Intake tube resonator.
 

The stock intake tube leading to the throttle body has a resonator chamber. Basically a hole routed to a square box. Now I am not sure if it is a pressurized chamber that regulates airflow, or just for sound deadening. I was looking on japanparts and noticed this overpriced cap. The brand is Revolution, which is a Japanese builder of plenty quick track RX-8's, RX-7's, and NSX's if that says anything.

http://www.japanparts.com/db/parts_d...&SEARCH_page=2


Has anyone removed the resonator and had ill effects?

We had a discussion about this a wihle back on one thread. Basically if you consider that the resonance chamber does nothing but add slightly more volume to the intake, there really is nothing to be gained from its removal except for more noise.

Here is the actual site for the product:
http://revo-tune.jp/catalogue/detail.php?id=255

Mines been capped off for 3 months on and off lol. No ill effects. Just need something better to cap it with.

an aluminum plug makes a great heat sink for hot engine bay air .... I cut the box off, taped off the inside end of the remaining tube portion, and filled it with urethane (remove the tape after it hardens)

^Good idea!

Thanks. Would you have the link to the thread by any chance? Having a hard time finding anything related to the resonator itself via search.

from the Mazda service literature:

https://www.rx8club.com/attachment.p...1&d=1338783218

I suppose that works too :rofl:

cut to the chase, that thread probably makes as much sense as a cage full of squawking parakeets

Lol not to mention i think it was just some half assed banter in the B@W thread.

Did a little more research on the resonator. I'll just leave this here.


http://www.brighthub.com/engineering...les/84316.aspx


And for us engineers out there that have taken high level physics and fluid/thermodynamics:


http://www.dinamoto.it/dinamoto/8_on...suonatore.html

that piece is known to be a resonator. well team already post the page out.

if u want it to look "pretty", Odula Japan sells a piece to replace the stock tube + box thing. I saw it before when I was in Hong Kong and it looks pretty nice.

if u want nothing fancy, just do whatever u want or just do what team suggested.

Okay, I would hit up the local hardware stores first. Ideally, the cap would be:

-round and smooth sealing surface for the clamp
-proper size
-minimal to no internal volume
-long enough to get clamped down

I surmise that any amount of volume added at that specific area, would decrease the sound output. Maybe I am wrong though.

I would go to Dixieland or a plumbing store first, as their PVC selection is better:

http://www.underway.us/rx8/resonance/dixie1.jpg

-Home Depot option-

If all you have is Home Depot, you might have to settle for a 3/4'' elbow with threaded cap. Their cap would work if you inverted it and inserted, but as you can see it was ridged and might not have provided the best seal:

http://www.underway.us/rx8/resonance/hd2.jpg

http://www.underway.us/rx8/resonance/hd3.jpg

The best I could find at Home Depot was the 3/4'' elbow, despite having a somewhat large internal volume:

http://www.underway.us/rx8/resonance/hd1.jpg


http://www.underway.us/rx8/resonance/hd4.jpg

Note the angle of the dangle to mate with the curved rubber inlet:

http://www.underway.us/rx8/resonance/hd5.jpg

Make sure to get the cap that is solid, not open at the end:

http://www.underway.us/rx8/resonance/hd6.jpg

Rigged up:

http://www.underway.us/rx8/resonance/hd7.jpg


-Dixieland/Other option-

Various assortment of caps versus Home Depot rig. Some caps were a bit too short, some had a ridge in the sealing surface to contend with:

http://www.underway.us/rx8/resonance/dixiehd.jpg

Obviously, the best option was the Lasco 1'' cap. It had a stop to prevent it from going inside the intake, had a perfectly round sealing surface with no bumps, and was long enough to get clamped:

http://www.underway.us/rx8/resonance/dixie2.jpg

It did have a small bit of internal volume though as it was hollow:

http://www.underway.us/rx8/resonance/dixie0.jpg

Close size match:

http://www.underway.us/rx8/resonance/dixie3.jpg

Installed:

http://www.underway.us/rx8/resonance/dixie4.jpg

http://www.underway.us/rx8/resonance/dixie5.jpg

Internal view:

http://www.underway.us/rx8/resonance/dixie6.jpg

Comparisions with VFAD cap mod:

I think capping the VFAD helped to improve noise under heavy throttle. However, I believe the resonance chamber cap helped to improve noise under light throttle as well. As they are both cheap and easy to do, I would perform both for optimal sound increase and best rotary signature rrrrrrrrrrrrsss. Recently I have been obsessed with making the rx8 louder, these intake mods proved vital in addition to the muffler delete.

-metal cap options-

I tried the 3/4'' copper cap, but it was soo small. And the 1'' copper cap was too large. No go.

-filling options-

I considered filling the cap with some type of high temperature substance, but was concerned about heat degradation of the filler over time and possible particulate contamination as it broke down.

-sound quality-

This is subjective and personal preference. Obviously, Mazda decided that the normal intake sound was too awesome for the 4-seater sedan, baby and kid in the backseat customer. I would say it is not too loud, and the sound is not rough to the ears at all. It would be a good stock sound, if this was marketed at the 2-seater coupe market.

I didn't notice any increase in sound or throttle response when I capped my resonator. After finding out that it is most likely for helmholtz resonating for increased volumetric efficiency (as stated before), I was assured to keep it on.

the only issue with doing it that way is you still have an air flow disturbance cavity

not sure why I didn't think of this previously, but take off the accordion tube, place a piece of duct tape on the inside of the accordion tube over the opening to seal it off smoothly, then position the opening vertically and fill it directly with urethane. Once cured you can remove the duct tape and tighten the clamp down on the outside to keep the urethane plug in place just like the resonator.

it is only for intake noise abatement as stated in the factory literature

Make sure to use something with a lip on the outside or the engine WILL ingest it (suck it in) already happened to people I know in various vehicles.

SM

It won't ingest it with a clamp keeping it in place, sheesh

Im gonna order the part from that site thx guys

Reviving this thread.
I was looking at purchasing this:JDM Japanese Auto Parts specialists | japanparts.com

but I wanted to read about it first so I wound up at this thread. I read the posted link on volumetric efficiency. Has anyone who has removed the resonator noticed any loss in tq? Can it honestly even be noticeable, seeing as our cars have no tq as is?
Thanks

Edit: going back and reading more thoroughly the engine it's describing is a piston engine. How would the same concept of volumetric efficiency be applied to our rotaries?

I bought one.

swapping it on/off back & forth multiple times with WOT logs and some statistical analysis is a fairly straightforward procedure ...

How do I even take the stock one off?

are you serious?

try opening the hood and looking at it, lol

Is it just the clamp? lol