To Resonate or Not Resonate
 

Hi - I just received my cone filter and adapter and i was wondering what all should be removed and what should be preserved? I have read some difference in opinions whether to leave the resonator on or remove it and was wondering if I could get some feedback on that. :D

I could be wrong, but I think he's referring to the Heimholtz resonator upstream from the VAF.

If that's the case, you're probably better off leaving it in, unless you are a drag racer (in a DX??? sorry:D). That resonator actually helps torque in the rpm ranges used for everyday driving.

What the hell is Heimotlz Resonator and where is it? :D

Its the black plastic 'box' that is mounted at the OUTLET side of the air meter.....

I've wondered if making/fabbing a bigger box would result in any gains on an engine that has been modded a little (intake, exhaust, etc..) ??

The outlet side being the side closest to the throttle body? It is hard to see how all the stuff is connected...I have no doubt it will be easoer once I get the stock airbox removed.

Yes.

OK, i've been looking at this box and i noticed the hose that connects it to the intake manifold....What does this do? Is this CONNECTION what actually results in the gains at low rpm???

I thought if nothing else i could experiment by taking the hose off and plugging up the holes on the resonator and the intake manifold....

And if i was to try and make a bigger 'box'...what da'ya think? Increase the heighth OR the width OR....both???

As I understand the purpose of the Heimholtz resonator (the square box, approx 6" x 6" x 3") upstream from the VAF, it is to eliminate intake reversion.

What happens is that (especially at WOT) when the intake valves close, a pressure wave is sent back up the intake tract. The intake plenum is designed to take advantage of that to use that pressure wave to fill the next open cylinder. Problem is that sometimes the pressure wave would prefer to leave the plenum and rush back down the intake tract, which among other things would push against the back of the plate in the VAF. The Heimholtz resonator prevents this pressure wave from pushing on the back of the VAF.

This effect is most pronounced at lower rpms (above a certain point, that only a Mazda engineer, or someone with a better understanding of the physics involved and perhaps access to a dyno could pinpoint exactly), and isn't that important at higher rpm.

An intake that someone made (Thread) used a smaller piece of pipe (2.25" dia) inside a 2.5" pipe for this purpose (anti-reversion).

Edit-Since Jesse never read this, I finally came across the name of the person and found it that way.)

hmmmm....
 

so the resonator doesn't necessarily MAKE gains, it just PREVENTS losses....so a bigger box may not do anything.
wonder if the box on both the SOHC and DOHC are the same size???

here's an article on the 200SX that got me making me thinking about all this:

www.se-r.net/about/200sx/scc/april98/april.html

a different engine, but they discuss some interesting stuff. look at the CAI part especially - they talk some about 'resonance' and its effect....