It's time to take your dub to the next level. The question is, should you invest in a cold air intake kit or not? Here's our take.
This aFe intake for late-model TDI Jettas adds 10hp, 23lb-ft of torque, installs with hand tools, and costs less than $300.
First, Do Cold Air Intakes Actually Work?
In a word, yes. They're not going to take a second off your quarter mile time, but they'll improve airflow into your engine, increase the density of incoming air, and give your engine a very nice sound upgrade (especially at WOT).
Cold air intakes are largely effective because they replace a somewhat restrictive factory air intake. Factory air intakes are restrictive because they're designed to be quiet. The average VW buyer doesn't want to hear the sound of their engine sucking down air at full throttle, so VW engineers add some baffling to reduce sounds. While this baffling isn't terribly restrictive, removing it is good for a few horsepower (especially when combined with a high performance air filter).
Cold air intakes are also effective because they change the location that your engine "breathes" from. Most factory air intakes break air from the engine compartment. Air that's outside the engine compartment and away from your hot engine is much cooler than the air that's been soaking up heat next to the engine block. Cooler air is denser, and denser air in your intake equals more oxygen making it's way into your engine. More oxygen means you can burn more fuel - or burn the same amount of fuel more efficiently - so cold air intakes add a few horsepower this way as well.
Here are the typical benefits of installing a cold air intake kit on your engine:
1. Improved Acceleration and Power
Depending on the current setup of your Volkswagen, a cold air intake can really boost throttle response and power. Most intake kits advertise gains of 5-20 horsepower — but more than that, they increase the responsiveness of the engine. Your car will seem quicker because of the reduced delay between the throttle and the accelerator pedal.
2. Better Gas Mileage
There aren't many modifications that actually increase power AND improve fuel economy, but this is one of them. Increasing the density and volume of the intake air mixture improves combustion efficiency. Most people who install a cold air intake experience 1-2mpg increase, assuming of course they drive the same as they did before (some people don't, as the sound of the engine revving is intoxicating).
3. It's a Performance Amplifier
Installing a cold air intake by itself will get you a few horsepower, but installing it in conjunction with an exhaust, an engine tuner, and other performance add-ons will get you even more power. This is because replacing the factory air intake removes a performance restriction...your upgraded engine tune won't be "starving" due to air flow. Your improved air intake won't be strangling your exhaust.
Is There A Downside To Installing A Cold Air Intake?
There are a couple of reasons some people don't like air intakes:
a) In and of themselves, they're fairly expensive in terms of dollars per horsepower. However, we don't recommend you install an air intake and call it a day. They're a much better value when they're installed alongside other performance parts (like an engine tuner, an exhaust system, etc.). Of course, you can install these parts in stages, doing the air intake now, the engine tuner in a couple months, the exhaust in a couple months, etc.
b) There are a lot of stories about problems with mass air flow sensors. It's important to understand that these stories are almost always related to incorrectly cleaned air filters.
Many of the air filters used in cold air intake kits (especially a few years ago) were "wet" cotton gauze filters, which use a very fine oil to "wet" the filter media. This oil helps capture grit and grime, but if the filter has too much oil on it, the excess oil can coat the mass air flow sensor and cause a check engine warning.
The good news is that many air intake kits available today use dry filters. With no oil, there's no chance of fouling the MAF sensor and causing a problem.
c) Some believe (incorrectly) that cold air intakes will violate the factory warranty. While many auto dealers will make this claim, it's patently false. The US Federal Trade Commission has published a consumer guide that addresses this myth, and there's a detailed explanation about new vehicle warranties here as well.
Conclusion
Cold air intakes are an extremely popular modification. Replacing the stock air intake is often the first thing gear heads do when modifying a car for better performance - and now you know why. In under an hour (in most cases), this relatively inexpensive swap can make your engine perform better, improve gas mileage, and make your engine sound better too.
