So, what exactly is the difference between Stage1 and Stage 2 air cleaners?

My dealer has a Arlen Ness stage 2 air cleaner on it's discount rack. Is there any reason I couldn't use it? I have 4" RH slipons, decatted headers and FL VIEDs.

 

Hey Rob I have never heard of a stage 2 air filter,
the only difference that I know of would be all the
things that come with it. Now if you are interested
in performance have a look at this.
http://www.harley-davidson.com/en_US..._SE13_Full.pdf

 

Any stage 1 Air cleaner should accommodate stage 2 mods...however there are some larger air cleaners out there for monster motors...I suspect the Arlen Ness Stage 2 is one.

It's listed as having 20% more filter capacity. You probably don't need the additional capacity, but it will work just fine.

 

I'm not sure of the exact part# that is at the dealer, but it is like this one. They have it for 50% off.

http://shop.arlenness.com/p-3720-200...-stage-ii.aspx

 

...is really not much. Mostly just marketing hype.

All the stage numbers are very loosely interpreted...there's not much black 'n white differences in them.

Generally...loosely speaking...
Stage 1 is a more free intake and exhaust system, and sometimes ignition.

Stage 2 brings a cam

Stage 3 brings more inside engine work...head work, blue printing

Stage 4...stuff like forced air via turbo or supercharge, nitrous, or insane displacement increases.

 

A little more than hype. It's all about cubic inches and cubic feet per minute: the more, the better.

 

Once you do away with the stock intake and go with a free flow, what really matters at this point is the size of the throttle body. The stock TB will only allow so much air flow, so I don't think what is in front of it would make any difference with a stage 1 set up.

 

It depends totally on the A/C manufacturer and how they hype it.
Generally, most Stage 1 filters in the round or oval design, like this one, have 2" wide filter elements. The same thing with a 3" element will often be called a Stage 2 filter.

Typically, unless you have a built motor with headwork and cams, a "stage 2" filter won't bring anything to the table.

 

That doesn't explain the differences (if any) in the filter. I'm very well aware about cubic inches. But it's not a high performance motor we're talking about on this forum here...once you get past a certain point in having "the intake"....additionally larger intakes are very simply a law of diminishing returns. It's not like you have to supply some insane volume of air to a Ferrari V-12 churning 14,000 rpms....it's just a low tuned twin cylinder here we're talking about.

I've yet to see any valid article/benchmarks/test/performance article showing that there are big differences in HP gains in aftermarket ACs. A tiny gain above stock...some let a little more sound out (cuz of being more porous...so more abrasive dirt getting in too) and then it's all about money drained from the wallet, and looks.

 

It all depends on your setup.

Point was... phrases like "stage 1" and "stage 2" simply refer to the process of increases in air flow demand through modifications to your motor (internal/external) and the corresponding A/C's are engineered to meet those demands based on the changes implied at that "stage". So, no... it is not just "hype".

Whether or not the engineering actually works, is another subject.