Almost all late model vehicles duct outside air into the intake or the manufactures wouldn't bother doing it.But probably cause the new vehicles have very hot engine bays.And yes it will reduce engine detonation if your engine is tuned to the point of detonation.
Anyways,if you duct in outsdie air,make sure the system has a sharp bend and a drain of some sort at that bend so any water or rain will not reach the carb or throttle body.I've read of a few newer vehicles suffering engine damage when driving through water and it was picked up by the air induction system.
The catch 22 here is many inline guys heat the intake for fuel vaporization ,better low speed performance,especially on a highly tuned engine.The heated intake can promote detonation when the engine is under load,so cooler out side air may help.A vacuum operated flap valve may be nice like on some newer engines to draw engine bay air when cruising and then open to outside air when you're on the gas pedal.But then the engine gets complicated like a 70's smog motor
