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What do you guys know about double pass radiators?

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  • What do you guys know about double pass radiators?

    http://search.ebay.com/search/search.dl ... arch&fgtp=

    The only reason I started looking at these is because they have the inlet and the outlet on the same side like the z31. However, I dont understand how this "double pass" design can be any better than just a regular design. It still passes through the same amount of surface area. Seems like just a selling gimick.
    85 Z31 6.0 LSX turbo 766whp/792wtq
    04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

  • #2
    ub smrt 4 lif

    double-pass = coolant goes in-right-down-left-out
    normal = coolant goes in-down-out

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    • #3
      I did some lazy searching on google and ran across a few things. From what I gathered the double pass isnt so great because it requires a higher pump pressure to flow the same amount of coolant. Check this thread out.

      http://fsae.com/eve/forums/a/tpc/f/1.../r/97010898731

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      • #4
        get this one

        http://cgi.ebay.com/ebaymotors/19-X-...spagenameZWDVW

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        • #5
          Stinky wrote: I did some lazy searching on google and ran across a few things. From what I gathered the double pass isnt so great because it requires a higher pump pressure to flow the same amount of coolant. Check this thread out.

          http://fsae.com/eve/forums/a/tpc/f/1.../r/97010898731
          See I guess thats what I had a gut feeling about. I didnt think the double pass radiator could be much better.

          Guess i'll just stick with the normal core.
          85 Z31 6.0 LSX turbo 766whp/792wtq
          04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

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          • #6
            if you read stinky's link, half the people say it's great and half say it's bad...

            the ebay item I posted would fit perfectly in a z31 and has double the thickness of the stock radiator, so your "flow potential" should be equal, while the cooling will be better

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            • #7
              G-E wrote: if you read stinky's link, half the people say it's great and half say it's bad...

              the ebay item I posted would fit perfectly in a z31 and has double the thickness of the stock radiator, so your "flow potential" should be equal, while the cooling will be better
              Yeah I read the first page and part of the second. They start going into designing radiators.I dont really want to do all that.

              I did catch that some people said they were great and somone said it cooled TOO good. SO...

              The TOO good cooling I would love. My car has never been too cold but has been TOO hot many times :? That and the $260 or whatever seems like a pretty good price and it has good construction.
              85 Z31 6.0 LSX turbo 766whp/792wtq
              04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

              Comment


              • #8
                I don't think the diagrams really show what is happening.

                I think the biggest problem with cooling on our cars is either the condition of the radiator or the design of a cheap aftermarket. The stock rad is fine, but they don't last forever, and effiency degrades over time, plus they wear out. Cheap replacements have smaller cores and fewer fins per inch. Compound that problem with the companies that sell a decent radiator then either jack up the price, or change designs or suppliers to something crappy.

                I send out all my radiators to a guy that can properly flow test them and clean and repair them. Not all can be saved, and most people would rather buy a crappy radiator for $130 than a nice custom radiator for twice that.
                Chuck Stong
                300+ Parts and Performance owner
                http://www.300-plus.com
                2002 ZCOT president and always active member

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                • #9
                  not quite, the coolant also has to flow through an area to be considered efficient, you can have all the airflow you like but if the coolant doesn't circulate you don't benefit.... that's what my diagrams were meant to show

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                  • #10
                    I'm not sure you said anything I didn't say in that last reply, I did mention pretty much all your points about coolant and air flow and sizing relative to the car...

                    except I should point out that both the audi and caravan have larger radiators in cramped engine bays where the ambient temperature is much higher, so they need better cooling than you might think, and price isn't the issue because a caravan is a low priced vehicle and audi is high priced, they both have radiators of a similar size, the caravan's being slightly longer and the audi's being taller

                    one thing you screwed up: the thermostat doesn't affect cooling ability at all, the t-stat is used for maintaining a higher coolant boiling point and to prevent coolant falling below a set temperature...

                    simply put:

                    increasing the thickness of a single-pass radiator will give you more flow but minor increase in cooling capactiy

                    going to a double-pass radiator in the same size would require twice the thickness to equal the same flow, however the cooling capacity per volume is increased by a greater amount

                    the question becomes what is more important, cooling or flow? and like I said it's all relative, if you identified that you need more cooling ability then sacrificing some flow for efficiency might be the key

                    I could make the same diagrams for intercoolers albeit no-one makes double pass ones - they'd be way too restrictive

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                    • #11
                      I'm going with this one. Pretty much the same as the one that you pointed out GE but it doesnt have stamped end tanks and it cheaper. Oh its an inch wider, but I measured the stocker and it is 27" so...

                      http://cgi.ebay.com/ebaymotors/New-Alum ... enameZWD1V
                      85 Z31 6.0 LSX turbo 766whp/792wtq
                      04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

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                      • #12
                        yea I was leaving a safety margin, as you know the stock location isn't a uniform size/shape... good price... hope it fits

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                        • #13
                          G-E wrote: yea I was leaving a safety margin, as you know the stock location isn't a uniform size/shape... good price... hope it fits
                          I'll make it fit :lol:
                          Attached Files
                          85 Z31 6.0 LSX turbo 766whp/792wtq
                          04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

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