The video stated a difference in single vs multi hole injectors with motor cycles. I did similar testing some years back on my 20k mile, 04 TJ on the dyno at my work. The TJ comes with a single hole injector and I swapped over to a 5 hole. The WOT power wasn't much different but what I was looking for was low end torque curve.
The single hole had a rough idle and a slight hesitation when you gave it slow throttle from 0% to 25%. The other issue was emissions. The amount of waisted fuel was horrifying. You could see that in the oil report from Blackstone. The injectors destroyed the oil. Comparing in the injector tester showed the single hole was more of a squirt gun and the 5 hole a fine mist.
End result was, oil cleaned up, idle smoothed out, torque curve wasn't as jumpy in the lower half, emissions were better and surprisingly I actually picked up a little over 1 mpg.
Even though I haven't tried an injector with even more holes on my Cruiser, his dyno results are what I expected. As the guy in the video stated, the fuel hits the intake valve and negates any real difference between 4 and 12 hole injectors. If we had direct injection, the results may have been different.
The K&N test was interesting. I'm at a trade tech and some of lab work the students do is, bolt on a "cold air" intake and cat back exhaust, then compare dyno results vs stock. The factory intake can have small chambers on the sides. This is to smooth out the turbulence caused by the intake valves. At a certain RPM this turbulence can resonate (vibrate) so hard it slows the airflow. These baffles act like accumulators (mufflers) and keep the air stream smooth.
Science aside. What this meant was, with the "cold air" intake installed, somewhere in the torque curve the vibrations got so bad, the torque flattened out and sometimes actually went down. Then as the rpm went past the flat spot, the torque shot up. This gives you that seat of the pants hard acceleration mid way in the power band. But you didn't make more torque and most lost around 7 hp. The stock intake was a smooth even torque curve.
My guess on the K&N test would be, the intake is tuned to flow at a certain rate and the K&N increases it enough to allow the turbulence. Not too much to notice but, enough to show on a dyno.
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