Blokko Posted March 2, 2014 Share Posted March 2, 2014 Given my last track day reading of 98.2 dB, I'm presuming that my Powerspeed exhaust could benefit from a repack. Being a complete numpty in this department, I was wondering if anyone has a guide for how to do this (as well as a recommendation on what type of packing to use, and how much I need to order)? Can the primaries / collector stay in place? I can see that I have hex bolts at each end of the can - is this all that needs to be disconnected, or do I have to disconnect where the primaries meet the collector? Does the fact that I've had to ask these questions mean that I should be paying someone to do the job My set-up looks very similar to this one - except that I have hex bolts on both ends of the can. Edited by - Blokko on 2 Mar 2014 21:12:16 Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted March 2, 2014 Share Posted March 2, 2014 On mine, the tail end cap comes off ... you rake out the old stuff and fill it with new stuff. PowerSpeed sell bags of long strand packing for the job. See also recent threads ref Acousta-Fill packing ... a blanket that expands to fill the silencer when warmed in use. Link to comment Share on other sites More sharing options...
Mankee Posted March 2, 2014 Share Posted March 2, 2014 Acousta-Fil from Thermal Velocity/eBay/Amazon/etc. Made my 6" Caterham/Cheesman silencer much quieter than the standard packing material, which was full anyway. No idea how it compares with the Powerspeed stuff. Here's a calculator so you can work out how much you need: http://www.thermalvelocity.co.uk/calc/calculator2.html Link to comment Share on other sites More sharing options...
Mucus72 Posted March 2, 2014 Share Posted March 2, 2014 +1 for Accoustafil. Great stuff, easy to use, don't overpack. I have an identical exhaust to you. You need to undo the two exhaust bobbins and get a medium rubber mallet and start whacking the silencer until it comes mm by mm away from the primaries. I put cloth up against the side skin as it's oh so easy to bounce a glancing blow off the silencer and dent your panel. Once the whole lot is off remove your hex bolts from the end pipe cap end, and whip out existing packing and replace with accoustafil. I wear gloves and a mask at this point because the e-glass strands are horrible things. Consider using an iPhone style sound meter and each service check the noise levels. You may get more than a season out of it before you need to repack. I'm starting year 2 with accoustafil and I'm still under db limits for all UK tracks. Before this point I failed drive by at Donington... Link to comment Share on other sites More sharing options...
Ozzy Posted March 3, 2014 Share Posted March 3, 2014 You don't need to take the can off to do this! Jack up the back off car, take the wheel off, take the end cap off the silencer, and there's enough room to pack it. Oz. Link to comment Share on other sites More sharing options...
Mucus72 Posted March 3, 2014 Share Posted March 3, 2014 Holy cow. That's twice in 3 years I didn't need to bash new dents in the side skin 😔 Link to comment Share on other sites More sharing options...
Guest Posted March 4, 2014 Share Posted March 4, 2014 I repacked my Powerspeed exhaust last year using Acoustafil I bought from the manufacturers ebay store. Can't remember the amount used but went off the calculator linked above and it seemed spot on. Rolled the blanket around a piece of plastic tubing with a diameter just a bit bigger than the perforated tube then wrapped the outside of the rolled up blanket in cling film to hold it. I put some gaffer tape over the end of the perf tube to stop it snagging then slid the packing from my plastic tube into the can. I put a bead of RTV sealant around the inside edge of the end cap when refitting as it was obvious this had been done previously. Here are before and after photos: Before After The noise level after repacking was approx 93.5dBA, a drop of around 6dBA. Link to comment Share on other sites More sharing options...
Mucus72 Posted March 4, 2014 Share Posted March 4, 2014 Hi mechanicalmoz. Looking at the pictures you took your exhaust off to achieve this too. Maybe I'm not mad after all? I went to bed thinking about this and I'm not sure even with the rear wheel off there would be enough space (with wheel arch fouling) to slip the roll of Acoustafil in. Link to comment Share on other sites More sharing options...
Mankee Posted March 4, 2014 Share Posted March 4, 2014 Quoting mechanicalmoz: The noise level after repacking was approx 93.5dBA, a drop of around 6dBA. That is a decent result and very similar to what I achieved with modifying a standard Caterham/Cheesman silencer. What's the length and girth of the average Powerspeed can? Link to comment Share on other sites More sharing options...
Guest Posted March 4, 2014 Share Posted March 4, 2014 No I can't see how you could repack with Acoustafil when the can is still on the car, the rolled up blanket is the same size as the can itself. Maybe it's only possible when repacking using the bags of loose fibre which can be stuffed in a handful at a time? Even then I don't think there was enough clearance between the can and the side of the car to be able to get all of the end cap bolts out. Mankee I think the can dimensions were approx 650mm long and 175mm dia but I don't know if all the Powerspeed exhausts are the same. Link to comment Share on other sites More sharing options...
Ozzy Posted March 4, 2014 Share Posted March 4, 2014 Sorry, I was indeed referring to the bags of packing, which is what I use. It's just easier to work with! You can get the end cap screws out easily, but you need to cut down an allen key to suit. Oz. Link to comment Share on other sites More sharing options...
Grim Reaper Posted March 5, 2014 Share Posted March 5, 2014 Was that 'After' shot, AFTER the Acoustafil has expanded or before? Seems a little overpacked if it's before as I understand it expands by quite some amount. Link to comment Share on other sites More sharing options...
Blokko Posted March 5, 2014 Author Share Posted March 5, 2014 Thanks for all the replies. Time permitting, I'll have a go at taking it all apart this weekend (putting stuff back together will be a whole different ballgame 😬) Some further questions then - 1. If I've understood correctly, with the two bolts / bobbins holding the exhaust to the car out of the way, the connection between the primaries and collector is just an interference fit and gentle use of a persuasion stick will separate the two 2. I've read elsewhere about slight exhaust leaks after taking an exhaust apart. I'm sure I've read that silicone sealant should not be used - what is the correct kit, and can it be used between the primaries and collector, or just on the can end cap? 3. As per the question from Grim, is the 2nd photo from mechanicalmoz what I should be looking to achieve, or is that a bit overpacked? Link to comment Share on other sites More sharing options...
Blokko Posted March 5, 2014 Author Share Posted March 5, 2014 Here's a thought - as I have hex bolts on both ends of the can (unlike the photo, which shows bolts only at the back of the can), would it be an option to leave the collector in place and disconnect the can by undoing the bolts at the front of the can 🤔 Link to comment Share on other sites More sharing options...
Grim Reaper Posted March 5, 2014 Share Posted March 5, 2014 If it's anything like my first Powerspeed can that had bolts at both ends of it, you will probably find that the centre perforated tube is welded to the front end, so trying to take the 'sleeve' off is impossible as it will need to be slid over the entire length of the centre tube. Link to comment Share on other sites More sharing options...
Blokko Posted March 5, 2014 Author Share Posted March 5, 2014 Ah! that makes sense.... Link to comment Share on other sites More sharing options...
Grim Reaper Posted March 5, 2014 Share Posted March 5, 2014 Before and after shots of the Acoustafil http://www.flickr.com/photos/95548186@N04/12956247353/ and http://www.flickr.com/photos/95548186@N04/12956256193/ from the websitehere Link to comment Share on other sites More sharing options...
stuart147 Posted March 16, 2014 Share Posted March 16, 2014 Looking at this thread as a numpty with most techy things, I have a Powerspeed exhaust fitted by them 7 years ago and having completed almost 25000 miles. How do you know whether they need repacking or not? Is it all down to noise regulations for track days? I do not use mine for track days and must say that over the years, the exhaust noise does not seem any louder now than when it was first fitted. Stuart Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted March 16, 2014 Share Posted March 16, 2014 Or your hearing is deteriorating ! I suspect it needs repacking. Get the end cap off and look. Link to comment Share on other sites More sharing options...
stuart147 Posted March 17, 2014 Share Posted March 17, 2014 Hi Ian. YHM Link to comment Share on other sites More sharing options...
gundersen Posted March 17, 2014 Share Posted March 17, 2014 Quoting Grim Reaper: Before and after shots of the Acoustafil http://www.flickr.com/photos/95548186@N04/12956247353/ and http://www.flickr.com/photos/95548186@N04/12956256193/ from the websitehereHaving talked with the acustafil sales rep about this exact issue, these marketing photos should not be taken too seriously. You will need to pack more than what the first picture shows. The calculator on their homepage is the way to go when determining how much packing to use. Link to comment Share on other sites More sharing options...
PL15 Lowflyer Posted March 17, 2014 Share Posted March 17, 2014 Hi, Recently Repacked my Duratec CC repackable 'track day' silencer with 1m of Acoustafil and then added another 1m. A lot better I think with the other 1m. The photos from acoustafil look too lean to be true. R. Link to comment Share on other sites More sharing options...
Blokko Posted March 30, 2014 Author Share Posted March 30, 2014 Got the exhaust off - not easy! Getting the collector separated from the primaries took a lot of effort and had to drill out a couple of the hex bolts (rusted solid) to get the end cap off. The stuff that was in there seemed to be quite densely packed in some areas, but a bit looser on other places. The fibres nearest the outside of the can were burnt - dark brown, turning to yellow and finally white nearest to the centre of the can. Got onto the website and, lo-and-behold, they are out of stock on the Acousta-Fil I need ☹️. Hope they get some stock in soon - I want to go for the Taffia Fish & Chips run! Edited by - Blokko on 30 Mar 2014 21:35:24 Link to comment Share on other sites More sharing options...
Blokko Posted April 22, 2014 Author Share Posted April 22, 2014 Now the job is complete, here's an update - 1. This is another (yet another) of those 7's jobs that took me much longer than anticipated! 2. As the packing had not been replaced since the can was first fitted, the hex bolts on the end cap were rusted - I had to drill 2 of them out. Managed to get replacements, but they are a thicker thread than those on the original unit. Going to get them machined down when I get a bit of spare time... 3. The internal tube on my PowerSpeed is not a constant diameter - it flares outward for the last 1/3 of the can (nearest the collector). This means that you cannot use a cardboard sheath around the matting if you want it to fill the whole can 4. Having tried a variety of methods, I ended up shredding the acoustic matting and dropping it into the first third of the can, using a long stick to 'tamp' the contents (trying not to compress the material too tightly). I was then able to use a cardboard tube as a sheath to fill the last two thirds of the can 5. After all that, the exhaust doesn't really sound any quieter - deeper tone, but not the hushed note I was expecting / hoping for. Does seem to be getting a bit quieter now I've got a couple of heat cycles through the exhaust. Will report back on noise once I can get to a track day to get a proper metered test..... Link to comment Share on other sites More sharing options...
Mucus72 Posted April 22, 2014 Share Posted April 22, 2014 Sure you will be fine with noise tests. Would be good to do your own iPhone app noise readings before you go to track though. Mine failed 2 years ago at Donington, but now I'm still passing noise tests after Acoustafil and haven't replaced in a season and a half. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now