need an electric fan expert

Heating, Cooling & AC

  1. peakandscoot

    peakandscoot Well-Known Member

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    I have a 62 Fury with a 383. Last year at the turkey trot i bought a cold case fan, shroud and 16 electric fan. Now that i put the engine in it turns out the fan will not fit. I tried moving the engine back but that was a no go. Didnt really want to throw all that money away and go back to a mechanical fan. Thought about putting it in the front and making it a pusher but thats a lot of trouble plus it will get in the way of my condenser. What im considering now is bending a new aluminum shroud and im fairly confident i could cut in 4 7 inch electric fans. Does any one know what the difference in CFMs would be if i were to do this? I tried to look up each individually but could not find it.
     
  2. Mike67

    Mike67 FBBO Gold Member FBBO Gold Member

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    Is it hitting the water pump? I know/think Derale/Flex-Lite makes a shallow shroud that offsets the fan and allows for a smaller one to be added...
    I believe there are others that also make custom shrouds.

    Screenshot_20200612-234252.png
     
    Last edited: Jun 12, 2020
  3. 70chall440

    70chall440 FBBO Gold Member FBBO Gold Member

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    The fans will move the same amount of air regardless of the shroud, but I think what you are asking is how efficient (or not) will be with a new shroud and that isn't an question anyone will have without some test equipment. That said, I would totally do exactly what you are thinking, I have a number of electric fans on several cars and I made shrouds for them and never gave much thought to the actual CFM when installed, I was much more concerned about fitment and clearing everything as well as working as I needed them to. Go for it!
     
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    • 451Mopar

      451Mopar Well-Known Member

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      Having two offset fans gives more clearance around the water pump pulley.
      Also, There are different thickness motors for the fans. The highest cfm fans (aftermarket, not sure about some of the OEMs) have thicker motors that may be a clearance problem. I have two 13" spal meduim profile fans that are 2.44" thick, and flow rated at 1168 cfm each.
      https://www.spalusa.com/products/fa...s-3-12v-30101507?returnurl=/products/fans/13/

      I looked at the high performance 13" fan that moves 1777 cfm. They are 3.45" thick and $67 more expensive.
      https://www.spalusa.com/products/fa...c-3-12v-30102044?returnurl=/products/fans/13/

      Cars not running, so have not verified how well they cool, but they do fit.
       
    • peakandscoot

      peakandscoot Well-Known Member

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      one reason i was thinking of 4 7 inch is when you have a big block in the 62 fury it is off set several inches to the passenger side of the car. I measured and am pretty confident i could get one in each corner and be good. Im pretty sure that 2 side by side fans will still be a problem.
       
    • origcharger

      origcharger Well-Known Member

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      Last edited: Jun 15, 2020
    • RJRENTON

      RJRENTON FBBO Gold Member FBBO Gold Member

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      IMO....
      When it comes to fans, impeller diameter relates to CFM as well as impeller RPM. Relate this to a shovel: the larger the shovel, the more material is moved per shovelfull. The same aspect applies to fans....the bigger the impeller diameter the more air is moved per given RPM. There are additional factors involved: the number of impeller blades and their pitch angle. The rule of thumb that "bigger is better" definitely applies. To accurately compare more fans with a smaller impeller diameter vs one fan with a large diameter you must look at TOTAL area presented. Shrouding affects the EFFICIENCY of the fan ability to move air by reducing the tendency for recirculation.
      Location of the fan, either on the front of the radiator or behind it, effects the performance as the air DENSITY is less on the hot or engine side of the radiator. Lower air density means MORE CFMs must be moved to acieve the same results, volume wise. But because the air is less dense, less HP is needed. Or...Refer to the following re gases..
      The density of dry air is 1.29 grams per liter (0.07967 pounds per cubic foot) at 32 degrees Fahrenheit (0 degrees Celsius) at average sea-level barometric pressure (29.92 inches of mercury or 760 millimeters).
      • At sea level and at 15 degrees C, the density of air is 1.225 kg/m3. This is the value of the ISA (International Standard Atmosphere). In other units, this is 1225.0 g/m3, 0.0023769 slug/(cu ft), or 0.0765 lb/(cu ft).1
      • The IUPAC standard of temperature and pressure (0 degrees C and 100 kPa), uses a dry air density of 1.2754 kg/m3.2
      • At 20 degrees C and 101.325 kPa, the density of dry air is 1.2041 kg/m3.
      • At 70 degrees F and 14.696 psi, the density of dry air is 0.074887 lbm/ft3.
      Affect of Altitude on Density
      The density of air decreases as you gain altitude. For example, the air is less dense in Denver than in Miami. The density of air decreases as you increase temperature, providing the volume of the gas is allowed to change. As an example, air would be expected to be less dense on a hot summer day versus a cold winter day, providing other factors remain the same. Another example of this would be a hot air balloon rising into a cooler atmosphere.
      And the effects of the "fan laws"
      The Fan Laws are a group of useful equations for determining the effects of a change in the speed, the diameter of the fan and the density of air in the system. They are most useful for determining the impact of extrapolating from a known fan performance to a desired performance. So, in short, the basic fan laws are used to express the relationship between fan performance and power.
      To start we will consider only the effect of a change in the speed of the fan on the flow rate, pressure and power consumption. We will assume that the fan size and air density are to remain constant.
      The first three derivations of the Fan Laws are predicated on a couple of assumptions:
      • That there is not an extreme difference in the change of rotational speed of the impeller in question and as such creating significant differences in the density of the air. However, it is unlikely that this would be a problem. You will not be looking at situations beyond the design speed of the impeller. Ignoring special applications, the upper limit for the RPM will be approximately 3600 (60hz supply frequency)
      • That there is no change in the diameter of the fan
      The First Fan laws: Volume of Air
      The first law of fans is a useful tool when working out the volumetric flow rate supplied by a fan under speed control or conversely working out what the RPM would be to deliver a required volume of air and hence what frequency to set a variable speed drive (VSD) to.
      Volumetric flow rate (V, m³/hr) varies directly proportional to the ratio of the rotational speed (RPM) of the impeller.
      The Second Fan Law: Pressure
      This second law describes the relationship between the pressure developed by the fan and its rotational speed. From this equation, we can see just how powerful the effect of increasing the rotational speed of the fan is on pressure development, double the speed and you quadruple the pressure development.
      Pressure (P, Pa) varies as the square to the ratio of the rotational speed (RPM, u/min) of the impeller.
      Eq. 2

      Equation-2-Fan-Laws-Pressure.png

      Where:
      p2: Pressure 2, Pa
      p1: Pressure 1, Pa
      U1: RPM 1, u/min
      U2: RPM 2, u/min
      Pressure Example
      The Third Fan Law: Power

      The third law provides the required power to deliver the performance change that the system designer is looking for. The cubic nature of this relationship between power and the rotational speed shows how even for small performance gains, large amounts of additional power are needed.
      Power (P, kW) varies as the square to the ratio of the rotational speed (RPM, u/min) of the impeller.

      Power-1-Fan-Laws.png
      Where:
      P1: Power, kW2
      P2: Power, kW1
      U1: RPM 1, u/min
      U2: RPM 2, u/min
      There are many different factors involved in making the correct size of the fan either by scientific methodologies or the "guess and by golly" principle.....I prefer the scientific approach.....the choice is yours as to method you prefer. If you want/need additional info, just Google three fan laws.
      BOB RENTON
       
      Last edited: Jun 15, 2020
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      • 440 4 speed

        440 4 speed Well-Known Member

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        How could Chrysler keep in business for HOW MANY years with using what they did. They should have died because of replacing overheating engines.
        Another comment. If overheating is so bad, how could they give a 50,000 mile warranty on the drive train. Exception Hemi and dedicated race cars. Have fun.
         
      • 70chall440

        70chall440 FBBO Gold Member FBBO Gold Member

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        So are you implying no one should use an electric fan? I agree that stock cars have operated for many years with mechanical fans with great success, however modified engines along with other changes in the engine compartment can negatively affect cooling capability. I would add that in some cases misunderstanding, poor products, etc. contribute to poor cooling which causes owners to seek other alternatives such as electric fans. Others choose electric fans to reduce parasitic HP loss as well. In other words, both have their place and there is a reason pretty much every modern car uses them.
         
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        • Axemaster24

          Axemaster24 Active Member

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          Can you post a couple pics of your application? We can see what you’re working with and provide the best advice.
           
        • peakandscoot

          peakandscoot Well-Known Member

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          here is what i have however once the engine was in and i attempted to attach the water pump i realized there was a problem. I bought it from cold case last November at Daytona they said it would fit but it doesn't. Now i think my best solution is to have a new should made and run multiple small fans. The small fans can be off set around the water pump to give me the clearance i need. 20191211_103236.jpg
           
        • RJRENTON

          RJRENTON FBBO Gold Member FBBO Gold Member

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          Out of curiosity, any thought to selling what you now have and purchasing a coordinated fan/shroud/radiator package from a single source supplier, now that you know the dimensions of what you need vs space available?
          BOB RENTON
           
        • peakandscoot

          peakandscoot Well-Known Member

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          That thought never crossed my mind. At this point i would probably lose to much. Also i think every build runs into hiccups along the way. There are not many 62 Fury convertibles out there. Probably none with 4 wheel power disc brakes, modern day power steering, AC, 65 727 transmission, and fuel injected 383 with a roller cam. So along the way i have had to adapt. If it were easy everyone would be doing it. Now i will have a one off cooling system.
           
        • Dan64

          Dan64 FBBO Gold Member FBBO Gold Member

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          Just throwing this out there, if you did sell what you have now you could go with a 26" Cold Case and that would give you move wiggle room to space your 4 fans out and also give you more cooling ability for a warmed up 383.
           
        • Axemaster24

          Axemaster24 Active Member

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          The easiest step would be to call Spal and see if their “slimline” product line has a 16” fan that will fit without modification. I wouldn’t build a fan shroud that puts the fan right up against the radiator since it wouldn’t pull air through the entire core.
           
        • steve340

          steve340 Well-Known Member

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          You could move the fan you have to the front of the radiator. If you can set that fan up as a pusher of course.
          I have the stock 22 inch radiator in my GTX with a 16 inch pusher fan mounted on the front of the radiator - no shroud required if you set them up as a pusher. Stock mechanical fan and stock fan shroud removed.
          No problems dealing with our summertime temperatures. Easier to work on the front of the engine also.
           
        • Dan64

          Dan64 FBBO Gold Member FBBO Gold Member

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          The same fan used as a pusher will be reduced to about 70 percent of its total efficiency, so i have been told. It really needs pullers with a full shroud that has about 3/4" gap space.
           
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          • peakandscoot

            peakandscoot Well-Known Member

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            Yes thats what i understand also plus a pusher interferes with my AC condenser.My mounts on my radiator will give me the gap space in need really i just need to get someone to put 2 90 bends on a piece of aluminum then i will cut new holes where i need them.
             
          • Brewzer67

            Brewzer67 Well-Known Member

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            Here is what I fabbed up for my '67 Coronet. Space was really tight also. 2 Spal 13" fit wat a little room to spare.

            Fan_Setup1.jpg Fan_Setup2.jpg Fan_Setup3.jpg
             
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            • ksurfer2

              ksurfer2 Well-Known Member

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              Check your PM's. I have a solution that may work for you. Plus, I am located in Tampa, so you can test everything out to see if it fits before buying anything.
               
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