Wiring 240v to 120v outlet?
Just NO
NEMA 5-15 is, by definition, designed for 120 V operation.

If you put 240 V on it, you are not using it as designed, therefore violating code.

Plus risking serious hazards because the parts may not be over-engineered enough to operate safely at 240 V.

Plus risking serious hazards if anyone ever forgot that this particular ordinary looking outlet was actually 240 V - e.g., what if you are doing some troubleshooting and need to plug in some other piece of equipment and unplug one of your servers to plug in a piece of expensive test equipment that gets destroyed - or a piece of cheap test equipment that starts a fire.


FYI (but not relevant, because you just can't do this!), such a change would not increase the ampacity (that would still be 15A) but would double the power because power = voltage * current.
But just don't do it. Not legal. Not safe.