Acoustafil exhaust wadding?

[R1 Indy]

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 (noise is all I've got to pass)!

Cheers

[PaulKemp]

If you've fitted a db killer and new wadding it should pass
You need to cycle the heat and gas through the silencer to expand the wadding, leave it ticking over on a fast idle then when the engine is warm give it a few revs, hold for a bit then pulse it.
Be aware of engine temperature and neighbours tolerance

[GinG15]

that exhaust does not really look big.

if you compare it to can´s used at actual caterham or westfield models it rather looks small (in terms of diameter)

[R1 Indy]

Thanks,

As for the actual test, where it states in the manual "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"

Does that mean like this:



As i don't really understand what it means, and I'm getting very different readings dependant on where the meter is placed.

[Dave Brookes]

As you have it in the picture is bob on.

[Steve_D]

The whole testing method is a little subjective with all sorts of factors comming into play.

We have exactly the same tester as in your picture. We recorded 94db on a car and the following day it scraped through the IVA test at 98.9db. Before I left the test centre I checked the calibration of my meter with their kit and it was spot on. Still don't understand where the difference comes from apart from the car not being as hot during the test. If it had faied I would have asked for a retest with it hotter.

Steve

[R1 Indy]

Excellant, thanks.

I've been getting a reading of 101db with the meter going directly towards the tailpipe, at 45d upwards.

So this should give a lower reading, and I don't think the acoustafil has fully expanded yet. I'm also thinking of sticking an extra baffle at the manifold end for extra effect as well!! As I'm really not prepared to fail again!!!

[Mr2Mike]

Steve_D said:

The whole testing method is a little subjective with all sorts of factors comming into play.

We have exactly the same tester as in your picture. We recorded 94db on a car and the following day it scraped through the IVA test at 98.9db. Before I left the test centre I checked the calibration of my meter with their kit and it was spot on.

So you also measured 98.9dB at the test centre using your own meter? The sound measurements will be greatly affected by reflections from surfaces, measuring you car whilst parked on grass would likely give a significantly lower value and with it on concrete for example. Ultimately the only measurement that is relevant is the one take at the test facility.

[R1 Indy]

One other thing, someone just suggested to me to spin the end cap around, so that the tailpipe is under the car.

This would obviously then not be blowing the gasses in the direction of the sound meter?? And give a lower reading?

But is there anything in the Iva manual that says I cant do this?

[GreigM]

R1 Indy said:

But is there anything in the Iva manual that says I cant do this?

My "quiet" track day silencer does the same thing - made about a 2db difference.

[Steve_D]

Mr2Mike said:

....So you also measured 98.9dB at the test centre using your own meter?....

No my meter was not used and I would not want to interfere with the testing process.
My meter was tested later against the test stations calibration device.

Reference positioning the tail pipe...I think you would get away with pointing it at the ground but suspect the tester would claim you were putting the occupants at risk from fumes if you pointed it under the car. There is nothing specific i can see in the manual.

Steve

[one eyed mick]

Don't keep putting more baffles in .best sit is lack of power worst being over heating and engine damage . Over packing can make it noisier

[PaulKemp]

Exhaust pipe direction is not an issue for IVA, point it where you want
My tiny Robin Hood silencer passed with just a db killer in it

This is a new one and saves my right ear

[GinG15]

does IVA allow you to install this:

http://www.demon-tweeks.co.uk/motorsport/universal...






anyway...imo your silencer is too small...should be slightly longer and the diamter should be much bigger...this would definately reduce the noise.

those guys have made me a really nice silencer which quietened my car:

http://www.wunoff.co.uk/

Edited by GinG15 on Tuesday 6th November 10:50

[PaulKemp]

You can use anything to kill the noise unless it has sharp edges.
Noise test is done at 2/3rds revs at max bhp
I.e. max power at 5,500
Tested at 3650

[Steve_D]

PaulKemp said:

You can use anything to kill the noise unless it has sharp edges.
Noise test is done at 2/3rds revs at max bhp
I.e. max power at 5,500
Tested at 3650

Test is 3/4 max power revs or if this figure is not available 2/3 of max engine design speed.

Steve

[R1 Indy]

Thanks, yes it could do with being a bit bigger, but there really isnt that much room.

I took the end cap off to have a look, and it's not really expanded yet. The stitchings have started to go, so I think I bit more heat should do it, I've also spun it around so the pipe is pointing at the floor which may help.

And yes it's 3/4 of max power of 12500, which means 9000 rpm for the test!

Oh andi tried fitting a db killer in front of the silencer, which made it a lot quieter, but could tell the engine was struggling slightly so took it back out, as don't want to damage it.

[Steve_D]

R1 Indy said:

....Oh andi tried fitting a db killer in front of the silencer, which made it a lot quieter, but could tell the engine was struggling slightly so took it back out, as don't want to damage it.

What damage do you think you will do during a 10 minute test...no load, free reving. Don't forget those thing are not held in very well and always seem to fall out in next to no time.

Steve

[R1 Indy]

Well it all passed this morning

Had a nice drive back (after removing the baffles!)

Been to DVLA to apply for a reg, just waiting for them to do a few checks, thankfully they no longer want to inspect the car themselves as well. So hopefully by start of next week I could have a reg.

Oh and fk it's fast, put my foot down at 50mph in 6th and it just went, did the same in 4th and nearly st myself!!

Just need to get used to the clutch and get my launches right, as kept stalling!!

[chongwong]

R1 Indy said:

Well it all passed this morning

Had a nice drive back (after removing the baffles!)

Been to DVLA to apply for a reg, just waiting for them to do a few checks, thankfully they no longer want to inspect the car themselves as well. So hopefully by start of next week I could have a reg.

Oh and fk it's fast, put my foot down at 50mph in 6th and it just went, did the same in 4th and nearly st myself!!

Just need to get used to the clutch and get my launches right, as kept stalling!!

So bloody Jealous, it's at least 3 months until i find out about purchasing 'my' Robin Hood, the wait will kill me. Enjoy your new toy and don't hurt yourself or the car