Intake Flow Simulation - ADDING INTAKE VELOCITY STACK

[sansnombre]

THIS PART JUST BELOW IS THE INTRODUCTION TO WHAT'S COMING. BELOW, AS I ADD INFO, LOOK FOR THE DIFFERENT SECTIONS, AND YOU'LL SEE THE NEW INFORMATION. THEY WILL BE SEPARATED BY WHAT YOU SEE BELOW. I WILL MAKES NOTES OF UPDATES IN THE SUBJECT LINE . . .=======================================================================================- INTRO- STOCK FLOW- SECTION A: REMOVAL OF LOWER SECTION OF SNORKEL- SECTION B: REMOVAL OF INTERNAL SECTION OF SNORKEL ONLY- SECTION C: REMOVAL OF TOTAL SNORKEL AND FILTER- SECTION D: REDUCING THE LENGTH OF THE AIRBOX EXHAUST TRACTS- SECTION E: MWR FILTER AND COVER- SECTION F: ADDING AN INTAKE VELOCITY STACK TO MWR SETUP=======================================================================================
INTRO:
I've been wanting to do this for a long time, and just decided to stay up late and finally get started. There is an analysis process called CFD (Computational Fluid Dynamics) which allows a computer to accurately simulate heat transfer, flow, and other things.
Here I've modeled our stock U.S. FZ-07 intake system - it is accurate and is how our bikes look stock.
The pictures/video show how the airflow works when you're stock. MAJOR simplification on how it's analyzed though, as it's only showing a static pressure differential and does not include the alternating pressure pulses of the two airbox exhaust ports, among other things. Conceptualize that this box is sitting there and you applied a vacuum to the exhaust ports of the airbox and it was allowed to stabilize - that's what the pictures show: a static airflow through the system that has stabilized. It offers the ability to optimize components in a general way, but absolutely does not model or reflect the actual dynamics of the engine and the airbox. So things like optimizing the intake runners to help low rpm, low flow conditions are not a part of this analysis. So it's leaving a lot of data out of the analysis, but my computer doesn't have to run for 7 days to solve one setup!
My plan is to change the models to reflect the stock system, a system with a removed "internal snorkel" (the oval part that goes into the filter), a stock system with the full snorkel removed, a system with the MWR filter and newly released cover, and then finally some optimization on intake and exhaust ports. That last bit is the fun part - I'm going to create a velocity stack like structure to go over the MWR cover and see what that does, and I'm going to shorten the exhaust port runners and see what that does. I have ideas already what's going to happen, but want to verify with the analysis. Also, the filter material is standardized among all setups - I do not know, nor can I get the specifics on the different elements, so I used a standard element and it's being used for all setups. So a K&N is not included because it's very close to stock in terms of geometry, so wouldn't show any meaningful information. Also, I do not have the DNA cover so do not know its dimensions, and it's relatively close to the MWR, so I'm not going there either. Sorry.
In the end we'll have volume flow rate numbers and graphs for all the systems noted above at a variety of pressure differentials, probably 4 or 5 different ones. So you'll have a graph of the differences in flow rate of all these setups at different pressures - simulating different RPM. It's kind of a no-brainer that opening the ports will allow more air to flow in with this type of analysis, but how much will it change is the question, and it's possible that we actually will have [em]lower[/em] flow rates with some of the more open setups if we get weird vortexes or dynamic chokes in the flow. It's possible.
Why? Lots of talk about removing the snorkel, lots of talk about only the inner section being removed, lots of talk of MWR's designs, etc. I want to see what's what and if I can optimize the intake system to have kick-a$$ performance in the mid-range. Hordpower already showed what can be done by opening her up all the way (well, nearly all the way - velocity stacks on a non-filtered unit is maxed), and if you look on his site, he's got a dyno run (see below - @hordboy , please advise if is not ok to repost this) that has always made me drool - it's where he gets a massive increase in midrange torque, and I've wanted that on my machine.
So that's what I'm doing. Can I still have a filtered intake system and change the design so that I can have a fat mid-range bump? I think so.
In the end I think I'll have a 3D printed velocity stack that will be attached to the top of the MWR cover and very likely will have shortened exhaust runners that have optimized openings.
Take a look at this preview and you'll see why - there is a tremendous choke on this system in several places, and much of the airbox is underutilized and the airflow past the filters and to the openings of the exhaust port is also choking off flow. It's easy to see in the graphics.
Anyway, this is a preview. It will likely take a month for me to finish, but I'll drop more data on here as I can. Next up is the run without the internal part of the snorkel. Take a look at the pictures and see how much of your filter is not being used because of this component - nearly all the flow is going out the bottom 1/2 inch of your filter. Not convinced? Look at your stock filter on your stock system when you take it out - only this little part at the bottom is dirty!
The video below shows the flow through the system of a bunch of particles and ends when all the particles have exhausted the system after they fart around in the box for a while. Again, this is a simplified, static system at steady-state. It provides useful, but limited, information.
Enjoy . . .
SECTION A:
[video src=https://youtu.be/bYjV6zBfvAk]
 
1. This is a cut across the center of the snorkel. You're seeing velocities - blue is slow, red is fast.
 

2. Similar to [HASH]1, this is a cut across the center of the snorkel. You're seeing velocities - blue is slow, red is fast. Just different way of showing the same thing.
 
3. This is a still from the video. All those lines are single particles traveling through the airbox and eventually exhausting out the exhaust ports.
 
 
4. This is Hords dyno run where he shows the potential of this bike in the midrange. I'm searching for something like this, but if there was a drop in system from someone (hint), I'd have it on the bike already and be sleeping instead of doing this analysis. Thanks Hord for the inspiration. Cheers.
=======================================================================================SECTION B: FOR THOSE OF US (ME INCLUDED) WHO THOUGHT REMOVING ONLY THE INTERNAL SECTION OF THE SNORKEL WAS A GOOD THING. IT'S NOT. SEE BELOW FOR WHY.
This next part of the analysis shows what happens when you remove the internal section of the snorkel. There was at least two of us who thought it best to leave the external part (to shape the flow), and remove just the internal part, helping to open up the surface of the filter and improve flow. Wrong. Take a moment to look at the pictures above . . . what's going to happen if you remove the internal section? Now take a look below. If you thought that the flow is moving forward (relative to the bike) and will continue to do so inside the filter and will bias towards the front, you're right. This is bad as a significant part of the flow *shoots past the intakes* of the exhaust ports, and has to come back before it can get out. Bad thing! Notice the additional vortices and time it takes for all this flow to fully exhaust the airbox.
@2wheeler might find this interesting - in his post https://fz07.org/thread/7085/donor-bike-2wdw-flash he comments on how he had 2WDW do a dyno run with this setup and it actually lost power. These graphics help to explain why.
So the airbox designers did a proper thing: they had this internal section in place to force the flow to a downward vector so it would not bias towards the front. Yeah, it's not perfect, but it's better than not having it in.
Of course this begs the question: how about a vertical intake section and what if we pull the exhaust tracts closer towards the engine, so they don't overlap the flow and it doesn't have to circle around and come back . . . to be continued.

[video src=https://youtu.be/aiEvZ-tx2Dg]
1. Note how much of the flow shoots past the intakes and has to circle around before it can exhaust. If you compare it to the ones above, you see more gets immediately inside the exhaust ports. Clearly, stock is a better design.
 
[video src=https://youtu.be/2SuymFTA1Ho]
===========================================================================================SECTION C:EXTERIOR PART OF SNORKEL REMOVED, AND REMOVAL OF FILTER.
Ok, this part was very interesting and also answered some questions. Two runs - one with full snorkel component and the filter element itself removed and then one with the full snorkel removed and the filter in place.
With the filter removed, the flow blasts down to the bottom of the airbox and gets blown all over the airbox, basically causing chaotic flow, but significantly increasing the overall flowrate.
Notice how the flow is all over the place. Even more apparent in the video, below.
[video src=https://www.youtube.com/watch?v=jbIJq3v2UGo&feature=youtu.be]
 
With the snorkel removed but the filter IN PLACE, presumably more flow restriction, the flow is BETTER than with no filter element installed. The reason is that having the hard bottom on the filter acts to pressurize inside the filter and directs the flow. So far, this is the best setup.

 
Notice the very clean flow here. The filter is actually shaping the flow and directing it toward the ports instead of blowing it around the box.
[video src=https://youtu.be/jM0EzkF5l5g]
Fascinating stuff and it actually explains many of the things the dyno tuners have been saying about what works, what doesn't, and what is not having any difference. I'll post actual reference numbers after I'm all done so you have objective data. That said, I did a preliminary on what Hordboy did to get that fat, fat midrange, and it's a big difference. If we can replicate it, we'll be in heaven. Stay tuned.
========================================================SECTION D: REDUCING THE LENGTH OF THE INTAKE TRACTS
This didn't go as expected. I was expecting the flow to increase, in at least one of the prior configurations, but it did not. The flow was unchanged (or very nearly so) or slightly reduced! Again, you have to look at the graphics to see what's actually happening . . .
I ran it three times (stock, snorkel removed, and wide open) at two different reduced lengths (35mm shorter and 90mm shorter). Here's what happened -
1) Here's a picture of the standard length:
 
 

 
what is image hosting
2) Stock with shortened tracts (35mm):
 

I'm not posting pictures of the flow, as there were no changes at this length. None.
Now with very short tracts (90mm shorter than stock):
1) With snorkel removed:
 

 
upload center free
2) Animation of the same:[video src=https://youtu.be/fByOtWrMaqY]
- Now with the cover of the airbox removed completely and the very short exhaust tracts:
1) Two different photos of the hardware, so you can see what the geometry is . . .
 

 

2) And now an animation of the same:[video src=https://youtu.be/rKvVyLhR1bA]
Conclusion: With the cover off and the 35mm shorter tracts, the flow was nearly identical in all cases except the cover removed configuration, where IT WAS ACTUALLY SLOWER FLOW. It was worse with the shortened tracts. In the 90mm shortened case, the flow was back to where it was before, same as stock length of tracts. There was no change in flow, at all, of the snorkel removed configuation.
Why? It's those dynamics again and how the flow is behaving in that box. It's easiest to see in the last video - see how the flow is hugging the walls all the way back, then has to flow back around again to exit. We're not getting a more direct flow with all the flow paths directly exiting, which is what I was expecting.
The more I analyze and continue with this simulation, the more I realize that the designers did a good job. The locations and designs are likely nearly best case FOR THE LIMITATIONS POSED BY EPA AND NOISE regulations. It seems that having the ports terminate right beside the filter helps to have the highest pressure differential at the place where it's most needed. It also seems to pull flow equally across the filter element, as opposed to the shortest ones, where the part of the filter closest to the ports was most active, so we actually lost some flow in some parts of the filter.
I think with the short tracts, the airbox would need to be significantly narrower to make any difference, as we're losing too much flow to the sides. At the STOCK lenghts, note how they open at a narrower portion of the airbox, so much of the flow has a higher likelyhood of hitting the orifice.
I also think that if we had LARGER openings that were IN THE CENTER of the airbox (they are offset to the sides), we might get higher flow. But from the current airbox dimensions, there doesn't appear to be any gains from making the tracts shorter. The designers did a good job it seems.
Next up is a MWR config. I anticipate better things here in the simulation, but I had an idea about something odd after installing one in my maching and did some hunting around, and I think there might be a design problem/limitation with it, but I'll comment on that when I get the next section done. After that, I'll post some numbers and conclusions, and I should have a prototype ready to show that hopefully gets those mid-RPM gains that I'm looking for.
=========================================================================SECTION E: MWR FILTER AND COVER
This one didn't surprise me in that it's the most open, free-flowing config available, besides taking off the cover completely. For those who haven't seen it, the filter is very large and the cover has a very large opening to match the opening in the filter. One would assume it would flow the best just by its geometry alone.
I ran the test with standard tract length and very short tracts, and the results were very similar, just like with all the other tests . . . the tract length is not having much effect by itself, but with additional mods, I think there might be some gains there. More on that later, but if they are close to the wall and large enough to reach to the middle, we might be able to "scoop" the flow better - this would require some large bell-like openings to the tracts. I'm going to explore that in the future.
I just have the video results for these tests . . .
[video src=https://youtu.be/VB-BZbrVqPA] [video src=https://youtu.be/Qs8IuIFUCU4]
And now shortened tracts:[video src=https://youtu.be/D0aG9npiVWU]
In short, they flow like hell, very close to having a wide-open airbox. In theory, with proper rejetting, this combo should produce power gains over stock, snorkel removed, or K&N/DNR stock filter replacement. I believe the gains will be similar to DNR, but this setup certainly has a larger opening.
One of the reasons this (and the wide open setup) is flowing so well is that the velocity of the flow coming though the opening is significantly slower, so it's not shooting to the bottom of the airbox, bypassing the ports, and being ported to the rear before it circles around and exits. Going slower as it comes through, it's able to turn and exit much easier.
BUT, the tuners I've communicated with have different feedback. There is one forum member who has done direct, back-to-back dyno runs with this and the DNR filter/cover setup, among other setups, and shown increases which seem to be inline with what I'm seeing. That is, a slight increase over the DNR setup and a large increase over the other setups. But a very well-regarded tuner with posts on this forum has stated very clearly he is not seeing any gains with either the DNR setup or the MWR setup, except in one specific situation, and even then only by a smidge. His perspective and advise was don't make these changes in an attempt to increase power. That said, there was another forum member who had some dyno tests done and was actually seeing a REDUCTION IN POWER from the MWR setup! That's a head scratcher, but got me thinking there is something else going on.
I pulled my FZ apart and watched the intake as I rev'd pretty aggressively, and you can see a significant vibration settle into this filter at certain engine speeds. It appears transient as you move throughout the rev range, coming and going, but this is not a good thing. It's equivalent to mixing up and churning your flow and has to have a negative effect on the flow when it's vibrating. The interesting thing here is that the vibration magnitude and RPM location is going to be specific to each bike, as it depends upon quite a number of moving and dynamic factors in your engine and exhaust, so it's possible that some bikes won't see this issue and others might. Vibration is complex and there is enough variance in all these factors specific to each bike to have the vibration occur at frequencies that do not induce the vibration in the filter, or only outside an RPM range that is not used and only theoretical. This would explain the differences between the two tuners. Hard to say, but my work shows that it SHOULD increase the flow and therefore power, at least by a little.
Next up, I'm going to look at a velocity like stack outside and see what that does, if any, and then a maximal velocity stack inside the airbox on shortened tracts, maximizing their openings.
==========================================================================================SECTION F: A VELOCITY STACK IS ADDED
The idea here is to see how much change there is, if any, to the flow by adding a well-shaped velocity stack to the intake. This was a quick one to satisfy a curiosity. In short, there was a minimal gain of about 1% to overall flow by adding this intake stack WITH THE SHORTER TRACTS; there was no gain with the stock exhaust tracts. Not much, but it seemed to really smooth the flow, as you can see below . . .
- Velocity Stack added to MWR filter with standard length exhaust tracts:
 
 
 

 
website for uploading photos
- Same but with the shorter exhaust tracts:
 

 

By adding this velocity stack to the stock tracts, there is no gain. None. By shortening the exhaust tracts we increase the air flow by 1.3%. Trivial I think.
The vids:
[video src=https://youtu.be/KzeFTguq5Do] [video src=https://youtu.be/n9JLi65dMsE]
With Short tracts:[video src=https://youtu.be/Ow308DAMicw] [video src=https://youtu.be/Ypgj0lmgRCc]
Conclusion:Nothing here I'm afraid. I thought that a tight intake design would help the flow, but in the OVERALL system, it doesn't make a difference. If we were to just analyze the section of the flow through the cover, we'd see a difference, but as stated in the introduction, an engine is a complex series of actions and dynamics and this aspect only adds the slightest bit of difference. Mostly you're trying to avoid a lower threshold where you introduce a meaningful flow restriction, while anything above that threshold doesn't add anything more - it doesn't really add anything to performance, but you can easily inhibit performance by being below this threshold. Removing the snorkel gets us very close to being over this threshold, these other changes take relatively small steps towards it, but are mostly trivial.
One more, then the overall conclusion and observations and raw data. I'm going to alter the exhaust tracts to have large velocity stacks whithin the airbox and see what that does, but looking at all the above experiments, at this point, I'm pretty sure it's not going to do much of anything. Perhaps 1-2%, perhaps nothing.
 

[Zephyr]

Intriguing to say the least. Definitely interested in the results of your analysis. The exhaust port mod has my attention. I could envision a much more economical airbox than what I'm seeing here. Looking forward to future posts and the tremendous discussions that should take place through this endeavor!

[peteinpa]

I'll be watching also.

[norcal616]

I have always wondered if cutting the long intake crazy straw tubes inside the stock airbox shorter or as close to the end of the airbox as possible will help you achieve that nice mid range to top end pull with the MWR filter... I have a stock airbox to donate if you need one to offer up to the gods of HP/TQ...you will still need a PCV to correct the fueling and ignition once you decide on what you want...i personally think the stock airbox is fine just needs diffrent intake tubes and I see why Hordpower went with his idea, it's impossible to get inside the stock airbox without destroying it to modify/play around with to do data testing...

[sansnombre]

@norcal616
I actually purchased a second airbox for this analysis. I get to still ride and have this box sitting next to me on the floor, so I can take measurements and what-not. Thanks for the offer, though.
 
I'm not sure if you can see it in these pictures, but the exhaust runners come up to and terminate near the very center of the filter element. So half of the element is *behind* the intake of the exhaust ports. So the flow has to route back and around to get out.
 
Also, notice the vortices on picture number 2, in the blue sections. This is because we're shooting all of our flow out the bottom portion of the filter and it's hitting walls and spinning around. I think there will be a big change with the interior of the snorkel removed. Looking forward to that analysis as that's what I originally did to my bike, until I dropped the MWR set in.
 
If I'm not mistaken, Hord removed the filtering element and snorkel completely and left everything else as stock to get that run you see above. Basically a big square hole in the top - not too efficient, but look at the change. Huge! That kind of torque increase at 5k is something you'll notice for sure. His comments were that he believed that the filter was blocking the intakes of the exhaust ports, and clearly they are. We can't really do anything about that and still use the standard filter location . . . unless we pull back the intakes of the exhaust ports 2" or so. I think there might be some magic there - in addition to opening up the intakes (not being so close to the filter and walls) it will remove some of the twists in the right-hand side tract. It's very twisty. So if we reduce them, they don't have to be pushed to the side to avoid the filter and can be straight.
 
3D printed liquid silicone is quite expensive, and it wouldn't make sense to have an injection mold created, so what I'll probably have to do is cut these down and then just do a 3D print of a nicely-shaped intake flair and glue them on. At least that's what I'm thinking now. With being able to design it and print it at home, I should be able to get one that fits well.
 
All talk at the moment, going to take weeks to find the time to do this, but I appreciate your interest.
 
Until then, I have a new MWR filter and cover to try out . . .
 
 

[stickshift]

Very interesting.
 
I too saw Hord's chart and wondered what could be done to improve the standard airbox and filter arrangement.
 
I'll be keenly watching this!

[sansnombre]

Bump - new information added . . .

[peteinpa]

Next take off the top leaving just the filter.

[Mr.Puss]

  [attachment id=2474" thumbnail="1]
 

[sansnombre]

Bump - new information posted: removal of full snorkel assembly (inside and out) and same with filter removed as well.

[peteinpa]

Just to clarify, on the last setup you removed the whole rubber part and the plastic part? That's how I'm running now with the stock air filter and flash.

[sansnombre]

Yes. If you look carefully you can see the hints of the parts inside the unit. On the one before the last, you can see the filter in there. On the very last one, just the cover is installed - the external snorkel and the internal oval "tubing" has been removed.
 
From what I've seen this far, that's what you should be running. It makes the biggest difference in my analysis and also matches what I've been told by 2WDW.
 
The only thing that will change this is an external filter solution that opens up the flow corridors in front of the intakes to the exhaust ducts. I'm working on a hard solution now, and I think it's quite doable.
 
Should have something to show in two weeks or so, and it should yield a solution very similar to what Hords dyno curve above shows. Wheelie central I'm thinking . . .

[rhb]

You did it, a lot of work to satisfy your curiosity, but interesting to see the graphics, what we do for academic knowledge.
 
I would only mention for those trying to see big differences from one scenario to another, that probably between an MRW filter, DNA filter with or without cover (should we see those data someday), that the overall measurable performance differences are within a fraction of a percentage point. not much.(only my guess based on velocity stack design differences) And as Sansnombre mentioned this is only benchmarking differences in scenarios, not indicating performance values of the system, a way of comparing away from the real world, only dyno tuning yields measurable system performance, and even then, on any given day so many variables come into play, its hard to pinpoint what is contributing to what. the dyno tuners experience over thousands of dyno runs is probably more important.
but none the less nice work so we can visualize what goes on in our airboxes.

[sansnombre]

I haven't posted actual numbers yet (I'm measuring flow rate on all scenarios for comparison) but you're right - most of them are very, very close and the differences are negligible. There are two major differences though - removing the entire airbox lid/snorkel/filter (best flow) and the removal of the entire snorkel (inside and out), which yields the second best setup. Both of those had large step changes in perf from the bulk of the scenarios thus far.
 
There are quite a few conclusions to be drawn from all of this, but I'm waiting until all the scenarios are completed before posting them as well as the actual data.
 
As @rhb points out, it's important to understand that the state of the intake flow (similar to overall engine performance) is a long chain of serial orifices and obstacles. If we focus on one of those links in the chain and optimize it, great, we can reduce *that sections* perf hit by ~25% and that's a big deal . . . in *that section* of the chain. OVERALL we've still barely done anything to increase performance. The tuners (those with lots of dyno time with this bike and all the variations) almost all point to the fact that there really is no measurable difference between the filters, filter covers, radiused vs sharp edge, etc. There is one exception I know about and that has to do with an interesting phenomena with one header in particular, but other than that, these changes are generally idealized increases, but not really impacting. For instance, there's no question that one gets better flow particulars with a radiused edge vs. a sharp edge, but the impact on perf is not going to be seen. It's change is equivalent to noise in the system - temp of the oil, ambient temps, gas quality, temp of the engine, etc.
 
Again, some major exceptions, and that's what this is about: what matters, what doesn't. Within the next several weeks I hope to be able to finalize and post those results.
 
Thanks for the input.

[hordboy]

This is interesting stuff, but static flow models are only one small part of the equation as I'm sure you know. The tuning of the intact tract has a far bigger impact. Runner length, volume, etc. The test I did removing the filter and snorkel assembly completely, proved the stock runner length is ok for midrange, but the volume of the airbox is too small, and the runners are badly shrouded by the filter. I think the solution there is a flat panel filter over the airbox opening, or an "upside down" filter on the outside of the box. Room is limited for that.
 
I did experiment shortening the intake runners and installing proper velocity stacks inside the stock airbox. It gave a decent gain and perhaps warrants further exploration. I did a LOT of testing of various things. OEM style replacement filters just aren't going to give a big gain. This is why my airbox design came into being.

[sansnombre]

Interesting you should comment on the flat panel filter on the outside . . . one is in transit now for fitment and experiment. Actually, two - one is a beveled one that's a little small, but should be an easy fit. The flat panel one is going to take an adapter but will likely work pretty well.
 
Thanks for the info on the work you've done - your dyno chart with that big midrange gain was the impetus for this analysis and got me pointed in the right direction.
 
For what it's worth, the work here is validating your analysis that the filter location is badly blocking the intakes for the exhaust tracts.

[5tonfan]

I need more popcorn and math. Excellent work can't wait to see the flow with altering the runners.

[sansnombre]

Bump - posted another section. This one with reduced exhaust tract lengths.

[sansnombre]

Bump - MWR tested . . .

[Guest 2wheeler]

I pulled my FZ apart and watched the intake as I rev'd pretty aggressively, and you can see a significant vibration settle into this filter at certain engine speeds. It appears transient as you move throughout the rev range, coming and going, but this is not a good thing. It's equivalent to mixing up and churning your flow and has to have a negative effect on the flow when it's vibrating. The interesting thing here is that the vibration magnitude and RPM location is going to be specific to each bike, as it depends upon quite a number of moving and dynamic factors in your engine and exhaust, so it's possible that some bikes won't see this issue and others might. Vibration is complex and there is enough variance in all these factors specific to each bike to have the vibration occur at frequencies that do not induce the vibration in the filter, or only outside an RPM range that is not used and only theoretical. This would explain the differences between the two tuners. Hard to say, but my work shows that it SHOULD increase the flow and therefore power, at least by a little.

I am assuming that you are seeing this vibration with the combo of the MWR filter and MWR lid. For those of us using just the MWR filter and the stock lid with the snorkel completely removed, I wonder whether the vibration would come into play with that combo. Then obviously you would not have the degree of air flow that you would have with the MWR lid which may help the vibration but not provide enough air flow to make a difference performance wise. Plus as you said, there are other variables that may be affecting the vibration too. 
Any thoughts on this?
 

[rhb]

Believe the tuner who says intake mods are not the place to look for great HP increases, especially between 2 different "high flow" brands, lid or no lid.
These difference while they may be visible on today's dyno run(vs, tomorrows or another bike etc), are largely academic.
my opinion.
 

[sansnombre]

For what it's worth, that's what being shown in my research as well - and actually is the point of all this. Sharp edge vs. radiused, K&N vs. DNA, snorkel out vs. in, etc. MOST are not worth our time or $ if we're looking for HP gains, but there are a few that make a difference. I have to say that I'm surprised that the MWR combo is not showing better on the dyno, as it's pretty well wide open and flows very, very well on the simulations . . .
 
I'll conclude this whole thing after two more rounds of changes. At that point, I'll add numbers and observations.
 
@2wheeler: I don't think it's related to the cover being used or the flow characteristics necessarily. It appears to be just standard engine rumble and vibration that is activating the natural freq of the filter at certain frequencies. It comes and goes as you rev, but, again, it's going to be specific to each bike and tolerances in all the things that make your bike rumble and shake and vibrate. I think it would be an easy fix to have a screen "cage" around it (similar to the stock) that keeps it from doing this, but it's very hard to say if this is what is causing this filter to show differently on different dyno runs and bikes.

[sansnombre]

Bump: added intake velocity stack with std and shortened exhaust tracts.

[pineappleunderthesea]

I put in the MWR filter and new lid a couple weeks back, and immediately noticed an increase in vibrations at a certain RPM. You get used to it, but does seem to match up with the simulations. Not sure my butt dyno saw any increase in power, but like many mods on this bike, it's the cumulative effect of many things that end up making a noticeable difference.

[sorkyah]

Bump: added intake velocity stack with std and shortened exhaust tracts.

What pressures/densities are you running the sims at?