I think I remember seeing a thread on this but here we go =P

Under acceleration (typically heard from 2k RPM - 3k RPM while windows are up and radio off) I hear something that sounds like a light rattle coming from the engine. The harder the acceleration the louder the sound (however the sound never gets too loud). It only happens if I'm in gear and the sound cannot be reproduced if I'm in neutral gassing it.

Is this a normal sound for rotaries?

 

it could be that ur engine isnt tight on the frame and its shaking when u hit the gas get under the hood and move stuff around and see if u can recreate the sound

 

Does that explain why it only happens in gear?

 

search marbles in a can

 

Too vague to help you.

Take it to a local club meet and show them.

It could be the metal heat shield over the CAT to something inside your car cubby hole.

 

Thanks for the replies!

Some info on my 8: 2006 MT with 36K miles. Owned it for about 2 months and the sound has been present ever since. Once again, it's a faint sound and can only be heard with the windows up and radio off. No modifications. The way I replicate this sound is being in 2nd gear with windows up radio off and get to about 2k RPM and go about 75% on throttle. You can distinctly hear it between 2k RPM and 3k RPM.

I took it to the dealer and brought it up and they told me that it was normal for rotaries to make that sound. They took me on a drive on an A/T RX-8 and the sound was reproduced (however the condition of this RX-8 was questionable). I don't want to believe it's normal.. but maybe it is

On this thread the noise is attributed to the intake:
https://www.rx8club.com/showthread.p...t=engine+noise

Here's the Marbles in a Can thread (one of them):
https://www.rx8club.com/showthread.p...highlight=MIAC

However, the sound from my engine doesn't seem to be nearly as violent as this description

This thread seems to match accordingly with the noise I'm experiencing:
https://www.rx8club.com/showthread.p...t=engine+noise

However, the issue was never really solved it seems.

Any other inputs would be greatly appreciated!

 

Its your exhaust ports. Also, when your around 6250 rpms the others will open. If you have loud mods like intake and exhaust it may be hard to hear them but stock you can. Its like a rattling sound or some may call it marbles in a blinder.
-Gil

 

Im pretty sure it's marbles in a can, but my car doesn't have that YET.

 

I'm satisfied with that answer Thanks for your input!

 

Yes even at low rpms you can hear them. Then as you add more gas they then to get louder if you keep the car at a speed like 15 or 25 you can hold it there and it will go away. Kinda odd yeah. Guess its norm due to the RX-7 vs RX-8 exhaust port(s) set up IDK. Sometimes it sounds like its coming from on side or another but if you drive down a street with not as much traffic and stick to the lane by a wall you will hear it. But not as much with the new 8's.

 

Spot on - hopefully anybody else with this concern can reference this thread and be at ease