Hi all,
Quick questions…I replaced my stock air intake on my 03 cavy with an AEM cold air intake. I discarded the hose that connects on the motor head and intake. In its place I installed one of those small fancy filters on the motor head and seal the air inlet on the cold air intake. My questions are; is that ok to do? Would it have any negative effect on the engine performance? and if it does not cause any problems why was the hose originally there?..just curious

Thanks all.
Jonathan

The hose is (was) part of the crankcase ventilation system. In many (most) engines with positive crankcase ventilation, there's a consistent vacuum draw through the crankcase (via the PCV valve) to removed boiled off contaminants and blowby gasses produced in normal running. (This is a good thing.) That hose provides the system with filtered air. But, crankcase dynamics vary in operation and the normal vacuum that occurs at idle may turn to pressure under heavy load as more blowby escapes past the rings. When this happens, the hose routes the gasses in reverse back to the intake system where they're drawn in and burned. If you remove the hose and install a filter vent on the engine, you'll still get filtered air during vacuum conditions, but on pressure conditions you'll get blowby out the filter which is now vented to the atmosphere. These gasses may normally contain oil droplets that will either get caught in your vent filter or be blown on the engine. The amount varies depending on load and engine wear. While it won't likely be detrimental, it's no longer a closed system and in some municipalities it wouldn't pass emissions inspection. And, whatever mess results on your engine, if any, is your problem. My personal preference is to keep the closed system and make whatever minor modification is necessary to provide a connection for the hose. Your method may vary.




Edited 2 time(s). Last edited Thursday, February 12, 2009 8:53 AM