[rillip3]

At peak efficiency most electric motors are ~ 95% efficient, but you're rarely running at peak efficiency (you're more likely to be running closer to peak power than peak eff.). A ballpark assumption I've seen is ~ 80% for a varried duty load. So take your peak kw output, find 20% of it, and you'll have to dissipate that much energy as heat. Now figuring out how many kw of heat your forced air can dissipate is beyond my ken, but you may be able to find something with ratings on it to give you an idea.