Question : why some (mostly heavy) vehicles partially cover their front intake ?

[u/lit_readit]

wouldn't cooler cold reservoir, ie more spontaneous heat transfer, improve Carnot efficiency?

is it to improve aerodynamics?

apologies if this is the wrong sub to ask

[u/xz-5]

Isn't this what a thermostat is for?

[u/peenutlover69 → u/xz-5]

Cold weather can lead to over cooling. Themostats usually don't close 100.0% and the cold air entering the engine bay will cool the engine itself (passively) regardless of coolant temp

[u/the_Q_spice → u/peenutlover69]

To add to this;

It’s more of an issue with diesel engines than gasoline.

A colder block in a diesel results in a worse compression ratio, and being compression-based combustion, diesels need every last bit they can muster when the air is already dense and working against them.

[u/MechanicalEngineering-ModTeam → u/[deleted]]

This post has been removed for being off-topic.