The Chevrolet 327 engine was a 5.4-liter aluminum V8 engine produced and designed by General Motors from 1964 to 2000. Stock versions of the 327 engine can make anywhere from 210 to 275 horsepower, depending on the model year and the vehicle in which they are installed. Horsepower in all gas-powered engines is produced by combustion, which requires the mixing of fuel and air. Increasing either the amount of fuel or the amount of air in each cylinder of the engine increases horsepower, and can be done via aftermarket modification.
Increase the flow of air into the engine. The easiest way to accomplish this is by replacing the General Motors air intake with a performance aftermarket cold air intake that allows for greater airflow. This procedure can typically be completed in under an hour. For less powerful versions of the Chevy 327 engine more drastic steps will need to be taken to reach 400 horsepower. Adding a forced air induction kit can increase horsepower by more than 50 percent, but this procedure is costly and time consuming. Installing a forced air induction kit requires making serious structural modifications to the engine and should only be attempted by a trained professional.
Increase the flow of air out of the engine. There are two components that affect the flow of air exiting the engine; the headers and the exhaust. Replacing one or both of those components will allow air to exit the engine more freely, which increases available horsepower. Replacing the headers requires the use of an engine hoist, while replacing the exhaust will require access to the underside of the vehicle. Check with your local state regulations before performing this step as some states restrict the installation of aftermarket exhaust systems due to the increase in emission that they cause.
Increase the flow of fuel into the engine. Newer vehicles containing the Chevy 327 engine will have an electronic fuel injection system which is controlled by an onboard computer. Performance chips are available which modify the functioning of this computer and cause the fuel injectors to increase their fuel output, which increases available horsepower. Another option is the installation of a nitrous oxide injection system, which may be necessary to reach 400 horsepower in less powerful versions of the 327. Nitrous oxide systems shoot a blast of nitrous oxide, a chemical compound, into the fuel line which temporarily increases horsepower.
