Reply to "Anyone with IR injection run "naked""

Mike, look at the filter-cans Porsche uses on 911s & 914s running Webers. A problem comes up when a filter-box is built over IR intake trumpets and it's volume is too small or uses foam filters (Porsche does both). An IR intake pulses airflow so powerfully that fuel flows in an airstream in both directions- into the engine and back out the trumpet mouths. There's often a visible fuel cloud hanging about 6" over naked intake trumpets in dyno photos, at certain rpms.

If the filter(s) you choose is foam, it soon gets saturated with raw fuel. DCOEs sometimes actually drip raw fuel out the bottoms of the air cleaners. Then a backfire from any cause will light off the fuel-soaked foam and you have a raging fire inside the air cleaner(s). Two of my engine fires and one on a friend's 911 were caused by exactly this; use paper air filters only.

Note- all of this happened on Weber-carbureted engines; dunno if it also holds true for EFI, but it should be simple enough to test- it's engine-speed dependent so you need not even be driving to see a cloud begin to appear above the stacks at some rpm.