If the quasiturbine engine takes in fuel after compression and then burns it at constant volume, wouldn't that increase the efficiency of the process as constant volume burning is more efficient than constant pressure burning at same compression ratios? If such a burning is not possible, what are the reasons? edit: one more question Why are the quasiturbines not busting into the market because from the descriptions I read on the net, they offer huge advantages over other engine types. What about rotary vane engines. What is their status?