despicabledan Posted August 24, 2018 Share Posted August 24, 2018 So in the past week I installed a BMC filter. I had 25$ in revzilla cash so the filter ended up costing me like 40$, and I hadn't even cracked the air box on my bike yet, but I went ahead and assumed it needed a filter. Upon opening the box there was a K&N filter installed, and it had collected a lot of leaves and dust, so my assumption panned out. Putting the filters side by side, the BMC definitely looks like it is capable of flowing more air, however that's not to say the K&N cant flow more than the motor can intake. After buying my bike and checking it out somewhat I saw that the PAIR and Flapper mod had already been done. Initially I sort of drank the cool-aid and just believed it was better off. I dug a little deeper, and reflecting on some interesting dyno results for various engines, I decided I would hook the flapper back up, because I know sometimes air flowing less freely will generate more torque. IDK if anyone here ever watched roadkill, but Mike Finnegan recently dyno'd his blasphemy car without an air filter and then with, and he actually generated 20ftlbs more torque with a quality air filter. Anyway I hooked the flapper back up, and after driving it around some, and reviewing my auto-tune trims, the bike feels much better at low RPM. When putting around town at 45-50mph previously, I would typically be in 4th/5th gear because at the 3000rpm rev range in 6th, it just had nothing. I would almost describe it as a buck and sputter. After hooking up the flapper, I can easily put it in 6th at those speeds, and don't have to worry about hills or inclines, it just trucks right along. Don't get me wrong, it didn't turn it into a diesel, but its definitely way smoother at low rpm. Anyway Just thought I'd share my experiences going in the a-typical direction with the flapper mod. throttle bodies looked pretty clean when I had the box apart. Cheers Link to comment Share on other sites More sharing options...
Member Contributer VARIABLE9 Posted August 24, 2018 Member Contributer Share Posted August 24, 2018 Could your improvement be from the new filter, versus reattaching the flapper? Or a sum total combination of the two? Versus only because you reattached the flapper. Good for you for doing some basic maintenance! Most modern vehicles are poorly fuelled or choked by emissions equipment from new. I personally don’t see changing mechanical controls like the flapper/PAIR/snorkel adding anything other than placebo hp. It’s the cams, pistons, valves, crankshaft and pistons and conn rods, then the fueling map and intake/exhaust that would result in the biggest efficiency increases IMO. Sure might any of those (flapper/PAIR/snorkel) add a hp or two? Maybe. Just like how a slip on can add 3-5hp over a stock exhaust canister. But in the big picture it’s not significant enough to justify for me, the physical work to make the ‘mods’ and the peace of mind knowing I’m not reengineering something Honda Corp. spent millions developing. Hey it’s JMO! Link to comment Share on other sites More sharing options...
despicabledan Posted August 24, 2018 Author Share Posted August 24, 2018 Well my thought process is, the BMC filter probably could have only improved he airflow, where the flapper can restrict it. Because of the order of operations as far as the air travel, I suspect the flapper has more to do with it than the increased filter flow. The flapper will physically reduce the inlet size, regardless of how well it flows through the filter behind it. Link to comment Share on other sites More sharing options...
Member Contributer VARIABLE9 Posted August 24, 2018 Member Contributer Share Posted August 24, 2018 Hey I’m right there with you. Just posing some counter arguments to ensure everything is considered. Link to comment Share on other sites More sharing options...
GreginDenver Posted August 24, 2018 Share Posted August 24, 2018 Maybe you shouldn't use words like "restrict" and "reduce" when talking about this situation. Doing this misdirects/confuses thinking on the issue (and encourages the "more is always better" crowd to do things like disabling the flapper valve). Most of your thought-process and writing on the issue (in this thread) sounds perfectly logical. Your feelings about the engine's air intake requirements seem right on to me. It's a VTEC engine, right? So, if I understand the 2006 VFR800 correctly, up to a certain RPM the engine is only breathing in through a single intake valve per cylinder. So the flapper stays closed during this phase of operation which probably increases the velocity of the air passing into and through the airbox and onward through the throttle body, and maybe as a result this improves engine response/smoothness/efficiency to throttle changes while at lower RPMs. Most people don't read Chapter 21 of the VFR800 Service Manual, but this is the chapter titled "Technical Features" (at least it's Chapter 21 in the 5th Gen VFR800). In this chapter Honda reveals details about the PGM-FI system's operating principles. If you read this chapter carefully you'll learn that the VFR800's PGM-FI system uses 2 completely different fueling strategies depending on the engine RPMs. At lower RPMs the PGM-FI fuels the engine via a "Speed Density" strategy which uses the intake manifold negative pressure that is provided by the MAP sensor located in the airbox as the controlling input. At higher RPMs the PGM-FI fuels the engine via "Alpha-N" which uses the Throttle Position Sensor located on the throttle body assembly as the controlling input. So the flapper valve stays closed during the phase of engine operation that the PGM-FI is using the MAP sensor as the controlling item in the fueling strategy. Makes sense to me. When the flapper valve is closed the airbox probably produces a much better (i.e. more accurate and more responsive) intake air pressure signal. Link to comment Share on other sites More sharing options...
Urbanengineer Posted August 24, 2018 Share Posted August 24, 2018 Myself, I have low rpm issues And my flapper doesn’t work for reasons I can’t comprehend. Wish I had the option to disable it like you guys. Link to comment Share on other sites More sharing options...
Member Contributer Grum Posted August 24, 2018 Member Contributer Share Posted August 24, 2018 Ah Yes. The Flapper Valve, the system that Honda has removed from the 2017 8gen. Same airbox and air filter as a 6gen. Interesting. Link to comment Share on other sites More sharing options...
GreginDenver Posted August 24, 2018 Share Posted August 24, 2018 27 minutes ago, Grum said: Ah Yes. The Flapper Valve, the system that Honda has removed from the 2017 8gen. Same airbox and air filter as a 6gen. Interesting. My guess would be that Honda has upgraded the technology and abilities of the ECU making the PGM-FI much more capable and responsive. Possibly the development efforts that went into creating the Fuel Injection system for the VFR1200 (and possibly other motorcycles in the Honda stable) may have been applied to the 2017 VFR. This may have rendered the flapper valve's effect unnecessary. However, the fact (possibility?) that the 2017 VFR800 has undergone further development to the point it doesn't need a flapper valve in the airbox doesn't retroactively nullify the flapper valve's positive effect on the lower RPM operating characteristics of earlier VFR800's. It would be rather anti-evolutionary, flat-earth thinking to suggest this as a reason to say the older generations of the VFR800 didn't need it. Link to comment Share on other sites More sharing options...
Member Contributer VARIABLE9 Posted August 24, 2018 Member Contributer Share Posted August 24, 2018 Thanks for the technical overview @GreginDenver. Link to comment Share on other sites More sharing options...
Member Contributer Grum Posted August 24, 2018 Member Contributer Share Posted August 24, 2018 1 hour ago, GreginDenver said: My guess would be that Honda has upgraded the technology and abilities of the ECU making the PGM-FI much more capable and responsive. Possibly the development efforts that went into creating the Fuel Injection system for the VFR1200 (and possibly other motorcycles in the Honda stable) may have been applied to the 2017 VFR. This may have rendered the flapper valve's effect unnecessary. However, the fact (possibility?) that the 2017 VFR800 has undergone further development to the point it doesn't need a flapper valve in the airbox doesn't retroactively nullify the flapper valve's positive effect on the lower RPM operating characteristics of earlier VFR800's. It would be rather anti-evolutionary, flat-earth thinking to suggest this as a reason to say the older generations of the VFR800 didn't need it. Agree with your thinking Greg. I simply wanted to remove a lot of clutter under the tank on my 8gen. (see the topic in the 8gen forum). So I removed the whole system. My bike performance is unchanged in all aspects from a subjective rider point of view, fuel economy is also excellent. I'm still of the firm belief that running a clean air filter will far outweigh any potential benefit the Variable Air Intake could offer. YMMV. Interesting thing my 3 6gen's all had the Flapper operational till the day I sold them! No issues there either. Cheers Link to comment Share on other sites More sharing options...
despicabledan Posted August 25, 2018 Author Share Posted August 25, 2018 10 hours ago, GreginDenver said: Maybe you shouldn't use words like "restrict" and "reduce" when talking about this situation. Doing this misdirects/confuses thinking on the issue (and encourages the "more is always better" crowd to do things like disabling the flapper valve). Just sharing my personal experiences, to each their own. The fact that mine also has auto tune running in the mix has potential to change things as well. Link to comment Share on other sites More sharing options...
despicabledan Posted August 29, 2018 Author Share Posted August 29, 2018 On 8/24/2018 at 4:14 PM, Urbanengineer said: Myself, I have low rpm issues And my flapper doesn’t work for reasons I can’t comprehend. Wish I had the option to disable it like you guys. So I accepted my autotune edits today and figured while I was looking at the bike why not check the flapper. Turns out mines not operating either, stays open all the time 😂 Pulled off the fairings, now to begin the shake down. Link to comment Share on other sites More sharing options...
Member Contributer Grum Posted August 29, 2018 Member Contributer Share Posted August 29, 2018 4 hours ago, despicabledan said: So I accepted my autotune edits today and figured while I was looking at the bike why not check the flapper. Turns out mines not operating either, stays open all the time 😂 Pulled off the fairings, now to begin the shake down. Just like Urban, my 6gen Variable Intake System did not test as per the service manual. Just unplug the connector to the Control Valve, then rig up a tempory 12v to the valve. With the tank up in maintenance position start the engine and each time you apply 12v to the valve you should see the Flapper close. If that's ok, then check you have a permanent 12v available with Ignition to On, on one of the pins of the loom connector (relative to Ground) the other pin is the switched Ground from the ECM to enable the valve. Most likely you are just not meeting the ECM criteria to drive the valve. I think I'm repeating myself! . Good luck with it. Link to comment Share on other sites More sharing options...
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