Turbo Cartridges (CHRA)

A turbo cartridge, or CHRA (centre housing rotating assembly), is the core of a turbocharger: the bearing housing with shaft, wheels, bearings and seals, built and balanced as one unit. Fitting a new cartridge into the existing turbine and compressor housings is often the quickest way back from a bearing or wheel failure.

Balance is a key reason to buy the assembly rather than separate parts. The shaft spins so fast that a tiny imbalance sets up vibration that destroys bearings and seals, and a cartridge arrives already balanced as a unit. Upgrade cartridges go further, with different wheels; check whether the original housings can be kept as they are or need machining.

Before choosing, check:

• Application: each cartridge is listed by car or engine, some by turbo model too, so compare the part number on your turbo as well.
• Replacement or upgrade: a standard cartridge restores the original behaviour, while an upgrade cartridge changes the wheels and so the flow.
• Compressor wheel: cast or billet, where both are offered.
• Stage: on two-stage systems, cartridges are listed for the low side, the larger low-pressure turbo, so make sure that is the turbo you are replacing.

Find out why the old cartridge failed first, because the same oil starvation, dirty oil or blocked drain will ruin the new one. Renew or thoroughly clean the oil feed line, clear the drain, and fit fresh oil and a new filter. Inspect the housings for cracks and rub marks, and clean the intercooler if wheel fragments went downstream. Use new gaskets, fill the centre housing with clean oil, and crank the engine with fuel or ignition disabled until oil pressure shows.