Are BMW Intake Kits Junk?

Are Intake Kits Good on BMWs – Or Just Junk?

There was a time when taking off your clunky stock air box was a given for making more power. Cumbersome, inefficient air cleaners robbed power from your car's engine. Changing to a simple tube and cone filter was said to give power.

But as BMWs evolved, so did their airboxes. The electronic fuel injection systems became more complex, and with the addition of OBD2 emissions systems, like those on the E36, E46, E9X and newer BMWs, making REAL power on a BMW engine got harder. Does installing an aftermarket intake kit still give results on naturally aspirated engines? What about Turbos?

We dive into this and more, as we demystify Intake Kits and work through the question: Do intake kits really work on BMWs?

Improving on Millions of Dollars of R&D

Every BMW starts with years of highly skilled research and design by Bavaria's best. How is it possible to improve on this? Well, for starters, the goals and objectives of the BMW engineers are often different than what our goals as BMW drivers are. As BMW fanatics and driving enthusiasts, we want the maximum enjoyment when we throttle down, the fastest 0-60(+) times and acceleration.

Unfortunately, poor Dieter and Helmut in the intake design department are also tasked with making the engine quiet. Muffled. Muted enough for the customers who don't want to hear their BMW engine sing. (Side note: Who are these people? And can you buy a Mercedes, please??) When you look up the stock airbox in the BMW dealer "ETK" system, the part is even called the "intake muffler," which says clearly where the priority is. As a result, we the BMW enthusiasts don't get the flow rate, power, or sound we want. This leaves much room for improvement in these areas, even on stock software and tuning.

What Makes an Intake Kit Perform?

One of the key ingredients to improving on the lackluster stock airbox, is FLOW. If we improve the flow rate of air to the manifold, there is less restriction to encumber combustion. The engine won't make any more power without more air. Restriction is the enemy. But so is contamination. We can't let foreign particles enter the combustion chamber, and so filtration is needed for all air that passes through the intake tract. Filtration introduces restriction, so it's imperative the best filter media is used. Here's where BMW goes off track and the compromises start: BMW uses disposable paper filter media. It's cheap, it works in the short term, and it's biodegradable.

These inexpensive filters serve the bean counters in the Financial Department, but hurt your flow. By using a high-tech, high-quality gauze filtration media, we can maintain safe and efficient filtration with less impairment to the movement of air as it's filtered. Ingredient #1: The best filter media available.

After the quality of the air filter construction comes size. Yes, size matters for air filters. Specifically, surface area. Ever wonder why many air filters have ridges or pleats like an accordion? That's to increase the surface area of the filter. More surface area means less restriction. So, we want the largest filter that can fit in the space provided. Ingredient #2: A larger filter. Given the fairly small size of many stock BMW air filters and the simple rectangular shape, achieving more filter surface area is a breeze for a capable manufacturer.

Next on our shopping list is an unobstructed path. Air moves like fluid. While it's usually invisible to us, it often helps to envision the movement of air into your engine as a fluid material. Engineers use the principles of Fluid Dynamics to understand and predict the movement of air. Applied to a BMW intake system, we want the air to move as fluidly as possible. This means as few sharp turns and narrow pathways possible. Ingredient #3: The smoothest air path routing.

With those items, we have plenty of air. But what about the quality of the air? Like us, you may hear the term "Cold Air Intake" tossed around a lot. So much so that people abbreviate Cold Air Intake to CAI in conversation. There are some truths to "cold air" and there are some myths. Without spending 5,000 words on this alone, we can safely say the concept of cold air could easily be called "fresh air" intake. While cooler air is preferred for combustion, what we really want is to avoid getting what we don't want – HOT, stagnant air, trapped in the engine compartment. The best way to not introduce hot air is to keep it isolated. Ingredient #4: Isolation from engine heat; Ingredient #5: A supply of fresh air.

Next on our list is to not let the total package weigh us down. Literally. We combine the above improvements, but if we add a ridiculous amount of weight with heavy, over-built materials, any power gains we make are offset by hurting our power-to-weight ratio. Light is fast. Ingredient #6: Simple, lightweight construction.

Putting the Pieces Together

Once you've designed with the right ingredients, it's all about details of design and the quality of the final product. For an intake kit to function its best for a particular BMW, it needs to be designed for that specific BMW. One size most certainly does not fit all! And cobbling together clamps and tubes and universal filters is usually a last resort to a well-built solution.

When your design is sound, your materials premium, and your execution polished, you can end up with a replacement to your stock airbox that will indeed outperform the extra-vanilla and super muffled stock BMW air box. And that's where the Magic happens….

Proving Power

At BimmerWorld, we race BMWs professionally. Proving the performance of a part or product is ALWAYS a given. That's why we frequently test power modifications on our own, in-house, DynoJet chassis dyno. This expensive measuring device is the true test of a product, showing the final gains as measured at the wheels. It can also be the canary in the coal mine for products that fail to live up to claims and expectations. Imagine testing an intake kit that claims big power gains, only to make 0. Or worse, for it to lose power. It's happened. There are definitely some junk "Performance" intake kits being sold out there. Fortunately there are some that are the real deal, and worthy of using.

If Not All Intakes Make Power, Which Ones Do?

Our dyno doesn't lie. We've tested several intake brands that failed to deliver. We won't name them by name, but rest assured – if it's not something we sell, your antennae should be up.

Our preferred intake manufacturer is Injen, and our reasoning is every kit we've tested has always shown repeatedly measurable power gains at the rear wheels. It may sounds biased - because it is! Injen was the brand we found repeatedly made power on our dyno. That's a bias we don't mind admitting.

Not a newcomer to performance intake systems, Injen is still emerging in the European and BMW market. They have a rich history in innovative design and manufacturing that spans decades, and the results on the BimmerWorld dyno helped restore our faith in TRUE performance intake systems. While Injen brand intakes are definitely our go to, we do offer some other intake kit options by other top-quality manufacturers to either give our BMW shoppers more choice, or to fill in applications where Injen hasn't developed a solution.

Another "plus" in the Injen column is their price and value. We've found that not only do the Injen intakes deliver the best results on the dyno and smile-meter, but they're also one of the most affordable brands on the market. While each application varies by BMW model, you'll find the pricing of an Injen Intake is typically well below some of their competition. It's worth noting, the kits that are less expensive than Injen are generally in the less proven realm of performance products.

For more on our viewpoint of Injen intakes, you can read here: Why Injen is the Best Intake for BMWs

Pay For Power – Get The Amazing Sound For Free!

One of the best before-and-after differences, after measuring the performance gains, is the very raw and visceral enhancement of your BMW's engine sound under full throttle and hard acceleration. Around town you likely won't notice it while enjoying mild-mannered street driving. Dip into the throttle to make a pass or pull out of a corner, and the SOUND of improved intake air flow makes itself known. Smiling usually ensues.

What you're hearing is the rapid "sucking" sound of air – free of intake muffling, and with less burden as the air passes through the larger air filter. While the sound is "cool", it's an indication of what's going on downstream of the air filter. We like to think of it as the sound of progress.

What About My Turbo BMW?

BMW brought turbo models to the US in 2007, with the potent N54 power plant of the 335i & 335xi. By 2012 or 2013, almost all BMWs had a turbo (or two) under the hood, with the last of the naturally aspirated BMW engines ending with the N52 "28i" 6 cylinder and S65 V8 in 2013. These turbo models suffer the same stock airbox dilemma as their NA counterparts. Maybe more-so since the characteristic turbo "whoosh" sound is absent with the stock air box. But due to their engine tune-ability, the restrictions and limitations of the stock intake system rear their ugly heads much sooner.

You simply can't make boost without intake air. While the stock airbox might work "just enough" to get a bone stock N54 to 300hp, the limits of filtration and airflow soon kick in if you've modified your turbo BMW. The intake path on a turbo BMW must bring in fresh, cool, outside air as well as cycle the hot recirculated exhaust gasses from the turbo(s). This is a super demanding environment, and achieving power gains requires all the ingredients listed earlier – with more design and testing than ever.

Conclusion: Good Intake Kits are Great; Junk Intakes are Junk

While some results, like sound, are subjective, we can all agree added performance with no downside is something everyone wants. Our goal was to demystify the Cold Air Intake Kit and hopefully make it easier to feel comfortable upgrading your BMW with another Proven Performance Product at BimmerWorld.

If you're ready to upgrade you BMW's stock airbox, or perhaps want to retire that old and suspicious intake kit the previous owner installed, we suggest checking to see if an Injen Short Ram or Injen Evolution intake kit is available for your BMW by visiting the Intake Kit department of our website. You may find some other viable and tested solutions as well, particularly if you have a popular BMW with multiple intake kits available, or one that Injen hasn't developed at kit for. We stand by the quality and performance of all the replacement and performance parts we sell on BimmerWorld.com, and guarantee satisfaction of the intake kits we sell.

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