Acoustafil Muffler Packing

Wondering if anyone has used this? It seems like a good thing. Apparently its new tech?
https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CCoQFjAC&url=http%3A%2F%2Fwww.thermalvelocity.com.au%2Fprod uct.asp%3FP_ID%3D425&ei=MeUnVOaxBcen8AX2ooCIBw&usg=AFQjCNEQBoi1CkcTUvQ8xlkTXVK-hdFLCg&sig2=IU5bXp2HefwARJN_N-Ra9A

Basically it comes in mat form, can be cut to size, doesnt need to go real tight on the perf tube, and expands into the can once it sees some heat.

Anyways i bit the bullet and bought some, gonna convert my muffler into a stubby and repack it, will report back.

Most guys here used to rip packing out in the old days to make things louder (and screw up the back pressure). Let us know how the reverse goes with this stuff.

No worries, yeah i do things arse about sometimes, lol. But about back pressure, im wondering what the ins and outs of that are ; im led to believe that a properly packed muffler aids bottom end grunt? Also, if i shorten my muffler, will that fuck things up at all? Do you reckon the length and volume of the can affects dynamics at all like that?
The muffler iv got is pretty loud, but its not small, i think it might be similar size to standard, its 460x100 with 50mm bore no baffle.
Wouldnt mind shortening it down to maybe 350mm. The plan is, when i pull it apart and the wadding is fucked, then ill shorten it, but if the wadding is good, then ill repack it and leave it the same size.
Its loud enough as is, but doesnt have that deep note that a good muffler gives, and i dont want to adversly affect bottom end grunt.
Was even considering putting a carfully placed and sized dent in the perf tube to aid back pressure if i go shorter?? I dont know, i get these stupid ideas sometimes.

Or is it that a properly baffled muffler has less back pressure because the exhaust charge gets to go through the perf tube unhindered without having to expand into an empty can??

Is back pressure even good or bad? Or maybe the better question is; is there such a thing as good backpressure and bad back pressure? :confused:

Backpressure = HORSE SHIT , reducing air flow kills power period. Positive Flow and pressure are very different , cutting up an exaust opens it up , increasing flow (Good) BUT it changes the Flow characteristics. Stock pipes are setup to give good average responce broad torque and a set volume at a set rpm. Race pipes open up the flow (cause noise is less restricted) and change the pulse tuning to improve top end at the expence of low down torque (usally anyhow).

If you increase flow by reducing resistance (backpressure) the CV carb will most likely need re tuning slightly. Quilting has little to do with resistance of flow on a cut can generally as it usally doesnt have baffling usally after cutting the can. The quilting does very little to abate or alter nosie once the baffles are removed as it rely's on the baffle to reflect waves of pulsation to be muddled with the Quilting.

Keeping a baffle , but opening up the flow (drilling out holes slightly) whilst reducing the length of the can and adding quality quilting will help flow but retaining a deep sound is usally easyer with a larger can . Increasing Dia of can whilst shortening can drop resonance freq and make it sound lower.

If you shorten the can to much the pulse length of the pipe tuning goes out the window and you loose lots of bottom end.

Good luck.

^ Thanks mate, that has given me a lot to think about. Im pretty much just doing it for aesthetcs, and only chopping about 100- 120mm off so hopefully that doesnt stuff up the note or the resonance needed for good torque too much. Will play around with baffles too. in the meantime im keeping an eye out for a nice oval muffler that will give a bigger cross section.
Cheers!

Ok i said id report back, so shortened my old Hindle stealth muffler from 460 to 340, cheap crappy chromed steel end caps were rusted on so i was spewing i had to chop 10mm of the front as well and thus expose the score marks where the mounting clamp was on the aluminium can, but at least the perf tube is stainless steel, and it weighs nothing so was worth keeping. The existing packing was the pink-bat fiberglass type, was still tight, but coked up pretty bad in places, and perished in one spot.

Ok so the acu-shit whatever its called - easy to use, not itchy, muffler sounds awesome - throatier and deeper note at civilised rpms, run-on crackles and pops sound ace, nice and shouty (loud!) with a fistfull up its arse, still looks oem-ish, very happy.

In the interests of science, iv included photos of an off-cut of the stuff before and after the application of heat. it didnt go as crazy as i thought, but you can imagine how much multiple layers of it would unravel inside a can.

I had an old trail bike (4Stroke) 125cc, open the throttle and about 2 seconds later the engine would increase revs. I drilled a hole in the header pipe and gained approx 500% power increase. I learnt alot about exhaust flow that day. Now all my bikes have drilled headers.

^ yeah, and if you make the holes point at the front tyres you get more grip. I did that with my camira station wagon, nothing could touch me. That one simple modification got me a lot of sex.

Quote:

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Originally Posted by davo

I had an old trail bike (4Stroke) 125cc, open the throttle and about 2 seconds later the engine would increase revs. I drilled a hole in the header pipe and gained approx 500% power increase. I learnt alot about exhaust flow that day. Now all my bikes have drilled headers.

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I did this to my lawnmower too, large exhaust port size hole through the salt shaker/shower head arrangement and through the baffle. note use of deflector to keep front tyre sticky. 500% increase in torque was evident in the way it mulched through 1/2" eucalyptus branches like they were tender dandelion stalks. Note is deep and crisp.

In other news after a bit more of a ride, my muffler is actually pretty quiet - can barely hear it cruising, but does sound nice under load with some rpms on board.

Ok sorry for un-SFing the place. as you were..