Cylinder head temperature





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  1. #1
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    Default Cylinder head temperature

    Good morning all, what is the maximum safe Cht for a water cooled enjin

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    Default Re: Cylinder head temperature

    Most people reckon under 110 deg C.
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    Default Re: Cylinder head temperature

    Thank you Jelo

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    Default Re: Cylinder head temperature

    Depends on what pressure cap is used as the higher the pressure the higher the boiling point. Ideal would be a max of 10deg below boiling

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    Default Re: Cylinder head temperature

    Quote Originally Posted by mplester View Post
    Depends on what pressure cap is used as the higher the pressure the higher the boiling point. Ideal would be a max of 10deg below boiling
    You've just contradicted yourself.

    A 1.1bar cap implies a coolant temp of 110 deg C at sea level. How can the head be below boiling?
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    Default Re: Cylinder head temperature

    Quote Originally Posted by jelo View Post
    You've just contradicted yourself.

    A 1.1bar cap implies a coolant temp of 110 deg C at sea level. How can the head be below boiling?
    118.6 not 110

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    Default Re: Cylinder head temperature

    For my own clarity: I assume CHT in this case actually means coolant temperature as it exits the head.

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    Default Re: Cylinder head temperature

    Quote Originally Posted by RoelfleRoux View Post
    For my own clarity: I assume CHT in this case actually means coolant temperature as it exits the head.
    no he said CYLINDER HEAD TEMPERATURE so that implies the metal material
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    Default Re: Cylinder head temperature

    Quote Originally Posted by mplester View Post
    118.6 not 110
    indeed which once again begs the question on 90 degrees?
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    Default Re: Cylinder head temperature

    If boiling is 118.6 and you subtract 10 = 108.6 not 90.

  14. #11
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    Default Re: Cylinder head temperature

    Strange that he asks specifically for CHT - not coolant temp in general.
    Coolant temp does not vary that much in the engine (block and head) because of the fast circulation.

    Maybe he was actually asking about EGT?
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    Default Re: Cylinder head temperature

    Quote Originally Posted by 4eTouareg View Post
    Strange that he asks specifically for CHT - not coolant temp in general.
    Coolant temp does not vary that much in the engine (block and head) because of the fast circulation.

    Maybe he was actually asking about EGT?
    Yeah..
    The EGT numbers generally posted on forums suggest that the gasses passing through the head to generate +100C coolant temperatures, should be 4 to 5 times higher than the coolant temperature. So at a specific moment it should be possible to get a head reading anywhere from 100C to 500C, depending on where you take the reading.
    Last edited by RoelfleRoux; 2019/08/20 at 12:55 PM.

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    Default Re: Cylinder head temperature

    Quote Originally Posted by mplester View Post
    If boiling is 118.6 and you subtract 10 = 108.6 not 90.
    aha then I misunderstood what you meant by boiling
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    Default Re: Cylinder head temperature

    Hi all, please see attached image for my cht and egt sensor setup. Name:  IMG_20190820_210855.jpg
Views: 167
Size:  39.5 KB

  18. #15
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    Default Re: Cylinder head temperature

    Very close to exhaust manifold? Probably not going to accurately indicate head temp ?

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    Default Re: Cylinder head temperature

    Quote Originally Posted by jelo View Post
    You've just contradicted yourself.

    A 1.1bar cap implies a coolant temp of 110 deg C at sea level. How can the head be below boiling?
    Boiling is not a function of only temperature, pressure also plays a part, hence the 1.1 bar cap NOT resulting in boiling at 110 C.

    Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere.
    In the case of a pressurised system, the pressure goes up and so does boiling temperature.

    Water boils at about 68C on Everest.

    https://en.wikipedia.org/wiki/Boiling_point
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    Default Re: Cylinder head temperature

    Quote Originally Posted by leonst38 View Post
    Hi all, please see attached image for my cht and egt sensor setup. Name:  IMG_20190820_210855.jpg
Views: 167
Size:  39.5 KB
    Is the temp probe for water temp installed in a waterport ? You need to have that as close as possible to the OEM temp sensor installed into a wateport.
    It is not what you buy its what you build.

  21. #18
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    Default Re: Cylinder head temperature

    Hi Grips, no it doesn't measure water temp. It's fitted to the head. I have a separate feed for water temp.

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