Intake Manifold Thermal Reduction

Discussion in 'Discussion Forum' started by Dr.Jeff, Dec 1, 2019.

  1. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    20190307_163644.jpg
    Maybe this will clarify things:
    Added a pic of the intake manifold. It's one piece that includes the throttle body mount, a plenum about 8" below the tb, and the runners that wrap around the plenum and bolt directly to the head. All one piece.
    Ignore the 72mm tb, that has been replaced with a 58mm.
     
  2. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    Ok, here's some readings from our Pontiac G6/2.4L, basically the same setup as in the 600 except the Fiat is 2.2L. Engine idling, hood open. Outside air temp 48F

    Coolant temp -- just under 225F on gauge.
    Highest actual was 227F on water pipe on back of engine, but near exhaust.
    Temp at water pump 174F.

    Cylinder head near intake manifold 135F.
    1" from head into runner 118F.
    1" from head with wife briefly holding an unsteady 2500RPM went down to 116F.

    Below tb at plenum about 8" into manifold 97F. (Stayed at 97F at 2500RPM.)
     
  3. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    Ya, I was picturing something completely different. That's kind of a funky design, most likely due to packaging/space requirements I imagine.


    So I see a couple things. 1) the temps at idle and at 2500rpm really are not significantly different, although it might be at full load/full throttle conditions. So lowering intake temps in general will benefit across the board. 2) the temp at 1" from the head is still quite high (relative to the head temp). So insulating the manifold at the junction between the head and the manifold should offer a significant decrease of intake temps. 3) the temp drop from the 1" reading and the "below the TB" reading is pretty significant (20*). Given your plastic manifold should have a similar insulating effect as the phenolic spacer, then I'd expect the spacer could offer a decent insulative benefit on the Fiat SOHC. It seems worth doing to me. Thanks for sharing the data. ;)
     
  4. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    Jeff, even though I was careful in taking the readings there are so many variables involved here that I think at best you can only get a general idea of what they are telling you.
    My feeling is that you are going to get better results if you can shield the intake manifold from the exhaust header. That's where your main heat source is.
     
  5. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    Agree on both points. However I'm still going to insulate the intake manifold from head heat in addition to other forms of thermal management.
     
  6. tonyism7

    tonyism7 Daily Driver

    Location:
    New Jersey
    The insulator sounds like a good idea. What do you think is the best way to make one?
     
  7. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    I bought a section of the phenolic material and will cut them out by hand. It is fairly easy to work with; band saw, hole saws, sanding drums, etc. However if you can make a digital file with the shape you want, then you can have them laser cut. That would be much better and cleaner. Unfortunately I do not have the resources (read 'ability') to make such a file. But if someone else does I know of a couple places that can cut them for us. ;)
     
  8. gene cooley

    gene cooley Autocrosser

    Location:
    Henrico, Va
    If they do laser cutting there's a good chance that they can scan the flange on the manifold and do everything right there. Costs more but
    it takes away the chance of having to redo anything ar your expense.
     
  9. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    Oddly the two sources I have for cutting will not scan things. Nor will they create files, use certain types of files, or do file conversions. I wish they did because there have been several things I wanted made but could not due to the inability to generate an appropriate file. On the plus side, they have very reasonable cutting costs.
     

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