I'm assuming (FWIR of your posts) you're using a Mongolian Burner?
Goomba
I tried with a 20 jet Mongolian using a 207kpa reg. It only just done the job and the centre jets glowed red.
I now use 2 x NASA burners. I think one would do it, but would take a bit longer and be a lot louder due to running it hard.
QldKev