Not something you could knock down Ft. Knox with, but of adequate power to enter into any of the national Punkin Chunks. Range, not weight here is the primary concern. Competition engines need to be somewhat portable. A full sized treb would be capable of pulverizing a medieval fortification with tremendous weight.
Size is unlimited, though range is usually no better than the competition grade trebs.
CW Mass is the dominant concern and can easily exceed several tons. The beams tend to be huge laminated constructs or sometimes an entire tree is used. Portability is an unthinkable nightmare.