Does 'Ram Air' Work?

Popularized by Pontiac back in the 1960s, the term “Ram Air” (as used by its space cadets—aka advertising staff) for a sealed induction system that receives cooler outside ambient air instead of really hot underhood air is a misnomer—at least when applied to road vehicles traveling at legal highway speeds.

- Marlan Davis

The correct term—although a lot less sexy—is a “cold air induction system.” There is a difference; let’s break it down.

For engineers, true “ram air” occurs when the air entering directly into the fuel metering system travels fast enough that a mild supercharging effect occurs—a boost gauge would show a few pounds of positive air pressure on a normally-aspirated engine if it actually experiences a ram-air effect. The operative term here is “fast enough”: Ram air only becomes effective at high speed, providing about 1.2% horsepower improvement at 100 mph, 2.7% at 150 mph, and 4.8% at 200 mph.