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The mkiv Supra Owners Club

Radiators and electric fans


Rob_Mitchell
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The radiator makes little or no difference , over stock .

It's simply a heat exchanger , look at the ratings , how many btu/ area or watts / area .

If you run hot at idle/ low speeds , the rad makes no odds as it's in it's most inefficient area and the rad ratings are not enough difference .

If you overheat at forward speed again the rad does not increase flow , it's a flow system .

Same pump speed,same stat flow ,same waterway dimensions - only difference is the rad rating -

race rads are made for specific installation and 10/10s performance - low weight and maximum fin density for a specific install

If the rad added cooling and temps dropped - the sat would close to balance .

If you wanted ECU control then an electric stat is the way - this allows the ECU to predict temp and open stat in advance and reverse .

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I'll get them to get a hurry on then! If you 2 definately 1 each I better get a bigger batch made this time. I'll get on the case..
keep us updated on the price too mate, you know I have been after one of these as well :) if you can make it cheaper then I am defo interested. Edited by ManwithSupra
smartphone word prediction wrong (see edit history)
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I've got the same rad as Podge, I also got the twin 12" fan shroud kit with it, £230 delivered. Much improved over stock, the fans rarely kick in unless its a hot day.

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I've got the same rad as Podge, I also got the twin 12" fan shroud kit with it, £230 delivered. Much improved over stock, the fans rarely kick in unless its a hot day.

 

 

This means very little as it's dependent on how much over the water stat the fan stat is set , the stock viscous fan is matched to the water stat by design and reduced cycling temperatures

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This means very little as it's dependent on how much over the water stat the fan stat is set , the stock viscous fan is matched to the water stat by design and reduced cycling temperatures

 

I had the stock rad with this fan shroud (ie twin 12's) before I changed to the after market rad. :)

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To clarify things ;

Toyota went to great lengths in the cooling system ;

 

The aim is to get fast warm up and fine temperature control from idle throught to maximum speed

the system both overcools and undercools;

undercooling - this is at low forward speeds and idle , it undercools to keep frontal area small -small rad and sump - it improves performance with less drag losses

to control undercooling(small rad ) they used a viscous fan -this works in conjunction with the water stat , flow control of both water and airflow -this keeps balanced temperatures and prevents surges of temps and cycling , they also calculated for aircon use and auto transmission cooling .

lots of design work and data and testing to match all components

 

If you now change to elect twin fans and shroud -( with no data or testing) the fans must have an independent stat to switch on -this must be higher than the original water stat or it would never switch on - but it cannot be too close in temp or there is a risk of the fans coming on and the water stat closing before the fans switch off - ie no cooling at all

So now it creates cycling temps between the water stat and fan stat( + ? degrees )rather than the matched situation of viscous fan (acting like a stat and having varying speed to load ) and all with no data at all

next post overcooling ;high speed

 

I reserve the right to change my opinion at short notice

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overcooling - At high speed (rpm) or loads

The sysyem is designed to overcool , this is what allows the power upgrades to not instantly cook the engine

Toyota again calculated at stock power levels the cooling flow required ,sized the pump ,stat,rad ,water passages and balance of heat between block and head .

then they added capacity -this allows fine control by the water stat .

in very high load conditions rpms etc - they have a safety net of sorts the heat excess goes into the oil system and your oil temp rises as the water system is maxxed out ( it has a max flow and a fixed quantity of coolant ) - the faster the oil temp rises the more it shows lack of cooling capacity for that power level .

Again heat rates and balance was the target from toyota

If you go beyond what both water and oil can absorb - then the head temp rises and heat goes to air -under the bonnet

Now if all three exits dont cope- air oil and water - your water temp rises - this is a sure sign of overheat !!! even a couple of degrees .

heat balance has gone out of whack !! - this is when your electric fans kick in ! as the water temp rises, usually after a hard run you slow down, water pump speed slows ,oil pump speed slows -the engine heat to air is maximum - but fear not Toyota calculated this for stock power levels with the viscous fan -it tries to smooth out the temperature changes at fixed rates .

If you punch power high enough then even the stock system cant cope , this is even at high forward speeds , here the aftermarket oil cooler comes into play , but if heat rise is too much and too fast - then the head simply runs hot , valve issues,valve seal/guide issues, plugs,det hot spots .yadda yadda - But toyota did such a good job this does not always appear in an instant

 

 

And I still reserve the right to change my mind!

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overcooling - At high speed (rpm) or loads

The sysyem is designed to overcool , this is what allows the power upgrades to not instantly cook the engine

Toyota again calculated at stock power levels the cooling flow required ,sized the pump ,stat,rad ,water passages and balance of heat between block and head .

then they added capacity -this allows fine control by the water stat .

in very high load conditions rpms etc - they have a safety net of sorts the heat excess goes into the oil system and your oil temp rises as the water system is maxxed out ( it has a max flow and a fixed quantity of coolant ) - the faster the oil temp rises the more it shows lack of cooling capacity for that power level .

Again heat rates and balance was the target from toyota

If you go beyond what both water and oil can absorb - then the head temp rises and heat goes to air -under the bonnet

Now if all three exits dont cope- air oil and water - your water temp rises - this is a sure sign of overheat !!! even a couple of degrees .

heat balance has gone out of whack !! - this is when your electric fans kick in ! as the water temp rises, usually after a hard run you slow down, water pump speed slows ,oil pump speed slows -the engine heat to air is maximum - but fear not Toyota calculated this for stock power levels with the viscous fan -it tries to smooth out the temperature changes at fixed rates .

If you punch power high enough then even the stock system cant cope , this is even at high forward speeds , here the aftermarket oil cooler comes into play , but if heat rise is too much and too fast - then the head simply runs hot , valve issues,valve seal/guide issues, plugs,det hot spots .yadda yadda - But toyota did such a good job this does not always appear in an instant

 

 

And I still reserve the right to change my mind!

 

Seems like your just wanting to start an argument, I can't be bothered. However, feel free to tell anyone designing / selling aftermarket rads that they aren't needed :)

Edited by ugp (see edit history)
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