For every 10 degrees (C) drop in temperature, expect a 3% horsepower gain. Expect performance to be worse if you're sucking in hot underhood temperatures. Colder air makes the motor run cooler as well as being more dense (remember Chemistry? PV = nRT)combustion is improved.
This picture shows the simplest way of introducing cold air in 88-91 Honda Civics. The air is drawn from the wheel well (the resonator box has been removed), through the intake hose to the stock air box (you will have to enlarge the opening of the stock air box) where it goes through the K&N air filter replacement to the T-body.
June 6, 1998
