This thesis describes the development of high efficiency turbochargers and turbogenerators to significantly increase the power to weight ratio and reduce both the fuel consumption and emissions from heavy duty diesel engines. A literature overview is provided for turbomachinery based exhaust energy recovery projects in the public domain. The technologies are discussed in detail and compared using real test data. The thesis describes some design issues that were experienced during engine testing one with a heat shield and one with a volute - and how finite element analysis was used to generate solutions and long term evolutions in the designs. A variable nozzle guide vane ring was designed but seizing of the mechanism occurred during testing. A low friction coating was shown to be the solution.