2001-2004 LB7 Duramax S400 Single Turbo Install Kit

Everything around an S400 single

This kit has the plumbing to replace the factory IHI-style turbo on an LB7 with a larger BorgWarner S400-style unit. The turbo (sold separately) sits on a fabricated steel T4 pedestal with spacer that works with Wehrli's 2 in. stainless up pipes.

Air comes in through a 5 in. fabricated aluminum intake with a 10 ga aluminum air box, dry filter and pre-filter. Both intercooler pipes step up to 3 in. mandrel-bent 14 ga aluminum, and Wehrli's billet 3 in. Y-bridge replaces the restrictive factory upper intake manifold.

Oil feed comes from the main oil galley through braided stainless Parker lines. The ceramic-coated downpipe meets the stock front pipe at its V-band, so the exhaust needs no cutting.

Who it's for

LB7 owners building toward a big single turbo who want a complete, matched install kit.

Key specs (per Wehrli)

What's included

• 5 in. intake, air box with lid, dry filter and pre-filter cover
• Braided stainless oil supply and return lines, fittings included
• Fabricated T4 turbo pedestal plus spacer and its mounting hardware
• 3 in. billet Y-bridge
• 3 in. hot and cold side intercooler pipes
• 3 in. ceramic-coated downpipe
• Driver-side transmission dipstick relocation tube (eases downpipe install)
• Heat wrap, V-band and stainless T-bolt clamps, silicone boots; powder-coated finish

Fitment notes

• Fits 2001-2004 Chevrolet Silverado / GMC Sierra 2500 HD and 3500 with the 6.6L LB7 Duramax.
• The downpipe uses an HX40-style turbo flange; a turbo not bought with the kit must have its exhaust housing machined to match.
• Must be installed together with Wehrli thermostat housing kit WCF100405 (billet, forward-facing) (the factory turbo coolant port interferes with the larger intake). Contact us before ordering if the truck runs dual fuelers.
• Turbo is sold separately. If you are not using a genuine BorgWarner turbo bought with the kit, the turbo brand and details must be given at order, and Wehrli may need the turbo sent in for mock-up before the kit is built.
• California: Wehrli does not ship this part to California.

Professional install available at Powertech Diesel, Idaho Falls — call 208-542-7793.