A four-cycle internal combustion engine has a single or multi-stage pre-cooled compression, which allows the temperature and pressure of intake air to the combustion cylinders to be tightly controlled, so that a much higher compression ratio and pre-ignition compression pressure can be achieved without approaching the air/fuel mixture auto-ignition threshold. The minimal threshold pressure of air intake is determined to be >1.8 Bars at sea level and a minimal temperature drop of at least 50° C. at the heat exchanger air cooling radiator. Because this design can effectively regulate and set the maximum pre-ignition temperature of the fuel-air mixture, it can combust virtually any type of liquid hydrocarbon fuel without knocking. This four-cycle engine, due to its higher compression ratio, generates power equivalent to or greater than a standard four-cycle engine in a smaller and lighter engine and at a higher efficiency.
