I don't think any other engine company has ruled over any AMA event for so many years straight. The FOX .36 dominated AMA C/L combat for over 30 years because of its' light weight [8 ozs] and it turned a 6 pitch prop well enough to do 120 mph hooked up to a pair of 100 pount test cables. The planes seem to pick up some speed from that point after the lines have been severed.
Jett and K&B came out with .35s and neither one out did the FOX, they never caught on. It wasn't until Nelson got involved that the FOX finally was dethroned. 99% of the RC community don't know about this little niche of the hobby but when it came to power to weight and toughness, FOX ruled for quite awhile....at least here.
The FOX COMBAT SPECIALS had tapered liners and great compression hot. Their RC .40 cousins did not have the same cylinder taper and would flame out after the cylinder expanded too far. For FOX, it was / is a question of being able to survive as a US based company that pays their workers a liveable wage, possibly with equipment that isn't as capable as what you find in the Oriental factories.