Constructor modules as engines
In a Suicidal game (DA, largest galaxy, all abundant, etc.) an amusing UP resolution just set the min speed for constructors at 7.
So, with Impulse and the +1 trade good, even non-engine constructors have speed 9. Just built one and confirmed it. If I go up in engine techs, I'll get another +1 or two. Hmmm, I wonder if two modules would be speed 18?
I think I will redesign all my warships to have a constructor module and no engines!