page_title: Steam car
section_title: Technology
hierarchical_section_title: Steam car / Technology
caption_attribution_description: 1924 Stanley Steamer Serie 740 Powered by a twin cyliner, double acting steam engine (under the floor in the rear). A kerosene/parafin oil heated boiler in the front giving 20-30 hp. Engine power 100 bhp. Price: 2750 USD. Weight 1774 kg. This car was fitted with more modern headlights in the 1970s to be able to pass Dutch vehicle inspections.
context_page_description: A steam car is a car propelled by a steam engine. A steam engine is an external combustion engine in which the fuel is combusted outside of the engine, unlike an internal combustion engine in which fuel is combusted inside the engine. ECEs have a lower thermal efficiency, but carbon monoxide production is more readily regulated.
  The first experimental steam-powered cars were built in the 18th and 19th centuries, but it was not until after Richard Trevithick had developed the use of high-pressure steam around 1800 that mobile steam engines became a practical proposition. By the 1850s it was viable to produce them commercially: steam road vehicles were used for many applications.
  Development was hampered by adverse legislation from the 1830s and then the rapid development of internal combustion engine technology in the 1900s, leading to their commercial demise. Relatively few steam-powered vehicles remained in use after the Second World War. Many of these vehicles were acquired by enthusiasts for preservation.
  The search for renewable energy sources has led to an occasional resurgence of interest in using steam technology to power road vehicles.
context_section_description: A steam engine is an external combustion engine (ECE: the fuel is combusted away from the engine), as opposed to an internal combustion engine (ICE: the fuel is combusted within the engine). While gasoline-powered ICE cars have an operational thermal efficiency of 15% to 30%, early automotive steam units were capable of only about half this efficiency. A significant benefit of the ECE is that the fuel burner can be configured for very low emissions of carbon monoxide, nitrogen oxides and unburned carbon in the exhaust, thus avoiding pollution.
  The greatest technical challenges to the steam car have focused on its boiler. This represents much of the total mass of the vehicle, making the car heavy (an internal combustion-engined car requires no boiler), and requires careful attention from the driver, although even the cars of 1900 had considerable automation to manage this. The single largest restriction is the need to supply feedwater to the boiler. This must either be carried and frequently replenished, or the car must also be fitted with a condenser, a further weight and inconvenience.
  Steam-powered and electric cars outsold gasoline-powered cars in the US prior to the invention of the electric starter, since internal combustion cars relied on a hand crank to start the engine, which was difficult and occasionally dangerous to use, as improper cranking could cause a backfire capable of breaking the arm of the operator. Electric cars were popular to some extent, but had a short range, and could not be charged on the road if the batteries ran low.
  Once working pressure was attained, early steam cars could be instantly driven off with high acceleration, but they typically take several minutes to start from cold, plus time to get the burner to operating temperature. To overcome this, development has been directed toward flash boilers, which heat a much smaller quantity of water to get the vehicle started, and in the case of Doble cars, spark ignition diesel burners.
  The steam car does have advantages over internal combustion-powered cars, although most of these are now less important than in the early 20th century. The engine (excluding the boiler) is smaller and lighter than an internal combustion engine. It is also better-suited to the speed and torque characteristics of the axle, thus avoiding the need for the heavy and complex transmission required for an internal combustion engine. The steam car is also quieter, even without a silencer.
caption: Boiler in a 1924 Stanley Steamer Serie 740, to the right is the condenser
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