Wehrli Custom Fabrication WCF100693-RED 3 Inch LB7 Duramax Y-Bridge Kit 2001 2002 2003 2004 Chevrolet GMC Sierra Silverado 6.6L Duramax LB7 WCFab Red

The Wehrli Custom Fabrication WCF100693-RED is the only high-flow 3-inch complete Y-bridge kit for 2001, 2002, 2003, and 2004 6.6L Duramax LB7-powered Chevrolet Silverado 2500HD, Silverado 3500, GMC Sierra 2500HD, and GMC Sierra 3500 trucks that maintains full compatibility with the factory IHI turbocharger and drop-in IHI-style chargers. Built in DeKalb, Illinois and finished in WCFab Red powder coat, WCF100693-RED delivers approximately 630 CFM of airflow compared to 420 CFM through the restrictive OEM unit, a 50% improvement that feeds your LB7 the air it needs to make real power. The kit ships complete with every component required for installation.

What's Included

• 3-Inch Fabricated Billet Y-Bridge (clearanced for OEM-style intake horn)
• 3-Inch Passenger Side Intercooler Pipe (14-gauge mandrel-bent aluminum)
• FPRV Block Off Kit (fuel pressure plug, fuel hose T-fitting, and hose clamps)
• Silicone boots
• T-bolt clamps
• O-ring bridge flange gaskets
• MAP sensor seal and hold-down bracket (straight-style, replaces factory angled bracket)

Why the OEM Y-Bridge Is a Restriction

The factory LB7 Y-bridge measures roughly 2-3/8 inches in diameter at its narrowest points and flows approximately 420 CFM. That ceiling is hit well before the LB7's potential is reached, and the angled intercooler boots that come with the OEM setup are notorious for cracking, collapsing, and blowing off under elevated boost pressure. The WCF100693-RED replaces that entire assembly with a full 3-inch intake tract running from the intercooler outlet to the engine. At approximately 630 CFM, it flows 50% more air than the factory bridge, removes every OEM boot-failure point in that tract, and opens the door to compound turbo builds and serious fuel strategy tuning. The included FPRV Block Off Kit handles the clearance requirement imposed by the larger bridge diameter so the upgrade is truly plug-and-play on all 16 supported application rows.

Construction and Finish

The lower Y-bridge section is CNC-machined from billet aluminum for precise port-to-port geometry and a leak-free mating surface at the intake manifold flanges. The upper section and passenger-side intercooler pipe are fabricated from 14-gauge mandrel-bent aluminum tube, preserving full interior diameter through every bend. A 1/8-inch NPT threaded boost port is located on the backside of the bridge for gauge taps, boost controllers, or wastegate references. The MAP sensor port is welded directly onto the bridge so the factory sensor relocates cleanly without adapters. Every WCF100693-RED unit receives a custom powder coat in WCFab Red prior to leaving the DeKalb, Illinois facility.

Powder Coat Lead Times: WCFab Red is a standard production color. Units in WCFab Red are in stock ship same day or next.

Fitment Table

Fitment and Compatibility Notes

Banks Intercooler: The WCF100693-RED is not compatible with the Banks intercooler. The Banks unit uses a different outlet configuration that prevents proper fitment with this bridge and pipe assembly. Do not attempt to combine these two components.

S300 and S400 Turbochargers: This kit is not recommended for use with S300 or S400 single-turbo installations. For S300 applications, Wehrli recommends part number WCF100478. For S400 applications, Wehrli recommends part number WCF100489. Both are purpose-built to accommodate the larger compressor outlet diameter on those chargers.

2001 Model Year MAP Sensor Note: On 2001 LB7 trucks, the MAP sensor is located on the intake runner rather than on the bridge. Installing WCF100693-RED on a 2001 requires additional installation steps beyond the standard procedure to properly route and secure the MAP sensor. Review the full WCFab installation instructions for the 2001-specific MAP sensor steps before beginning the install.

Federal Emissions Vehicles Only: This product is designed and sold for use on Federal emissions vehicles only. It is not legal for use in California and cannot be shipped to California addresses. Do not order this part if your vehicle is registered in California or if your shipping address is in California.

Color Variants

Full Specifications

California and Emissions Compliance

This product is not legal for use in California and cannot be shipped to California. The WCF100693-RED is designed exclusively for Federal emissions vehicles.

Proposition 65 Warning: This product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, visit www.P65Warnings.ca.gov. This warning is provided for informational purposes. Again, this product cannot be shipped to California.

Made in USA

Every WCF100693-RED kit is designed and manufactured at the Wehrli Custom Fabrication facility in DeKalb, Illinois. WCFab has built its reputation among LB7, LLY, LBZ, and LMM Duramax owners by engineering parts in-house, machining them in-house, and powder coating them in-house. When you install WCF100693-RED, you are putting American-made billet aluminum and American-bent mandrel tube on your LB7. No overseas sourcing. No outsourced fabrication.

Warranty

Wehrli Custom Fabrication warrants the WCF100693-RED against defects in material and workmanship for 12 months from the date of original purchase. This warranty is limited and non-transferable. It applies only to the original purchaser and is void if the product has been improperly installed, misused, modified, or altered in any way.

This warranty gives you specific legal rights. You may also have other rights which vary from state to state. In accordance with the Magnuson-Moss Warranty Act (15 U.S.C. 2301 et seq.), this written limited warranty is provided in plain language so you understand exactly what is and is not covered. Nothing in this warranty limits any rights you may have under applicable federal or state law.

Frequently Asked Questions

Q: Does the 2001 model year require extra steps when installing the WCF100693-RED?

A: Yes. On 2001 LB7 Duramax trucks, the MAP sensor sits on the intake runner rather than on the bridge itself. Because the WCF100693-RED ships with a MAP sensor port welded onto the bridge and a straight-style sensor hold-down bracket (replacing the factory angled bracket), 2001 owners need to follow the additional MAP sensor relocation steps in the WCFab installation instructions. The 2002, 2003, and 2004 model years do not require these extra steps.

Q: Will this kit work with a Banks intercooler?

A: No. The WCF100693-RED is not compatible with the Banks intercooler. The Banks unit has a different outlet geometry that prevents proper fitment with this bridge and pipe assembly. If you are running a Banks intercooler, this is not the correct kit for your build.

Q: Can I use this kit with an S300 or S400 single turbo setup?

A: This kit is not recommended for S300 or S400 single turbo applications. Those chargers have larger compressor outlets that require a different bridge configuration. For S300 builds, Wehrli recommends WCF100478. For S300 builds, Wehrli recommends WCF100489. Both are purpose-engineered for those outlet diameters.

Q: Can this product be shipped to California?

A: No. The WCF100693-RED is not California-legal and cannot be shipped to any California address. This kit is built for Federal emissions vehicles only. If your shipping address is in California, your order will be cancelled. Do not attempt to have this product shipped to a California freight forwarder for in-state delivery.

Q: What color options are available and how long do they take to ship?

A: The WCF100693-RED (WCFab Red), WCF100693-GB (Gloss Black), and WCF100693-SGB (Semi-Gloss Black) are standard production colors that ship within 3 to 5 business days. The WCF100693-CAT (CAT Yellow) and WCF100693-SY (Shocker Yellow) are custom powder coat colors that carry a 10 to 15 business day lead time before shipment.

Q: What is the 1/8-inch NPT boost port on the back of the bridge used for?

A: The threaded 1/8-inch NPT port on the backside of the bridge is a boost reference port. Common uses include plumbing a mechanical or electronic boost gauge, connecting an aftermarket boost controller, providing a signal reference for a wastegate solenoid, or tapping into intake tract pressure for a data-logging sensor. A plug is included if you do not plan to use the port immediately.

Q: What does the warranty cover and how do I make a claim?

A: The warranty covers defects in material and workmanship for 12 months from the date of original purchase. It does not cover damage from improper installation, misuse, or modification. To start a claim, call WCFab at 630-277-8239 to get a Return Authorization number before sending anything back. The warranty is non-transferable and applies to the original purchaser only.

Q: Do I need to remove the turbocharger to install the WCF100693-RED?

A: Turbocharger removal is not required for a standard WCF100693-RED installation on 2002, 2003, and 2004 LB7 trucks. The kit is designed to work with the factory IHI turbocharger and drop-in IHI-style replacement chargers in the stock location. On 2001 trucks, refer to the WCFab installation instructions for the MAP sensor-specific steps, but turbo removal is still not part of the standard procedure. Always disconnect the batteries and allow the engine to cool fully before beginning any intake work.

Q: Is the FPRV Block Off Kit really necessary, or can I skip it?

A: The FPRV Block Off Kit is required. The larger 3-inch diameter of the WCF100693-RED bridge directly conflicts with the fuel pressure regulator vent (FPRV) fitting in its stock location. The block-off kit reroutes that line to provide the clearance the larger bridge needs. Skipping it will result in a clearance problem that prevents proper installation and could cause fuel system issues. WCFab includes the block-off kit in every WCF100693-RED package for exactly this reason.