Just because mine blew up doesn't mean yours will, I could have had a bad one, I could have ingested something, I don't really know. I'm honestly surprised at the amount you're getting out of a ST90, but all the better! Just be sure to keep it rich (just at that point before it goes off the pipe) on the ground so that it won't lean out in the air, you don't want to seize it or blow a bearing either.
As I say, I could have had a bad engine, or maybe even just one to many runs, I guess my personal opinion is I don't try to use non speed engines for intense speed, but if it's working, then work it!
