WhiningKhan
Regular
You get a greater density of fuel in the cylinder head, making a more powerful explosion when the spark goes off. It's the same reason why engines give greater power at sea level and in colder temperatures.
No.
For non-turbocharged engine, limiting factor for performance is not the amount of fuel, but the amount of oxygen. Amount of fuel injected can easily be increased by increasing the injection length (and pressure, if you need to go that far), but since gasoline engine needs a mixture close to stoichiometric, it does not do you any good unless you get more oxygen to burn the fuel with.
The reason why engines give greater power at sea level and colder temperatures is because air is more dense at those conditions, and you get more oxygen molecules per volume unit from intake. This is also the same reason why intercoolers are used with turbocharged engines.