Yep, so after reading a bit here, and on VFRD, I find it's interesting that a couple VFR folks, Mohawk & Highside get decent gains in a slight air box velocity stack filter mod, so much so I figured what the hay.. might as well try it. But first, I needed an air box to mess with. Luck had it I found one on good ole ebay for 10 pesos. Now time to play with how it should be.
The short of it is lengthening the Velocity stacks making them into a dual pull sort of thing, that in turn makes them taller, now one now needs to rework the top of the air box for a new air filter placement The read I read has it giving 5hp in the upper mid range while not hurting the lower mid-range.
I have had good luck with R6 velocity stacks. Noticeable bump up top, not really any noticeable loss in low end.
IF there is no loss at lower RPM's this would be great. But I have almost always seen a loss in low rpm's and gains in higher rpm peak HP and torque. Any dyno numbers from changing out stacks?
I'm sure a dyno sheet would have to show something, but I didn't pick up much loss of low end on the butt dyno. Between the Two Brother's header, over bore throttle bodies and R6 velocity stacks, you would think that I would have a bike that was dead on the low end, but I got it all back plus more from more aggressive ignition mapping. I would say my bike is a little soft from idle to 2500, but at 2500 the ignition starts ramping up and it pulls lit a freight train. I don't really see any reason to be in the 1000-2500 range, so I would gladly take a hit there, for more mid and top end.
So, could a RapidBike be used to alter timing to take advantage of the velocity airflow, or does it really make much difference, unless you have the mods you have? Because it seems you could be limited on port size, intake and exhaust and header design. I know on the Delkevic header I have, it appears that the collector is kind of a box. It's weird.
I am running the standard Rapid bike ignition map and a custom street tuned fuel map. I suppose I could spend some dyno time optimizing the ignition mapping for my setup, but it is really nice as is. I had a Motad header and I can tell you that it didn't do much for me. Sent from my Nexus 6 using Tapatalk
While I'm tinkering, I do know I need a header that will support this mod. Both High and Mo have put in the time working out the kinks. IIRC even Mo had a few dyno pulls checking this and that playing with gap spacing. we'll see if he catches this thread, maybe he'll speak up.
I would bet on the low end the rpm the bike would not be happy any more-you want to go faster just use more rpm. A r6 is not a vfr-much lower rpm's. It might work, but the air box mod taken off the snockel plastic piece=looks like a fail to me as well as the aftermarket air filter too-then tune for the change.
air box mods aren't gonna do ya good if you haven't cleaned the chipmunk poops off your valve seats. your bike's probably down 15 hp.
