if you can minimize the thermodynamic loss (thermal loss, friction, mechanical loss ...) your engine will perform better for this, I can recommend the book reading Lucien Borel

there are several technical they have already done for example put a turbocharger to recover energy from the exhaust gas, the principle is to increase the pressure of the inlet gas, allowing better cylinder filling mixed "air / fuel ", thereby increasing the power density of the engine to increase power or reduce consumption with an engine smaller displacement

The most important source of the exergy destruction in diesel engine is combustion processes.  In the compression ignition engine combustion generated exergy destruction can be reduced by  preheating the intake air, insulating the combustion chamber walls, reducing the amount of excess air which results in an increase combustion temperature, and hence,more fuel exergy is converted to brake power that is higher exergtic effficiency. But it must be said that higher combustion temperature results in higher exhaust exergy loss if not utulized. consequently in order to increase exergetic efficiency, combustion efficiency must be increased

One simple solution is diesel engines have better part load efficiency, at about 60%[SI engines-90%], burns comparatively lean,cool & complete and exergy destruction would be low.

I recommend you this book, It presents in a clearly way the optimization of a cycle, also it includes thermo-economic optimization of power plants, because the if you make a tecnic optimization, you going to obtain some results that can not be viable eocnomically, for instance a combustion with oxygen going to reduce lost work, could be expensive, because you need to obtain oxygen with other process, it means more costs, and bigger investment recovery time.

http://www.wiley.com/WileyCDA/WileyTitle/productCd-0471584673.html