What are the limiting factors involved in engine technology? Specifically, I am wondering why we are still using big old engines. Just easier to work with what already works? Development: First came gas otto cycle, then came diesel. Diesel is more efficient since the combustion is more complete due to the higher ignition temperatures. The major difference between gas and diesel (besides one uses gas and the other diesel) is in the compressed mixture and the igniting of the mixture. Gas mixes fuel and air at the carb or intake. The mixed fuel and air is compressed then ignited to preform the work of moving the piston which transfers the power to the crankshaft driving the flywheel, transmission, then wheels. Diesel draws air into the cylinder. The air is compressed raising the temperature of the air to over 400. Fuel is then sprayed into the cylinder where it instantaneously combusts. This process makes it possible to run the engine off vegetable oil. Von Diesel originally designed the engine so farmers could grow their own fuel(soybean oil). Gas has won over diesel because until recently the diesel engine's higher compression ratios required a much thicker engine, making it much heavier, the power to weight ratio of the gas engine made it a much more attractive engine. However recent advances in materials has enabled light diesel engines(Golf TDI). Inefficiencies of the engine: the transfer of power to the crankshaft and other parts, and this is the one that interests me the most LOSS OF HEAT Why do we waste this heat? Can we not use the heat to create steam to drive turbines? Why use pistons at all? Why not just add fuel to an enclosed chamber (spherical) then ignite it. If the sphere was strong enough not to explode from the force would it not transfer the energy of the ignition into heat which could then be used to heat water driving a steam turbine. Locomotion would be accomplished by electric motors. What are the inefficiencies involed with electric motors? Any thoughts? I realize the sphere would have to be able to blow off extreme pressure to prevent a possible explosion. Why is steam a bad idea?