A crude but complex example of the future Wankel engine.[25] 1951: Engineers for The Texas Company—i.e. now Chevron—developed a four stroke engine with a fuel injector that employed what was called the Texaco Combustion Process, which unlike normal four stroke gasoline engines which used a separate valve for the intake of the air-gasoline mixture, with the T.C.P. engine the intake valve with a built in special shroud delivers the air to the cylinder in a tornado type fashion and then the fuel is injected and ignited by a spark plug. The inventors claimed their engine could burn on almost any petroleum based fuel of any octane and even some alcohol based fuels—e.g. kerosene, benzine, motor oil, tractor oil, etc.—without the pre-combustion knock and the complete burning of the fuel injected into the cylinder.