner wall of the thermos that keep its "cool" "warm" inside, as it reduces heat transfer

    the bonnet covers the engine bay, you need to worry bout a heat wrap, and good air flow, not bout polishing summit up

    hope that help
  3. Frequent Poster Joined: Nov 2003 Tayside Posts: 893 S/c VT!?
    #3
    Just remember - that heat can be 'hot' or 'cold'

    Using your example of the Thermos flask;
    Not only does it keep hot things hot, it keeps cold things cold.
  4. Established Member Joined: Apr 2009 just aroon the corner Posts: 1509 Audi S5, Corsa, Defender 90 CSW
    #4
    Quote:
    Originally Posted by gd16 View Post
    Just remember - that heat can be 'hot' or 'cold'

    Using your example of the Thermos flask;
    Not only does it keep hot things hot, it keeps cold things cold.
    the joke with david beckam and his coffee and ice cream in the thermos comes to mind haha
  5. Banned Joined: Jul 2007 Posts: 4328
    #5
    Things like wrapping the manifold in quality wrap will help.
    Changing inlet bolts from mild steel to stainless also readuces temp transfer
    dark colors for air intake pipes will help to keep intake temps which helps with bhp
  6. Saxperience Hardcore! Joined: Oct 2008 Birtley Posts: 22253 VTR Turbo, 106 xsi track slag, Transit recovery, B
    #6
    you mean reflective things for intake pipes? you dont want air going into the engine being hot, and thermos flask work because theres two "cells" in the flask, inner and outer, theres a vacuum inbetween them that stops heat transfer as heat cant travel through a vacuum,
  7. Established Member Joined: Jul 2008 Taunton, Somerset Posts: 1182 Millenium Falcon
    #7
    Does heat-wrapping the manifold actually improve performance at all by not heating it up?
  8. Established Member Joined: Apr 2009 just aroon the corner Posts: 1509 Audi S5, Corsa, Defender 90 CSW
    #8
    Quote:
    Originally Posted by -Dan- View Post
    Does heat-wrapping the manifold actually improve performance at all by not heating it up?

    offcourse it does, cooler/more dense air going into the intake, which means you can get more into a certain space if its more dense, this then has more air in the cylinder, more air, ecu then sends in more fuel, = more power from compression/power stroke
  9. Saxperience Post Whore Joined: Mar 2007 Reading Posts: 8980 French tin can
    #9
    The colour of your cam covers ain't gonna make any differece.

    There's 3 types of heat transfer: Convection, conduction and radiation. Convection is like a fan oven. The hot air moves around, heating up anything in the area. Conduction is where items in contact with each other transfer heat, like the oil touching the cam covers for example... Radiation is like the heat from the sun. A Thermos keeps things hot or cold because it uses a vacuum and reflective materials.