Mapp gas burns a lot hotter than propane. I don't know how much, though.

I think my two-brick forge with the JTH7 torch could get that file glowing in three or four minutes. If you line your little forge with some kind of refractory coating, like ITC-100, it'll get more efficient. Does the inside of the forge glow bright yellow-orange? If not, you're just kind of containing the heat and concentrating it a bit. That's better than just using the torch in the open air, but ideally the flame heats the forge liner, which absorbs the intense heat and reflects it for more even temperatures.

Sounds like you're having fun, which is important.

Josh