A pre-combustion chamber comprising: a passive prechamber comprising: a prechamber comprising an external surface and an internal surface enclosing a prechamber volume; one or more ejection ports communicating between the external surface and the internal surface for introducing a fuel-air mixture into the prechamber volume; a spark-gap electrode assembly, comprising a primary electrode disposed within the prechamber volume; and one or more ground electrodes disposed within the prechamber volume and offset from the primary electrode to form one or more electrode gaps; and a crevice volume; characterized in that the passive prechamber further comprises one or more auxiliary scavenging ports each comprising an inlet for communicating with a main combustion chamber and an outlet communicating with the crevice volume, wherein the one or more auxiliary scavenging ports have a length over diameter ratio greater than about 3 and the outlet of each of the one or more auxiliary scavenging ports is proximate the spark-gap electrode assembly. a passive prechamber comprising: a prechamber comprising an external surface and an internal surface enclosing a prechamber volume; one or more ejection ports communicating between the external surface and the internal surface for introducing a fuel-air mixture into the prechamber volume; a spark-gap electrode assembly, comprising a primary electrode disposed within the prechamber volume; and one or more ground electrodes disposed within the prechamber volume and offset from the primary electrode to form one or more electrode gaps; and a crevice volume; characterized in that the passive prechamber further comprises one or more auxiliary scavenging ports each comprising an inlet for communicating with a main combustion chamber and an outlet communicating with the crevice volume, wherein the one or more auxiliary scavenging ports have a length over diameter ratio greater than about 3 and the outlet of each of the one or more auxiliary scavenging ports is proximate the spark-gap electrode assembly. a prechamber comprising an external surface and an internal surface enclosing a prechamber volume; one or more ejection ports communicating between the external surface and the internal surface for introducing a fuel-air mixture into the prechamber volume; a spark-gap electrode assembly, comprising a primary electrode disposed within the prechamber volume; and one or more ground electrodes disposed within the prechamber volume and offset from the primary electrode to form one or more electrode gaps; and a primary electrode disposed within the prechamber volume; and one or more ground electrodes disposed within the prechamber volume and offset from the primary electrode to form one or more electrode gaps; and a crevice volume; characterized in that the passive prechamber further comprises one or more auxiliary scavenging ports each comprising an inlet for communicating with a main combustion chamber and an outlet communicating with the crevice volume, wherein the one or more auxiliary scavenging ports have a length over diameter ratio greater than about 3 and the outlet of each of the one or more auxiliary scavenging ports is proximate the spark-gap electrode assembly.