Originally Posted by Brisyboy
Ummmm - whats an airsep and what does it do (or not)?
As the pistons go up and down in their cylinders, the total volume of the crankcase changes. Since there is often a mist or fog of oil in the crankcase, the crankcase vent can breathe in and out, exhaling oil in the process. That's one reason why many engine rooms smell like oil.
An AirSep is a filter that captures the oil in the air and returns it to the crankcase preventing oil in the engine room air. It also muffles the "breathing" sounds of an engine.
I tend to agree with the others that a good set of engine mounts would do far more to quieting down an engine (or two) than the crankcase vent noises.
I've not seen the alternatives to AirSep from Tony Athens, but have read his work and in my opinion he knows what he talks about.
If you have turbos, a bigger air filter with more surface area can cut down on some of the turbo whine. Just remember, when you hear them, they are not working... Under load, a turbo operates far above our ear's audible range.