The fan and motor must be (reasonably) matched. You cannot assume that any motor will work. The power a fan needs is a function of the cube of the speed. If you double the speed (from 1740 to 3480) you have increased the power required by 8 times! So you actually need something like 40 HP to run that fan at 3480 RPM. So no surprise the motor burnt up. You need to get the right fan and the right motor to flow the necessary air.