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Optimizing Airflow: Upgrading Project Stockish’s 3.0L Duramax

Helping Project Stockish Breathe Better

With the rise of OE manufacturers adding smaller diesels to their trucks and SUVs, it’s important for aftermarket companies to make parts to help the diesels run better and more efficiently. Most of the big vehicle manufacturers have a small-platform diesel as an option that automatically gets more miles per gallon than most of the big V-8 engines in today’s vehicles.

For this project, I picked up a 2023 GMC Sierra with the 3.0L Duramax that is commonly referred to as the baby Max. Even though this engine doesn’t provide as much towing and torque as its bigger version, it still packs a punch and gets better fuel mileage. I have driven this truck across the country and back and was averaging 26-34 mpg all while having the cruise set around 85 mph. This truck has the new GM engine, the LZ0, which in ’23 replaced the LM2 in the trucks. SUVs still run the older engine until the 2025 model.

The factory engine bay layout has a plastic cover on the small OEM intercooler and a restrictive intake, but that’s about to change.

Knowing I wanted this truck to breathe a little better than stock, I found a couple companies that already had a few engine upgrades available. For the most part, a lot of the LM2 upgrades work on the LZ0 since the big changes were internal, so getting parts to fit wasn’t too hard. For upgrades, I added an AFE Power Momentum HD intake (Part #50-70064T with a $436 retail) to let the truck pull in air a little easier. Next in line is the PPE Zilla carbon fiber intake tube (Part #115020360 with a $440 retail). This new tube allows for smoother flowing air from the intake to the turbo, which gives you better throttle response.

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Now that air flow into the engine was improved, it was time to better cool the air than than the factory setup. The PPE air-to-water intercooler was added (Part #15030012 with a $1,600 retail). This not only provided cooler air for the turbo, but being the color theme with this truck was red, it also added a touch of color matching to the engine bay.

To expel the gasses out of the engine, we picked up another AFE Power part—the brand new DPF exhaust it just released for the new LZO engine (Part #49-34145-B with a $880 retail). This new Rebel XD 3-inch exhaust not only lets the exhaust gasses flow smoothly out of the truck, but it does so with dual black tips that finish off the system nicely.

Follow along as we install these parts and let #projectSTOCKISH breathe a little better.

The clamps that hold the factory air box lid and tube were loosened and removed.
The front engine cover was then removed and set aside with all the clips.
Next, we removed the driver side corner support. This needs to come out to allow clearance for the lower air box to be removed.
The wiring harness from the side of the lower factory air box assembly was then unclipped from the truck.
The rubber boots from the factory air box were taken off and installed on the new AFE airbox. These are needed to secure the new air box to the truck.
The MAF sensor from the factory intake tube was swapped to the new AFE intake tube ensuring it’s in the right direction.
The new air box was installed into the factory holes the stock box came out of.
The new air filter was slid into the box.
The new intake tube was installed and secured to the factory tube and the air box with supplied hardware. The corner brace and front engine cover were reinstalled at this point and the wire harness was secured to the side of the new air box.
Next up was the PPE air-to-water intercooler. The required hardware as well as a new base bracket come included.
Next, we removed the factory intercooler cover as well as the NOx sensor and set it aside.
We then disconnected both inlets into the factory intercooler.
The hoses were then clamped before removal to keep the coolant spilling to a minimum.
The entire stock intercooler was removed as one unit.
As you can see, PPE did a full casting of the new base bracket, so the new intercooler fits as good as the factory one did. A couple of the studs need to be moved over to the new PPE bracket.
The factory temperature sensors needed to be moved to the PPE intercooler.
The new PPE base bracket was then installed with factory hardware.
The new intercooler was installed and all lines were connected with supplied hardware.
The NOx sensor was reinstalled to the new intercooler with supplied bracket and hardware.
The overflow tank was filled with the appropriate coolant, the tank was lifted and the bleeder valve was loosened. We kept filling the tank until the coolant flowed out of the bleeder hole.
Once the air was purged from the intercooler, the bleeder screw was tightened.
With all of the electrical connections and coolant hoses installed, the new intercooler was good to go.
The Zilla carbon fiber intake tube wasn’t available when the intake and intercooler were installed, so we had to go back and add it after the fact. If you are installing all these parts at the same time, it will make the process easier, but it’s still not hard adding it later like we did. You can see how much more unrestrictive the new carbon tube is compared to the massive factory tube.
After removing the two mounting connectors from the factory tube, as well as the AFE intake tube installed in step 10, it was removed with a little finesse. Once removed, we slid the new PPE tube into place where the factory tube was.
With the new tube in place, we tightened all the supplied hardware to secure it in place. The carbon fiber looks right at home tucked against the firewall too.
We then reinstalled the AFE intake tube that now goes from the new PPE carbon tube to the air box.
We cut the factory exhaust 3.75 inches behind the rear weld on the exhaust valve, which is just before the factory exhaust hanger.
The AFE 3-inch exhaust completely replaces the factory exhaust with minimal connections and mandrel bends.
We also cut the factory exhaust before the rear axle. This wasn’t required but made the removal of the factory exhaust easier.
We started with the front connection then moved to the rear, and aligned and tightened the new piping with supplied clamps.
The new dual black tips I chose for this truck look much better than the factory cut tip ever did. Once everything was tight, we went back through and ensured there were no leaks and adjusted the clamps as needed to eliminate the leaks.

SOURCES

AFE Power    
951-493-7100
www.afepower.com

PPE
725-238-2002
www.ppepower.com

Tameless Performance
828-505-8195
www.tamelessperformance.com 

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