Muffler Position

[Leve]

Hi guys
We have a cbr600rr engine and i'm thinking of using a yoshimura rs 3 muffler. What muffler do you use? has anyone tried rs3?
In which position do you believe muffler should be in order to pass easier the noise test? (for example behind tyre)

[Leve]

Hi guys
We have a cbr600rr engine and i'm thinking of using a yoshimura rs 3 muffler. What muffler do you use? has anyone tried rs3?
In which position do you believe muffler should be in order to pass easier the noise test? (for example behind tyre)

[rmk36]

Noise is measured relative to the exhaust outlet, not relative to the car.

[AxelRipper]

really doesn't matter where you put it as long as it is in someplace that does not resonate under your aero/bodywork and its generally not a good idea to point the tip at the ground because the sound reflects in a not beneficial way

[vikram.]

we fabricate

[mech5496]

As AxelRipper said, do not point it to the ground. We had ours pointing the inner sidewall of the rear tire, but this was also a bad idea, due to excess temperature at that particular tire area. Yoshimura sounds pretty damn expensive...Why not start with a fabricated muffler fron a local exhaust builder, which will cost you a fraction of the Yoshimura, measure the noise level and then make any changes if it is not OK? You could try add some bends, a second muffler, a parallel resonator chamber, the list is almost endless....

[shark.ashwa]

We fabricate our own mufflers. Sometimes more than one, with varying cross-section of perforated tubing for different attenuation levels. Regarding location, we try to keep it as simple as possible, take care of the exhaust lengths, orient it parallel to the chassis and angling upwards. We did have some issues clearing noise this year in the first attempt. Nothing a re-orientation of the exhaust outlet could not fix. We just angled it straight up, clearing noise test!

Regards,
Sharath

[Leve]

Thank you all for your replies!
Harry what is approximately the cost of the fabricated muffler you said? The yoshimura choice is because there is a chance of having the muffler as sponsorhip( it's not sure yet).
Does it worth the money and the time you waste??
Thanks in advance!

[mech5496]

Actually we used an FMF titanium exhaust muffler until FSG this year. We have measured noise on that a couple of months before competition and it was 109dB. After using it for those 2 months we went to the noise test and failed. We welded on some U-bend sections and filled the last part of the exhaust with metal wool which passed us through noise, but created a hell lot of backpressure. Back to Greece and in preparation for Formula ATA, we opted to switch for the manufactured one we now have on the car. Pros: 98dB, unrestricted flow (we removed metal wool and additional bends), 80 euros compared to about 500 for the FMF, cons: almost 2kg heavier...

[Mbirt]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by mech5496:
we opted to switch for the manufactured one we now have on the car. Pros: 98dB, unrestricted flow </div></BLOCKQUOTE>Less than half as loud AND unrestricted flow? Most dirtbike and ATV exhausts with restricted flow (quiet cores) only meet 94 dBa at a laughable 3500 rpm. Did the mic at this competition read low for everyone or was this measurement taken with the same mic that showed 109 for your FMF muffler?

[mech5496]

Mbirt, different competitions so I assume different mics... The thing is that the manufactured one is pretty huge, well over 150mm in diameter and about 500mm in length, which makes a bulky exhaust. Thank god it is mounted low inside the right hand sidepod....