I din't even include NHRA top fuel motors that make 22 horsepower per cubic inch (11,000 horse power out of only 500 cubic inches) because they only run for four seconds at full power. An F1 car runs for six hours at full power (19,000 RPM) before it is rebuilt. It will cover 100,000 KM in the two races it is entered in (8 engines per 20 races per year by the rule book). It cranks out 5.1 horsepower per cube from a 2.4 liter V-8 engine. Idles at 5,000 RPM so it won't do very well in a car on the street; but then again neither would a top fuel engine.
I limit myself to about 750 horsepower on the street as you can not control a car while driving with any more. But Americans like a challenge. Gas is cheap and power is plentiful. Jeremy Clarkson of Top Gear fame (who owned and drove a Ford GT40 on London's streets) believes that American cars are too brutish and unsophisticated for his European tastes, even if they can make more power and have a higher top speed.
You can have all the power in the world, but if you can not keep a car on the road, or put that power to the ground it is useless. So you can keep your 1.2 to 3.6 liter motors. In America life begins at five liters and grows bigger and bigger from there.