Airfoils and grooves on the rotor or carrier for the airfoils have generally complementary dovetail shapes. The engine includes an engine body having a plurality of cylinders, an exhaust manifold through which exhaust gas discharged from each of the cylinders of the engine body passes, and a controller for controlling various instruments provided to the engine body and the exhaust manifold. The microvalve is formed of three flexible membranes, one of which is responsive to pneumatic pressure applied to the valve and the other two of which deform to produce a more sealable channel cross-section.