Do After Market Air Intakes REALLY Work?
The modern internal combustion engine is, first and foremost, a pump. It pumps in an air/fuel mixture, and it pumps out power, heat, and combustion byproducts. If you want to improve the efficiency of any pump, one method is to remove any restrictions placed on intake or output. When it comes to most engines, that means intake and exhaust. Since we’ve already covered the Tundra Exhaust System, we’ll focus now on the intake system.
First of all, Toyota’s factory air intake system is excellent. It’s a great compromise between the need to move high volumes of air into your engine and the need to keep overall engine noise down. Keep in mind, a modern engine operating at peak efficiency will require nearly 14 times as much air as the amount of fuel it burns (read all about stoichiometric air-fuel mixture). At 65mph, that’s about 32 liters of air per second. Moving 32L of anything in one second requires a powerful pump, and it’s a miracle of modern science and technology that engines do this without making a tremendous sucking sound. How is this accomplished? Engineers use a small baffling chamber called a silencer which is tuned to dramatically reduce the “swoosh” sound that a heavy-breathing engine should be making.
Obviously, the need to reduce intake noise also reduces efficiency. Since the advent of computer modeling, automobile engineers have managed to abate this loss in efficiency quite a bit. In fact, a factory air intake from a vehicle manufactured in the last five years or so is nearly as efficient as the best after market kit — at least in terms of air flow. So why bother with replacing the factory air intake if it’s so good?
1. While it is small, there is an efficiency loss with a factory air intake. The fact is factory intakes are designed to be quiet first and efficient second.
2. If you add any other performance equipment, like an upgraded exhaust, you’ve changed the characteristics of your engine enough to see a respectable gain in terms of performance.
If you add an after market air intake (sometimes referred to as a cold air intake, or CAI) respectable gains usually equal 3 to 5 hp and 5 to 10 lb-ft of torque. However, when you combine this with gains from an upgraded exhaust, you’ll see a total gain that’s greater than the sum of the parts.
Additionally, you’ll experience better fuel economy, and in most cases you’ll enjoy noticeably better throttle response. Remember how we said a Tundra at 65mph breathes about 32L of air per second? That’s at sea level. For every thousand feet of altitude above sea level, your engine requires another .8 L of air — per second. Obviously, if you live at higher altitudes you will see greater performance gains.
After market air intakes improve performance and efficiency because they’re not designed to be quiet. Therefore, adding one will increase engine noise. While most people we know don’t mind the extra “womp” when they mash the throttle, if you’re not interested in making your interior a little louder than an after market air intake is not for you. After market air intakes also can improve performance and efficiency by pulling air from below the vehicle. The concept is that air near the engine compartment is slightly warmer than the rest of the atmosphere, so pulling air as far away from the engine as possible will result in cooler, denser air entering the engine. Obviously, when you’re trying to help your engine get as much air as possible, dense is better.
At this point in time (July 2010), we have yet to see an after market air intake that offers this benefit on the Tundra. All of the kits we’ve seen pull the air from the same location as the factory intake (just above the wheel well). This is a pretty good spot to pull air from, and there’s little risk of ingesting water at this location, so it’s doubtful we’ll see any kits that pull from below the Tundra.
When buying an after market air-intake kit:
- Make sure the kit is offered by a reputable after market manufacturer with a full research and design department. There are many companies on the internet producing air intake kits that have no business doing so. Adding one of these garage designed kits, at best, won’t improve efficiency.
- Consider buying an after market kit made from plastic. Because plastic has a lower heat capacity than metal, it will insulate the incoming air from the heat of the engine compartment better than a metal kit.
- Insist on seeing dyno results before purchasing a kit. Some kits do an excellent job of adding low-end performance, but do so at the expense of top end performance, or vice-versa. Make sure you study the dyno graph to make sure you understand how your engine’s performance is going to change.
- Make sure you understand what type of filter comes with the kit and the maintenance required on that filter. Some kits have dry filters that must be replaced, other kits have a light coating of oil and must be thoroughly cleaned every 25k-50k miles (like this K&N air filter for the Tundra)
- As far as pricing goes, expect to spend $250 to $400 for a decent kit.
Bottom line: The factory Toyota Tundra air intake is fine as-is. However, if you plan to upgrade your truck’s exhaust system, if you add a performance modifying computer chip, or if you’re willing to trade some engine noise for a slight improvement in gas mileage, buying an after market air intake kit makes sense. If you live at higher altitudes, you should consider adding an after market air intake to your Tundra regardless. While there will be more noise from the engine, you’ll also feel more power, better throttle response, and improved fuel efficiency.
Filed Under: Toyota Tundra Accessories