SHOULD YOU BUY A COLD AIR INTAKE
If you’re considering upgrading your vehicle’s intake system, you’ve likely heard the hype around cold air intakes. But do they really provide the performance gains you’re looking for? No. They don’t. Read on to be an informed consumer and try not to judge (or laugh at) the guy who claims they can tell a big difference from their “cold air” intake.
If your goal is peak power and optimal performance, you may be better off sticking with your factory airbox and simply upgrading to a reusable drop-in filter from a company like Green Filter. This will offer improved filtration without sacrificing the engineering behind the OEM design.
On the other hand, many aftermarket air intakes do look impressive under the hood and can enhance the sound of your engine. The induction noise that aftermarket intakes make is often a big selling point for enthusiasts, and if you want your vehicle to sound more aggressive or enjoy the aesthetic appeal, then go for it. Just be aware that you’re primarily buying a look and a sound—not significant horsepower gains.
Many cold air intakes claim to add “up to” 30 horsepower, but that’s often at extremely high RPMs—around 6,500 or more. Be wary of marketing phrases like “up to,” as they can be misleading. The truth is, many of the horsepower gains claimed by intake manufacturers are at best exaggerated and sometimes outright false. Some companies may take credit for performance increases that are actually due to tuning changes rather than the intake itself.
One common trick is dyno testing with the hood open and large fans blowing cold, dense air directly into the intake. While that setup may boost power in a controlled environment, it’s far from real-world driving conditions. You don’t drive with your hood open or a big fan blowing air at the engine, so those results don’t translate to everyday performance.
In typical driving, most people rarely push their engines to such high RPMs, and even when they do, it’s only briefly before shifting gears. Furthermore, a 10 horsepower gain on a 480 horsepower engine is barely noticeable—it’s only about a 2% increase.
Companies like S&B claim their products increase airflow, often referencing tests done in their climate-controlled lab using the ISO 5011 Filtration Standard. The tests show improvements in airflow from less restrictive filters, which sounds impressive.
However for most drivers this doesn’t translate to noticeable power gains. In the real world, if your engine pumps 850 cubic feet per minute (CFM) of airflow at maximum horsepower, and your stock air filter and tube already allows for 1,000 CFM, then upgrading to a filter and tube that allows 1,500 or even 1 million CFM won’t make a difference – your engine is just pumping the same amount through a bigger tube and filter, and this won’t add power. Modern (and by modern we mean anything made since 2000) intakes are more than enough to allow for maximum airflow without restriction.
The exception to this rule is forced induction engines. If you’re blessed with a factory turbo or supercharged vehicle then yes, a larger tube and filter will possibly add power, but only to an extent. The other thing about modern cars is that they have a system called torque management. The amount of torque the engine is allowed to make is hard-coded into the ECU. When you add a high flow intake to your turbo vehicle, the ECU will read this extra flow as more torque, and it will take action to bring torque down to the factory programmed levels. This action can be to close the throttle (remember the throttle is opened and closed by a small DC stepped motor now, and there is no physical cable between the pedal and the throttle), reduce the boost psi, reduce ignition timing, or any combination of these three items.
To understand this better, it’s important to know how your engine works as an air pump. Your engine’s power output is directly related to how much air it can move. For example, a modern V8 engine producing 480 horsepower will require roughly 847 CFM (cubic feet per minute) of airflow at peak performance. We can calculate this using the following formula:
CFM = (HP × VE × 3456) / (Displacement × RPM)
Where:
For a rough estimate, you can also use a simplified rule of thumb:
CFM ≈ (HP × 1.5) / VE
For a 480-horsepower V8 with an 85% volumetric efficiency, the CFM requirement is roughly 847 CFM. So, if your engine can only move 850 CFM at full power, and the stock air filter already allows for 1,000 CFM, changing to an air filter that flows 1,500 CFM—or even 1 million CFM—won’t make a difference. The engine is an air pump, and it only uses the air it needs.
On top of that, modern (with modern meaning anything made after 2005 for imports and 2015 for domestics) engine management systems utilize torque-based control strategies. This means that even if you install parts that should, in theory, allow your engine to make more power, the vehicle’s computer can still limit performance. It does this by adjusting parameters like throttle blade position, ignition timing, and boost pressure for forced induction setups. Essentially, the computer ensures that the engine doesn’t exceed factory-set torque limits, regardless of the upgrades you add.
The best value for improving your vehicle’s performance isn’t always in hardware, you will always find the most HP per dollar spent in a custom tune. A tune recalibrates the factory settings in your vehicle’s ECU (engine control unit), raising the torque limits that the stock system is programmed to maintain. By lifting these restrictions, a tune allows the engine to draw in more airflow, even with factory components, and can maximize the benefits of any performance upgrades you’ve made. In many cases, a tune alone delivers a more noticeable performance boost than bolt-on parts like a cold air intake.
What really matters is air density, not airflow. OEM airboxes are designed to pull the coldest air possible into your engine because cold air is denser, meaning more oxygen, which makes more power. Many aftermarket “cold air” intakes, ironically, bring in hotter air from under the hood, which is less dense and can actually reduce performance. Some intake manufacturers use tricks like opening the hood during dyno tests and aiming high-powered fans at the intake, which delivers cooler, denser air, not more airflow. In some cases, they may even exaggerate horsepower numbers.
So, should you buy a cold air intake? If you want your engine bay to look great and enjoy the air induction sound then go for it—but understand that’s what you’re really paying for.
Some intakes could even cause you to lose power. If you do decide to buy an aftermarket intake, look for one that focuses on keeping hot air out, with features like rotomolded plastic, double-wall insulation, and sealed filter boxes to ensure you’re getting cold, dense air into your engine.
In short, be informed: while cold air intakes have their appeal, they may not deliver the performance boost you’re hoping for. A custom computer tune, on the other hand, will give you the best performance value by unlocking the potential already programmed into your vehicle’s ECU.
