Temperature vs. MPG ?

[MadisonMPG]

Originally Posted by saddlsor

I tried that and haven't done enough testing to see if it makes a difference but I can tell just by the miles I'm getting on a tank that it's not going to be the same thing. the increased mileage I got on this trip in the southern states and warm air is what got me to thinking about a wai. I know some on here have had good results and some haven't so thought I'd try it myself.

Warmer air is easier to drive though (less drag), and Summer fuel is hotter(more BTUs) too.

So it's not just engine air temp.

[user removed]

I believe one of the least understood mileage killers in cold weather is the radiator.

The temperature of your coolant when it comes out of the radiator in hot summer conditions is about 120 degrees.

In winter temps, the colder the ambient temperature the lower the temperature of the coolant exiting the radiator back to the engine. The difference can be dramatic. At 32 degrees the coolant exit temps are around 60-80 degrees. The colder the ambient temps the colder the exit coolant temp.

When your radiator is in new condition without any grunge in the tubes the coolant is even colder than when the radiator is not working as well as it did when new.

The colder the coolant going from the radiator to the engine the more heat it absorbs from the engine and the result is less efficiency.

Cooling systems are designed for the "worst case scenario" ambient temps of 120 degrees AC on max climbing a steep grade at higher speeds.

Hypermilers who get significantly greater mileage than EPA ratings suffer from colder exit coolant temps because they are maximising the heat energy potential of the engine, especially if they are using EOC and to a lesser degree even if they are gliding with the engine idling.

It would be nice if you could build a thermostatic control that maintained coolant exit temps at 100-120 degrees regardless of ambient temps.

Radiator blocks are a decent solution but when you drive at sustained higher speeds a radiator block can cause the electric cooling fan to operate more which cost mileage.

I think some of the European cars are now coming from the factory with coolant exit temperature control systems.

In the old days I remember the Packards had vertical fins in front of the radiator that opened and closed to control coolant exit temperatures.

It would be neat to measure the exit temps and adjust the air flow over the radiator to keep them above 100 degrees regardless of the ambient temps.

regards
Mech

[bustedprop]

Hello everyone. I am new to this forum but I love it. Please excuse any naivety as I am quickly learning. Although I believe there are innumerable variables that affect cold weather MPG's, I can't help but wonder about the actual fuel temperature. Maybe this has been explored before but it has got to have some affect when temperatures where I live range from -25F in the winter to almost 100F in the summer. Any thoughts on reduced atomization, higher viscosity, etc…? Although it doesn’t seem very safe, I would love to experiment with fuel heating.