Long Tube Cold Air Intake G37

So, you're thinking about slapping a Long Tube Cold Air Intake (LTCAI) on your Infiniti G37, huh? Good choice! They're a popular upgrade for a reason, offering a noticeable bump in horsepower and torque, especially in the higher RPM range. But before you dive in and start wrenching, let's break down exactly what a LTCAI is, how it works on a G37, and what you need to consider during installation and maintenance. We'll cover the technical aspects without getting lost in the weeds – just the stuff you need to know to do it right and enjoy the results.

What is a Long Tube Cold Air Intake?

First, let's clarify the basics. A cold air intake's primary function is to get cooler, denser air into your engine. Denser air means more oxygen per unit volume, which translates to more efficient combustion and, ultimately, more power. The "long tube" part refers to the extended length of the intake piping compared to a standard or short ram intake. This longer path helps to draw air from a location further away from the hot engine bay, ideally into a cooler area, maximizing the density of the intake air.

Think of it like this: hot air molecules are more energetic and spread out, while cold air molecules are closer together. The engine can "breathe" in more air mass if it's cold. The colder the air, the better the potential for increased power.

On the G37, the stock intake system is, well, adequate. It's designed for reliability and low noise, not peak performance. It pulls air from within the engine bay, which, as you can imagine, gets pretty toasty after a few minutes of driving. A LTCAI relocates the air filter(s) to a lower, more exposed location, often near the front bumper or behind the fog lights. This area typically has access to cooler ambient air.

Components of a LTCAI Kit

A typical LTCAI kit for a G37 will usually include the following:

Air Filters: Usually conical or cylindrical, high-flow filters designed to allow more air passage than the stock paper filters. These are often oiled filters, requiring periodic cleaning and re-oiling.
Intake Tubing: Mandrel-bent aluminum or plastic (usually polyethylene) tubes that replace the restrictive factory intake ducting. Mandrel bending is crucial; it ensures a consistent diameter throughout the bend, minimizing airflow restriction.
Couplers and Clamps: Silicone couplers connect the intake tubing to the throttle bodies and air filters. Worm gear clamps or T-bolt clamps secure the connections.
Mass Air Flow (MAF) Sensor Adapters: The MAF sensor measures the amount of air entering the engine. The kit must include adapters to properly mount the sensor on the new intake tubing. Incorrect MAF sensor placement can lead to serious running issues.
Heat Shields (Sometimes): Some kits include heat shields to further isolate the air filters from engine heat.
Hardware: Nuts, bolts, brackets, and other necessary hardware for installation.

How it Works on the G37's VQ37VHR Engine

The G37's VQ37VHR engine is a high-revving beast with a complex intake system, even before you start modifying it. It uses a dual throttle body setup (one for each bank of cylinders) and continuously variable valve timing (CVTCS). The LTCAI aims to improve airflow to both throttle bodies by providing a less restrictive and cooler air source. Here’s the process:

Air Intake: The air filters suck in ambient air, ideally cooler than the air in the engine bay.
Airflow Measurement: The MAF sensors measure the volume of air entering the system. This data is crucial for the ECU (Engine Control Unit) to calculate the appropriate fuel mixture.
Throttle Bodies: The air then flows through the intake tubing and into the throttle bodies. The throttle bodies control the amount of air entering the intake manifold.
Intake Manifold: From the throttle bodies, the air enters the intake manifold, where it's distributed to the individual cylinders.
Combustion: The air mixes with fuel in the cylinders, and the mixture is ignited, creating power.

By reducing the restriction in the intake system, the LTCAI allows the engine to breathe more freely, especially at higher RPMs. This translates to improved throttle response and increased horsepower and torque, particularly in the upper rev range.

Installation Considerations

Installing a LTCAI on a G37 is a moderately challenging DIY project. Here are some key considerations:

MAF Sensor Placement is Critical: The MAF sensor must be installed correctly, both in terms of orientation and depth within the intake tube. Incorrect placement can cause the ECU to miscalculate the air/fuel ratio, leading to poor performance, rough idling, and even engine damage. Pay close attention to the kit's instructions and any markings on the MAF sensor itself.
Proper Sealing is Essential: Any air leaks in the intake system can disrupt the MAF sensor readings and cause similar problems to incorrect sensor placement. Ensure all couplers and clamps are properly tightened and that there are no gaps in the connections. Silicone couplers are preferred for their flexibility and sealing properties.
Heat Soak: While the LTCAI aims to draw in cooler air, it's still exposed to engine heat to some extent. Consider wrapping the intake tubes with heat-reflective tape or using heat shields to further minimize heat soak.
Filter Placement and Water Ingestion: Because the air filters are often located lower in the engine bay, they're more susceptible to water ingestion, especially during heavy rain or if you drive through puddles. Hydro-lock (water entering the cylinders) can severely damage your engine. Consider using filter covers or a bypass valve if you live in a wet climate.
ECU Reset: After installing the LTCAI, it's a good idea to reset the ECU to allow it to learn the new airflow characteristics. This can be done by disconnecting the battery for about 30 minutes or by using a scan tool to clear the ECU's memory.
Tune (Optional but Recommended): While some LTCAIs will work fine with the stock ECU tune, you'll get the most out of the upgrade by getting a custom tune. A tune can optimize the air/fuel ratio and ignition timing to take full advantage of the increased airflow.

Step-by-Step Installation (General Guide)

Note: This is a general guide. Always refer to the specific instructions included with your LTCAI kit.

Disconnect the Negative Battery Terminal: Safety first!
Remove the Stock Intake System: Carefully disconnect all sensors, hoses, and clamps connected to the stock airbox and intake tubing. Remove the entire assembly.
Assemble the LTCAI: Follow the kit's instructions to assemble the intake tubes, couplers, and MAF sensor adapters.
Install the MAF Sensors: Carefully install the MAF sensors onto the adapters, ensuring they're properly oriented and secured.
Install the Air Filters: Attach the air filters to the ends of the intake tubes.
Connect the LTCAI to the Throttle Bodies: Connect the assembled intake tubes to the throttle bodies using the provided couplers and clamps. Ensure a tight and secure seal.
Secure the Intake Tubes: Use the provided brackets and hardware to secure the intake tubes to the chassis, preventing them from moving or rubbing against other components.
Check for Leaks: Double-check all connections and clamps to ensure there are no air leaks.
Reconnect the Negative Battery Terminal: Reconnect the negative battery terminal.
Start the Engine: Start the engine and listen for any unusual noises. Check for any air leaks by spraying carb cleaner around the intake connections. If the engine revs up, there's a leak.
Reset the ECU: Reset the ECU to allow it to learn the new airflow characteristics.

Maintenance

Maintaining your LTCAI is crucial to ensure its performance and longevity.

Filter Cleaning: Clean the air filters regularly, usually every 15,000-30,000 miles, depending on driving conditions. Oiled filters require a special cleaning kit and re-oiling. Follow the manufacturer's instructions carefully.
Inspect Connections: Periodically inspect the couplers and clamps for cracks or leaks. Replace any damaged components immediately.
Check for Debris: Inspect the intake tubes for any debris that may have entered the system.

Potential Issues and Troubleshooting

Here are some common issues you might encounter with a LTCAI and how to troubleshoot them:

Check Engine Light (CEL): A CEL after installing a LTCAI is often caused by incorrect MAF sensor placement or air leaks. Use a scan tool to read the trouble codes and address the underlying issue. Common codes include P0101 (MAF Sensor Range/Performance) and P0171/P0174 (System Lean).
Rough Idling: Rough idling can also be caused by MAF sensor issues or air leaks. Check the sensor placement and all intake connections.
Poor Performance: If you don't notice a performance improvement after installing the LTCAI, or if the performance is worse than before, double-check all connections, MAF sensor placement, and consider getting a custom tune.
Water Ingestion: If you suspect water ingestion, stop driving immediately and have the engine inspected by a qualified mechanic.

Conclusion

A Long Tube Cold Air Intake can be a great upgrade for your G37, providing a noticeable boost in horsepower and torque. However, it's important to understand the technical aspects of the system and to install it correctly. By following the steps outlined in this guide and paying attention to detail, you can enjoy the benefits of a LTCAI without running into any major problems. Happy modding!