ISX15 / X15 Cummins Turbo Upgrades — The Complete Guide to Every Option

When the turbo on your Cummins ISX15 or X15 needs attention, you have more options than simply buying the same unit back. Diesel Power Source® has engineered a full range of upgrades for the ISX15 and X15 platform — from a direct factory replacement with a larger compressor wheel, to a single S400 conversion, to a full S400-over-S400 compound kit that dramatically reduces EGTs and adds real power. This guide covers every option in one place so you can make an informed decision for your truck.

Option 1 — Direct Replacement: HE470VG for ISX15 / X15

The Diesel Power Source® HE470VG turbo for the ISX15 and X15 is a direct bolt-on replacement for the factory HE400VG (OEM part numbers 6382093RX and 5459710). It uses a 70mm compressor wheel — three millimeters larger than the largest factory option — which means more airflow, lower exhaust gas temperatures, and measurable gains in fuel efficiency without any modification to your truck's mounts, electronics, or Jake brake. It fits CM2250, CM2350, and CM2450 platforms on 2016-2025 trucks, as well as CM871 on 2010-2016 applications. If you are running an EGR or non-EGR truck, DPS offers both configurations, with standard (~1,000°F) or premium Cerakote (~1,800°F) coating options available.

Option 2 — S400 Conversion Kit

For drivers who want to move away from the factory variable geometry turbo entirely, the Diesel Power Source® S400 conversion kit for the ISX15 replaces the stock HE400VG with an S400-platform turbo matched to a DPS T6 exhaust manifold. This is a deleted-truck application. The most popular configuration is the S478 (78mm compressor), which covers 550-650 HP and represents the sweet spot for most ISX and X15 hauling builds. S475 (75mm) and S480 (80mm) options are also available for lower-output or higher-performance applications respectively. The conversion kit includes the DPS T6 manifold and all hardware needed to complete the swap.

Option 3 — HE470VG vs. S400: Which One Is Right for Your ISX15?

The short answer: if your ISX15 or X15 is emissions-intact and you want a direct replacement that outperforms the factory unit with no deletion required, the HE470VG is the correct choice. If your truck is already deleted and you want to run a fixed-geometry S400 platform with more tuning flexibility and higher power ceiling, the S400 conversion kit is the right direction. Both products are engineered specifically for the ISX15 and X15 — ESN verification is required for either order so DPS confirms the correct configuration for your specific engine before it ships.

Option 4 — EGR Exhaust Manifold Replacement

The factory ISX15 exhaust manifold uses ring seals at the joints between its three sections. Those seals fail with heat cycling, and an exhaust leak on an ISX15 is not a minor inconvenience — it affects emissions function, exhaust brake performance, and turbo efficiency. The Diesel Power Source® ISX15 EGR exhaust manifold replaces OEM part numbers 3687063 and 3692604 with a 3-piece, hydraulically press-fit assembly that is pressure-tested before shipping. The press-fit joint design seals progressively tighter as exhaust temperatures rise — no ring seals, no consumable gasket material at the expansion joints. DPS also offers a non-EGR manifold for deleted ISX15 and X15 trucks. Both versions are available with standard (~1,000°F) or premium Cerakote (~1,800°F) coating. Browse the full ISX15 manifold category for all available configurations.

Option 5 — S400-Over-S400 Compound Turbo Kit for ISX15 / X15

For ISX15 and X15 operators who want the maximum improvement in thermal management and power capability, Diesel Power Source® builds a complete S400-over-S400 compound turbo kit — both turbos on the S400 platform, which is what makes ISX compound kits different from pickup compound configurations. The kit includes both turbos, all piping (hot side and cold side), oil lines, intake tubing, DPS exhaust manifold, downpipe, and all hardware. Nothing additional is required. HP range is 550-800 HP depending on configuration, with EGT reductions of approximately 250-450°F under hard load compared to a single turbo. This is the largest thermal management and performance upgrade available for the ISX15 and X15 from Diesel Power Source®.

ESN Verification — Required for All ISX15 and X15 Orders

Every ISX15 and X15 order from Diesel Power Source® requires your Engine Serial Number (ESN) before the order ships. The ISX and X15 platform spans multiple ECM configurations — CM871, CM2250, CM2350, and CM2450 — and chassis variants across Freightliner, Peterbilt, Kenworth, Volvo, International, and Western Star applications. The ESN allows DPS to confirm the correct product configuration for your specific engine before anything leaves the warehouse. Contact DPS at 801-930-8404 or through the contact page to verify fitment before ordering.

Diesel Power Source® is a manufacturer of performance diesel parts based in West Jordan, Utah. All ISX15 and X15 products ship free on orders over $350. Cummins® is a registered trademark of Cummins Inc.; Diesel Power Source® is not affiliated with Cummins Inc.