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Thread: V12 engine cooling info and knowledge, sharing the love:

  1. #1
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    V12 engine cooling info and knowledge, sharing the love:

    Guys, I received this as an email, probably as a response to other vehicle enquiries. The sender appears to claim some knowledge of helping to keep cool V12 engines, design of cooling systems etc that I thought may be of use to builders of Countachs etc with V12s, or maybe other engines. I remember after reading the build thread of the Audi V8 engined Lotus Esprit that cooling was a major issue..

    I can't verify or vouch for the sender or the information, but thought I'd share it just the same. I'm not responsible for the content etc. etc....

    K9

    " V12s - Our Passion?
    Good afternoon,

    if this email has been sent to you in error then we apologize, you can easily remove your name below by unsubscribing.

    Although v12s started out 16 years ago with a Jaguar XJS V12 (you can read more about that at
    our website [www.v12s.com] ), we have since expanded what we do, to cover most British and European makes as well as some American cars.

    Our passion for anything that has a V12 hasn't changed, our focus on the things that can be improved with modern technology hasn't changed either.

    Cooling V12-engined cars of the 60s, 70s, 80s and 90s isn't that hard with the modern technology that we have now.

    Read my article '
    Cooling System Design and Your Engine'

    There are six essentials to cooling a V12:


    • electric cooling fans mounted on an aluminum fan shroud
    • a temperature controller that activates the electric cooling fans at the proper temperatures
    • post-shutdown cooling
    • additional fluid capacity in the cooling system
    • an aluminum radiator
    • waterless coolant

    So, you ask:
    Why electric cooling fans?
    Because they run fast even when you are idling, unlike a mechanical fan.
    Why an aluminum fan shroud?
    Because it lets the fans draw air across the whole radiator core, not just the area of the fan. The aluminum acts like a 'heat-sink' and adds more cooling power. It looks nice :-)
    Why a temperature controller?
    Because it allows you to dial-in a suitable temperature setting to start your fans, remember you want to start your fans before you reach thermostat opening temperature - read my
    FAQ for more info.
    Why post-shutdown cooling?
    It's good for your engine if you can keep cooling it after you've turned it off, this prevents 'heat-soak' where internal engine temperatures actually increase even though your engine isn't running.
    Why additional fluid capacity?
    This allows sufficient time for fluid to be cooled before it recirculates back to the radiator.
    Why an aluminum radiator?
    As above, aluminum acts like a 'heat-sink' - it heats up and cools down very rapidly. It makes a significant difference to cooling an engine.
    Why waterless coolant?
    Water, through corrosion, is damaging to your engine. Waterless coolant has a much higher boiling point than water. You can use a lower pressure radiator cap thus protecting your coolant hoses, radiator and heater.

    I personally design and handcraft all the electric cooling fan systems that you see at
    my website (www.v12s.com), and I'm always ready to design one for your car if it is not listed.

    Any questions etc. Please feel free to email me.

    Thank you,
    Wolfgang
    www.v12s.com

    P.S. v12s is in tax-free New Hampshire - No Sales Tax!"


  2. #2
    After countless attempts at trying to maintain a proper temperature I can say that the Spal fan was the only thing that worked.

  3. #3
    Senior Member TRcrazy's Avatar
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    Thanks K9 and Jim for the info here. I have a question on how to plumb dual radiators. I attached a pic here to assist. I dont know if the hoses criss-cross up and down or top hose goes across to the other top hose. There must be a proper way to do this. On my 512TR I will move the cooling to the rear and would like to have a left and a right radiator. Not v12 by the way, stock 2.8v6 for the time being. Thanks Vinny
    .
    Remember, there is always next year.

  4. #4
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    Hot goes from the thermostat into the top, cold out the bottom into the motor.
    Think of it like aaa batteries & the motor is the lamp :-)
    Name:  2 COOLING.jpg
Views: 374
Size:  90.7 KB
    Cheers Jose'

  5. #5
    Senior Member TRcrazy's Avatar
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    Thanks Jose!, -Vinny
    Remember, there is always next year.

  6. #6
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    Agreed with Jose, but that's from a layman's perspective. I don't claim knowledge, was just passing on the contact.

    Again, I strongly recommend you read this Esprit conversion thread. It's very long, but very thorough and the cooling information/theory is excellent...

    K9

    http://www.motorgeek.com/viewtopic.php?f=6&t=9648

  7. #7
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    The way Jose recommends routing the hoses is called "in-series". From an ease of installation point of view, it's often the preferred routing of the hoses. However if you're looking for the greatest cooling capacity, the radiators must be plumbed "in-parallel", like so:

    Name:  Coolant Flow.jpg
Views: 319
Size:  57.5 KB

    The reason: The cooling efficiency of a heat exchanger (radiator) is directly proportional to the difference in temperature between the water and the air flowing through it. In other words, if the hot water flows to one radiator first, then the water temperature entering the second radiator will be cooler. That cooler water reduces the temperature difference between it and the air flowing through the second rad. That reduction in temperature difference reduces the efficiency of the second radiator.

    On the other hand, if you plumb the radiators in parallel, the temperature of the water entering both radiators will be the same, (ie hot) and both will operate at the same peak efficiency as the first one in Jose's example. The end result is cooler water re-entering the block.

    Some have disputed this line of reasoning in another thread, citing that the different cores in multi-core radiators are in series with each other, therefore series routing must be better. But many factors influence the internal layout of a multi-core radiator including modular design, manufacturing, and packaging constraints. The thermodynamic laws that govern heat exchange don't lie though: parallel plumbing is more efficient than series.

  8. #8
    Senior Member TRcrazy's Avatar
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    Good info here, My initial concern was forcing the coolant to pump 'uphill' to the 2nd radiator when running the rads in series. I was wondered whether that would create flow issues. The two methods explained here are a real opener. Thank you, -Vinny
    Last edited by TRcrazy; 07-04-2016 at 12:40 PM.
    Remember, there is always next year.

  9. #9
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    Just A Side Note: Pay attention to your rad caps pressure ratings. Make sure your coolant fill cap or caps (water inlet) are highest point(s) in system to ease bleeding air to avoid air locks.


  10. #10
    Some of my experiences with cooling system plumbing and overheating engines.
    If you decide to run your system in parallel I suggest doing flow and volume tests with the tube routing you plan on doing. Length of tubing, size of tubing, placement of Tee's and construction of Tee's are critical in having your system operate properly.
    Don't believe me? Will this system work both rads equally?



    If you want a cooling system that works then I suggest a series system. I am a huge fan of 'rad 1' cooling the coolant then 'rad 2' cooling it some more and then return to the engine. I do not understand the issue with reducing the efficiency of 'rad 2'.
    When you are in stop-and-go traffic at 105*F you will soon see that 'rad 2' is far more efficient.

    I had many issues with my V12 running hot.
    I added shrouding, electric inline water pump, engine oil cooler, 4 cooling fans (cheap jobber fans), wrapped the exhaust and nothing made it run cool.
    I added two 13" pusher Spal fans and that made all the difference in the world.

    I had to fix a car made in a bodyshop that was overheating. Simply by re-routing the radiators hoses from parallel to series made it run twice as long without overheating.
    Adding a pressure tank cured the overheating issues.
    Just my experience, that's all.

    This is how my system is constructed and it works.

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