Kweassa,
There are many stories of bomber pilots who "blew out" engine fires by going into a steep dive.
Granted its not going to do anything to an internal fire, but they had estinguishers for that. What a bomber crew can't reach is a fire out in the engines.
No it was not a "sure thing" but it was better than the alternative, which was watching the wing melt off then taking the same long dive only out of control.
After all, havn't you ever "blown out" a candle?
BTW just for reference, fire is a 3 sided triangle, Air, fuel, heat.
Take away one leg and it falls down.
(goes out)
What happens to your heat if you go from 175 mph to 400 mph? Blown away in the slipstream perhaps?