[Martinjlm]

Originally Posted by ember1205

There should be zero need to "reinvent the wheel" in terms of R&D for a diesel engine like this... Locomotives have been built like this for years with engines that put out FAR higher levels of voltage and current than what a car or truck would need. Additionally, the small 3-cylinder engines used in CUT/SCUT tractors have also been around for years and are commonly used for driving generators through the rear PTO on farms. These engines are designed to operate at a constant RPM which means they can be very specifically tuned and adjusted for both optimal fuel consumption AND minimal emissions. There's a lot of R&D that has already been done one these that can easily be re-used to create a diesel-electric power train for automotive use.

DEF is NOT used in engines under something like 115HP as it is not required. A 45-50HP diesel engine would be fairly capable of being used for nothing more than a small electrical powerplant. Even where DEF is required, variable RPM diesel engines consume somewhere around 1 gallon of it per 1000-ish miles of operation (give or take). With engines like I referred to above, there would be no need for DEF (although we all know the EPA would stick their noses into it at some point).

There are vehicles on the road that use engines that have been modified to run, at least part of the time, in Atkinson-Cycle "mode". But these engines are ALSO designed to be able to directly power the vehicle if need be. That's different than the concept of a diesel-electric setup.

Reduced complexity is derived from not just lack of spark plugs (which also don't require high-voltage / high-current plug wires or any sort of distributor / electronic ignition system) but also from "less stuff" throughout the entirety of the system. As you mentioned, no catalytic converter required on these kinds of systems). The varying RPM of engines in cars and trucks is why we have so many additional components to monitor and control exhaust outputs.

What you describe has already been done in vehicles with gasoline engines. Got one in my garage. The thing is, feature-for-feature, for the same duty cycle, a diesel engine will cost more to engineer and manufacture than a gasoline engine developed for the same purpose. This is true until you get to scenarios of load and performance where large gas engines cannot continue to compete with similar sized diesel engines. These high load situations are typically beyond the range where gas engines are even reasonably efficient no matter what the content. But what you are talking about is constant low-load situations. Gasoline engines do just fine there and approach the thermal efficiency of diesel engines while costing less to produce. Diesel range extenders are basically a solution in desperate need of a problem to solve. At one point, early in the development cycle, diesel was considered as an optional powerplant / generator for Volt (actually, its European twin Ampera). It died an early death at the alter of cost justification.