Niles Nimmo

The Holset HE531VE is the variable geometry turbocharger doing the heavy lifting on two of the most common Class 8 engines on the road today: the PACCAR MX-13 and the Cummins ISX15. If you run a fleet or wrench on big-bore diesels for a living, you’ve already seen these units come across the bench with

The Holset HE400VG turbocharger is the backbone of boost management on the Cummins ISX15, and when it acts up, the whole truck feels it. Sluggish throttle response, active regens that never finish, derate codes flashing on the dash, and fuel mileage falling off a cliff. If you run or wrench on ISX-powered Class 8 trucks,

The Holset HX55 turbocharger is the workhorse boost unit bolted to millions of large displacement Cummins engines, and if you turn wrenches on ISM, M11, or L10 platforms you already know it by heart. This is the turbo that keeps 11-liter fleet trucks moving freight, and when it starts smoking, surging, or leaving power on

The Holset HX40 turbocharger is one of the most recognized names in medium and heavy-duty diesel performance, and for good reason. Bolted to countless Cummins ISC 8.3L engines, box trucks, RVs, and marine applications, the HX40 built its reputation on a simple, rugged design that keeps making boost long after fancier variable-geometry units grenade themselves.

The Holset HX35 turbocharger is the workhorse that put the 5.9L Cummins on the map. If you own a Dodge Ram 2500 or 3500 from the mid-’90s through the early 2000s, chances are there’s an HX35 or its close cousin bolted to the exhaust manifold right now. It’s a fixed-geometry, wastegated turbo built to move

The Holset HE300VG is the variable geometry turbocharger bolted to millions of 6.7L Cummins engines since 2007, and if you turn wrenches on Ram 2500/3500 trucks or medium-duty Cummins ISB platforms, you already know it lives and dies by that sliding nozzle assembly. When the variable geometry mechanism sticks, the actuator fails, or the electronics

If you run a 6.7L Cummins in a Ram 2500 or 3500, the Holset HE351VE is the variable geometry turbocharger bolted to your exhaust manifold, and when it fails it takes your power, your fuel economy, and sometimes your whole workday with it. This is the turbo Cummins used from 2007.5 through 2012, and it’s