User24

iTrader: (1)

Notes:

The stock cat and its built-in resonator is still there. I prefer straight pipes after the cat, as mufflers inevitably thicken an engine's natural exhaust note and ends up masking the highlights in the tone.

Small 4 banger engines are especially cheap sounding when equipped with a very deep exhaust note. There is not enough complexity in those engines' sound to balance out the deeper tones, leading to a one note fart.

The rx8 without mufflers, is basically the same sound we are familiar with, just a bit louder and with more rotary-ness at the upper rpm.

Recording:

Driver's window down or cracked open. Full-bandwidth microphones recording 24-bit/96khz .wav to sd card.



5 comparison files, such as idle, interior idle, v8 straight pipe comparison, freeway driving with overpass reflections, and a stoplight scenario with oncoming ambulance and easy acceleration.

3 file types available. Hi-rez flac (for audiophiles), standard flac (for compatability), or standard compressed m4a (for itunes/apple/devices):

24-bit/96khz flac

standard flac

standard m4a

monchie

Interesting research you did. Thanks for sharing your info.

User24

iTrader: (1)

Listening to the files, I think overall it is pretty tame. I had been led to believe this would be unbearable, clearly it is not the case at all. At idle it is almost stock, due to the smooth motion of the rotary engine. I have heard some pretty intense sounding rx8 on the internet videos, but not sure how they get that awesome sounding. Maybe bridgeported, hiflow cats, etc.

The harmonic spectrum of the idle, it does not extend very low:



This is basically how the pipes look like, the shop used 2.25 inches all the way. I opted for 3.5 inch tips though.

xexok

The reason you had been lead to believe it would be really loud is that generally when someone says "straight pipe" they mean header back with no cat. I would still like to hear this in person but I think that my car with the ap midpipe and stock exhaust is louder than this. It is just hard to tell because the sound files are kind of soft sounding

User24

iTrader: (1)

That makes sense then.

Standing a few feet behind the idling vehicle, measurements are around 83db(a) at ear height.

Inside the vehicle with windows up, crusing in 6th gear is a solid 95db(a) most of the time. There are a few quieter zones in the rpm range at 91-93db(a).

On acceleration, interior peak noise levels can reach 100db(a).

xexok

I wish i had all the fancy stuff you have to record and measure the sound levels so I could compare my exhaust.

DarkBrew

+1

User24

iTrader: (1)

I will have to get one of those gopro cameras, then just record the sound separately, and sync the a/v into one video file.

The next step is to remove the resonator that is on the back-end of the cat. Maybe some more edge to the sound, maybe a tiny bit louder?

8 Maniac

iTrader: (1)

I'm sure it would be possible for a couple of people to meet up to take similar measurements/recordings. That would definitely be fun to see and would possibly give us more of a point of reference, other than stock.

I'm at work, unfortunately, so I'll have to listen to the files later. At there very least, it seems interesting from the way you described it!

ShawnMua

Do you still get that 'F1' sound on 5k+?

It sounds just like disconnecting the muffler

User24

iTrader: (1)

Yeah, the sound continues to get louder toward redline 7000 plus. Some of that effect comes from the intake noise. If you have a stock intake like me, I would do the vfad cap and resonance chamber pvc mod if you havent already. Really helps with the off-throttle wind-down noise too.

I wish I could do more with regard to the cat, but I have to follow emissions laws on this street driven vehicle.

The gopro arrived yesterday, should have something this weekend to post.

User24

iTrader: (1)

The resonator is off.

First, I have to clarify some misconceptions. I have read that the resonator does not make that much of a difference. Maybe that is the case if one has mufflers. Without mufflers, I can tell you that the resonator delete is a big difference. And I have the recordings to prove such is the case.

Minus resonator, the idle note is noticeably improved with an irregular beat. Also, now during acceleration above a certain rpm, the signature changes to more of a race-tone. The so called "carbon clear-out" procedure must be carefully timed, due to the pure intensity.

Compared to the 7 liter v8 with no mufflers, the rx8 with no resonator/no mufflers is about as loud at high rpm, but quieter during idle and low rpm.

Quite happy with the result. I'm working on the idle video now so you can hear for yourself. My guess is, most people would be happy to keep the resonator intact. Removing it does drown out some of that special intake noise. A bit of compromise either way to get a louder sound.

User24

iTrader: (1)

Enjoy, video uploaded to youtube:

RX8 youtube

Also, if you want to have a version to download to your computer/ipad/whatever, here is a link to a 68MB file:

Download 1080p mp4 .zip file

ShawnMua

Good stuff man! Tnx ill check the file in a bit (maybe do a ringtone lol)

Edit: is it ear raping? Loving the distinct idle

Edit2: maybe its extra loud because its on garage and not outside?

User24

iTrader: (1)

Ear raping at WOT. It is subjectively 2 or 3 times louder, compared to leaving the resonator on. There are of course, various throttle and rpm ranges where it is almost silent. At least now I don't have to flog it to get decent volume.

The reasonator seems to be a main reason why all the aftermarket exhausts sound so similar. It cost $45 to have that resonator removed though. Not for everyone, just throwing it out there.