winter-fronts, why are they no longer needed or used?

Ok , so obviously the reason for a winter front is to keep the engine compartment warm , the reason for that was years ago all trucks had direct drive fans and at highway speeds the engines had a very hard time maintaining a sufficient operating temperature ( 180 deg. F ) when the ambient got down into the teens or lower . Simply too much cold air blowing on the engine , and the same problem existed at idle because although the truck was sitting still the pitch of the fan blades still blew cold air on the engine that was not working hard at idle . SO the winter front served as a method for the driver to customize the necessary amount of air needed based on the conditions . Eventually engine manufactures started using shutters and they worked kinda like blinds on your window and controlled by a shudderstat , basically a vacuum operated device based on engine cooling system temp . They were problematic but more or less got the job done . Fast forward to today and as I’m sure you know thermostatically controlled clutch fans are in wide use today and they do a very good job of maintaining sufficient engine temperature and like everything else are very expensive. Fact of the matter is when the temp gets in the sub zero range it’s hard to keep an engine warm if it’s not working very hard and a winterfront can still be beneficial. Internal combustion engines that is gas or diesel are fundamentally inefficient ( why you need a transmission) and to achieve optimum volumetric efficiency that engine needs to be operating at a certain temperature, typically between 180 degrees F and 205 degrees F , anywhere outside these parameters and the engine will not perform at its best . This is a basic explication obviously there are more variables at play here that I could go into at length but I hope this was explaination enough .

 

I saw a few had them on new Cascadias when it was 35f. I found everything works fine on a current Detroit without a winter front down to about -13f. Below that it seems to help.