If it had no valves, it wouldn't be an engine (something many people fail to grasp).
jenn4:
Fully destructible = 10p
An engine being fully destroyable is impossible. Valves can be made from: Cleverly placed ARAY (large, quick, but complex) - Indestructible STOR (compact, but slow and could preignite fuel) - Indestructible Walls (Large, but quick and simple) - Indestructible
Basically, I'd change "Fully destructible" to "No walls"
i don't like the idea of no walls since this woul ruine the pressure and velocity fatal for the most engines on tpt.. otherwise it seems like a good challenge, you should probably post this in creations instead