A fairly significant portion of the energy produced by an internal combustion engine (ICE) is in the form of heat which MUST be removed from the engine by means of your coolant system to prevent damage to the engine. Using that energy to drive a low-pressure reaction turbine stage or two would not rob anything from the engine, but would produce useable power from what your engine is already throwing away. I don’t think it would be simple or quick, but doubling an ICE’s efficiency seems quite possible. And if the turbine system failed, you’d still have a functioning ICE to power your car.
Not true. Starting torque for steam locomotives is very low and they found it difficult to start a heavy freight train they could pull with ease once it was rolling. A common practice in starting was to back the locomotive against the train a bit to take up all the coupler slack, then start forward. That way, you were starting one car at a time and you had some speed – five or six MPH by the time the whole weight of the train is moving. It would give the crew in the caboose quite a jerk when they started.
One attempt to solve the problem was to apply a booster engine to the trailing truck on the locomotive or the lead truck on the tender. It would be used in starting and automatically cut out at about eight MPH. They cost money and added to maintenance woes, so they did not prove popular.
Diesel-electrics, as you said, have maximum torque at stall. A common saying in the transition days was that steam could pull more than it could start, diesel could start more than it could pull.
To get back to the OP, I vividly remember a scene in some biographical TV-movie about Howard Hughes (Not The Aviator – this was years ago.). He was trying to develop a steam automobile in the twenties and was standing in the workshop with the design engineer and the prototype, quietly simmering. Looking at the blueprints he asks, “You put the condensors in the doors?!”
“Yeah, it was the only place we could find the room.”
Hughes picks a four-pound hammer up from the workbench. “This is a Model-T,” he says, and flings it at the car door. With a loud roar, clouds of steam jet from the damaged door. “Call <name> and tell him we’re out of the steam car business,” he says, and walks out.
DD
Trouble is, a turbine must likewise reject heat.
A turbine’s efficiency is tied to the inlet-outlet temperature difference. Using the ICE’s radiator as the heat source gives an inlet temperature of perhaps 120 degrees C. With a condenser of manageable size on a warmish day, the outlet temperature would probably be something like 70C. To match the power output of the ICE with this small difference and the limitation of the waste heat energy available from the ICE does not seem at all realistic. And you’d have the expense & weight of the turbine (it could not be a small one), condenser & tubing, plus the drag of the air passing through the condenser and some pumping losses.
Make that are always deisel-powered generators driving electric wheel motors.
The railroads answers the OP’s question. Steam was used right up until the 1950s. It ultimately was replaced by deisel because it was much more economical (steam engines require much more servicing and maintenance). Today steam is only feasable once you reach a certain (rather large) size, namely large ships.
The word you wanted there was practical. Steam power is feasible on any scale.
Maybe this is a dumb question, but what would happen then if you had a train pulled by both a steam-powered locomotive and a diesel-powered one at the same time? Could the diesel do more of the starting work and the steam locomotive more of the pulling?
I know that sometimes trains are pulled by two diesel locomotives coupled together because they aren’t as powerful as steam engines, but I’ve never heard of two different types of engine being used.
Everyone’s probably found this out for themselves already, but…of the handful of steam-engine cars built in the 1960s-70s, at least one, the “Dutcher Steam Sedan,” can be seen in the National Automotive Museum in Reno. I have a book, Steam on the Road, which goes into a smidgen more detail on a few of these other designs—one, the “Gvang,” supposedly had a 400 hp engine that could go from a cold start to full power in 30 seconds—and mentions feasibility studies conducted by Ford and GM on installing steam engines in existing car designs. (Since the book was written in 1973, I’m guessing they didn’t turn out too well.)
And diesel engines are making serious inroads there - check out this beauty
The link also notes that the thermal efficiency is over 50% - quite remarkable.