Home - Return to Previous Page
Additional Images

2001-2004 LB7 Duramax Y-Bridge Kit

-3" Fabricated Billet Y-Bridge (clearanced for OEM style intake horn)
-3" Passenger Side Intercooler Pipe - 14g Mandrel Bent Aluminum Construction
-FPRV Block Off Kit
-Silicone Boots
-T-Bolt Clamps
-O-Ring Bridge Flange Gaskets
-Map Sensor Seal and Hold Down Bracket
-Powder Coating
Availability: WCFab Red, WCFab Grey and Gloss Black in stock and ships in 3-5 business days. 10-15 business day lead time on other colors.
Shipping: This Product cannot ship to the state of California
Pricing: $849.00

Customize Your Item

- Model Year -
 * required
- Powder Coating -
 * required
- 3" Driver Side Intercooler Pipe -
 * required
- High Flow Intake Horn -
 * required
- Up Pipes & Manifolds -
 * required
- Fastener Type -
 * required
- What intercooler do you have? -
 * required


The only High Flow 3” Complete Y-Bridge kit on the market for your LB7 that is compatible with the factory IHI turbo and aftermarket drop in IHI style chargers! Replace the restrictive OEM Y-bridge and cold side intercooler pipe with this high flow 3” kit to increase throttle response and turbo spool up by creating a full 3" intake tract from the intercooler outlet to the engine. Eliminates the angled OEM intercooler boots that are prone for failure. Includes FPRV Block off kit to allow proper clearance to larger diameter Y-bridge.

***NOTE: NOT RECOMMENDED FOR USE WITH S300 OR S400 STYLE TURBOCHARGERS. If you are planning to run a turbo other than an OEM / IHI style upgraded drop in on your setup, please check out our S300 Single Turbo Kit WCF100478 and our S400 Single Turbo Kit WCF100489 or call us for help placing your order.***



Hey, everyone, and thanks for tuning in. I'm Jason Wehrli with WC Fab. Today, we have our LB7 Duramax high-flow Y bridge kit.

The LB7 Duramax is the OG (original gangster) truck of WCFab and what started it all for us, and we still offer a complete product line for the 2001-2004 LB7. We offer bundle kits, twin-turbo kits, single-turbo kits, and everything you can think of for the LB7. What we have here today is our very popular three-inch high-flow Y bridge kit. The three-inch high-flow Y bridge is one of the first products I manufactured when I started the business nearly 14 years ago. It's changed a lot since then.

One of the most notorious issues on the LB7 cold-side intercooler pipe is the boot connection at the Intercooler. It's an angled, very thin intercooler boot notorious for tearing open and leaking. When we set out to design upgraded intercooler pipes for the LB7, one of the biggest things was eliminating those angled intercooler boots, both on the hot side and on the cold side.

On the cold side, we use a three-inch straight silicone boot, high quality made in the USA five-ply boot that connects to our three-inch 14 gauge mandrel bent intercooler pipe. We route the pipe slightly differently than OEM so that the pipe can be a direct shot to the intercooler versus using that angled intercooler boot. Similar in size, the OEM pipe is aluminum as well, with a little bit thinner wall. However, the biggest issue with the OEM pipe, aside from the angled boot at the bottom, is its connection to the Y bridge, the factory intercooler pipe. Necked down to about two and three-eighths of an inch. Before connecting to the bridge, we designed our pipe for a full three-inch flow to the Y bridge, connecting to our bridge with another three-inch straight silicone boot from the intercooler pipe.

We move on to the high-flow Y bridge, one of the nicest components of the whole kit. This replaces the very, very restrictive OEM Y bridge. The factory bridge measures about two and three-eighths of an inch. We have a full three-inch high flow bridge, mandrel 14 gauge aluminum on the top section into a billet aluminum CNC machine, lower section. So this bridge is phenomenal compared to the factory, be it a full three-inch track the whole way on the flow bench.

This wide bridge flows 50% greater than the OEM bridge, which does 420 CFM versus 630 CFM on our three-inch high-flow bridge. If you've got an early 2001 model LB7, you'll notice that this bridge looks slightly different. The bridge in our kit replicates more of what the OEM bridge looks like in an oh two to oh four application, meaning it's got the bend built into it on the oh one Y bridge. They end right about here. Again, use another angled boot to connect to the intercooler pipe. So, for the ‘01 application, we upgraded it to be more like the ’02 to ’04 styles using a straight boot connection to the intercooler pipe.

We include an eighth-inch threaded port on the backside of the Y bridge to connect any boost gauge or other type of sensor. Then, we also have the map sensor port welded onto the bridge. Again, if you have an ’01 LB7, a lot of things were different in that very first model year. In the 2001 LB7, you'll find the factory map sensor on the passenger-side intake runner, conveniently located directly underneath the Y bridge. Now, with our bridge being so much larger than the factory, it is not clear what the OEM location of the map sensor is.
So if you've got an ’01 LB7 after you pull your factory bridge out, you will be required to remove that factory map sensor and tap that hole where the map sensor sat to a quarter inch MPT and install a plug-in it, and you will then relocate your sensor to the same location found on the ‘O2 to ‘04, which is on the bridge itself, using our supplied map sensor seal and hold down bracket. Now, this is a small item that a lot of the competition overlooks. Again, we're dealing with a 20-plus-year-old truck, and trying to reuse seals and things like that is never a good idea. So we include a new gasket seal for the map sensor itself and a new straight style hold-down bracket to replace the factory angled bracket. So, how else do we make this bridge so much bigger than the factory unit?

One of the biggest bottlenecks in the factory application is the fuel pressure relief valve that sits right above the OEM bridge. A large banjo fitting with a hard line assembly is on the end of that fuel pressure relief valve. What we include with our Y bridge kit is what's known as a fuel pressure relief valve delete. This package allows you to remove the large banjo bolt and hard-line system on the end of that fuel pressure relief valve. Installing our fuel pressure plug and replacing that hard line with supplied fuel hose T fitting and hose clamps, getting rid of the end of assembly on that fuel pressure relief valve allows all the room for that larger bridge to sit down there, as you can see here in the installed application. Another thing to note is that we get a lot of questions about the installation of these Y bridges on all Duramax Y bridges; we do supply a new O-ring seal for the bridge flange to the intake runner, and it is a very important note that when installing the Y bridge on a Duramax, the four lower holes of the bridge on the intake runners are an angled stud.

You need to install those four lower bolts first in a crisscross pattern, and that takes the Y bridge because it's in a V shape and sucks it down into place, which then allows you to install your four upper bolts. So, what does all this mean for you with your LB seven? You won't notice a huge difference if you have a bone stock truck. This isn't a 20-horsepower bolt-on upgrade. Yes, your engine's going to breathe better. Yes, getting rid of the angled boots and some worn-out components on your 20-plus-year-old truck will be more reliable. But where this product shines is when you're upgrading, tuning, or upgrading other performance parts on the engines, like turbochargers. These LB7s came out of the factory with just about 300 horsepower. And with a simple tune and turbocharger, they can quickly make 550 and 600 horsepower.
When you double the output of the factory engine from what the engineers figured 25 years ago, you will run into issues with how well those factory parts flow. So, getting these high-flow components, again, the Y bridge flowing 50% better than the OEM bridge, will let your engine breathe so much more easily and work so much more efficiently and help you produce more power. In an application dealing with upgraded turbochargers and higher boost levels, performance tuning, et cetera. It's a straightforward installation much easier than some later model-year Duramax platforms.

It's not required to remove the turbocharger to install this kit, so it can be done if you're doing performance tuning as well. You will also find this high-flow three-inch bridge included in our upgraded turbocharger kits. If you're doing an S300, S400 style upgraded single charger or our S400 over-stock style compound kit, you'll have this same high-flow Y bridge in that turbo kit.

This color is our very popular WCFab Red. WCFab Grey, gloss Black, and Gloss White will be our in-stock colors. If you're in a hurry to get a kit or in the middle of a project on your truck and decide you want to upgrade, we've got a handful of colors to pick from that are available to ship quickly.

If you've got extra time, you can wait, or you want to do a custom color; we've got hundreds of different colors you can pick from. So, if you’ve got any other questions about our LB seven upgrades, feel free to leave a comment, reach out to our sales team, or check out the website. As I said, we've got a complete product line for the LB7. It is the truck that started our business, and we will never stop making products for the good ole LB7.

So, thanks a lot for watching. If you have any other questions, feel free to reach out. Thanks again.



Shipping Information

  • Item Requires Shipping
  • 10.0 lbs.
  • W12.0000” x H12.0000” x L32.0000”
  • This item ships in its own box.
  • This Product cannot ship to the state of California

Customer Reviews

Comment Total Reviews (0)

Write the First Review!

You must login to post a review.