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Thread: cooling V8

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  1. #1 cooling V8 
    frequent forum contributor Club Member Michael Turpin's Avatar
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    General question -
    Does making the water pump go faster (compared with its manufactured speed in relation to the engine) have any benefits?
    Real Steel offer a new pump for the 3.5 V8 which has a smaller billet machined pulley making it run faster and saying its good for Hot Rods and Kit cars. But not for high revving engines.
    Does moving the water round faster just give it less time in the radiator to cool down? or am I missing something?
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  2. #2 Re: cooling V8 
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    have you tried the cooling adatives which seem to work ??
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  3. #3 Re: cooling V8 
    Club Member lil_red_roadster's Avatar
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    I would imagine it would move the heat away from the block quicker...but only assuming the pipework can handle the increased flow and the radiator is sized accordingly for the flow.
    Engine-driven pumps are optimised/compromised around a certain rev-range...idling they pump less than ideally required but higher up the rev-range may pump more than the rest of the system can handle...hence the warning.
    I'd suggest an upgraded radiator and if that doesn't help look at an electric pump & controller.
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  4. #4 Re: cooling V8 
    frequent forum contributor Club Member greyV8pete's Avatar
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    I have read that the additives give little benefit as most antifreeze already has these properties? In my Marlin there is so much torque from the 3.9i V8 that you tend to use the higher gears when tootling along so engine revs are lower than they would be in a Land Rover. Hence the suggestion for using a smaller pulley / higher pump speed which may help for lighter / kit cars. However if the flow rate is too high no only does the rad not have time to cool the coolant but the other theory is that the coolant doesn't have time to absorb the heat from the engine.

    I believe that the fundamental problem is that the rad surface area in a Marlin is only about 40% of the area of the Land Rover Radiator, so there is insufficient cooling for the size of the engine.

    To overcome this I have added an extra rad under the front apron, plumbed in line with the main coolant circuit so it is controlled by the main engine thermostat. The result is no more cooling problems. I plan to do an article about this improvement for Pitstop in the near future. Peter.
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  5. #5 Re: cooling V8 
    frequent forum contributor Club Member Alan c's Avatar
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    The head (press) will increase with speed - its a square law formulas will be on internet. As the system resistance will stay the same the flow rate will therefore increase as there is more pressure to overcome that resistance.

    It wont help. as the heat load from the engine is same and the ability for the radiator to cool is the same - all you will do is move coolant around faster at higher press putting strain on the pressure components (Hoses) and putting water pump seals and bearing under excess conditions.

    Don't do it
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  6. #6 Re: cooling V8 
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    I believe in the earliest days cooling relied on natural convection only. The pump was added to increase the rate of heat exchange, allow simplification of the design and reduce the volume of water. I have observed the rate of flow into a radiator and it is fairly slow. The thermostat restricts the flow when the cooling effect is too much. So donít think increasing the speed will do much other than take a little more energy from the engine than is strictly necessary.
    Do you have a cooling problem? If so is it at rest or at speed? I have observed that most cooling problems in this country are due to incorrect mixture generating too much heat in the engine. Although, it is true that the shape of the Marlin engine compartment restricts the size of the rad and does not encourage good airflow around the engine.
    Paul
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  7. #7 Re: cooling V8 
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    Pete, look forward to your article on the additional rad fitted to your V8 for Pitstop. No pressure (sorry about the pun!) but the deadline for the next issue is 25th March if you can manage it.
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  8. #8 Re: cooling V8 
    frequent forum contributor Club Member Michael Turpin's Avatar
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    Thanks for all the comments and advise. The reason I asked was that during an engine out and replacement of the gearbox, when re assembled and filling the cooling system most of the coolant came back out of the small hole under the pump body, so in the search for a replacement I came across this one, however I did purchase a new unit from Rimmer Bros. which will be fitted in the next few days. I also look forward to the article on additional radiator but unfortunately that space is currently occupied by an oil cooler.
    Overall I don't have a cooling issue but I suspect its borderline and additional cooling will not go amiss. I did think another small rad under the wing may help. something like an inter-cooler

    intercooler.jpg
    Last edited by Michael Turpin; 01-03-2016 at 09:22 PM.
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  9. #9 Re: cooling V8 
    frequent forum contributor Club Member greyV8pete's Avatar
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    Ah yes! Forgot to mention I also have an oil cooler under there too!

    I had considered rads under the wings but plumbing for the coolant gets rather tortuous.

    Peter.
    Last edited by greyV8pete; 02-03-2016 at 08:07 AM.
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  10. #10 Re: cooling V8 
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    I understand modern multicore rads are considerably more efficient than old school ones. Made a big difference on a Mustang I once had.
    Maybe coupled with a higher flow rate that would assist ?
    Serves you right for stuffing such a huge engine in such a weeny car!
    Tim
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