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  1. #1
    Self Confessed Day Dreamer toomanytoys's Avatar
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    Cold Air Boost Pressure

    I'm having this "discussion" with a Seadoo owner, and you know how these guys are always right, I mean they bought the best ski and all... hahahaha

    So it goes like this. I'm chasing what I think is lower boost.

    In summer I was running ~17PSI now in winter I'm running ~15'ish PSI.

    Without stopping to think about this I thought maybe something is wrong, but now I'm not so sure.

    I'm thinking cool air hold less volume (is more dense) so given our supercharger is a "pump" it seems to make sense. It can only move a certain volume of air and that volume is colder so has less mass than before. Like putting air in a tyre and then heating the tyre, the pressure rises. If it's colder pressure drops.

    That's what I'm telling this n00b Seadoo owner, but he thinks there is more "pressure" in colder air.

    I'm 100% on more energy per PSI, but pressure no.

    Is the n00b Seadoo owner wrong or is it me?

    Mal.


  2. #2
    nicjak's Avatar
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    mal my speeds are also down since the b2b but our speeds have always been slower down under

  3. #3
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    Cold, dense air always means more power in my experience - esp boosted. You have to remember that after the heat of compression (blower) and then passing through the IC the charge temps are probably around 10-20 degrees above water temp, so IC efficiency is more of a critical parameter, perhaps your IC is fouled

  4. #4

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    Quote Originally Posted by Lake Wylie Skis View Post
    Cold, dense air always means more power in my experience - esp boosted. You have to remember that after the heat of compression (blower) and then passing through the IC the charge temps are probably around 10-20 degrees above water temp, so IC efficiency is more of a critical parameter, perhaps your IC is fouled

    i agree, colder intake air would give you slightly more power and not less power

  5. #5
    Self Confessed Day Dreamer toomanytoys's Avatar
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    Guys, I know the air contains more "power" that's not the question.

    It's more about PSI.

  6. #6
    nicjak's Avatar
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    mal im running same boost as up there nothing has changed, last ride out was only getting 116kph, up there 122kph, rpms all the same.

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    Quote Originally Posted by toomanytoys View Post
    Guys, I know the air contains more "power" that's not the question.

    It's more about PSI.

    cold air particle are already in a more compressed state than the hot air, so compressor would need to work less with colder air....i think psi would be same cold or hot

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    Self Confessed Day Dreamer toomanytoys's Avatar
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    so let's say you have X volume of air going to the intercooler at 40 degrees C, it cools the air, say by 10C, then it surely have less volume (same energy in a smaller package of course) then what went in??

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    Quote Originally Posted by toomanytoys View Post
    so let's say you have X volume of air going to the intercooler at 40 degrees C, it cools the air, say by 10C, then it surely have less volume (same energy in a smaller package of course) then what went in??

    Its for sure a great Fken question, part of me thinks it be the same pressure and at the same time i see your point.

    I need to burn a few more brain cells.

  10. #10

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    Quote Originally Posted by ange5583 View Post
    Its for sure a great Fken question, part of me thinks it be the same pressure and at the same time i see your point.

    I need to burn a few more brain cells.


    where's Sirbreakyaballs when u need him

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