Estimating Car Engine Temp. with Load: A Simplified Approach

[Zver]

Hello
Can someone tell me basic equation of car engine temp. that depends on load.
I don't need a precise equation - i need something simplified for simulation.

 

[S_Happens]

Not really (certainly not at this point).

Which temperature; combustion, coolant (where it's measured and displayed in the dash), exhaust, drivers side rear tire sidewall, passenger AC vent, etc.?

And why is whichever temperature you specified going to change with load? My assumption is that you're asking about the temperature that is displayed in the dash, which is coolant temperature at some location such as the cylinder head. This won't change much with load unless the cooling system is either underloaded (??) or overloaded. A normal car has a thermostat in the cooling system that opens and closes, which will maintain a certain temperature range that will be mostly independent of load.

My assumption is also that you will be looking for something else like how much HEAT you will need to remove via the cooling system for a certain load range.

I might be wrong, but at this point we can only guess at what you want and really need.

 

[mrspeedybob]

ASE certified master mechanic here...

As stated above engine temperature is controlled with a thermostat, but the thermostat does not simply open and close, it is not digital, in can be part way open. Most thermostats are set to start opening at about 195 degrees F and be fully open at about 210. Probably 98% of the driving you do is in this window, but that's not the end of the story. There are extreme conditions that the car is engineered to operate in which may have the thermostat fully closed or fully open. Most modern cars use electrical controlled cooling fans. There are various configurations but they all let the computer scale cooling fan operation to match load and conditions. Some GM models do not max out the cooling fans until coolant temperature reaches 225 degrees. So to answer your question...

A car idling, with the heat on, in Alaska in January should reach an operating temperature of about 175 degrees, the thermostat will never open at all but the computer will keep the car at a high idle to generate heat for the cabin.

The same car, fully loaded and towing it's maximum load at wide open throttle up a steep hill in death Vally during a heat wave in August with the AC on full blast will get to about 230.

Anything cooler or hotter then that range indicates there is a problem

 

[S_Happens]

Gearhead/Return ME student/Chemical Process Operator...

I'm not sure if you think we have a different understanding of thermostats, but we don't. I think your post is a very good (and more considerate) elaboration of my post. Your specific examples are exactly what I was talking about, although I used "load" referring to engine load and then "underloaded/overleaded" in reference to the cooling system in the same sentence, which was not a good idea.