Basically ive been struggling to get my 08 R1 powered Indy through the noise test at IVA.

I've now fitted about as big a silencer that I can fit with the manifold, it's 6" by 26" long.




I have removed the original wadding, and filled with acoustafil, but it's still quite loud, I have bought a sound meter and it's showing 80db at idle, but I fear at 9k rpm it will be over 99db!

Oh and I've fitted a db killer inside the perforated tube, which in theory should hold the gasses inside the silencer longer.

I understand I need to get it hot, and the acoustafil will expand, and give more silencing.

But how hot do I need to get it, will I be able to get it hot enough on the drive? Would leaning the fuel off help get it really hot?

Can anyone give me any advice/ experience?

As I really don't want to fail a third time!

Cheers

Drive it to the IVA! That will get it hot enough! All you are doing is breaking down the binding the holds the material together, allowing it to expand. Mine got noticeably quieter after about a 20 minute drive....

Yes, i plan on driving to IVA, but its only a 20 min drive, so would really like to get it to expand first.

Or i could risk a road test, and hope i don't get stopped! (its insured)

Oh and I've also fitted a piper cross air box, which should hopefully keep the induction down. (i will point the intake as far away as poss for the test).

Just make sure your car is warm before you set off, and then take a scenic route to the IVA centre. Don't go mad, but a good 20 minute blast should be fine.... You didn't follow the packing advice on the Acoutasfil website did you? I did initially, and it would have been massively over packed....! Use the photo guidance rather than the measurements supplied by their calculator.

Hi
Our car has a 2001 carbed engine on that
we used a bike can with a decibel killer in it + a S/S
elbow & a straight chrome trim bashed on the end
we got the cat from the US. & I modified the original air box to fit the other way
which is very quiet on induction. (if its ok for Yamaha why change it)
this lot came out at 97 db for the IVA. That was great but we failed
on emmisions. I assume your silencer has a cat in it ,
It would be a lot easier to tell you what we did to overcome it over the phone
if you send me a UTU I'll send you my No or send me yours.
Good luck
René


IVA exhaust with cat


Modified Yamaha airbox

[Edited on 3/11/12 by renetom]

Hi, no it doesn't have a cat anymore, as i have now passed the emissions test, i thought it would give me more room for silencing.

Thanks for the offer, but I'm pretty confident now, that once the acoustafil has expanded, it should give me the required silencing with my current setup to pass.

Out of interest, I've got a db killer in the far end of the silencer, is it worth fitting one in the manifold side as well? would it make any extra difference? just as a bit extra.

Well I've got the exhaust nice and warm now, and its a little quieter, but i don't think its fully expanded yet, but I've tried to take a reading at 9K RPM, and got a reading of 103DB!

But i don't think i had the Meter set quite right, i had the meter horizontal, at the hight of the tailpipe (which is very low), and 500mm away.


Having another look at the manual, this is not right. So have had another go.

Ive got the meter head height at 200mm, 500mm away from tailpipe, and at 45D angle.

Is this right?




cheers

Just got 101DB set up like this.

But still not 100% sure thats how to set it up. As the manual says to set height at 200mm, then set at 45D angle.

So is that the base of meter or tip of meter at 200mm?

i imagine its the microphone at 200mm

i always thought sound levels were usually measured at 1 metre? depends on the meter itself, and what the instructions say though.
in the photo, that doesn't look like 45 degrees to me either? looks about 15-20 degrees. if thats a 45 degree bend in the tail pipe, then the meter should be at 90 degrees to the side of the car? or parallel to the rear tyre.

will be interesting to see what different agles give different results


[Edited on 4/11/12 by blakep82]

Its defiantly 500mm away from exhaust outlet.

But having another read of the angle bit which says "with the sound meter horizontal, set the microphone so that its 200mm from the ground. At an angle of 45D to the exhaust outlet in the direction which gives the greatest distance between it and the vehicle contour"


So does that actually mean the meter needs to be horizontal, but 45D from the outlet like this:

That looks about right to me, wonder if you could swivel the silencer round, so that the outlet is pointing under the car?????

I was having this discussion today. I felt that the accustafil in my silencer was still making changes to the tone of my car 1500 miles later. My car used to rasp but does not now. It not that much quieter or cant really tell but has changed the tone.

Good luck.

if it has smoked then stopped smoking then its expanded. the best way to test if you have enough in there is to tap the can, it should sound like a dead thudding sound rather than a hollow sound.

i would be surprised if its still too loud with a 6inch can on it. also make sure you have got your meter set to dbA

40 inches, your right, I could spin the end cap around, and it would point underneath the car. I have a feeling the inspecter may have an issue though? But I cant think why really??

I could also point it further towards the ground, but I'm guessing the sound would bounce back off the ground??

How's the induction noise ? is the meter being upset by that noise instead of the noise from the exhaust ?

Might be worth angling the outlet down one hole pitch and checking the reading again

I'm pretty sure the induction side is ok. The pipercross air filter is silent compared the the ITG filter I had on before!

But it's got me thinking now about the tailpipe angle. I will have to have a play in the week.

Oh and I've also got another db killer that I plan on putting between the manifold and silencer for added effect. As I'm really not prepared to fail again!!

When I failed SVA, I asked "Do you just re-test the failed items?". I was told "Yes, unless we see something else you've changed".

Taking the cat' out might be an issue. I think if a repair/alteration could effect another tested item (that passed previously) that item can be re-tested.

If they think a different exhaust could effect the emissions they MIGHT re-test them. If they suspect the cat' is gone they WILL re-test the emissions.

It passed!!!!!

so glad, and had a nice drive home aswell (after removing the baffles!)

Off to the DVLA now.

CONGRATS.

Know drive steady.

Brad.

I will be driving very steady, it's a complete beast!!

Even at 50mph in 6th, put my foot down and it just goes. Did the same in 4th and nearly crapped myself!!

Just need to get used to starting off/getting the clutch right, as I stalled a lot.

Now just waiting for DVLA to do a few checks, then should hopefully get a reg by start of next week. Thankfully they no longer want to inspect the car themselves as well.

[Edited on 13/11/12 by -matt]

quote:

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Originally posted by -matt
Now just waiting for DVLA to do a few checks, then should hopefully get a reg by start of next week. Thankfully they no longer want to inspect the car themselves as well.

[Edited on 13/11/12 by -matt]

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Great stuff. Did you go without the 'cat and what Db's was it?

Take it easy. Cold tyres and damp, green roads can catch you out very quickly. 4th at 50 is still short shifting in mine; What sort of revs were you at?

Yes passed with no cat. And at 99db!

Yes it probably was still short shifting, not sure what revs that was, but in 6th gear, it's almost bang on 10mph per 1000 revs.

I'm using a 3;62lsd. So is quite low geared.

I will be taking it very easy, especially as all the geometry has only been guessed at the moment, so wouldn't take much to upset the balance.

Wow DVLA are really on the ball here. Brand new 62 plate reg docs arrived this morning.

Just got some plates made, updated insurance, and I'm now all ready to go

Exciting times, as above take it easy out there, especially this time of year, lots of leaves and mud round the country lanes......

My vote would be set it up and get it on track, you wont have more fun

didto to taking it easy... The surface can be much like ice at this time of the year with wet leaves ect.. with RWD and little weight on the back it can catch you out..