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Using a lower temp thermostat improve performance???

Multi

By Multi,
in Performance and Tuning

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Multi

Multi

3rd Gear
(edited)

Hi all,

 

Just wondering, does changing a lowered temp radiator thermostat will improve performance? Be it FC or power...please advice, thank you. [sweatdrop]

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Genie47

Genie47

1st Gear

Overcooling will have its own set of problems. I read it in a book on automotive cooling in the library before. Can't remember what damage occurs.

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Genie47

Genie47

1st Gear

Actually no. If coolant system is too efficient removing too much heat, what will happen is that the ECU might compensate by giving the engine more gas to burn! Yikes! sweatdrop.gif Remember, ECU will work to protect the engine. I must get hold of that book. Overcooling will damage pistons just as overheating will too.

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Apollo

Apollo

1st Gear

dun think so... cos the replacement thermos r usually operating at 4 degC lower than stock, which is sure hell not gg to make much of a difference. what the thermo does is act as a switch for the radiator fan to operate, and nothing more.

 

the ECU operates to pump more gas into the engine when the result it recieves fr the intake O2 sensor, lamba sensor, etc does not map into the richer scale of the flammability

diagram. ie there is too much air and that makes the premixed air-fuel too lean. so the ECU adjust itself by adding more fuel into the premixing to ensure more richer mix.

 

this happens when superchargers are used to try and reduce the rich mix to the stoichiometrical line. the ECU thru closed looping learns and adjust.

 

and if u look into the FC data for cars, the results fr temperate countries are usually much better than those locally, reason... local climate is hotter.

 

and there is a way to check if hotter engine makes better cars, just remove the fuse for the radiator so it would be operating... yeah?

 

(WWE disclaimer; do try this at home.)

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Multi

Multi

3rd Gear
  • Author

I thought the thermostat is to release the water flow when the preset temp is reach. So, if we change to a lower temp thermostat, maybe 20 degree lower, the frequency of flow will be more thus the engine will not be as hot as before and thus improve some performance...correct me if I'm wrong... [sweatdrop]

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Apollo

Apollo

1st Gear

flow rate of ur coolant water is based on the water pump which is in proportion with ur timing belt.

 

more flow does not equate to better cooling.

 

a lot depends on the coolant used, the radiator, radiator fins, dirt accumulating on the radiator, water pump condition, engine oil temp, etc.

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Genie47

Genie47

1st Gear
(edited)

OK finally got the book. Apparently overcooling is bad even at 4 deg C difference. True enough the thermostat controls the fan but it also controls the flow of coolant to the radiator via a valve.

 

At the start up cycle, the valve is shut when the coolant is cold. So the engine builds up heat and then the thermostat kicks the fan to move and the valve to open to allow the coolant to flow to the radiator.

 

Now in the case of overcooling, the engine's real life blood which is the engine oil itself will become sludgy. Acid will also build up in the oil shortening its life. Because the oil does not reach operating temperature, the engine becomes sluggish and poor fuel economy will result.

 

So much for temperate climates getting better FC than our local cars. With an engine operating at optimum temperature, the deciding factor for FC is the intake air temperature and not the ambient temperature's effect on the coolant. The other effect of temperate climate is the heater's performance. With the thermostat, you will get the cabin heated sooner because the coolant is does not lose its heat too fast. Very important for them.

 

The other result of the fan running frequently is that the fan's life is also shorten with the possibility to taking out another critical component out of a good working engine sooner than expected.

 

So in summary, Normally_aspirated's question if the coolant making the oil more viscous than it is supposed to be is correct. Not just more viscous. An acidified mixture too! shocked.gif

 

Which means that replacement thermostats are best to be as close as possible to the stock ones for optimum operation.

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Genie47

Genie47

1st Gear
(edited)

OK lower coolant temperatures will not increase performance. Read the post above this.

 

So how to improve performance. Reach operating temperature faster! Interestingly, engine oil warms up much faster when driven lightly between 1500-2000RPM as compared to idling. So all those guys taking a smoke and letting your engine idle are doing yourselves a bad favor by burning more petrol and getting nowhere.

 

Apparently, if it is at idle, the engine is not shearing the hydrodynamic properties of the engine oil. Shearing will generate heat. But when you start moving your car, you are subjecting the engine to a load and thus need higher RPM which in turn shear the oil generating heat! idea.gif

 

This also explains why on the NSH going up to KL and beyond at speeds in excess of 120kph or more, your engine has higher temperatures! sunny.gif Sometimes in excess of 110 deg C! jawdrop.gif

 

So your quest for lower cooling temperatures is flawed and what you should be asking for is more efficient cooling! thumbsup.gif

 

Buy that bottle of Redline Waterwetter! scholar.gif

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Genie47

Genie47

1st Gear
(edited)

I've read up more. Apparently, many are in favor of very hot engines but the materials used in todays engines just can't do it. Explains the obsession by a maker in developing ceramic engines. shocked.gif Imagine an engine that does not require coolant! Somehow, they figured out that the internal combustion engine is most efficient when extremely hot. So hot that after the start up, spark plugs are not needed! Got read up on the theory about this.

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Yeobh

Yeobh

4th Gear

The on-board computer, if it continues to recieve coolant temp voltage reading below the default setting, it will continue to increase the fuel trim cycle - that means it will trigger the fuel injectors to open for a longer period resulting in more fuel being injected into the system.

For some model of VW, the cooling system has two coolant temp sensors - one for the lower limits and the other for high limits. There is many cases of mechanics accidently switching the wire harness resulting in the car always running on rich on fuel

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