Just thought I would share this with you guys.

I was looking for a way to make the intake “little” louder. I started with the stock system and thought I would try removing the resonator and give that a whirl. Result: TOO LOUD! Anytime I cracked the throttle I knew I was drawing all kinds of attention. The sound was also way to deep for me. The floorboards would rattle!

So what next? I decided to take a look at the stock resonator and see if there was anything that could be done with it. Ah ha! I noticed that the stock bock uses a 2-chamber system joined by a port. Knowing what I know about acoustics I decided to block the port that joined the two chambers turning what was a third order filter into a first order filter. To those that don’t understand what that means, first order filters allow more sound through them then third order filters.

The result was very pleasing! The car has an incredible tone to it that is very addictive without being annoying. Much quieter then AEM equipped cars that I have heard but loud enough to make you grin. I can’t imagine that there have been any gains or losses in the engine side of the equation, but it does feel quicker. But that is probably just me squeezing the throttle harder trying to squeeze out more music.

Here is what to do:
- Removed the resonator via the tire well (Simply remove the plastic inner fender and you’re there).
- Remove the port that is mounted to the resonator (the one on the top)
- Cut a piece of 1/8” plywood (thick plastic would work) to fit over the port (2-1/2” x 3” is what I remember)
- Epoxy the plywood over the port and let dry
- Put the hole thing back together including the port you removed.
- Listen to the music…

Enjoy!

 

ttt

 

You mean you sealed the inlet to the silencer box?
So basically you chose to have some sound in exchange for losing a lot
of flow to the intake.

 

That's even too Ghetto for me

 

Now put the top back on and let her rip

 

No thatˇ¦s not what I did. Let me see if I can explain how the stock resonator works.

First, the pipe that comes from the filter box enters the side of the resonator. It passes through the secondary chamber and enters the primary chamber where it turns up. Note there is no air exchange between the pipe and the secondary chamber. It simply passes through it.

Second, the pipe then stops inside the primary chamber. There is about a 1" gap between this pipe and the pipe that is mounted to the top of the resonator, which is where the air comes from. It is actually fairly straight through between the two pipes. But the gap is what allows the resonator to do its job.

Now the resonator is configured as two separate chambers (primary and secondary) and they are joined by a short section of pipe. In acoustic terms this creates a 3rd order filter which reduces the amount of sound that is carried through the resonator. Note that no real airflow actually travels through the resonator (only sound waves do), the only part of the resonator that is actually exposed is this 1" gap between the 2 pipes (which sit right on top of each other).

What I did was seal off the port that joined the 2 chambers. This turned the system into a 1st order damper which would allow more sound to come through while still offering some sound reduction.

The primary air path is not affected at all by this change. I am not saying that I haven't changed the tuning of the intake system but my but dyno tells me that the car liked it!

And yes this is very GHETTO RACING!

Regards,

 

I think i see what you are saying.

In effect you extended the inlet pipe into the second chamber is that right?

 

Asci picture didn't work I'll send you a .jpg of what I'm talking about! If you can post it here that would be great as I don't have anywhere to host it right now.

Regards,




[Modified by BABY NSX, 10:53 AM 10/16/2001]

 

No, he just closed the second chamber from the first one. So the second chamber is doing nothing..
I still prefer a zero order system.....

 

He sent me this pic:



I see what he is saying now, but I would have done what i said in my
previous post instead.

 

Correct! but in actual fact even an AEM is a first order system. The length of pipe coming off the throttle body acts as a sonic filter. I didn't want to mention this fact before because it would only confuse things.

So to be more acurate the stock system is 4th order, I modified it to be 2nd order and the AEM is 1st order.

Regards,

 

Thanks!

 

What is 3rd order filter then. I have short ram open filter. Is this a zero order system? I like the sissss sound at low rpm..... And of course the BWAMMMMMMM sound at VTEC..

 

Good question!

A 3rd order system would exist if the length of pipe coming off the resonator was long enough to effect the tuning frequency of the system.

Let me explain:

The fact is that the intake system could be modeled as a nth order system but that would not be reasonable. With the stock system discussing any of the effects beyond the 4th order does not factor heavily in the result, so they are ignored. Now if, like I said, increased the length of pipe coming out of the resonator the system would start to behave like a 5th (3rd with my setup) order system.

Hope this helps.

Oh yeah, in case you guys are wondering, I am a product designer in the audio industry so this stuff is right up my alley.

Regards,

 

So the sound is defintely noticeable huh? I really want to get rid of my AEM. Too obnoxious. But I do like the performance of the AEM.

 

It was much quieter with this setup when compared to no resonator at all (i.e. just sucking air from the bottom of the filter box). Since the AEM and "no resonator" setup are similar I would expect the sound to be close.

It is definitely louder then stock, but no so much so that it is annoying. It just gives the car a little more bark when you're on it!

Since it is simple to block off the second chamber and easy to remove this restriction if you don't like it I'd say give it a try if you're going to be swapping the stock box back in there. You don't have anything to loose!

Regards,

 

I took my dremel and cut off the second chamber completely! Ghetto comptech!