or throttle body intake speed depending on which bike you have. Interesting to note, sportrider magazine did a study on the ram air effect on bikes. Now, I was chatting with someone else the other day and a shop told him that V-Stax didn't make any difference. My thought was that maybe this guy dyno'd a bike with them on and didn't notice any discernable gains......which is entirely possible......but seeing as how they are designed to work in a pressurized airbox which can't be simulated on a dyno(or the one the guy was using thta made htis claim), I don't know how he can make that claim. anyways, here's the sportrider test on the ram air effect. I will also start this in another thread too......Part 1 of the test. Part 2 is at the bottom of the page.
a quick synopsis based on our bikes.......
YAMAHA YZF-R6: First up was Yamaha's 15,500 rpm YZF-R6. Note that the pressure drops below zero-that is, below ambient pressure-accelerating through second gear, and it finally builds once the bike gets past 85 mph. The spikes (present in all of the graphs) represent pressure buildup during shifts, since the throttle plates are closed momentarily. Pressure peaked at 17mb.
On each of the dyno graphs, the bold lines represent ram-air-assisted readings-solid for horsepower, dotted lines for torque.
YAMAHA YZF-R6: Here is obvious proof that ram air works on smaller-displacement engines. Ram air helps the R6 hold its peak power higher and longer (12,000-14,000 rpm), and the torque curve is higher and flatter as well. This isn't just an incremental increase on top, either. We're talking about an average difference of five horsepower through the midrange and a far more usable power spread. The ram-air assisted reading would probably be higher at 13,000 rpm, but we were unable to generate the required airbox pressure on that particular run at that point. To give a relative reference, without ram air the Yamaha registered -11mb. Again, remember the lower peak-horsepower reading of 84.4 is due to the Eddy Current dyno.