The variable vane turbocharger appeared in 2004.5 with the Duramax LLY and in subsequent years in the LBZ and LMM. The vanes control drive pressure and respond to the engine load. For example, if the engine is operating at low speed, the vane nozzles may be closed to generate enough pressure to keep the compressor wheel operating. If the engine is under a heavy load, the vanes open to increase drive pressure. Turbine braking is another feature of the variable vane turbocharger. The application of the brakes causes the vanes to close creating back pressure to reduce engine speed.

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