Do you think it's possible to build one (not expecting to be the best motor, but one that can have a nice performance)?
Motors are full of big, precise pieces of metal, so this is one thing I would definitely buy, but there are possiibilities to re-purporpose something industrial:
Some years back, a number of us did some research for using industrial 3-phase AC motors in EVs. One of our members went as far as cobbling some industrial gear together:
http://www.evalbum.com/1149
This was very successful and cheap to do. It used SLA batteries and an off the shelf industrial controller because it was an experiment.
A relatively small industrial induction motor can be used (11kw ~15hp) and still deliver lots of power and torque. The motor in question was a 4-pole type and has a free running speed of 1500RPM (1800 at 60Hz). Also, these idustrial motors have big (and heavy) output shafts, about 40mm on the unit used. with robust bearings designed for pulleys and belt loads. They are designed to operate on hot, dirty industrial environments and endure frequent serere overloads.
The over-torque capability on 2-pole motors is a lot lower than the 4-pole types, making the 4-pole types far better cadidates for EVs.
If you're looking at motors, the 4-pole type can deliver 3 to 4 times their rated torque for short periods of time (about a minute), making the 11kw a 40+kw motor.
Also, they can be run at frequecies considerably higher than the normal line frequency. The makes the motor turn faster, producing more power at a particularl torque. That 11kw motor could deliver up to 120kw peak for a minute or two by doing both. The 30kW VSD used in the Red Suzi project is capable of somewhere around 150hz.
One issue with 'overclocking' a motor like this is that the required terminal voltage goes up linearly with the speed, so 2-3x the orginal line voltage. This can be overcome by rewinding the motor for lower voltage, but this increases the running current (at that lower voltage) and also decreases the inductance, which can cause the controller problems.
Later, the red Suzi motor got rewound by bringing out a pair of terminals in the middle of each winding, allowing them to be connected in either series (same as the original) or parallel (1/2 the voltage of the original) This decreassed the peak torque some (controller limit), but allowed considerably higher road speeds in excess of the approx 80kph safe speed limit on the Suzuki.
I've had trouble giving one of these motors away recently.
Good luck & happy motor hunting.