There's nothing in the Ship Modeler's Bible that says a Fed battleship has to have 4 warp engines, or a DN must have 3 (or any warp engines for that matter). The whole 3 engine/4 engine thing is from SFB, and even that only applies to the TOS ships. This is all redundant anyway since it is based on the same ship design from the Klingon Academy game. I didn't design the thing, I'm just making my own higher detail version of it, just like what I did with the Klingon fleet.