Large fan no shroud or small fan and shroud?

Heating, Cooling & AC

  1. Mark1972

    Mark1972 FBBO Gold Member FBBO Gold Member

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    Hey guys. I'm currently running a 17.5"H x 25.5"W 3 core, large tube, Champion aluminum rad purchased from Jegs. They offered a shroud for it which I didn't buy, because the shroud was made for a 16" fan, and I am running an 18.5" clutch fan that came from the 1977 New Yorker donor car. My questions is, would I see better cooling from the 16" fan with a shroud, or keep my 18.5" fan and no shroud? Cooling as is only becomes a problem in 90+F when the car is sitting idling, like in heavy traffic. My 440 has a 195F stat, but will get to 215 in the conditions stated above. I'd love some feedback. As always, thank you.
     
  2. Gort

    Gort Well-Known Member

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    I have a Champion radiator and I added a couple little brackets to it so I could mount my original shroud and keep using the fan/clutch like you have...Seems fine so as cooling but I never had any issues before...I run a 190* but I just have the factory gauge so I'm not sure what it actually runs at...It stays steady at the lower end of the normal range sitting in traffic or whatever...
    IMG_5628.JPG
     
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    • diesel_lv

      diesel_lv FBBO Gold Member FBBO Gold Member

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      If you have a factory shroud for a 26" radiator, it will support a 19" fan. If you don't have the factory one, go to Mancini, they have a Mopar authorized fan shroud. Always best to run largest fan you can "With" a shroud.

      A thermostat temp is not what the engine will run at. It is when the t-stat will "start" to open. They are fully open about 15° warmer. ie.. 180=195, 195=210.
      I live where my summer temps are 120+, 496" stroker. 19" fan w shroud, 2 row 1.25 inch each aluminum radiator, a/c car, 180 t-stat and idles at 196 in the summer.
       
      Last edited: Jun 2, 2021
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      • Canadian1968

        Canadian1968 Well-Known Member

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        I don't get why people running a 195* stat are confused when their car runs in the low 200s

        195 is when the stat STARTs to open. If it stays at 215 I would say things are pretty normal for those conditions . If your looking to lower things, why not put in 180*

        I think most will agree any setup with a shroud will work better than one without. The shroud allows you really to focus the air being pulled threw the rad . This is very important at idle as the fan is not spining as fast. So whatever air that fan is moving you want to make sure its pulling all that air threw the rad and drawing that heat out .
        Without one the fan is just pulling air from anywhere it can ......a lot of wasted air flow.

        I personally just switched to 2 12" electric fans in a nice tight shroud works great .
         
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        • WileERobby

          WileERobby Well-Known Member

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          I had a champion radiator and I threw it in the garbage.
           
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          • Mark1972

            Mark1972 FBBO Gold Member FBBO Gold Member

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            I've contacted Mancini as they sell the rad that I bought from Jegs, part number CCSCC375. I've asked for a shroud that will work with my fan. Thanks for the heads up guys. We'll see what they say.
             
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            • Ron H

              Ron H FBBO Gold Member FBBO Gold Member

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              After going through some cooling gremlins doing some research on this, some aftermarket shrouds can make things go from bad to worse. A deeper tunnel can skew the airflow and includes where the fan sets inside of it. A shroud is usually helpful to direct airflow to the engine. In my case I went from a 4-blade to 7-blade fan and found an OEM shroud. I installed a 160-temp thermo as when I drive my car it’s in warmer weather anyway and have the core bypassed. Other tidbits I did included a top-seal over the radiator to direct more air to the engine (an option on my car that it didn’t have w/o AC). Also reduced the anti-freeze to water mix in the area of 70-30 since my car sits in a heated garage during winter anyway. A higher anti-freeze ratio can contribute to more engine heat. At the advice of a friend, I added a product ‘Water-Wetter’ and add some of this when needing to add to the rad maybe once a season.

              Another odd thing, doing all sorts of research, is higher vis oils can create more engine heat. I was sold on heavier weight ‘racing’ oil and noticed the oil pressure always super high. This kind of racing oil, by some oil gurus, is strictly for racing, not street driving. I reduced the weight finding oil pressure more in range with what it should be. I have solid lifters so need to run a hi-zinc oil. Just my two pennies…
               
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              • Ranger16

                Ranger16 Well-Known Member

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                From personal experience, a fan shroud is worth it's weight in gold.

                For what it's worth, when I got my Road Runner, it was running 210° or more. I replaced the OEM 190° stat with a 180° and added a shroud. Now I rarely run over 190° with an OEM radiator and OEM 7 blade direct drive fan.
                 
                Last edited: Jun 3, 2021
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                • diesel_lv

                  diesel_lv FBBO Gold Member FBBO Gold Member

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                  Don't blame you. They market "3 row" those 3 rows are 5/8" each. Plus 1/4" between. The coolant volume is 1-7/8", total core thickness 2-3/8". A 2 row is 1-1/4" each equalling 2-1/2" coolant volume and total core thickness of 2-3/4". More cooling capacity.
                   
                • MoparLeo

                  MoparLeo NRA BENEFACTOR LEVEL LIFE MEMBER FBBO Gold Member

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                  Simple answer. Run what components the factory installed when new. It has always worked. Don't try to reinvent the wheel.,
                  Who knows what worked better than the engineers that designed these systems in the first place. Backed by thousands of hours of testing and millions of dollars in tooling/production costs.
                  Problems tend to occur whenever someone strays from the factory specs whether it is cooling system, engine/fuel system etc...
                   
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                  • furious70

                    furious70 Well-Known Member

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                    I also made the oem shroud fit on that style radiator.
                     
                  • RJRENTON

                    RJRENTON FBBO Gold Member FBBO Gold Member

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                    EXCELLENT ADVICE.....most, but not all, after market suppliers are interested in one thing....selling radiators. Remember, its the fins/inch count, which determine the heat exchanger's surface area of the radiator; the tubes that connect the inlet tank to the outlet tank simply convey the entrained heat in the coolant to the fins where the heat is transferred to the air stream.
                    Most aftermarket suppliers NEVER disclose the fins/inch count, just the number of tubes and their size....wonder why? The higher the fins/inch count, the greater the surface area the heat exchanger....and better cooling.
                    BOB RENTON
                     
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                    • Mark1972

                      Mark1972 FBBO Gold Member FBBO Gold Member

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                      On Champion radiator part number CCSCC375, like the one I have, the fins per inch is 14-16 fins per inch advertised. Not sure if that's good, bad, or average. Honestly I never looked at that before. I always learn something from your posts Bob. I'll link the rad below.

                      https://www.manciniracing.com/chalra4.html
                       
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                      • RJRENTON

                        RJRENTON FBBO Gold Member FBBO Gold Member

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                        Thank you for your email and link.....interesting. The www fins are formed by a special machine, developed by Modine Corp, A little bit of my background....in another life time, I use to design high temp heat exchangers, specifically gas to gas in heat recovery systems, using exiting waste gas to preheat incoming gas process streams, as in unfired pressure vessels, but using ASME methods. The other types of heat exchangers are: gas to liquid and liquid to liquid. Gas to liquid (automotive cooling systems) and liquid to liquid (chemical process ) as in Alpha-Laval plate type exchangers with 2 different liquid streams. In all regards, surface area of the heat exchanger is paramount along with velocity of the exchange media and its volume and the temperatures involved, both the incoming and exiting temperatures of both streams. The principles are directly related to the fundamentals of thermodynamics.
                        If you're curious, Google heat exchangers and thermodynamics....a wealth of information and explanations....
                        BOB RENTON
                         
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                        • Mark1972

                          Mark1972 FBBO Gold Member FBBO Gold Member

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                          Hey guys. As always, thank you for the responses. Always helpful. I've ordered a Mopar replacement shroud from Mancini for a 26" rad. After looking at the dimensions of it and my rad, I think it should be straight forward to fit it up. The electric fan I mounted when sitting at idle in +30c(86f) certainly helps, so now the shroud should take care of any overheating issues. I'll post again when it arrives and is mounted.
                           
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                          • JG71B

                            JG71B Well-Known Member

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                            I just dealt with all this in my 71 the past week. Got the system sealed and overheating issues arose. Similar set up, 78 400 4bbl from a New Yorker, using its original 7 blade clutch fan, 440source pump housing, 195 tstat and an ebay aluminum radiator ($130 shipped, 5yr warr!). Fan about 1.5" away no shroud, kept running hot and would slowly overheat. Turned it off and it puked out the overflow. Ended up using the shroud you mentioned from Jegs but thru ebay, a small block w.pump pulley (about 10% smaller od) and a bottle of water wetter with 30/70 coolant/water an inch below full and temp now holds low 180's- mid 190's on the laser 90* outside. Shroud made all the difference, this is the radiator...
                            https://www.ebay.com/itm/375-3-Row-...-/392277934001?_trksid=p2349624.m46890.l49286
                             
                            Last edited: Jun 27, 2021
                          • Mark1972

                            Mark1972 FBBO Gold Member FBBO Gold Member

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                            So my shroud came in. Of course it wouldn't fit with my current fan, so I swapped my current fan for a 17" 6 blade flex fan, which fits the shroud nicely. Where I've screwed up is while the shroud bolts directly to the Champion CCSCC375 radiator, there is a 3/4" gap along the top and bottom between the rad and the shroud. I've got to seal that up some how. I'm more concerned with function than form. Any thoughts on closing this gap to force the maximum air through the rad?
                             
                          • furious70

                            furious70 Well-Known Member

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                            Door/window frame insulation
                             
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                            • Ranger16

                              Ranger16 Well-Known Member

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                              The number of ways to close that gap are probably limited only by your imagination.

                              Maybe some heavy gauge aluminum tape and then paint it flat black?
                               
                            • droptop

                              droptop Well-Known Member

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                              What you are describing is a lack of air flow. Yes a shroud will help at low rpm’s and at idle.
                               
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