Internal-combustion engine with catalyst (porous structure) to promote combustion [56]: 52-piston; 53-piston ring; 54-catalyst member (porous structure with catalytic coating); 56-combustion zone; 58-intake port (air); 60-fuel supply port; 62-exhaust port; 64-intake valve; 66-fuel supply valve; 68-exhaust valve; 70-piston rod.