A Mini engine, or any engine for that matter, will perform better with cold air available to the carburettor or injection intake. The reason for this is because cold air is denser. Most Mini engine tuners and race engine builders will know this.

Under normal circumstances the air under the bonnet will be at a high temperature because of heat given off by the engine and cooling system. This means that the air will be less dense. The air in turn will be sucked into the engine via the air intake manifold. There is an easy and inexpensive way to improve your Mini engine performance by several brake horse power by making use of this principle.

All you need to do is acquire some air duct tube and place it under your Mini bonnet with one end just behind the radiator grill where the cold air enters and the other end at the carburettor or injection air intake. You could have either one or two of these air duct tubes, and they come in different diameters, either side of the air intake. This will depend on how much room you have to spare.