How Much Horsepower Does a Cold Air Intake Add to a 4-Cylinder Turbo?

The horsepower increase from a cold air intake on a 4-cylinder turbo engine can vary widely based on several factors, such as the specific vehicle, the design of the intake, and how well it is tuned. Generally, you can expect an increase in horsepower ranging from 5 to 20 horsepower. Aftermarket cold air intakes are designed to improve airflow to the engine, which can enhance performance, especially when combined with other modifications like a turbocharger upgrade or an electronic control unit (ECU) tune. However, the actual gains will depend on the overall setup of the vehicle and how well the intake integrates with the engine#39;s existing systems.

Notable Differences on Turbocharged Engines

For turbocharged or supercharged engines, a cold air intake is more important in conjunction with an effective aftercooler, also known as an intercooler. Typically, the air box is replaced with a cold air intake when combined with a turbo back exhaust and a reprogramming of the ECU. By itself, a cold air intake would have little or no effect on performance.

Case Study: 2002 WRX STI

I had a 2002 WRX. When the KN cold air intake, an STI cat-back exhaust, and a Cobb tuning re-programmer were combined, the car's performance increased from 227 horsepower to around 310 horsepower. However, the cold air intake alone did not make a significant difference. The actual gains came from the integration of the three modifications.

A dyno test was conducted using an accelerometer, and the results were recorded. With the STI exhaust and KN cold air kit, the horsepower was virtually unchanged from the stock configuration. After reprogramming the ECU, the car accelerated to 100 KPH in 4.9 seconds, showing 310 horsepower in 2nd and 3rd gear pulls.

Real-World Impact

Despite advertised claims, these systems add very little horsepower, and that only at max RPM with a wide-open throttle. In normal driving, you will derive little to no noticeable benefit. The improvements seen are more pronounced under specific conditions rather than in everyday driving.

For the most accurate information, it's best to consult specific dyno results for your particular make and model, as the benefits can vary greatly depending on the individual vehicle and its setup.