A flame trap housing 36 for a flame trap 34 of a compression ignition engine has an inlet 38 configured to engage an air outlet of a turbocharger and an outlet 40 configured to engage an inlet of an inlet after-cooler. The housing 36 is double skinned, having an inner skin 46 defining a flame trap compartment 35 and an outer skin 48 arranged in a spaced relationship relative to the inner skin 46, to define a fluid flow path 52 for the flow of a cooling fluid about the inner skin 46 of the housing 36.