Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel

Official title: Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture (adding secondary air to fuel-air mixture F02M23/00; adding exhaust gases F02M26/00; fuel-injection apparatus operating simultaneously on two or more fuels or on a liquid fuel and another liquid F02M43/00)

F02M25/00 (Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel) appears on 5,902 US grants and 5,038 published applications in this corpus.