Product description
T4i 2-Piece Exhaust Manifold for 6.7 Cummins | Stock Turbo Replacement | 2007.5-2018 Ram 2500/3500
The Diesel Power Source® T4i exhaust manifold is a direct OEM replacement for the factory exhaust manifold on 2007.5-2018 Dodge Ram 2500 and 3500 trucks with the 6.7L Cummins engine. This manifold uses the factory T4i turbo flange and bolts directly to your stock HE351VE or HE300VG turbocharger with no modifications. CFD testing confirms approximately 72% more exhaust flow than the factory manifold, while solving the cracking, warping, and shrinkage problems that plague the OEM single-piece casting.
Designed using Computational Fluid Dynamics (CFD) testing, the DPS 2-piece design allows the manifold to expand and contract with heat instead of fighting it. The result is a manifold that lasts significantly longer than the factory casting, reduces exhaust gas temperatures by approximately 25-75°F (particularly on the rear cylinders), and improves turbo spool and throttle response.
Why the Factory 6.7 Cummins Manifold Fails
The factory 6.7 Cummins exhaust manifold is a single-piece casting that spans all six cylinders in one rigid structure. Because the 6.7L is a long inline engine, every heat cycle forces that rigid casting to expand and contract across its full length. Over thousands of cycles, the manifold develops cracks and shrinks permanently, shifting the exhaust ports out of alignment with the cylinder head ports. That misalignment drives gasket failures, bolt stress, exhaust leaks, and visible cracking - most commonly around the rear cylinders where temperatures run hottest.
Once the manifold starts leaking, exhaust energy that should be driving the turbine escapes through the gaps. EGTs climb, boost drops, fuel economy suffers, and the problem accelerates. This is one of the most consistent failure points on high-mileage 6.7 Cummins trucks. Replacing a cracked manifold with another factory-style single-piece unit restarts the same cycle.
DPS has tested competitor replacement manifolds in this application and documented approximately 40 HP of power loss on trucks in the 400-450 HP range - the result of oversized runners that slow exhaust velocity and force the turbo to reaccelerate exhaust through the turbine. Runner sizing matters more than runner diameter, and that requires CFD to get right.
How the DPS 2-Piece Design Solves the Problem
The DPS T4i manifold uses a 2-piece design with an expansion joint between the front and rear sections. Each section expands and contracts independently with heat cycling, eliminating the internal stress that causes factory manifolds to warp, shrink, and crack. The two sections are hydraulically pressed together and pressure-tested before shipping, so they arrive as one assembled, leak-verified unit.
Cast from HSMD (High Silicon Molybdenum Ductile iron), the DPS manifold uses material rated approximately 200°F higher than traditional cast iron - a direct structural advantage over the factory casting. The alloy composition also resists the thermal fatigue that initiates cracking in OEM manifolds.
This is also why single-piece stainless steel manifolds are the wrong choice for this engine. Stainless steel expands and contracts at nearly twice the rate of ductile iron. While the manifold itself may not crack, it transfers that expansion force into the cylinder head, head bolts, and gaskets - causing failures in those components instead. The DPS HSMD 2-piece design absorbs thermal movement internally and protects both the manifold and the head.
