Turbo aftercooled vehicle engine is widely accepted today. Two-stage turbo intercooled and aftercooled engines up to 300–350 bmep are in initial application stages for some medium speed stationary and marine diesels. Turbo compound engine has been tested and developed; the adiabatic engine concept has recently been advanced. For these advanced diesels, exhaust heat is a major source of engine performance improvement.Rankine bottom cycle has been applied the last few years to stationary engines for further exhaust heat recovery. Due to initial cost, complexity, and reliability of additional heat recovery equipment needed, few prototypes have been installed.Engine cycle exhaust is used as bottom cycle source heat as shown in the illustration below. This simplified H-S diagram gives a birds-eye view of how a basic diesel cycle and Rankine bottom cycle are coupled. The advancement of the adiabatic concept renders interesting potential for additional exhaust heat recovery.