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Fans, mech.vs electrical??

Discussion in 'The Hokey Ass Message Board' started by Cosmo49, Sep 17, 2007.

  1. squirrel
    Joined: Sep 23, 2004
    Posts: 47,424

    squirrel
    Member

    on a vehicle with an open engine compartment, the best solution is to remove the fan altogether, and plan your trips accordingly....
     
  2. 1/4 mile at a time?
     
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 47,424

    squirrel
    Member

    or just so you don't get stuck in traffic. I know some guys who don't run a fan, they seem to do just fine...although the cars in question are not used for daily commuting!
     
  4. Brad54
    Joined: Apr 15, 2004
    Posts: 6,014

    Brad54
    Member
    from Atl Ga

    All the "trad this" and "poser that" bullshit aside, here's what I'd do if I were you:
    Find a steel fan shroud from something like a '54 Buick--it's a stamped steel shroud that fully encloses the back side of the radiator. The stamped steel looks right at home in an early engine bay, plus, you can cut and weld to work, rather than a later plastic shroud. I think caddilacs and Pontiacs also used this type of shroud, and I've seen stamped steel shrouds on earlier cars too. Look around and find one.
    Then, put a 7-blade mechanical clutch fan on your water pump. It'll move a ton of air for you, especially with a shroud, and the clutch is actuated by underhood temps--it'll "come on" when the temp reaches a certain point, and it won't when you're honkin' on down the highway. That'll give you better economy, plus it'll give you lots more time before overheating in traffic.
    I did this on my '62 Suburban, and without a shroud, and the fan set waaaay far back from the radiator (I have a new 4-core for a '62 3/4-ton truck radiator, which is bigger than the factory 1/2-ton), the tired 283 never overheated this summer during my daily commutes...and when I pulled the engine out, there was enough sludge in the block water passages that I had to poke into the lower plugs with an ice pick to drain the water out of the bottom of the block.
    The stamped shroud will look good in the engine bay, it'll look great chromed ('50s custom) or pinstriped, and it'll hide the clutch and most of the 7-blade fan.
    I got my fan blade and clutch from YearOne (I work here). The fans come in several different diameters too, so match one to the shroud you get.

    -Brad
     
  5. I saw a really nice camoflage set up for a electric fan right here on the HAMB. If he wants an electric fan that's his business. If he wants to stay traditional then obviously he needs to do a little more research. As for some of the other ideas, I don't recall seeing shrouds or clutch fans on any of the '20s - and not many late '50s cars I have owned, so wouldn't that make them non-traditional also?

    I used to go to muzzleloading mountainman rendevous years ago and we would be careful to hide or camoflage modern stuff (ice chests, etc.). Then one group came along and started a rule the unless it was an item was pre 1840 or copied from a pre 1840 item then you couldn't have it in camp. Anyone noticed there aren't as many rendevous being held these days?

    I guess what I am saying is that some times a new guy may start out missing the mark on a traditional "theme" but as his skill and knowledge grow he will come around. And a helping hand instead of harsh criticism will make sure he hangs around long enough to mature into the traditional rod guy.
     
  6. scootermcrad
    Joined: Sep 20, 2005
    Posts: 12,368

    scootermcrad
    ALLIANCE MEMBER

    Here we go again...

    ...traditional drama
     
  7. Brad54
    Joined: Apr 15, 2004
    Posts: 6,014

    Brad54
    Member
    from Atl Ga

    My '54 Buick came with a factory shroud, I bought a spare from a '55 Buick, and had a '58 Buick with one. In fact, the 1955 Buick TSBs list a fix for the metal shrouds rattling at 60mph and faster. These are nice, stamped steel full-coverage shrouds.
    Then of course there's the "half a 55 gallon drum" type found on '58-'60 Chevys, and in a junk yard a couple years ago, I saw a narrow (side-to-side) shroud, not very deep (rad-to-engine), full length stamped steel shroud on a late '40s or early '50s car...I don't remember if it was a Ford, Olds or what, but it was from that era. The Chevy one was also found on pick-up trucks, and was modified for the '62--the barrel hoop covers more area, and is more funnel-shaped, being wider at the radiatr than it is at the fan. I've had my '62 for a year and a half, and have only seen two of the '62 style (both on ebay--bought one for $100, missed the other) and two of the '61-older style, both in junk yards, and both rotted to hell. Saw a third one that style pictured on a craig's list truck...but I've looked at dozens and dozens of these trucks in the last two years, and have looked through all the trucks in the member's galleries on Stovebolt.com, and the shrouds are ALWAYS missing. My guess is, as radiators and water pumps were replaced over the years, the annoying shrouds were thrown in the corner of the garage. Same with cars. I'll bet several '50s cars came with shrouds.

    On a '49 Chevy pick-up truck, this set-up would be perfect...and the shroud would cover the clutch, so you'd never see it. That's what I'm doing on my '62 Chevy truck...they didn't have clutches then, and I want that truck to look period-correct--just a different period! Form AND function...the best of all worlds. Planning trips according to how far you can go before your 4-blade fan can't keep the engine cool on a July afternoon is stupid. It may be "trad" but it's still stupid. Driving our cars is traditional too. I'd rather drive.

    -Brad
     
  8. SinisterCustom
    Joined: Feb 18, 2004
    Posts: 8,269

    SinisterCustom
    Member


    "MOST" new cars have the engine mounted "wrong".....ie. sideways, preventing a "proper" fan to be mounted......:p

    HUH?????:confused: The shroud is for the rad, when designed correctly, will help the fan PULL alot of air THROUGH the rad......doesn't matter if the engine compartment is open or closed......may be better, as the air now warmed from going through the rad, is dispersed, rather than 'stuck' in the engine compartment.:D
     
  9. scootermcrad
    Joined: Sep 20, 2005
    Posts: 12,368

    scootermcrad
    ALLIANCE MEMBER

    This is a VERY good point actually! It doesn't matter if you have an open hood or not. It's the design of the shroud that makes a difference. Of course an open hood will allow hot air to escape easier, but it doesn't necessarily mean that you will get more efficient flow through the radiator.

    Example. On our pretty non-traditional 35 coupe, the hood is off, we run two electric fans on a Walker Z-series radiator. (We just couldn't make a mech. fan work for our application because of the angle it sits at and the room we had) It's the biggest radiator and fan combo we could jam in there. We spent money on very high quality fans. WE GET HORRIBLE COOLING! If you put little streamers in the airflow as the air is pushing through the radiator, you can see that there are actually streams of air going AROUND the outside of the radiator and grille shell, pulling hot air back into the radiator. NOT GOOD! Among the make over that the car needs already, this is something that needs to be addressed.

    Point being... it's not size, or quality or what type of fan you're running (in most cases) it's the way you handle the air with the fan. It just doesn't matter for some engine/radiator combinations, but on some of these smaller cars with BIG engines in HOT places, it will make a world of difference on shroud selection and how the air is being moved/handled.

    Not arguing. Just stating. :cool:
     
  10. I stand corrected, I never messed with anything newer than a '56 in the Chevy line and did have a '58 Ford but everything else I had was in the 30s and 40s before getting my '27 T. I am trying to remember but I don't think my '38 Packard 120 had a shroud and my '36 Dodge business coupe certainly didn't.
     
  11. Cosmo49
    Joined: Jan 15, 2007
    Posts: 1,214

    Cosmo49
    Member

    [​IMG]

    Not much room for a fan clutch. That's a flex-a-lite 16", I don't overheat much despite the overflow in the RC Cola bottle. I like the idea of a fan shroud, 4" wide perimeter with 4 'L' brackets to the radiator support.


    [​IMG]
     
  12. leftcoast66
    Joined: Aug 30, 2006
    Posts: 56

    leftcoast66
    Member
    from Duvall

    I've got both on my c10. The electric fan works great, but drains the battery a lot so I have issues runnin the electric fan w/ my air compressor for the airride. That's w/ a powermaster alternator aswell.
     
  13. squirrel
    Joined: Sep 23, 2004
    Posts: 47,424

    squirrel
    Member

    That particular fan blade is about the worst design there is....could you maybe put a stock 4 blade fan on it? or is clearance too tight?

    A shroud would definitely help pull air thru the rest of the radiator.
     
  14. Cosmo49
    Joined: Jan 15, 2007
    Posts: 1,214

    Cosmo49
    Member

    Clearance is WAY too tight. I don't trust a 58 year old fan blade, besides the original wouldn't fit. That's a '56 235 with the low water pump.
     
  15. Brad54
    Joined: Apr 15, 2004
    Posts: 6,014

    Brad54
    Member
    from Atl Ga

    Definately use a shroud--that will help a bunch, as it makes sure that the air isn't cavitating, or getting pulled from around the sides of the fan back through it, as that's less resistance than pulling air through the radiator.
    How about a factory or reproduction 7-blade steel fan?
    Or, to gain a little clearance, can you notch the upper bar on the core support to clear the top tank, and move the radiator forward an inch or two?

    -Brad
     
  16. FuelFC
    Joined: Feb 12, 2003
    Posts: 764

    FuelFC
    Member

    Dammit just lost a long post.

    Shroud it, use odd number blade fan and whatever you do get rid of the flexiflyer.

    Will post more in a few when I can find the rest of what I had.
     
  17. FuelFC
    Joined: Feb 12, 2003
    Posts: 764

    FuelFC
    Member

    This area is a part of my business and I will help you with a few things here I will put in two areas of the post.

    Staying out of the trad or not areas.

    1) Nothing is free. If you are cooling with electric or belt it is still HP. Period. 746 Watts per Hp you can't cheat this I have tried many times. Mr. Watt and that physics guy Newton prove this to me every damn day. If you need 10HP cooling it is 7,460 watts. Fact.

    2) Shroud information. General rule I said general is 1/3 of fan out and 2/3 fan inside of shroud for proper immersion to get max cooling. And make sure you make the shroud transition from the square to the round fan shape. Just putting a round tube in the middle of the pack sets you up for an immanent failure especially in aluminum packages. You need to cool the whole package not create hot and cold spots. You will have fatigue issues and odd cracking if you do not pay attention to this.

    3) What works in Drag Racing for cooling is not generally a good idea for the street. 7-15 HP gain by not running the fan is ok on the track but you won’t get far on the street.

    4) Big trucks class 8 use mechanical due to the fact they need at least 70Hp of cooling. Anyone seen the size of a 12V 70HP electric fan motor size? Huge! And not very practical.

    5 Yugo or Lambo or even a Geo. Materials folks and heat dissipation are the keys for newer models. Aluminum heads/blocks….north or south east or west there is huge difference in all models and cooling characteristics.

    6) If you run air it is really a good idea to run an electric fan at least for the condenser. It saves on life of compressor and valves. Really.

    7) Fan Clutches either electric or viscous work and work well. However you must know what a good viscous is and isn’t. Locked up or not and operating to proper temperature. Electric must turn on and off at the right set points.

    8) Electrics can be concealed very well (paint it same color as rad pack.

    9) Keep everything clear and remove all obstructions at least 3” in front of radiator or cooling package. Fan must run unobstructed sweeping area so blades do not load and unload to keep flexing to a minimum. Keeps fatigue down.

    10) Use good blades with odd count. Go back to Newton and study your fluids power books. There is a reason. More blades the better, generally. Look for good angle of attack. And NEVER use a Flex blade over 14” in diameter. Period. Flex blades are great but unless you know what to do, where to look and know what the operating characteristics are stay away. Use it for your ceiling fan. Or a clock. Squirrel is right on here (more below on this subject).

    11) Beat to worst in fan materials.
    A) Plastic or actually glass filled nylon for you phobes
    B) Metal
    C) The previous two (Flex is a limp home blade unless you know what you are playing with and want to dig deep.

    OLDER INFO FROM ONE OLDER POST I MADE:
    1st thing is blade to radiator clearance. A general rule of thumb to start is 3/4 to 1" space from fan to radiator. This will allow for flexing and movement of blades

    2nd thing is the clearance from blade tip to shroud. If you are not running one and have no problems good. If you are having heat issues then put one on! Clearance from tip to shroud should be 3/4" on average. NOW take into account for motor and tranny mount movement along with total chassis flex. If unsure go a little bigger so it doesn't hit! And inspect the tips after running it hard to see of they are rubbing or chaffing.

    3rd thing. Flex fans. They are not too good for the street. There are millions of flex fans out there. Really. You would be amazed at the number of flex fans in vehicles and industrial applications. They go BOOM! And yes metal fatigue is the culprit but you can fatigue anything plastic or steel too! Just keep pushing past the modulus it was intended and it will fail.

    It is generally (I said generally) not the fan itself that is the issue for bursting (technically term for kablewy). RPM is usually the cause. I run a flex fan and I run my big block up to 8 grand. No problem, but my fan ratio is .73:1 and only 12” in diameter (way underdriven) and it is very well within the burst limit. BTW this same fan has been on 4 or 5 cars! I use this blade due to the fact it cools well down low and lays flat at RPM That is what a flex blade really does and was intended for when originally designed!

    Fans are rated by a number of specs but the main one is burst speed in feet per minute. If you go past that line it will go boom. Using a 24" steel stock blade and replacing it with a 24" flex blade is not exactly the best idea. Most times if you look at line to line applications you go up or drop 4-6 inches on different composition blades, See first sentence!

    Fans are also rated by air movement. This is called CFM Yup cubic feet per minute. That is what is measure at the whole RPM range up to burst or layover of the blade.

    There are sheets available to the general public called Fan Curves. Use them and pay attention to ratios!

    Just a primer but should get you where you need to go for now. Post if you need more pr PM me.

    Happy motoring!
     
  18. Von Rigg Fink
    Joined: Jun 11, 2007
    Posts: 13,428

    Von Rigg Fink
    Member
    from Garage

    Ok all the bullshit aside..a mechanical fan will run when the engine runs..thats when you need it to run..an electric fan can be made to run when ever you want it to..or it can malfunction when ever you dont want it to..but the mechanical fan will not quit unless the engine (the source of heat) quits..end of story//or so i would think
     
  19. cruzr
    Joined: Jan 19, 2006
    Posts: 3,125

    cruzr
    Member

    I run a MECHANICAL fan on my flat powered Track Roadster, and my 31 coupe with small block,,,,,,,,,,,,,,,both run COOL .............both look COOL !!!
     
  20. AHotRod
    Joined: Jul 27, 2001
    Posts: 11,144

    AHotRod
    Member

    \


    Excellant job !
    Extremely informative.
    Thank You for taking the time for all of us.
    Glenn
     
  21. Cosmo49
    Joined: Jan 15, 2007
    Posts: 1,214

    Cosmo49
    Member

    FuelFC, Brad54, I too am blown away by your sound, practical advice. Thank you.

    There is a CAD plate available for the Chevy 235-262 straight six to mount the water pump/fan assembly in the upper position, 1954 and earlier engines. This move I believe would give me more fan clearance from the harmonic balancer and the higher position would blow air to the upper portion of the radiator (heat rises).

    I have a couple questions.

    Can you reccomend a particular brand of fan? All the flaps carry are flex-a lite clones.

    Really hard to get my head around your reccomendation of an odd # of blades, all the odd ones I've seen have non symmetrical blades and I just think 'bad harmonics'.

    I guess a good start is to at least get rid of the 16" fan I've got and go with the 14" you suggested.

    Don't understand the bad to worst fan materials in 11, what material is best?

    Thanks, Cosmo
     
  22. hotrod mike
    Joined: Nov 21, 2006
    Posts: 1,728

    hotrod mike
    Member

    Great post FuelFC! Lots of good information there. Thanks for the time and effort to post it. Mike
     
  23. Brad54
    Joined: Apr 15, 2004
    Posts: 6,014

    Brad54
    Member
    from Atl Ga

    Yeah, the harmonics always threw me too...and what's REALLY cool is when you look at them, the blades aren't spaced equally apart. You can see it on a 5-blade fan, but it REALLY is evident on a 7-blade. If you look at a metal OE-type fan with odd blades, there is a balance slug on them.
    My understanding is that the odd spacing is so the air doesn't cavitate at the face of the fan blade. If you think of air as a fluid, and imagine the blades taking a "bite" of air as the blade spins, you can see that the fan spinning at high rpm might just create the effect of becoming an almost solid wall if the blades are evenly spaced. With the odd spacing, it breaks that up and the fan will keep grabbing air, rather than blocking it.

    Again, not to pimp YearOne, but we carry 5 and 7 blade fans in different sizes...I know this because I spent a LOT of time going through our catalog to find a fan for my '62 Suburban. I went through a lot of different options and sizes before selecting the one that gave me the clearance between the blade and the shroud that FuelFC described. If I didn't work there, I'd have done the exact same thing. I poured over our catalogs AFTER I tried with with two different junk yard fans that turned out to have slightly tweaked blades. One was pulled by someone else and sitting on the engine, one I pulled off what I thought was an untouched truck engine. When I got each home, one blade was clearly bent--and it didn't happen on the way home sitting on my front floor board. After that, I started flipping through the catalog and went with a new fan. I went with a 7-blade rather than a 5, because I drive it every day in Georgia...that includes hot summer days, and getting stuck in traffic.

    Water Wetter will also help--in Florida I noticed several degrees improvement on my Buick. I also have a 160-degree thermostat, while most people run a 180-degree. I think that having the t-stat open sooner means I can maintain a cooler temperature, rather than having the fan try to play catch-up. It gives me a lot more time in traffic before things get hairy. If I'm sitting there at 170 and it starts to climb, I have a lot more time before 210 degrees/overheating than if I'm sitting there at 190 degrees and it starts to climb. Again, this is for Atlanta summers...Once fall gets here, I'll pop in a 180-degree for the winter.

    -Brad
     
  24. FuelFC
    Joined: Feb 12, 2003
    Posts: 764

    FuelFC
    Member

    Try to put the fan in the middle of the package or as close to as you can get. A little higher is better that lower. Heat does rise there Grasshopper however it is flow in the rad (I love this all the canadians speak this way) that matters and you are cooling either cross, up or down flow so heat rising doesn't really paly all that much here. And the hot goes in top on majority of rad's :) then down right?

    There are many good manufacturers of fans out there. Flex a lite is a good brand and they have different styles other than the flex version. Borg Warner, Horton, American Cooling Systems and a host of others are out there and are all good. Find an independent truck parts store in your area. I believe Ross Equipment is close to you. They have catalogs not computers that ask stupid questions. They can take your specs (diameter, mounting pattern, number of blades, material and pitch width) and find what you need. It might not be on the shelf but they can order it in, in a few days.

    Oh yeah pitch width. That is the side view of the blade or like the height of the fan if layed on the floor. Also you can get reverse, neutral or forward sets in reference to the mounting to the rear of the blade. These also come in increments too so you can get damn near everything you need to fit your car by just asking and looking.

    Odd seems wrong and I understand but all of us in the busness learned a ton over the years and air is a different animal when it comes to moving it efficiently. Looks are unimportant as well symetry when it comes to working right and flowing max airflow over a range of RPM's. Harmonics only come into play if it is unbalanced no matter the material or blade number. No worries on that end. That said you might only find an even number in your size just get the max number you can and look at the flow rates.

    DO NOT go by my diameter! I am not normal and I have a large package...I mean radiator cooling package. Plus I abuse the piss out of my shit and I set mine up for 8K RPM (and I use a camoelectric in front of package behind grillshell) Use the biggest blade you can within reason leaving about one to two inches from the sides or tops of the tanks. That should dictate your fan size. And makes for easy shrouding. Use a shroud when and wherever possible.

    Sorry of the confusion Plastic is the best in my book. Better peripheral velocity and better flow rates as well. They flat work like a banshee. Metal is ok too and more traditional and will be fine just get everything you need to do the job and more.

    My disclaimer: Flex fans have to be really looked at to see if it is right. They have their place. An average rod or street car no need for them really and have caused many a headache. I use one yes but I want it to lay over at 5500 RPM and go flat. That is what they do at high rpm. People have bought them thinking it will move more air. True to a point then it lays over and gives less. The fan curve on a flex looks kind of like a broken bell curve it goes up then down pretty fast. USE at own risk and use them right.
     
  25. scootermcrad
    Joined: Sep 20, 2005
    Posts: 12,368

    scootermcrad
    ALLIANCE MEMBER

    Wow. uhhhh... wow! Very good info here!
     
  26. DieGrindersPres
    Joined: May 26, 2007
    Posts: 91

    DieGrindersPres
    Member

    gotta tell you... easier to change electrical quick if there are problems on the road.
     
  27. DirtyThirty
    Joined: Mar 8, 2007
    Posts: 2,396

    DirtyThirty
    Member
    from nowhere...

    You really think so? I'm curious as to why?
    What even goes wrong with a mechanical fan? ( other than flex fan disintegration )
     
  28. fms427
    Joined: Nov 17, 2006
    Posts: 864

    fms427
    Member

    Regardless of traditional or not, a good summary would be : Mechanical fans can move more air,ie:the engine puts out more horsepower than an electric motor can, BUT electric fan can put out air when you most need it - at low speed and idle. Mechanical fans tend to waste a lot of power at higher engine speed, which is the reason for fan clutches.Most new cars use electric fans for packaging reasons - east/west engines, restricted space, etc, and many new cars use both. If I were looking strictly for performance, I would use ane electric fan and only use it when needed. My road race cars have an electric fan that is used only going into and out of the pits, as it is not needed on the track - plenty of ram air. Hope that helps !
     
  29. beetlejuice55
    Joined: Feb 18, 2007
    Posts: 738

    beetlejuice55
    Member


    this doesn't make much sense to me. how can an electric fan cool the motor, once the motor is shut off ?
    unless you have an electric water pump, there is no water circulation once the engine is shut off. a fan blowing on the radiator with the engine off...will just cool the radiator. the engine will stay hot, as long as there is no circulation.
    besides that...electric fans are ugly on trad. rods in my opinion.
    on a relatively stock engine...h.p. gains by going to an electric fan will not be noticeable. but, and electric fan will help with air flow, while idling in a traffic jam on a 90 degree day. if a stock engine doesn't stay cool with the stock mechanical fan...there is another problem like a plugged radiator, or weak waterpump.
    if you insist on an electric fan...the right way to do it is to have it pull air through the radiator, and use a fan shroud. you can set up electric fans to push air through the radiator, but it's not as effective.
     

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