About this product
WCFab's WCF100505 Stage 3 High Flow Intake Bundle Kit covers the whole air path on the 2011-2016 LML 6.6L Duramax in Chevrolet Silverado and GMC Sierra 2500HD/3500HD trucks: 4" intake and air box, 4.8" turbo horn, both intercooler pipes, the Y-bridge and a 3" stainless downpipe. You buy it to clear restrictions and boost leaks on both sides of the turbo in one job.
Fitment
Listed for the 6.6L LML Duramax in 2011-2016 Chevrolet Silverado 2500HD/3500HD and GMC Sierra 2500HD/3500HD. WCFab writes this kit up for 2011-2015 LML trucks, and the downpipe is what sets the limit. It is for use with the factory turbo or a factory style drop-in turbo on trucks using a v-band connection style exhaust, NOT the 3 bolt flange style exhaust. If you have a 2015.5-2016 truck with the 3-bolt style flange, please see part numbers WCF100439 and WCF100705 instead. The kit is compatible with stock trucks and needs no additional modifications, upgrades or tuning to install. Verify fitment by VIN or call us before you order.
Why this part
The factory LML air system has weak points that cost power and, on hard-working or high performance trucks, lead to boost leaks and complete failures. The intake pipe and air box are restrictive plastic. The driver (hot) side intercooler pipe is a two-piece 2.5" pipe, the passenger (cold) side is a plastic two-piece pipe, and the factory boots can blow under higher boost. The OEM Y-bridge, which supplies air to the intake runners and cylinder heads, is a bottleneck in the intake tract that limits what the engine can make. After the turbo, the factory downpipe is crushed and restrictive.
Stage 3 takes on all of it at once. WCFab combines its Stage 2 High Flow Bundle with the 3" stainless downpipe, so the turbo and engine get more air in and more exhaust flow out. The goals are better efficiency, throttle response and turbo spool-up. The upgraded silicone boots are built to withstand higher boost pressures than the factory components, which increases reliability and stops horsepower-robbing boost leaks. If you only need the air box side, browse our intakes.
What you get
- 4" aluminum intake pipe with smooth aerodynamic bends, rated by WCFab at a 37% gain in air flow over stock. It improves intake air velocity and volume and gives a more aggressive engine and turbo sound during acceleration.
- Air box and lid built from 10G aluminum sheet that draws cold air through the inner fender for more horsepower and torque, quicker throttle response and cooler intake temperatures. The removable lid makes filter inspection and maintenance easy.
- Dry air filter with hydrophobic pre-filter cover to help keep the MAF sensor, turbo and engine airways free of contaminants.
- 4.8" cast aluminum turbo intake horn (5.6% gain in air flow over stock) that removes restrictions in the OEM setup to improve turbo spool and top-end power. It eliminates the factory resonators and is fully compatible with OEM and upgraded drop-in VGT style turbochargers.
- 3" driver (hot) side intercooler pipe (18% gain) that replaces the factory two-piece 2.5" pipe.
- 3.5" passenger (cold) side intercooler pipe (23% gain), a one-piece 14 ga. aluminum pipe that replaces the factory plastic two-piece pipe.
- High flow, precision CNC machined, cast aluminum Y-bridge that replaces the OEM upper intake manifold. WCFab rates the bridge on its own at 40% more airflow than stock.
- 3" fabricated aluminum upper intercooler crossover pipe, 20% larger than stock, sized to take full advantage of the Y-bridge's larger inlet. Together the bridge and crossover improve total air flow by 33% over the stock setup, the most airflow volume WCFab could fit in the available space.
- Billet resonator plate that eliminates the stock plastic resonator for a cleaner engine bay and a more aggressive turbo and engine sound.
- 3" stainless steel downpipe with v-band flange and heat wrap that replaces the restrictive crushed factory downpipe.
- Silicone boots, seals, stainless steel t-bolt clamps and high-quality hardware for durability and an easier install.
Specifications
WCFab's feature list for this kit:
- 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 with 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 & Stainless Steel T-Bolt Clamps
- Connects to factory throttle valve, grid heater, EGR and stock intake runners
- 3" Stainless Downpipe (v-band flange) with Heat Wrap
- NO Tuning required, bolt on.
- Will fit on stock truck no other modifications or upgrades necessary.
- Durable Custom Powder Coat Finish
- Made in USA
Finish: your choice of 25 custom powder coat colors. Part number WCF100505 supersedes WCF100716.
Installation notes
This is a bolt-on kit for a stock truck. It connects to the factory throttle valve, grid heater, EGR and stock intake runners, and it is compatible with the OEM throttle valve and EGR controls. A threaded bung lets you reinstall the OEM intake temperature sensor, and the factory intake air heater grid stays in the system for cold weather performance. The downpipe works with the factory turbo or a factory style drop-in turbo, on v-band style exhaust only. No tuning is required for installation. WCFab says the kit pairs best with emissions-compliant tuning and drop-in turbochargers for optimum performance gains.
About Wehrli Custom Fabrication
Wehrli Custom Fabrication (WCFab) opened in 2010 in DeKalb, Illinois, and builds fabricated intake, intercooler, cooling and traction parts for diesel pickups. Its High Flow intake bundles come in Stage 1, 2 and 3 versions, and the bulk of the lineup is designed around the 6.6L Duramax. See the full WCFab lineup.
Frequently asked questions
Will the downpipe fit my 2016 LML?
Only if your truck uses the v-band connection style exhaust. If you have a 2015.5-2016 truck with the 3-bolt style flange, this kit's downpipe will not fit. Look at WCF100439 and WCF100705 instead, or send us your VIN.
What does Stage 3 add over Stage 2?
Stage 3 is WCFab's Stage 2 High Flow Bundle plus the 3" stainless downpipe with heat wrap, packaged as one kit. You get the intake, horn, intercooler pipe and Y-bridge upgrades along with better exhaust flow after the turbo.
Do I need a tune to run this kit?
No. It is compatible with stock trucks and needs no additional modifications, upgrades or tuning. If you want more from it, it pairs best with emissions-compliant tuning and a drop-in turbocharger.
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.
