Proponents of the metric system always seem to trot out the argument that 'metric' is the choice of science, and imply that the two are always linked - as though 'metric' is more accurate, and science can't be done without 'metric'. What tosh. The two greatest scientists of all time (Darwin and Newton, if you must) didn't use 'metric' - Newton used Paris measures! It comes as a shock to some people to realise that that there are other ways than 'metric'...

Time
Sadly for the 'metric' folk, the second came along long before their system.

Force
One of the units of force in the imperial system is the Poundal - the force needed to accelerate a 1lb mass through 1 foot per second per second. A Pound-force is the force needed to accelerate a 1lb mass through the rate of gravity, i.e. 32.174 feet per second per second, or , to put it another way, is the force exerted by a 1lb weight (on earth). There are therefore 32.174 Poundals to the Pound-force. A kip is 1000 Pound-forces.

Work/energy
Work is defined as force x distance moved, so it comes as no suprise that a unit of work is the foot-poundal, and the related foot-pound-force. Another unit of work is the British thermal unit (Btu) which is the amount of energy needed to raise 1lb of water through 1 degree F. However, just as the calorie depends on what temperature the water is to start with, there are different Btus depending on the temperature - eg 39F, 60F. A Therm is 100000 Btus.

Power
The most common unit of power is the horsepower - BEWARE - there are many different horsepowers, including 'metric' ones! The one normally encountered is equivalent to 33,000 foot-pound-force/minute, in metric if you must, 745.7 Watts.