A totally unrestricted air filter [cone style, etc.] will allow more air volume to enter the engine than it could ever physically utilize, whether sitting at idle or tooling down the road at 115 mph. And you can direct this incoming air all you want with a scoop, you can make it swirl, and even shoot it down tubes and hoses, but the idea that a smaller orafice can be used to "ram" air into the intake port is wrong, as this small opening [ie., in the case of the stock Harley ham can] only serves as a bottleneck to increase incoming air pressure, and you're not looking for added air pressure, you're looking for added AIR VOLUME! These are two totally different things! And the only way to get more volume of air through a hole is to make it bigger or remove any restriction in the way.

[of course turbos and superchargers are another story but we're talking normally aspirated engines]

Going down the road may "force" some air into the intake but for all intents and purposes, when the engine is running it's a vacuum pump, which will gladly pull in air from anywhere it can get it, restricted or otherwise...to which the EFI system [if so equiped] will then respond and adjust to this incoming air volume [obviously the more and cooler the better] accordingly with proper fuel adjustments for correct combustion.

=8^)

 

Well you totally contradicted your self, there are TWO ways to get more air into a hole.
#1- make it bigger or remove any restriction in the way.
OR
#2- increase the air pressure.

 

Without a free flowing exhaust it doesn't matter what you do with the air cleaner. You can only get more air in if you are letting more air out.

 

One of the issues I have with the open back (I've got Fuel Moto's "Stage 1" kit) is that with the stock football or ham can cover, with the back open, it's pulling the intake air from the cylinder side of the AC. With the Power Vision set up to display intake air temp (IAT), I've seen as high as 165 degree intake air temp when trapped in stop and go traffic, when the ambient air temp was around 90. The IAT is always at least 10 -15 degrees hotter than ambient air with this setup. I don't like the looks of the big elbow K&N type setups, but they at least should be getting fresh air.

One point about "ram air" on carbureted bikes is that to work properly, the float bowl has to be pressurized so that it's seeing the same air pressure as the throat of the carb or you'll be trying to blow backwards through the main jet (the reason that the old McCulloch supercharger setups had the carb setting in a can). Not an issue on FI's, as the MAP sensor sees the incoming air pressure.....

 

If we were talking multi stage air compressors/roots style compressors/turbos then YES you can FORCE by compression more air through an [x] diameter hole and get more volume through it, but...this is not a compressor and oriface plate we're talking about. We're talking about a simple normally aspirated motorcycle engine so there is no real contradiction in this scenario, because...the amount of air pressure increase from simply riding down the road at 1 atmosphere "forcing[?]" the engine to suck air through a small hole is not enough to make any noticeable difference in volume on a normally aspirated engine, unless you're travelling down the road at 200+mph with a 24" long, 36" diameter into a 2" diameter venturi hangin' off your engine. 'Haven't seen many of those. That's why I mentioned excluding turbos and superchargers, which are air compressors, which provide the only means to increase air "pressure/volume"...neither of which were the topic of discussion by the OP...

=8^)

 

The Hammer intake w/2" filter and hamcan cover shown on this bike can support 100+ hp proven thousands of times on the dyno...one with a 3" element is only slightly better. I would not lose sleep over it.

 

I agree with Rick. The difference between the ham can with a good filter (non oem) in it and an open face non ham can probably couldn't be felt.........only measured.

 

Just curious...how does the backing plate improve the performance? Isn't it still an enclosed system making the filter the only improvement? I just made the modification to an open system so I'm wondering if I made the wrong mod. I'm not going to get it Dyno'd, but can tell a noticeable difference in my ars.

 

 

Here you go...SE air cleaner kit plus an open-front ham can cover. The SE for performance and the screened opening for looks...