Upgrading a 2015 Sierra with Cold Air Inductions

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photos by: the author

Getting a Full-Sized GM Truck to Breathe has Never Been Easier

After the LT-Series engines had replaced the LS just a few years ago, the aftermarket had to completely undergo a severe update to accommodate the owners with these vehicles. Everything from induction and exhaust systems, engine components and especially ECU calibrations all had to go back to the drawing board, as very little would be able to carry over from the previous platforms. Throw in the fact that the LT1 and its GEN-V variants coincided with new vehicle launches, and it was clear to see that we’ve entered a new era in performance.

The 2014+ Chevy Silverado and GMC Sierra were among the new vehicles launched with the LT1-based, 6.2L EcoTec3 L86 that picked up where the LS-based L92 had left off in the previous generation. Packing 420 hp and 460-lb ft at the flywheel, most consider this enough power to tow the boat to the lake, drop the kids off to school and make the morning commute. However, if you’re reading this publication you’re probably not like “most people,” and are more than likely looking for ways to squeeze more power out of your L86-equipped Silverado or Sierra.

That’s just the case with the owner of this particular 2015 GMC Sierra Denali. Owned by FJ Performance friend and customer, Justin Schmidt, the Sierra was a completely unmolested example that Justin picked up fairly recently to use for the daily grind and to haul his 4th-gen Camaro race car to and from the dragstrip.

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Cold Air induction Part #512-0103-B, features an insulated airbox/lid, ceramic-coaed intel tube, air filter, silicone elbow, installation pack, and three stainless steel screws for the airbox lid.

Not wanting to tear too much into it, in attempt to protect his factory warranty, Justin was still interested in simple bolt-ons — that will keep him warranty safe and emissions legal in his home state of Pennsylvania. Besides, since when is a few more ponies and an improved soundtrack a bad thing? Looking to help Justin out, we suggested going with the newly-released cold-air induction kit from our friends over at Cold Air inductions. Citing Part #512-0103-B, the kit is a complete system that includes everything you need; from the airbox to the adjustable clamp securing the intake tube to the throttle body, and everything in between.

Part of the main selling point for us, was the heat insulation that CAI includes in all of their cold-induction kits. becasue not only does it look fantastic, it works! Unlike some other brands on the market, the heat insulation prevents engine compartment heat to be fed through the air filter and back into the engine.

Part of the main selling point for us, was the heat insulation that CAI includes in all of their cold-induction kits. Not only does it look fantastic, but it works! Unlike some other brands on the market, the insulation prevents engine compartment heat to be fed through the air filter and back into the engine –which is rather counterproductive and defeats the purpose of a cold air kit.

Helping us install the CAI kit, was our friends at FJ Performance — Francis Johns and Matt Neubaur — who operate one of the fastest-growing, late-model GM tuning shops in Western Pennsylvania. Having made a name for themselves in LS and Ecotec engines, it seemed only natural that we team up with them and their in-house, in-ground Dynojet dyno for installation. Besides, someone had to use the camera!

The air filter (available as a separate part if need be, CF-9400), is a washable, reusable piece designed specifically for Cold Air Inductions, as evidenced by the "CAI" branded end cap.

The air filter (available as a separate part if need be, CF-9400), is a washable, reusable piece designed specifically for Cold Air Inductions, as evidenced by the “CAI” branded end cap.

The CAI intake tube is 4-inches in diameter, and is thermal coated in black to protect against engine bay heat.

The CAI intake tube is 4-inches in diameter, and is thermal coated in black to protect against engine bay heat.

 

The CAI silicone intake elbow allows for zero-turbulence air induction with the ability to flex under engine load. It's slightly different than the piece used in 5.3L variants, so be sure to specify the correct kit intended for your truck, because you don't want to purchase the incorrect system!

The CAI silicone intake elbow allows for zero-turbulence air induction with the ability to flex under engine load. It’s slightly different than the piece used in 5.3L variants, so be sure to specify the correct kit intended for your truck, because you don’t want to purchase the incorrect system! It also comes with the hose for the smog system provisions that replace the OEM lines.

 

Under the hood, is a complete stock 6.2L L86... and one ugly and restrictive airbox!

Under the hood, is a complete stock 6.2L L86… and one ugly and restrictive airbox!

 

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In order to install the CAI kit, you must remove both diagonal braces and disconnect the battery.

 

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Next, leaving the MAF connected to the harness, pull the sensor out of the inlet tube slot. Carefully set it aside — without letting the sensor making contact with anything. DO NOT disconnect the sensor. Even with the key off and battery disconnected, unplugging the MAF wiring will trigger an engine fault code when the engine is started next.

 

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After removing the bolts securing the airbox in place and pulling the two PVC tubes from the OEM restrictor box, just past the throttle body, you will be able to yank the stock ‘box out of the engine compartment.

 

Again, you'll have to pull both PVC hoses on both sides of the OEM inlet tube's housing.

Again, you’ll have to pull both PCV hoses on both sides of the OEM inlet tube’s housing.

 

It's amazing how much room the airbox takes up, however...

It’s amazing how much room the airbox takes up, however…

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Fitting the CAI airbox into its rightful place is quite simple, however, it’s probably best to remove the front cross brace prior to installation. It’s possible to install the kit without doing so, and even CAI doesn’t necessarily suggest it, but it does help if the truck sits high from a lift or if you have large forearms.

 

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The silicone coupler assembly is now ready to be installed onto the throttle body.

 

Slide the intake tube into the silicone coupler, followed by the hole of the airbox.

Slide the intake tube into the silicone coupler, followed by the hole of the airbox.

 

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With the intake tube now fed into the box and connected to the throttle body, we slid the filter cone to the end of the tube, then tightened down the clamp, securely. As a side note, make sure that the metal pleat clamp is facing down. The MAF is so sensitive that CAI puts an arrow on the filter so the pleat is strategically located. This won’t affect drivability, but it will make a few horsepower worth of difference. Air intake science is now a combo of reduced airflow restriction, keeping the air as cool as possible and designing the system in a way that works with the MAF to let the PCM allow the engine to make more power.

 

 

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If you have trouble reinstalling the MAF connector, you may have forgotten to adjust the inner-sleeve for proper fitment. Keep this in mind during installation. You can remove it entirely, if you have a custom tune installed in the vehicle. We preferred to leave in the factory tune, just to see what kind of results we’d get with a CAI kit on this 2015 Sierra, so the inner-sleeve stayed in place.

 

Every detail of the CAI kit is high-quality. This aluminum emblem on the airbox is a nice touch.

Every detail of the CAI kit is high-quality. This aluminum emblem on the airbox is a nice touch.

 

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After the kit was installed, we fired up the Dynojet for another pass. Even with the 8-speed automatic still giving the dyno some technical issues, we were at least able to see what our peak horsepower was, based on speed. We could have easily tuned the governor out of the equation, but between Justin’s warranty concerns and the fact that the OEM driveshaft is only reliable to a certain point (around 110, on a good day), we felt it best to leave it well enough alone.

 

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Despite working perfectly all day, both before and after our Sierra’s dyno pulls, we weren’t able to get a solid dyno pull highlighting the torque band and the peak RPM levels. As a result, we were relegated to speed and horsepower levels, only, and with the factory governor still in place. Our peak output was roughly seven horsepower to the rear tires. We feel that removing the sleeve from the intake tube and installing a HP Tuners calibration would have done wonders, but we wanted to show you the raw changes in power output with just the CAI system. That being said, everyone in the shop that day, including the truck’s owner, were all blown away by the improvement in the soundtrack. Typically you resort to an exhaust upgrade for a more audible tone, but the CAI intake system really lent not just a few ponies, but a throaty growl, a potential improvement in fuel mileage (if Justin can keep his foot out of it, now) and improved looks in the engine bay. Plus, it helps pave the way for a more substantial improvement in horsepower increases in future performance modifications.

 

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The finished product looks absolutely amazing in the Sierra’s engine bay. With the open element air filter exposed for the world to see, albeit, in a sealed and insulated airbox, it adds a touch of class over the drab and restrictive, black plastic factory induction system.

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