How Much Horsepower Does an Intake Add?

Performance enthusiasts often wonder whether upgrading their vehicle's air intake system can boost power output. The answer, unfortunately, is not as straightforward as one might hope. This article explores the factors that influence the amount of horsepower an intake can add, highlighting the realities of modern engine design and the limitations of after-market modifications.

Understanding Intake Systems

Several years ago, a respected truck magazine conducted a series of tests on various air intake systems. Their findings revealed that while some intakes could add minimal horsepower (one or two points), the majority did not provide any noticeable gains. In fact, many enthusiasts were buying these parts more for their cosmetic appeal than for any real performance improvement, given that most modern vehicles leave the factory with a cold air intake system.

The Role of Engine Design

The amount of horsepower an intake can add depends heavily on the vehicle's baseline configuration. If the original intake system is already efficient, adding an aftermarket intake may not result in significant power gains. However, if the stock intake is restrictive, upgrading to a high-quality intake can potentially boost performance. Nevertheless, a comprehensive package upgrade including the intake, heads, exhaust, and tuning might be necessary to see noticeable improvements.

The Limitations of Modern Vehicles

Modern engines are designed to meet stringent emission regulations, which often result in optimized air intake systems. Mass airflow (MAF) sensors and engine management systems (EMS) control the intake process, making it challenging for aftermarket parts to make a substantial impact. While some EMS maps may allow for increased airflow, this is typically limited to forced induction systems. In most cases, the power gains from adding an intake are minimal, if not nonexistent.

Real-world Examples and Engineering Considerations

Consider a typical car manufactured in the last 15-20 years. If its intake is the only change, the expected power gain is likely to be minimal, ranging from negative 8 to 0 horsepower. This is because the car's fuel injection system relies on precise measurement of the intake air, and a pod filter can disrupt this balance. The stock intake is designed to harness resonant frequencies that jam in the most air when needed, a level of engineering that aftermarket systems find hard to outperform.

For those with performance-oriented vehicles like rally cars, Formula 3, DTM, or NASCAR, the situation is different. These cars often operate under strict power limits set by organizers. Removing these restrictions can indeed result in significant power gains, but without an appropriate retune, the engine may run poorly. Additionally, the entire powertrain is optimized for these restrictions, so lifting them can lead to serious issues with other components.

Conclusion

While aftermarket air intake systems can provide some benefits, the power gains are often marginal and highly dependent on the vehicle's stock configuration. For the average car owner, the cost of upgrading might not justify the benefits. However, for enthusiasts with high-performance vehicles, understanding the intricacies of engine design and performance optimization can help in making informed decisions about whether and how to proceed with intake modifications.