Thermostat question

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Derek
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Thermostat question

Post by Derek »

Does a high flow thermostat keep the engine cooler by allowing the water to flow 30% faster.
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Pete
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Re: Thermostat question

Post by Pete »

Hi Derek, I cannot say that I have proved that, as the last High Flow Stat I bought was jammed shut and I had to gut it to get any flow!!!

The one area that I find - especially on the race car (or not) - is the rate of flow of the pump that makes the most difference to overall heat dissipation.

The Race car has an electric pump and the flow rate is pitiful. I would never run one on the street.

Maybe it is worth checking the pump impeller out.
Pete Wiseman; Cambridge.

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Dave999
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Re: Thermostat question

Post by Dave999 »

the flow isn't everything
its needs to flow but not too fast and not too slow

if the 30% means 30% less time in the radiator, and 30% less time in the motor, but 30% more of the same water by weight passing every point. You would in my opinion narrow the effective RPM range of your cooling system it will be too fast or too slow at one or the other end of your usual rpm range
which might be fine on a race motor that will never lug a car up a hill at 50 mph and 2500 rpm but not so great for anything street driven

if the 30% means 30% bigger door way, through the thermostat, id suggest it increases the chances of cavitation in the pump, you are dependent on a level of back pressure caused by the thermostat at higher rpm in order to stop the interior of the pump and its pump vanes being eaten away by microscopic bubbles of vacuum like the worlds most aggressive ultrasonic cleaner.
a bigger hole at the thermostat housing causes less restriction and effectively lowers pressure at the pump outlet which makes it is easier for high speed pump vanes to rip molecule form molecule in the coolant causing free bubbles of true empty space to batter the surfaces they hit

and in this case it won't equate to 30% more flow
it will equate to just a bit more flow and less restriction.

i have read that a more effective way to cool a race motor is a standard pump with a tiny crank pulley and no fan on the front engine spins at race speeds
water pump spins at the driving to Tesco speed it was designed to run at
obviously some parasitic loss that would only be offset from an electric pump if you ran an alternator to keep battery charged and electric pump happy. an electric anything will always waste more energy as you have to convert mechanical energy to electricity and then back to mechanical in the pump and that is not efficient use of engine power. this may well be a 1970s view i read it in a really old book. i guess you risk lost belts and all sorts, there will be better modern ways i'm sure


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Re: Thermostat question

Post by SAV@RPM »

Following on from what Pete said I would be very wary of aftermarket high flow/ race thermostats. Generally Chinese made and pretty much guaranteed to stick shut. Best to run a standard good quality thermostat, I usually drill a small hole in the outer edge of the stat to allow any air to bleed out when refilling the coolant system. Some thermostats have a provision already built in and don’t need the hole drilling.
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Derek
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Re: Thermostat question

Post by Derek »

Thanks for the replies. I used to have a 180 in the Charger and once opened it never went higher, about 2 years ago I put a 160 in and to start off it seemed fine, a few week ago on the way home from Brighton it went up to around 210 so I put in another 160, on the way home from the Nats it was around 200, I also put on a water pump a few weeks ago as it was leaking. Is it worth trying to get another 180 high flow.
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Dave999
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Re: Thermostat question

Post by Dave999 »

sounds like the 180 style you had before nicely matched your pump capacity and radiators ability to shed heat and provided the best balance.
the 160 may be too open too early and have the water racing round too quick too early, hence the higher 200F temps

if you think how long it takes to boil a kettle the water needs to hang about for a bit to do its heating up and cooling off.... there is a balance, a sweet spot

dave
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morgan
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Re: Thermostat question

Post by morgan »

Interesting. Hi flow pump, big ally rad and 180 here.
How high will they go ? If I ever see 210 I am on the way to a boil up. 20-30 stationary minutes on a sunny day would see me on the way…
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Blue
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Re: Thermostat question

Post by Blue »

Personally I always use 180 degree high flow stats without issue. I'm also a firm believer in coolant recovery tanks to keep the radiator free of air.
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