Cummins Turbocharger

Cummins Turbocharger Models by Engine Family

Cummins powers a wide range of trucks and equipment, and the turbo setup changes significantly from one engine platform to the next. Holset is the turbocharger brand behind almost every Cummins diesel, and each engine family runs a different Holset model tuned for its displacement, power rating and emissions configuration. Knowing which turbo belongs to your engine is the first step to ordering the right part.

ISX15 and Signature — Heavy-Duty Highway

The ISX15 is the backbone of North American Class 8 trucking, running in Kenworth, Peterbilt, Freightliner and International tractors pulling 80,000 lb loads coast to coast. The turbo setup evolved through several emissions tiers. Early ISX and Signature engines run the HX55W, HX60W or HE600WG. EPA07 (CM870/CM871) engines commonly use the HE551V or HE561VE — large VGT units sized for high exhaust flow at sustained highway RPM. From EPA10 onward, Cummins moved to the HE451VE, with part numbers split by horsepower rating: 450-500 HP and 550 HP engines take different units. Turbo part numbers on this platform change with the CPL, ESN prefix and emissions generation, so verifying all three is critical before ordering. The X15 that replaced the ISX15 in 2017 runs the HE400VG and has its own page.

ISB 6.7 and QSB — Medium-Duty and Industrial

The 6.7-liter ISB serves a long list of medium-duty commercial trucks and buses, while the QSB covers industrial and construction equipment. Commercial ISB 6.7 applications run the HE351VE VGT turbo with electronic actuator; QSB Tier 3 engines run the simpler fixed-geometry HX35W. If you are looking for the Ram 2500/3500 pickup version of these engines, the turbos differ by calibration and part number — see our Dodge Cummins page for the full pickup lineup from 1994 to current.

ISL and ISC — Vocational, Transit and RV

The ISL (8.9L) and ISC (8.3L) engines show up in everything from school buses and transit coaches to concrete mixers and motorhomes. Turbo models depend on the generation: older ISC engines run the HX40W fixed-geometry turbo, while newer ISL engines use the HE431VE or HE300VG variable geometry turbo. The HE431VE is especially common in transit bus applications where the engine cycles between idle and load hundreds of times per day. On these engines, matching the turbo to the correct CPL and emissions spec matters as much as matching the engine model.

ISM and N14 — Legacy Heavy-Duty

The ISM (10.8L) and N14 (14L) are older platforms that still run in large numbers. Many fleets keep them because the engines are mechanically simpler and parts are well understood. The ISM typically runs an HX55 or HX55W turbo — a fixed-geometry unit with a wastegate. The N14 uses the HT60, a large fixed-geometry turbo with no electronic controls. Both are robust designs, but age and mileage take a toll on bearings and seals. New replacement turbos for these older engines are getting harder to source through traditional channels, which is why we keep them in stock.

Quick Reference: Engine to Turbo Model

This table covers the most common configurations. Actual turbo part numbers vary by CPL, ESN prefix and emissions tier. Give us your engine serial number and we will confirm the exact match.

VGT Actuator Failure — The Most Common Cummins Turbo Problem

On modern Cummins engines with variable geometry turbos, the electronic actuator is the weak link. Here is what happens: exhaust soot gradually coats the nozzle ring and vane mechanism inside the turbine housing. As the buildup gets heavy, the vanes start to stick. The actuator motor pushes harder to move them, draws more current, and eventually burns out its internal gears or motor windings. The result is loss of boost control, a dead exhaust brake, high EGTs and a check engine light.

This failure pattern is well documented on the ISX15, ISL and commercial ISB 6.7 platforms. Common fault codes tied to VGT actuator problems include P2262 (turbo boost pressure not reached), P003A (turbo boost control position exceeded), and Cummins SPN 2387 (VGT actuator sticking). Trucks that idle heavily or run short duty cycles build soot faster and fail sooner.

When replacing a failed VGT turbo, it is worth doing two things: first, replace the turbo and actuator as a matched set rather than swapping just one. Second, check the root cause — inspect oil condition, intake piping for leaks, and the EGR system for excessive soot recirculation. A new turbo installed on an engine with a bad oil supply or cracked intake boot will fail again within months.