While hydraulically self adjusting valves are sometimes used for their lack of required adjustment they do not work well in engines capable of high RPMs.
They did seem to notice when they heard the sound of a second Zodiac motor cranking out some high RPMs.
However, in an advanced system like the T20, which was expected to operate for longer periods at higher RPMs, this would have been unsuitable.
This is beneficial at high RPMs.
The engine redline raised from 6,500 rpm to 6,800 rpm to take advantage of the new power band and higher power output at higher RPMs.
High performance engines and engines that rev to high RPMs also tend to wear out quicker.
The automatic transmission also has the ability to change the shift points, and hold the gears longer when the engine is operating at higher RPMs.
This allows higher RPMs to be reached and more power produced.
This was intended to provide easier take-off at low RPM and better reponsiveness at higher RPMs.
The smaller rotary tools use high RPMs to maintain the correct cutting conditions for the tool bits.