Wow!  I looked it up and that's some interesting reading.  It said they use screens to reduce pressure without effecting velocity.  Cool!  Thanks.  

I'm gonna read some more on it and see if I can get a handle on this concept.  

Try putting your desk organizer on the stock tube, I gotta feeling the flow is too turbulent.



I put in some super quiet bathroom fans in recently.  I put them in and they were just as noisey as before, so I read the directions (if all else fails) the duct had to go straight out of the fan a certain distance before it could turn up.  The explanation was it had to build up momentum.  Who knew air had momentum?  so changed it around and eureka, it was quiet.

So I'm thinking the same issue applies here and the stock rubber ducky is exactly the length it needs to be.  Therefore your comical assy V1 has a distinct advantage over the HomeDepot rubber connected desk org V3.  So I think a comical org V4 will be a winner.

Kind of like this?  


Thanks.  Hadn't thought of that but I can see where it would have some good potential.  Cool.

There's something else I learned this weekend.  Saturday we took the son to a Boy Scouts meeting at a U.S. Fish and Wildlife bird sanctuary where we saw a film about falcons.  It detailed how the peregrine falcon, the one that does the insane dive from high altitude to catch food, has a unique feature to help it breathe during rapid descent.  Wikipedia puts it like this- "... small bony tubercles in a falcon's nostrils guide the shock waves of the air entering the nostrils, enabling the bird to breathe more easily while diving by reducing the change in air pressure."

Years ago that very feature was studied extensively by designers and engineers.  That research led to the development of a feature on jets that fly at supersonic speeds:


Of course, this is of absolutely no benefit to my experiments or designs but I just thought it was cool when I learned about this.    

LMAO!!!

From coffee filters to suppositories.  Who'd ever had thunk it!

That info about the quiet fan was interesting.  I guess the longer tube allowed the turbulence to smooth itself out before the air curved through an elbow.

cool stuff.
The way I understood it, the screen create uniform micro turbulence which settles down quickly to laminar flow.  Now I would think an OF type filter would perform this task quite nicely.
I would reverse the coffee filter so the OD sits in the transition of the reducer (4" to 2") stuff OF filter on top of that and retain it with the screen.  Of course I think it would be better to have an even thickness of filter material.

Pretty sure it's Oldfeller's cheap air filter: http://suzukisavage.com/cgi-bin/YaBB.pl?num=1183640744

Lo-Buck, High Flo, Lo Maintenance,tiny crapgrabber= OF filter

Ver 4 worked good but had a minor problem.   Twice when cruising at 75mph while very windy out I was hit with two very powerful gusts of wind.  It’s been windy and drizzly the past few days.  When the two gusts hit the bike, the bike had a slight surge for a moment.  Nothing major but just enough to notice.  I think the large tapered opening and the pressure change with the gusts of wind had issues working together as the bike was sucking a lot of air at highway speeds.  I’ve had bigger gusts with the other versions on the bike with no problem.  At first I thought the two little surges were an indication that I needed to move up to a 155 main.  But then I realized they both occurred exactly when I felt the gusts hit.  Still, upsizing the main is likely in order.  

I’ve made a Ver 5 which is actually Ver 2 with an even less restrictive cover, more tapered internal tube and filter consisting of cotton gauze treated with K&N oil filter lube.  Up to this point, Ver 2 has been the clear winner.   Ver 5 edges it out as my favorite performer.  

Here is a chart of my impression thus far of engine power/performance over the rpm range using the pod filter, stock setup and Ver 5.


My pod filter performed nicely at higher rpm ranges when max airlfow is needed but doesn't develop as much low end torque.  I believe it is because my pod filter lacked the ability to develop very good vacuum at low rpm.

My stock airbox was great for low end torque as it allowed a good vacuum to develop at low rpm but it had some restrictions to high flow at high rpm that became evident with mods.  

Ver 5 feels like it develops better torque at low rpm than my airbox. I feel this is because it has both the ability to develop a vacuum while having less restriction than my airbox.  In midrange Ver 5 outperformed both.  As for high end, I haven't actually experieced any decrease in the performance of Ver 5 vs pod filter at redline or near redline.  Actually, throttle response feels snappier, the bike pulls harder and it's just more fun riding the highway with Ver 5 vs. my pod filter.  However, common sense tells me that around redline the engine is creating a very good vacuum and the pod filter will start to outperform Ver 5 due to absence of tube resistance.  Maybe, maybe not.  I don't spend much time riding at redline but still I reflected this theory in my chart.  

So, there you go.