Right, I'm on a mission...
American Honda CRX/Civic Forum
1) Of course, they were dead wrong. The "resonator'' that they were all referring to actually directs airflow into a swirl pattern into the intake throat, increasing it's velocity to help atomize the fuel better.
2) My first Civic VX was hit in the corner where the air intake is and the resonator had been broken and removed, the rest of the intake was intact, after owning the car for a few months I chose to buy a used intake so I could get that broken resonator back, engine noise dropped, engine ran smoother, power increased and my MPG improved slightly.
3) The reason is NVH. Noise, Vibration, Harshness. It has little if anything to do with power, since the resonators are usually placed in such a way that they don't restrict airflow at all, only allowing sonic waves a place to reflect into each other, canceling themselves out.
ScoobyTuner.com
1) The intake resonator chamber is located inside the passenger side fender-well. The resonator chamber is basically a muffler designed to reduce the intake noise. However, it also restricts intake airflow. Removing it will allow your turbo to breathe easier and should result in a slight performance gain. A side benefit is that you will be able to hear the turbo spool-up better as well as the stock bypass valve when it goes off.
American Nisaan Sentra Forum
1) I ran a test with some Heat Tape type sensors in the engine bay with and without the resonator fitted. The temperature in the bay was consistently lower when sat idling when the resonator wasn't there. Possibly due to less heat soke through the plastic casing/less plastic casing present to absorb heat from the engine? Without using a dyno I don't want to commen on HP increases, but there's more induction noise now and that itself is great!
Team-Integra.net
1) Taking the resonator off is like taking your exhaust muffler off.... Its job is to keep the sound down by inducing a lower resonance frequency and will slow flow into the intake tube. Aftermarket intakes (Short Ram type and CAI type) ask you to remove it anyway. You'll get some increase in power with the stock paper filter intake but it ain't anything to write home about. Please don't ask about removing the lid on the box and getting an increase on the dyno...it's a false increase. Keep the lid on, take the resonator off, swap to a K&N filter if you don't want to spend a lot of money on an intake.
Conclusion!?!
These were the most relevant bits of info I could find on forums... Obvisouly the one from ScoobyTuner is a little irrelevant because that's FI and not NA, but it still made for interesting reading. It seems to be quite a popular thing to do in the Honda/Nissan circles in the States and Australia and although nobody on those forums had any solid dyno' tests to back up what they've said, the common consensus is that removing the resonator increases induction noise and slightly aids throttle response. Although, the increase in throttle response could be a placebo effect from hearing more noise.
The only exception was that CRX/Civic quote where somebody seems to have done some investigation themselves and reports that they think the resonator helps to add turbulence to the stream of air to the airbox, which is a good think in an NA engine as it helps the air/fuel to mix better. I'd read something similar about turbulence in inlets/plenums myself a few years ago on a Wiki' style website about Ford/Yamaha NA engines so I'm inclined to think that there could be some truth in that.
I'll keep reading...
