RR Dart Water Methanol was 55/45 mix.
IIRC the Dart 520 series were restored power and the 530 series were boosted power. The engines were the same, just the W/M unit different.
With system armed it cut in at 14500 rpm as the engine accelerated to 15000 rpm for T/O. In the climb when the rpm was reduced to 14200 the W/M stopped.
If you forgot to turn the pumps on before T/O and did so at 15000 rpm there would be a massive surge in power as the Water Meth unit on the engine adjusted its valve to control the flow and limit the torque. I saw this done once on an HP Herald by a training captain who had forgotten to arm the system.
Me, I was just a travelling spanner man, I wonder how often this happened?