Answer
The claim is false.
Work Step by Step
The inventor claims that the engine is 67 percent efficient.
$$e=\frac{W}{Q_H}=\frac{2.00MW}{3.00MW}=0.667$$
However, at the operating temperatures specified, the theoretical maximum operating efficiency is less than that.
$$e_{ideal}=1-\frac{T_L}{T_H}=1-\frac{215K}{425K}=0.494$$
Even if the engine were ideal, the efficiency couldn’t be close to 67 percent. The claim is false.
