Premium Twin-Stage Turbocharger CHRA Set for Mercedes-Benz OM651 Engine Restore the seamless multi-stage power delivery and highway efficiency of your luxury vehicle with this premium Twin-Stage Turbocharger CHRA (Center Housing Rotating Assembly) Set . Custom-engineered for the widely utilized Mercedes-Benz 2.1L / 2.2L OM651 4-Cylinder Diesel engine , this complete dual-cartridge core set balances both high-pressure and low-pressure induction loops to eliminate lag, cure oil smoke leaks, and correct boost faults.