Just to add a bit more info about Cold Air Intake (CAI) systems.
These systems do two things:
1) Make it easier for air to enter the engine
Just as a dirty air filter will affect performance, the stock air filter and the path the air has to follow to get into the carburetor restrict the air flow.
As you can see from photos, the CAI is basically a curved metal tube with a filter on the end. The CAI is matched up with a “high performance” air filter, which passes air more easily than the standard paper filter.
Because the filter is out in the open, air can enter from all directions and there’s very little to get in the way after that. The result is an engine that breathes easier and develops more power.
2) Cold air Vs Warm Air.
Most Cold Air Intakes pull in air from just behind the grill at the front of the engine compartment so the the air coming into the engine is cooler. The regular air cleaner draws air across the top of the engine and the exhaust manifold.
Cold air is denser so it expands more in the combustion chamber than air that was warm to begin with. This means that, for a given air volume coming into the engine, more hot gasses are produced to push down on the pistons and make the wheels go round.
I don't know if cold air would carry more fuel - my guess would be the opposite. I know that cold air carries less humidity than warm air so maybe the same rule would apply for gasoline but thats just a guess on my part.
--------------------
Some things to consider:
1) Cold air may be good but cold-cold air may not be so good. In cold weather, the stock air intake is designed to draw air over the exhaust manifold. During engine warm-up, pre-warming the air improves fuel vaporization, compensating for the cold carburetor and intake manifold. (With fuel injection you don’t have to worry as much).
In very cold weather you might find the vehicle with a CAI takes longer to warm up. I'm talking cold as in Edmonton, Calgary, Montreal so I don't know if this would be such a problem in warmer climes.
2) Cost – A CAI and filter goes for around $150 US. Installation is pretty straightforward.
For about $60 you can purchase a K&N filter to replace your standard air filter. These filters are washable and reusable so they last pretty much forever.
K&N claims using their filters give a 5 to 10 % increase in horsepower over standard air filters. I’ve never used one so I can’t say from personal experience.
There is some debate about how much extra horsepower you get from going the added step of the CAI instead of just using a hi-perfromance air filter. Of course they sound pretty cool and that should count for something.
4) If you have a newer vehicle, installing a CAI may affect your warranty.
