How to Identify a Holset Turbo

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Where to Find the ID Tag

Holset turbochargers carry their identification on a small metal plate or stamped tag riveted to the compressor housing or, on many models, to the center bearing housing. On popular units like the HX35 and HX40, you will usually find this tag near the compressor outlet or on the flat machined surface of the bearing housing. The tag is held in place by two small rivets and is often coated in a layer of grime, oil, or road dirt, so a quick wipe with a rag and some solvent makes the stamped characters far easier to read.

On the variable geometry models such as the HE351VE and HE431VE, the data plate is frequently positioned on the actuator side of the center housing, close to the electronic or pneumatic control unit. Some older H1C and H1E turbos used a stamped marking directly into the casting rather than a riveted plate, so if you cannot locate a separate tag, inspect the smooth machined areas of the housing closely for hand or machine stamped digits.

Reading the Tag

A Holset tag typically lists three key pieces of information: the model designation, the Cummins or Holset part number (often called the assembly number), and a serial number unique to that unit. The model designation is what most people use day to day, and it follows a recognizable Holset format. The first letter or two indicates the frame family, for example HX, HE, H1, or H2, while the number that follows indicates the relative size of the compressor wheel and housing. An HX35 sits in the HX family with a roughly 35 series compressor, and an HX40 steps up to a larger wheel and housing within the same family.

The HE prefix denotes the more modern frame range, and a trailing letter set such as CW or VE tells you the wastegate or variable geometry configuration. An HE351CW is a fixed geometry wastegated turbo, while an HE351VE and HE431VE use Holset’s variable geometry sliding nozzle system. The assembly number is the most precise identifier because it ties the unit to an exact build specification, including wheel trim, housing A/R, and wastegate calibration. When you are sourcing parts or a rebuild kit, the assembly number matters far more than the model name alone, since a single model like the HX35 was produced in many different internal specifications.

Common Identification Mistakes

• Confusing an HX35 with an HX40 by eye alone. The housings look similar at a glance, but the compressor wheel diameter and the outlet size differ, and mixing them up leads to the wrong rebuild kit being ordered.
• Assuming an HE351CW and an HE351VE share parts. One is a fixed wastegated unit and the other is a variable geometry turbo, so internals are completely different despite the matching 351 number.
• Reading only the model name and ignoring the assembly number. Two turbos both stamped HX35 can have different wheel trims and housing A/R ratios, which changes the correct components entirely.
• Trusting an aftermarket relabel. Some imported copies are stamped to mimic a Holset HX or HE unit, and the casting quality, machining, and tag font often reveal that it is not a genuine Holset.
• Overlooking superseded part numbers. Cummins frequently replaced older assembly numbers with updated ones, so an H1C or H1E may carry a number that no longer matches current catalog listings without cross referencing.

What to Send Us

When you reach out about identifying your turbo, include as much of the following as you can:

• The full model designation (e.g. HX35, GT3782VA, S400)
• The assembly or part number, if visible on the tag
• The serial number, if present
• A clear photo of the complete tag
• A clear photo of the complete turbo
• The vehicle, engine, or equipment it came off of, if known

Email photos to [email protected], or use our Contact form and include what you know in the Turbocharger Info field — we’ll help identify it from there.

Frequently Asked Questions