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Radiators: Dual Pass vs. Single Pass and how much it will take...

Discussion in 'The Garage' started by mikey_d05, Apr 27, 2006.

  1. mikey_d05

    mikey_d05 1 ton status GMOTM Winner

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    I'm currently looking at radiators for my buggy and I'd really like to have one I can slip down between my frame rails so I can lower the hood line. One of the things I've stumbled on is dual pass vs. single pass. The way I understand it a dual pass rad is the same thing as a single pass except it uses half the radiator to put coolant one way and half the radiator to push coolant the other way as opposed to a single pass which uses the entire radiator to push coolant one way.

    My understanding of heat transfer is that it's basically a function of time, and that the surface area of a dual pass would be the same as a single pass. However, the volume you can force into a dual pass radiator would be half of a single pass and the velocity would be doubled, basically rendering them two executions that are nearly equal in cooling capacity.

    Is this correct? Do I understand dual pass radiators correctly or am I off?

    My stock rad should be 31x19 and I've never ever had any problems with it going over the thermostat temp (210). Obviously it's a brass copper piece and I'm looking at aluminum stuff. If I ran a 180 'stat, seperate trans cooler and oil cooler could I get away with running a 26x19 or even a 24x19 aluminum piece? Single pass or double pass? Thanks for any input. My only other option would be to lean the radiator way back and that would screw up my plans for a 90 degree approach angle since I'd have to move the bottom of it out to the front of the frame.
     
  2. mikey_d05

    mikey_d05 1 ton status GMOTM Winner

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    TTT...someone has to know their chit about radiators.
     
  3. freeflow

    freeflow 1/2 ton status

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    Depends what motor u are gonna use. With a stock 350 and seperate tranny and oil coolers i think u would be fine going with a smaller rad with an electric fan.

    But then again what the hell do i know haha.

    When i get my damn project done we are gonna have 2 go wheeling.


    brad
     
  4. ryan22re

    ryan22re 1/2 ton status

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    just a friendly bump.

    shouldnt the decrease in flow equal and increase in cooling? coolant spends more time in the radiator, cools down more. right?
     
  5. mikey_d05

    mikey_d05 1 ton status GMOTM Winner

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    Bumpity bump bump.

    Coolant should spend more time in the single pass because you can push twice the volume through. Twice the volume means half the velocity, so I think coolant would stay in either for the same amount of time. That is of course if I'm correct in my assumption of how dual passes work.

    Come on guys, somebody's gotta know this. Don't make me take this to Pirate.
     
  6. marv_springer

    marv_springer 1/2 ton status

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    Well.... I can't advise on the "Single or Double" pass thing.... I thought they were all single pass - but I have seen differences as far as "cross flow" and "down flow". I guess I'll just tell you what I did:
    [​IMG]

    This is a pic of my 454 powered FunBuggy [rev 1 :laugh: ]... It uses a Summit aluminum [I think 24x19"] crossflow and I have never had any problems w/ it cooling my BB. I strongly recommend aluminum radiators...!

    Marv
     
  7. mikey_d05

    mikey_d05 1 ton status GMOTM Winner

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    So an aluminum single pass 24x19 will cool a big block. You're the man Marv :waytogo:
     
  8. marv_springer

    marv_springer 1/2 ton status

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  9. mikey_d05

    mikey_d05 1 ton status GMOTM Winner

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    Works either way. I was planning on trying to fit a 26x19 in there but I've gotta go measure tonight and see if it'll work. Even if it won't I should be able to get away with a 24x19 considering my engine is a stock SBC and will be in an open engine compartment.
     

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