balls to the wall

term used by pilots. when accelerating quickly, the throttle is pushed all the way to the panel and the throttle lever (ball) actually touches the panel (wall). Hence, balls to the wall.

To push to the limit, go all out, full speed.
A very colorful phrase, one needs to be careful when using "balls to the wall". Although its real origin is very benign, mos people assume it is a reference to testicles.
In fact it is from fighter planes. The "balls" are knobs atop the plane's throttle control. Pushing the throttle all the way forward, to the wall of the cockpit, is to apply full throttle.

This term significantly predates airplanes all together. The term "balls to the wall" originated with James Watt's invention of the centrifugal governor used on early steam engines (circa 1774, well before the Wright brothers at Kitty Hawk). Over the years, these types of governors were adapted for use on various other types of engines, including many aircraft engines. Some aircraft have a ball shape at the end of the throttle control, which is actually a clever reference to the governor mechanism, no doubt conceived by a witty designer. It is easy to see where one could get the (wrong) impression that "balls to the wall" would indicate the position of the throttle lever, when in fact, the term, strictly speaking, is a reference to the position of the weights on the governor.

To go at full (unregulated) power

Steam engines had mechanical regulators that consisted of a pair of hinged lever arms with a ball on the end of each arm, as the engine sped up the centrifugal force caused the arms to raise up closing a valve. If you adjust the regulator so that the arms go to horizontal (with the balls pointing to the wall) without closing the valve you are not limiting the speed of the engine.

Intense, extreme, to the max. The phrase comes from olde-fashioned steam engines; basically, they had two weighted balls attached to a vertical shaft which was connected to the engine. As the engine speed increased, these two balls would be raised higher because of centrifugal force! At top speed, they would be parallel to the ground, nearly touching the "walls" of the shaft! Hence, "balls to the wall."

A term referring to the rotating governors used on steam locomotives and related steam engines such as tractors. The brass balls acted as weights on the end of linkages, and rotated with the increase in RPM of the engine. As speeds rose, the balls swung outwards, rising on the linkages. At a pre-set height, the release valve would engage, lowering steam pressure and reining in the RPM to the allowable maximum. The balls rose towards the firewall and/or the walls of the cab., hence the term.

Originally a military term for pushing maximum G-Forces in a jetfighter aircraft, as in pushing the ball of a throttle as high up as it will go (virtually touching the wall of the dashboard).

Fast; hectic; pushed to the limits