Guys...horsepower is simply the result of the calculation of torque at a particular RPM. Horsepower is a measure of work done based upon, in this case, rotary motion. Torque and horsepower can be equal at 5252 RPM ONLY if the motor can spin to that rpm. In the case of diesel engines that are high torque at low RPM's they may not be able to get up to 5252 RPM.
Small motors like F1 build peak torque at very high RPM and have transmissions that keep the RPM in the desired range.