This is a rough guide only, but:
1kW = 1.34hp
1hp = 0.743kW
Remember:
* when you're reading a new car mag (such as Wheels, Motor, etc.) or looking in a new car brochure, the quoted power figures are at the flywheel.
* when you're reading a performance/modification kind of magazine (HPI, Zoom, FF, etc.) them most of the figures stated are at the wheels, so count on *roughly* 20-30% lower figures compared to flywheel, and this accounts for frictional and other losses.