Carbon Fibre for Silencer Stuffing

[Rusti Evo]

Goodwood on Monday really finished off the e-glass stuffing in the silencers - its melted it into sort of pea shingle size pellets.

Seems to me the obvious fit and forget would be scrap carbon fibre fluff. The high cost would be offset by a permanant fill.

Any ideas for a supplier?

[GreenV8S]

Rusti Evo said:

Seems to me the obvious fit and forget would be scrap carbon fibre fluff. The high cost would be offset by a permanant fill.

Is it obvious? The main advantage CF has in structural applications is strength-to-weight, which is of no benefit here. The fibres are still brittle so it will break down and blow out over time just as glass does, and I suspect it would burn rather better than glass does too if it gets hot enough.

[Wilder]

Pure CF has a melting point far in excess of anything you would find in a silencer.

Edited by Wilder on Wednesday 5th August 22:14

[GreenV8S]

Wilder said:

Pure CF has a melting point far in excess of anything you would find in a silencer

Yes, the melting point is probably over 3000C, the exhaust would melt first. But I was thinking about burning rather than melting.

[Wilder]

I dont think carbon burns as it is an inert material.

[crafty]

Where did you get the stuffing? Is it specifically for muffler packing?

If you are using construction grade insulation it may be a problem with the resins used.

Certain types of construction grade insulation can also be used for fireproofing to structural members, generally rockwool (not glasswool), however, you still need to be careful in considering this.... when they say "fire rated" it doesnt mean that it wont be damaged by heat... best look for one specifcally for muffler packing.

[Pb3]

I am about to invest in this stuff, see http://www.bathpotters.co.uk/productdetail.php?pid...

I have done a lot of searching regarding this topic and have tried a few in the past:

Loft insulation (rockwool) works for a bit but turns to dust and blows out.
Fibreglass stands (proper exhaust stuff) - melts, breaksdown and goes.
Normal fibreglass matting - the best to date, I get it free, but melts into big lumps, breaksdown and blows out.

I am adding this new stuff to a third box I am about to make and will try it in the two standard silencers. Reports I have read suggest that this 'superwool' lasts and lasts.

Stainless steel scrubbers is another option!

[Rusti Evo]

I used e-glass silencer material. It's lasted 4 trackdays so I suppose thats not too bad. Have used silencer grade basalt before and the SBC blows it out double quick.

It seemed to me that as carbon doesn't melt it may be a long term fix.

Edit to say also used ceramic felt sheet from Car Builders on previous SBC that appeared to last better than e-glass.

Edited by Rusti Evo on Thursday 6th August 09:20

[Rusti Evo]

Phil, thanks for the hot tip on BathPotters - material ordered.

For Snett on Wednesday I will try BathPotters packing one side and CBS ceramic felt on the other to see if there is a difference.

[Pb3]

Hi Rusti, I just ordered mine, wanted the 25mm thick stuff, they have had a run on it and are now short. I had to go for the 13mm thick stuff, next time I will keep quite

I am at Silverstone 17 Aug evening 98dB, wish me luck.

[GTWayne]

^^^ GOOD LUCK Phil ( you will need it )

[Rusti Evo]

Pb3 said:

Hi Rusti, I just ordered mine, wanted the 25mm thick stuff, they have had a run on it and are now short. I had to go for the 13mm thick stuff, next time I will keep quite

I am at Silverstone 17 Aug evening 98dB, wish me luck.

Seriously interested in your bid for 98db!!!! I would desperately like to get to Combe @ 100db.

(It wasn't me that nabbed the last roll of 25mm.............)

[Steve_D]

Rusti Evo said:

Pb3 said:

Hi Rusti, I just ordered mine, wanted the 25mm thick stuff, they have had a run on it and are now short. I had to go for the 13mm thick stuff, next time I will keep quite

I am at Silverstone 17 Aug evening 98dB, wish me luck.

Seriously interested in your bid for 98db!!!! I would desperately like to get to Combe @ 100db.

So am I.
Repacked mine with wire wool and basalt.
First run out was to Goodwood where it tested 104/105 so 98 will be an interesting target.

Steve

[Pb3]

The last three times at Cadwell I have come in at 101dB, so with a third box I hope to drop another 3dB! You need to lower you rev limit

Edited by Pb3 on Thursday 6th August 18:53

[Fat Arnie]

OK, I have been trying to preserve the contents of my silencer for 16 years and have found teh following works:

To make eGlass last a little longer you need wrap your baffles in stainless steel wool and fix it in place with locking wire. Then fit the eGlass without packing it too tight.

Also make sure the holes in your baffle are not too large, and the diameter of the baffle relative to the diameter of the silencer can is not too great. If you are running a 3" baffle your cans need to be 8" dia to have any change of preserving the contents.

[YIIHAA]

Wilder said:

I dont think carbon burns as it is an inert material.

Tell that to the owners of Didcot and Drax power stations. I believe they burn quite a bit of carbon

[ezakimak]

Are you sure that you dont have issues with valve train noise. In Australia we have a limit of 85Db or something low like that, I remember reading that some of the guys that were building Gt40s found that if they had aggressive cams and the thin sheat metal valve covers they would get a lot of noise. replacinging the valve covers with thicker cast items, and moving to hydralic lifters and a more mild cam made things a lot quieter.

I still love listening to that video of Gman's car at Vmax though, that racket of the solid lifters is great.

[Pb3]

Hi Ryan, you are right to talk about the valve train / general engine noise. I tested with a sound meter all round the rear of the car and parts are very loud. For trackday testing, I have read that if engine noise is considered to be interferring with the exhaust measurement that they can discount it and you can get through.

Ultima have posted the noise limits for both a SBC and LS7 with their new 3rd silencer, so it is possible to significantly reduce exhaust noise.