Breathing Fresh Air – Intake R&D, Part 1: Stock Review

There’s something about hitting the road, leaving the smog and haze of the city, and breathing in the crisp, fresh air of the wilderness that brings a person to life. The Jeep Wrangler JL, like all Wranglers before it, was built to take you there. To let you escape those everyday boundaries and breathe fresh air. And for the JL equipped with the new 2.0L turbo engine, breathing fresh air is more important than ever.

While you’re taking a deep breath in and enjoying the view, your Wrangler’s two-liter engine is using that same air to drive you both forward. It breathes air in through its intake, compresses it with the turbocharger and even more in the cylinder, ignites it with fuel and a spark, then breathes out through its exhaust. In this never-ending cycle, air is as vital to your Jeep as it is to your lungs. And it all starts with the intake system.

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When the internal combustion engine was first invented, the intake system was a filter attached to the carburetor. That was it. Now, intake systems have provisions for sensors, emissions systems, hot and cold starting, noise reduction, noise generation, and more. It seems as engines become more efficient, the intake systems become more complex. The intake system of the 2.0L turbo Hurricane in the Jeep JL is no exception.

Like most stock parts, the intake on the Hurricane-powered JL is sufficient for driving around and using the Wrangler as a standard A-to-B road car. But like most stock parts, it could also be improved upon. Before we can start improving a part, however, we need to learn everything we can about its stock design. The more we know, the more we can identify weaknesses and make a better product. So, let’s look at the Hurricane’s intake and break it down to its main parts.

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The Hurricane’s intake system is made up of four major parts: the airbox, the intake tube, a muffler, and a coupler/sensor housing connecting the muffler to the turbocharger. Each component is made up of several pieces that all play an integral role in how the engine breathes. To fully evaluate and improve the stock intake, we need to look at each of those pieces in detail. First, we’ll start with the heart of any intake, the airbox.

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The airbox can be thought of like the mouth and nose of the intake system. It’s where air first enters the intake. Inside the airbox is a filter that traps dust, dirt and larger debris that may harm the engine. In the case of the Hurricane, the lower airbox also plays a key role in off-road situations. A dense filter material covers most of the lower airbox’s opening to outside air. This filter material is similar to what is found in industrial wet-dry vacuums and its role is to keep water out of the airbox while letting air in. This allows you to ford water up to a depth that would submerge over half of the airbox.

A small opening above that filter lets air into the box when the filter is submerged. When the vehicle isn’t driving through a few feet of water, that filter allows fresh, cool air in through the fender well. Like most vehicles, the Hurricane’s airbox is located close to the edge of the engine bay so that it can enjoy the smell of the great outdoors. Or, maybe it’s there to pull in much cooler ambient air outside of the engine bay.

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In the past, the airbox was the first part of the intake to go in the quest for more power. Stock intake airboxes were thought of as blocking cool air from getting into the intake. So, the airbox was ditched and an open cone filter replaced it. Awesome induction noises were made, and your car or truck ran “better”. Modern vehicles, however, have a lot more thought put into their airboxes. New vehicles, and especially those with turbochargers, have well designed airboxes that are great at directing cool ambient air into the intake and they flow more air than the engine can consume. In fact, we’ve found in previous projects that installing an intake without an airbox can often cause inconsistent airflow and temperature, resulting in a loss of power. In the case of the Hurricane’s airbox, the upper lid includes vacuum ports for the turbo and fuel systems. No matter what we do with the airbox, we’ll have to incorporate these fittings.

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We’ll be testing every part of this stock intake to see how it affects flow, but we have a feeling that the Hurricane’s airbox flows just fine. What’s inside that airbox, however, can likely be improved. Automotive panel filters have been around for decades. Formerly made of foam, and now mostly made from pleated paper or cotton, the panel filter’s main goal is to keep anything but clean air from entering the intake. Flow specifications for stock panel filters are typically minimal; if it doesn’t choke the engine and cleans the air, it works. Swapping the stock panel filter for a larger and better-flowing cone filter could yield better performance. The challenge will be fitting a larger filter into the stock airbox to maintain consistent airflow and the additional benefits that the stock box provides.

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As we follow the air out of the airbox, we come to the next component of the intake system: the intake tube. This component is often where we can pick up the most performance by removing restriction and increasing flow, and the Hurricane’s intake tube is certainly a good candidate for some simplification. Sprouting out from the intake tube like tree limbs are three resonator tubes. These resonators help reduce noise coming from the induction system. While many daily drivers would prefer a silent ride, enthusiasts who bought a turbocharged Jeep probably want to hear that turbo. These resonators also create turbulence in the intake pipe as air travels through them, reducing overall flow. By removing these resonators, we can move air into the engine faster. The intake tube also narrows slightly between two of the resonators. We’ll look to round out the tube and remove that restriction. One piece that will have to stay, however, is the intake air temp sensor. This critical sensor helps manage fueling and it will have to stay close to its current location to function properly.

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The last two components of the intake system are becoming more and more widespread among turbocharged vehicles. Bridging the intake tube and the turbocharger are a muffler and a coupler. We’ll start with the muffler.

If you’re thinking that a muffler seems out of place on anything but an exhaust, you’d probably be surprised to hear that most turbocharged vehicles from the past five years have a muffler on the intake system. Our 2016 Camaro 2.0T also had a muffler built into the intake. The purpose of these mufflers is the same as the mufflers on your exhaust. They reduce “noise.” Just like on an exhaust, the muffler uses chambers and ported cylinders to re-route airflow and reduce noise to lessen the volume of the moving air. But they also cause turbulence and reduce flow. And just like many owners like the sound of their exhaust when it’s breathing freely, many also love the woosh of a spooling turbocharger. While we will most likely remove this muffler in our design, we have found in the past that some intakes flow better with the muffler. Like the airbox, we will thoroughly test the muffler to see how it affects flow and power before finalizing our design.

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The final component in the intake that needs consideration is the coupler between the muffler and the turbocharger. Usually, making a coupler is something our engineers can accomplish in their sleep, but this one is a little different. Aside from the obvious job of connecting the rest of the intake to the turbo, this coupler plays two other roles in the crankcase ventilation system (CCV).

On top of the coupler is a port with an electrical connection and a small hose barb. This port acts as the main vacuum source for the CCV system when the engine is producing boost and the manifold is under pressure. That electrical connection provides a power heating element similar to a car cigarette lighter. The purpose of that heater is to keep oil, fuel, and other blow-by vapors (learn more about blow-by here) from condensing on the turbocharger’s compressor wheel and causing damage to the seals and bearings inside the turbo. Removing this heater would certainly be detrimental to the engine unless a catch can was installed, and even with a catch can, removing it would constitute tampering with an emissions device. Last we checked, the EPA frowns upon that.

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The small hose barb on the side of this port is also important to the vehicles emissions system. The small port connects to a reference line for a sensor that calculates pressure inside the crankcase. We’ve learned from other projects that these sensors are extremely sensitive to any changes in pressure that fall outside of their strict parameters. If the pressure at that small port does not match the range programmed into the vehicle’s ECU for the given running conditions, the ECU will throw a check engine light. The EPA and our customers won’t go for that. Aside from the shear precision needed to replicate this coupler and the risk of throwing a check engine light, it’s just a pain to remove from the car. To save you the headache of removing it, and us the month of design and testing time to replicate it, we will probably keep the stock coupler.

Now that we’ve examined the stock intake from top to bottom, we have a lot of testing to do. In the next posts, we’ll look at the effects of each component on the overall flow of the intake and begin the design process. We’ll see exactly what will be staying and what will be ditched to let your JL Wrangler 2.0L breathe fresh air a little bit easier.

Thanks for reading!
-Steve

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