About this product
The WCFab WCF100439 Stage 2 kit replaces the factory intake, turbo intake horn, both intercooler pipes, upper crossover pipe and Y-bridge on 2011-2016 Chevrolet Silverado and GMC Sierra 2500HD/3500HD trucks with the 6.6L LML Duramax. Owners buy it to clear the restrictions and leak points of the factory plastic air path in one install.
Fitment
Fits 2011-2016 Chevrolet Silverado 2500HD and 3500HD and GMC Sierra 2500HD and 3500HD trucks with the 6.6L LML Duramax. WCFab says it is compatible with stock trucks and needs no additional modifications, upgrades or tuning for installation. It connects to the factory throttle valve, grid heater, EGR and stock intake runners, and it has a threaded bung so you can reinstall the OEM intake temperature sensor. The 4.8 in. turbo intake horn works with the OEM turbo and with upgraded drop-in VGT style turbochargers. If you're not sure which engine your truck has, verify by VIN or call us before you order.
Why this part
The factory air path on the LML is a run of restrictive plastic parts and two-piece pipes. WCFab's Stage 2 kit combines its Stage 1 High Flow Bundle and its Stage 2 Cold Air Intake Kit into a single package, so every restriction from the inner fender to the cylinder heads gets replaced in one job. The goal is more airflow for your turbo and engine, which improves efficiency, throttle response and turbo spool-up. It also removes weak points in the factory design that can contribute to lost power, boost leaks and complete failures in hard-working and high-performance applications.
Intake and air box. The high-flow, fabricated aluminum intake pipe and air box enclosure with a dry filter assembly replace the restrictive plastic factory parts. Drawing cold air through the inner fender, the new design significantly increases airflow to your turbo, which WCFab says produces more horsepower and torque, quicker throttle response and cooler intake temperatures. The large 4" piping has smooth aerodynamic bends to improve intake air velocity and volume, and you will hear more engine and turbo sound during acceleration. The air box lid is removable, so checking and servicing the WCFab filter is easy, and the included hydrophobic pre-filter cover helps keep your MAF sensor, turbo and engine airways free of contaminants.
Turbo intake horn. The high flow 4.8 in. cast aluminum turbo intake horn removes restrictions in the OEM setup to improve turbo spool and top-end power. It also eliminates the factory resonators, which cleans up the engine bay and gives you a more aggressive turbo sound.
Intercooler pipes. The 3" high flow driver (hot) side pipe replaces the factory two-piece 2.5” pipe. The 3.5" high flow passenger (cold) side pipe replaces the factory plastic two-piece pipe with a one-piece pipe made from 14 ga. aluminum. Upgraded silicone boots withstand higher boost pressures than the factory components, which increases reliability and eliminates blown factory boots and horsepower-robbing boost leaks.
Y-bridge and crossover pipe. The Y-bridge is the upper intake manifold that supplies air to the intake runners and cylinder heads. On these trucks the OEM Y-bridge is a restrictive part that creates a bottleneck in the intake tract and limits engine performance. WCFab's LML Y-Bridge Kit replaces it with a high flow, precision CNC machined, cast aluminum intake bridge that flows 40% more air than stock. It is paired with a 3" fabricated aluminum upper crossover intercooler pipe, 20% larger than stock, so you can take full advantage of the bridge's larger inlet diameter. Together they improve total airflow by 33% over the stock setup, the most airflow volume WCFab could fit in the available space. The kit keeps the factory intake air heater grid for cold-weather performance, eliminates the stock plastic resonator for a cleaner engine bay and more turbo and engine sound, and stays compatible with the OEM throttle valve and EGR controls.
What you get
Everything from WCFab's Stage 1 High Flow Bundle and Stage 2 Cold Air Intake Kit for the LML, in one package:
- 4" fabricated aluminum intake pipe
- Aluminum air box enclosure with removable lid
- Dry air filter and hydrophobic pre-filter cover
- 4.8 in. cast aluminum turbo intake horn
- 3" driver (hot) side intercooler pipe
- 3.5" passenger (cold) side intercooler pipe
- Precision CNC machined, cast aluminum Y-bridge
- 3" upper intercooler crossover pipe
- Silicone boots, seals, stainless steel t-bolt clamps and hardware
The full assembly is finished in your choice of custom powder coat colors, sold as 25 color options (the SKU suffix is the color code, for example WCF100439-RED).
Specifications
WCFab's spec list for WCF100439:
- 4" Intake Pipe (37% Gain in Air Flow Over Stock)
- 4.8" Intake Horn (5.6% Gain in Air Flow Over Stock)
- Air Box & Lid Constructed of 10G Aluminum Sheet
- Dry Air Filter & Pre-Filter Cover
- 3.5 in. Passenger (Cold) Side Intercooler Pipe (23% Gain in Air Flow Over Stock)
- 3 in. Driver (Hot) Side Intercooler Pipe (18% Gain in Air Flow Over Stock)
- High Flow, Precision CNC machined, Cast Aluminum Y-Bridge (33% Gain in Air Flow Over Stock)
- 3 in. High Flow Upper Intercooler Cross Over Pipe
- 14g aluminum construction
- Incorporated threaded bung to reinstall OEM Intake Temperature Sensor
- Silicone Boots
- T-Bolt Clamps
- Connects to factory throttle valve, grid heater, EGR and stock intake runners
- NO Tuning required, bolt on
- Will fit on stock truck no other modifications or upgrades necessary
- Durable Custom Powder Coat Finish
- Made in USA
Installation notes
This is a bolt-on kit for a stock truck. No tuning is required, and it connects to the factory throttle valve, grid heater, EGR and stock intake runners, so the factory controls stay in place. Move the OEM intake temperature sensor over to the kit's threaded bung. Because the kit replaces the Y-bridge as well as the intake and both intercooler pipes, it touches more of the engine than an intake-only swap. WCFab says it pairs best with emissions-compliant tuning and drop-in turbochargers for the most performance gain, but neither is needed to install it.
About Wehrli Custom Fabrication
WCFab, short for Wehrli Custom Fabrication, started in 2010 in DeKalb, Illinois. It builds fabricated intake, intercooler, cooling and traction parts for diesel pickups, and its Stage 1, 2 and 3 High Flow intake bundle kits package those parts together for Duramax and Cummins trucks. Most of the line is built for the 6.6L Duramax.
Frequently asked questions
How is Stage 2 different from the Stage 1 bundle?
Stage 2 combines WCFab's Stage 1 High Flow Bundle with its Stage 2 Cold Air Intake Kit in a single package. Everything listed under What you get comes in this kit.
Does it keep the EGR and grid heater working?
Yes. It connects to the factory throttle valve, grid heater, EGR and stock intake runners and stays compatible with the OEM throttle valve and EGR controls. The factory intake air heater grid is kept for cold-weather performance.
Will it work with my turbo?
The 4.8 in. intake horn is compatible with the OEM turbo and with upgraded drop-in VGT style turbochargers.
Questions on fitment? Call the shop at the number in the header. We install everything we sell.
Description supplied by Southern Diesel Supply through its current Shopify listing. Product, performance, and health claims are the seller’s and have not been independently verified by StorkScout.
