emechelmi said:HP is general measurement of power. BHP is measured by applying a resistance (brake) to an engine until it ceases to run. 1 HP is equivalent to 746 W in metric system.
bar and PSI are the unit to measure pressure, not power. One is a metric and the other is imperial. 1 bar refers to 100 kN/m2 or 100kPa. PSI (pound per square inch) comes from Imperial unit system.