S400 Cummins ISX15 / X15 Complete Turbo Conversion Kit | T6 Manifold, Turbo, and All Hardware
The Diesel Power Source® S400 Complete Turbo Conversion Kit replaces the factory Holset VGT turbocharger on your Cummins ISX, ISX15, or X15 engine with a BorgWarner S400-series fixed-geometry turbo, a DPS T6 performance exhaust manifold, and all piping, oil lines, and hardware needed for installation. This is a complete, single-box solution for previously deleted 2008–2024 trucks looking for improved airflow, lower EGTs, better reliability, and increased horsepower over the factory HE561VE, HE451VE, or HE400VG turbo.
Three turbo sizes are available to match your horsepower goals. The S475 (75mm compressor) is sized for towing and daily driving up to approximately 550 HP. The S478 (78mm compressor) provides a balanced combination of spool and top-end airflow for builds targeting 650 HP. The S480 (80mm compressor) supports up to 750 HP for trucks running more aggressive fueling and tuning. All three options use a 96mm turbine wheel, T6 flange, forged milled compressor wheel, 360-degree thrust bearing, and ported compressor housing for durability and surge resistance.
Why Convert from a Holset VGT to an S400?
The factory Holset HE561VE (CM871), HE451VE (CM2250/CM2350), and HE400VG (late CM2350/X15) are variable geometry turbochargers that rely on an electronic actuator and moving vanes inside the turbine housing to control boost. Over time, these components wear, carbon up, and fail, leading to actuator faults, low boost, and expensive repairs. The VGT design is also limited in total airflow capacity, which restricts horsepower potential on trucks running performance tuning.
BorgWarner S400-series turbochargers are fixed-geometry units with no actuator, no moving vanes, and far fewer failure points. The S400 platform has been the industry standard for performance and fleet applications for years because of its reliability, simplicity, and airflow capacity. On an ISX15, converting to an S400 turbo typically delivers measurably lower exhaust gas temperatures, improved fuel efficiency, faster turbo service intervals, and significantly higher horsepower potential.
Diesel Power Source® performs CFD (Computational Fluid Dynamics) testing on all air and exhaust components to optimize flow. Our T6 manifold and S400 turbo combination dramatically outflows the factory ISX turbo and manifold setup.
Turbo Size Options
| Turbo Option | Compressor / Turbine | HP Range | Best For |
|---|---|---|---|
| Stage 12 — S475 | 75mm / 96mm | Up to ~550 HP | Towing, daily driving, fleet trucks, fastest spool |
| Stage 13 — S478 | 78mm / 96mm | Up to ~650 HP | Balanced spool and top-end, moderate tuning |
| Stage 14 — S480 | 80mm / 96mm | Up to ~750 HP | Higher HP builds, aggressive tuning, heavy haul |
All three turbo sizes use the BorgWarner S400SX4 platform (cross-references 171702 and 171710) with T6 twin-scroll turbine housing, forged milled compressor wheel (FMW), 360-degree thrust bearing, and ported compressor housing with anti-surge groove. The 1.32 A/R T6 turbine housing is standard.
What's Included
- DPS S400 Turbo (S475, S478, or S480 based on selection) — Forged milled wheel, 360-degree thrust bearing, ported compressor housing
- DPS T6 Performance Exhaust Manifold — Press-fit 3-piece design, high-silicon ductile iron, ceramic coated
- Cast Turbo Compressor Elbow — 90° or 45° (selected at checkout)
- Rubber intake elbow
- Turbo oil supply line with fittings
- Turbo oil drain tube with gasket
- Exhaust stainless steel V-band adapter or cast exhaust adapter (determined by ESN and truck year)
- 5.5" and 4.4" V-band clamps
- Hose clamps
- Manifold bolts and spacers
- Turbo studs and nuts
- Manifold-to-head gaskets
- Turbo gasket
- Oil drain gasket
- Coolant block-off fittings
- Air compressor filter kit (filters approximately 15–20 microns)
Note about the air compressor filter: If operating in dusty or off-road conditions, use a lower micron filter or route the air compressor back through the intake filter for additional protection.
Fitment
This complete S400 conversion kit fits Cummins ISX and ISX15 engines with CM871, CM2250, CM2350, and X15 ECM platforms (2008–2024). Compatible with Freightliner, Peterbilt, Kenworth, Volvo, International, and Western Star trucks powered by these engines.
This kit is for use on previously deleted, non-emissions trucks only. Diesel Power Source® does not sell or support emissions delete components.
Please provide your Cummins Engine Serial Number (ESN) when ordering so we can verify compatibility and determine the correct exhaust outlet adapter for your truck.
How to Find Your Exhaust Outlet Connection Part Number
When ordering, you'll need to select your exhaust outlet connection part number. This number is cast or stamped on the exhaust outlet pipe that connects to your truck's exhaust system. The available options are:
- 3686707, 3686708, 3686721, 3686722
- 3684411 (direct exhaust connection, no adapter part number)
- 3689539, 3689540
If you are unsure where to find this number, refer to the image below or contact our team with your ESN and we'll identify the correct adapter for your truck.
Engine Braking
The S400 is a fixed-geometry turbo and does not have the VGT vane control used by the factory Holset turbo during engine braking. Engine brake will still function with this kit, but braking force is typically reduced compared to the factory VGT setup. Many drivers report that engine braking improves significantly with camshaft upgrades, which increase exhaust restriction during the braking cycle.
For trucks that need stronger engine braking with an S400 turbo, the Diesel Power Source® Turbonator® VGT exhaust housing adds variable geometry capability to the S400 platform, restoring VGT-style exhaust braking and improving spool-up. See: Turbonator® VGT for Cummins ISX Turbo
Cross-Reference Part Numbers
The S400 turbos included in this kit are commonly cross-referenced with the following BorgWarner and aftermarket part numbers:
171702, 171702BW, 171710, 23523197, D91080006N, D91080006R, 170-070-0483, 23518588, 23518597, 2585838C91, 466713-X005, AVT171702, BWC171702, KYS171702, TUR103DD
Already Have a Turbo or Manifold?
If you already own an S400, S410, S475, S478, S480, or other T6-flange turbo and just need the piping, oil lines, and hardware to install it on your ISX15, see our kit-only option (does not include turbo or manifold):
S400 Cummins ISX Turbo Conversion Kit (Piping and Hardware Only)
Want More Power Than a Single S400?
If your horsepower goals exceed what a single S400 turbo can support, or you want faster spool with higher top-end flow, consider our ISX15 compound turbo kit. This kit uses two S400-series turbos in a compound (twin-stage) configuration for 550–700+ HP with faster boost onset and cooler charge air.
Cummins ISX15 / X15 Compound Turbo Kit | S472/S488 and S475/S488
Why Choose Diesel Power Source?
- Complete Kit — Turbo, manifold, all piping, oil lines, and hardware in one box. No hunting for parts.
- CFD-Tested Airflow — Every air and exhaust component is tested using Computational Fluid Dynamics for optimized flow
- BorgWarner S400 Platform — Industry-standard reliability with forged wheels and 360-degree thrust bearings
- DPS T6 Manifold — Press-fit 3-piece construction eliminates the seal-type leaks common on OEM manifolds
- ESN-Verified Fitment — We confirm compatibility and correct exhaust adapter before shipment
- Made in the USA
Warranty
This Diesel Power Source® S400 Complete Turbo Conversion Kit includes a 1-year warranty (100,000 mile) and is backed by our technical support team for fitment, installation, and tuning guidance.
Related ISX15 / X15 Products
- S400 ISX Turbo Conversion Kit (Piping and Hardware Only, No Turbo or Manifold)
- ISX15 / X15 Compound Turbo Kit | S472/S488 and S475/S488 | 550–700 HP
- Turbonator® VGT S475 / S478 / S480 / S483 Turbo
- ISX15 T6 Exhaust Manifold for S400 Turbo (Manifold Only)
- ISX15 / X15 Non-EGR Exhaust Manifold (Stock Turbo Fitment)
- HE400VG Turbo Replacement for Cummins ISX15 / X15 (Factory VGT)
- ISX15 / X15 Exhaust Manifold Hardware Kit
Not sure whether an S400 single conversion, compound kit, or stock VGT replacement is the right path for your truck? Contact us with your Engine Serial Number (ESN) and your horsepower goals, and we'll help you choose.
Frequently Asked Questions
All three options use the same BorgWarner S400 platform with a 96mm turbine wheel, T6 flange, forged milled compressor wheel, and 360-degree thrust bearing. The difference is compressor size. The S475 (75mm) spools the fastest and supports up to approximately 550 HP, making it the best choice for towing and daily driving. The S478 (78mm) balances spool and top-end airflow for builds targeting up to 650 HP. The S480 (80mm) moves the most air and supports up to 750 HP for trucks running more aggressive tuning.
Engine braking will still function with the S400 turbo, but braking force is typically reduced compared to the factory Holset VGT because the S400 is a fixed-geometry turbo without variable vanes. Many drivers find engine braking improves with camshaft upgrades. For trucks that need stronger braking, Diesel Power Source® offers the Turbonator® VGT exhaust housing, which adds variable geometry capability to the S400 platform for improved engine braking and spool-up.
This kit fits Cummins ISX and ISX15 engines with CM871, CM2250, CM2350, and X15 ECM platforms (2008–2024). It is designed for previously deleted, non-emissions trucks. Compatible truck platforms include Freightliner, Peterbilt, Kenworth, Volvo, International, and Western Star. Please provide your Engine Serial Number (ESN) when ordering so we can verify fitment and determine the correct exhaust outlet adapter.
Yes. This is a complete kit that includes the DPS T6 performance exhaust manifold, the S400 turbocharger, and all piping, oil lines, clamps, gaskets, and hardware needed for installation. If you already have a turbo and manifold and only need the plumbing and hardware, see our kit-only option: S400 ISX Turbo Conversion Kit (Piping and Hardware Only).
The exhaust outlet connection part number is cast or stamped on the exhaust outlet pipe that connects your turbo to the truck's exhaust system. When ordering, you will select from three groups: 3686707/3686708/3686721/3686722, 3684411 (direct connection), or 3689539/3689540. If you are unsure, provide your ESN and our team will identify the correct adapter for your truck before shipment.
10 Reviews
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Truck feels stronger
Installed the S478 version on my ISX. Noticeably stronger pull.
