ORIGINAL: carmatic1

colder air is denser, hence just by being cold the air is already making your engine run leaner in a way... thats why you richen it , to compensate for it... thats what i read on threads on rcu anyway

but yeah youve gotta worry about the working temps too, on one hand you squeeze more performance out of the engine this way , on the other hand the operating temperature is wrong and the engine wears out faster... or something...