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Thread: doubt about mufflers

  1. #21
    Originally posted by mario_rbr:
    How exactly do they measure the engine speed at competition?, just by looking at the tach? or do they attach something to the coils or something, to measure real speed, beacuse if it's just by looking at the tach, you can set it up to lower than real values, son when it shows 11000 rpm, the engine it's only at 9000 rpm
    That would be closer to stepping over the rules line than most of us would like.

  2. #22
    Senior Member
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    Kirkland, Washington
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    Originally posted by Alex Kwan:
    <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by mario_rbr:
    How exactly do they measure the engine speed at competition?, just by looking at the tach? or do they attach something to the coils or something, to measure real speed, beacuse if it's just by looking at the tach, you can set it up to lower than real values, son when it shows 11000 rpm, the engine it's only at 9000 rpm
    That would be closer to stepping over the rules line than most of us would like. </div></BLOCKQUOTE>

    However, if you search this forum you will find people admitting to doing this.
    Josh Gillett
    Oregon State FSAE '04-'06

  3. #23
    Instead of trying to cheat (or call it as you want), did someone ever try to make is own muffler and succeed in it?

    As I see, many of you are like me. A little bit late on the countdown and you're trying to make a muffler on the side, as fast as you can. Do not really have the time to test a lot of designs.

    Wich kind of wool is the best and can resist to that heat? I don't want to blow it off at the face of the competitor during the race...

  4. #24
    We use chopped fibreglass packing, as many teams also do. In a pinch, we've tore up some fibreglass mat to make muffler packing.

    We've made our own muffler, because the turbo has a certain silencing effect, allowing use to run a very short muffler.

    Matt Gignac
    McGill Racing Team

  5. #25
    Yeah, i'll second the "Who needs a muffler? We've got a turbo" argument. We were recorded at 105 at West last year and 106 at Aus. And that last one was with a straight through perforated core muffler, a bit over 200 mm long, 2 inch core ID. Turbos are amazingly effective silencers.

  6. #26
    Originally posted by Pete M:
    Yeah, i'll second the "Who needs a muffler? We've got a turbo" argument. We were recorded at 105 at West last year and 106 at Aus. And that last one was with a straight through perforated core muffler, a bit over 200 mm long, 2 inch core ID. Turbos are amazingly effective silencers.
    I'll second that Pete. However i liked the sound without the muffler, chirp chirp...
    Andrew

  7. #27
    Malkovich,

    I have seen several teams design and succeed with their own mufflers. It is not easy, and it is very difficult to do properly without a lot of "guess and check". However, as has been mentioned, adjusting your AFR and ignition can have just as much an effect. We recently ran a test and found that adjusting the AFR could drop sound as much as 3-4dB and we stopped as soon as it read 109dB. Probably could get it quieter...

  8. #28
    We're running a turbo and without any muffler, we were at 120dB. I made a muffler, 2.5in ID, 4in OD, 12in long, and run of the mill pink panther fiberglass insulation. It's my first muffler, but we're at 105dB. I'll probably make a smaller one before competition.

  9. #29
    There is muffler packing for dirtbikes that is tailor made for a custom muffler. Yes, it's more expensive then pink panther fiberglass, but is denser and has the right design intent.
    Off hand Moose racing makes some and they sell it in Dennis Kirk catalogs but I'm sure it can be found at the local motorcycle shop.

    The trick I know from repacking dirtbike mufflers is take your core out from the can. Wrap the core tight enough that the wrapping is all touching but don't crush it much. Wrap enough so it is a snug fit into the can, but don't over do it. Saftey wire the packing 3 or 4 times down the length of the muffler and slide the core back into the can. Loose packing can hurt both noise suppression and hp as the exhaust gases see the extra area in the muffler.
    'engine and turbo guy'
    Cornell 02-03

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