Hi can anyone shed any light on how much wasted heat a Diesel engine gives out. For example for every kw of energy at the fly wheel to drive the vehicle along, how many kw's are wasted in lost heat? Is there a constant that engineers use for this? Like for every gallon of fuel, what percentage goes to turn the generator or pump and how much goes through the radiator?  

I'm no engineer, but I think I've read typically, IC engines in general are about 20-30 percent efficient. I'd imagine the efficiency percentage would be slightly higher on a turbocharged vehicle, but ultimately, that exhaust still goes out the tailpipe.

I think the biggest efficiency loss is in the heat dissipation. The dilemma is the heat contains a lot of potential energy, but the trick is harnessing it successfully without causing damage to the rest of the vehicle. Like the old saying goes, "heat is the enemy of performance."