Mufflers?

[Ian M]

Just wanted to get a thread started about what mufflers teams were using.

We are trying to use an undertail Two Brothers (small and light = good), but are having a hard time getting it under the noise requirement (loud = bad).

We ran a Scorpion slip-on the past couple of years, and with a few modifications last year, it worked for us the last 2 years. The first year, it passed right off of the bat with a 4 to 1 header with minimal bends.

Just wondering if anyone has any experiences with four-wheeler mufflers or any other off-road mufflers, as I was wondering if they may be a little quieter due to the off-road noise restrictions being passed lately.

Do you think they would work on a 600cc or would they create significant back pressure?

Any experience with brands, sizes, or baffling secrets would be appreciated.

Hope everyone is getting lots of seat time and very little sleep!!!

[Ian M]

Just wanted to get a thread started about what mufflers teams were using.

We are trying to use an undertail Two Brothers (small and light = good), but are having a hard time getting it under the noise requirement (loud = bad).

We ran a Scorpion slip-on the past couple of years, and with a few modifications last year, it worked for us the last 2 years. The first year, it passed right off of the bat with a 4 to 1 header with minimal bends.

Just wondering if anyone has any experiences with four-wheeler mufflers or any other off-road mufflers, as I was wondering if they may be a little quieter due to the off-road noise restrictions being passed lately.

Do you think they would work on a 600cc or would they create significant back pressure?

Any experience with brands, sizes, or baffling secrets would be appreciated.

Hope everyone is getting lots of seat time and very little sleep!!!

[screwdriver]

F1 grade custom MHG muffler here...
http://www.formulastudent.de/fileadmin/user_upload/all/...85_Hirvonen_35pc.jpg (http://www.formulastudent.de/fileadmin/user_upload/all/2007/bilder/FSG07//FSG20070812/FSG20070812_1285_Hirvonen_35pc.jpg)

[Superfast Matt McCoy]

I bought an OEM R1 muffler off ebay for my f4i. It is very small so it packages well, light (titanium) and quiet. Maybe perfect for FSAE. I paid $10 plus shipping for two of them (R1 is a dual muffler setup) so for next to nothing you can get one for this year and next year.

[MikeDutsa]

down side to that Is that you have to cost it on the report. Ours was $878. Bummer. We are going to build our own and submit a revision on the report.

[Drew Price]

Matt,

We are actually using one of those R1 mufflers on our 450 single this year. I just weighed the extra that we had, right about exactly 4.5 lbs.

Be warned though, the tubing into the inlet side is some sort of easy-machining, easy to form alloy, and is nearly impossible to weld. Ever accidentally try to weld a piece of leaded free-machining steel? It looks just like that.

LT-R450 + R1 Muffler (http://www.youtube.com/watch?v=Sc0jaZUTbVg)

Also, as Matt said, it is very quiet. It registered in the 7X dB range at idle. Have not checked it at the test RPM yet, as we are awaiting a new crank position sensor.

Best,
Drew

[Wesley]

A lot of noise attenuation depends on chosen lengths, as well as weld quality and smoothness (how much slag is in the tract creating turbulence) etc. If you do any modeling in WAVE it's worth a shot to use the Noise package to determine sound levels.

And then there's testing. We're running an Akrapovic titanium muffler for the second year in a row, gave us no problems. Also, messing with the fuel and timing maps can make a huge difference in sound levels.

[Ian M]

So to lose a few decibels through engine tuning the fueling should be leaned out and the timing should be pulled back, correct?

I tried playing with a few things last year and nothing seemed to change it more than 1 Db, but I haven't done any research on tuning for noise either.

Yeah, next year I am hoping to get a free copy of WAVE and see how much theoretical analysis I can get done concerning intake and exhaust design.

[TMichaels]

1dB is a lot. Never forget that dB is a logarithmic scale!

Regarding the noise reduction by engine tuning: Every approach that decreases the mean pressure inside the cylinder should lead to a decreased soundlevel.

Regards,

Tobi

[murpia]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ian M:
So to lose a few decibels through engine tuning the fueling should be leaned out and the timing should be pulled back, correct? </div></BLOCKQUOTE>
Watch out for a big increase in exhaust gas temperature if you try this...

Regards, Ian

[Discretely elite]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ian M:
Just wanted to get a thread started about what mufflers teams were using.

We are trying to use an undertail Two Brothers (small and light = good), but are having a hard time getting it under the noise requirement (loud = bad).

We ran a Scorpion slip-on the past couple of years, and with a few modifications last year, it worked for us the last 2 years. The first year, it passed right off of the bat with a 4 to 1 header with minimal bends.

Just wondering if anyone has any experiences with four-wheeler mufflers or any other off-road mufflers, as I was wondering if they may be a little quieter due to the off-road noise restrictions being passed lately.

Do you think they would work on a 600cc or would they create significant back pressure?

Any experience with brands, sizes, or baffling secrets would be appreciated.

Hope everyone is getting lots of seat time and very little sleep!!! </div></BLOCKQUOTE>

We use a Two Brothers Carbon Fiber muffler, it may be the same one you are using. Its $$$ but light as can be and looks good. Since we are turbo this year I have no worries regarding passing sound. Last year, however, the same muffler was used but on an NA setup. From what I've heard they packed more fiberglass into the muffler (since it can be dissasembled) and passed that way.

[Biggy72]

We built our own this year for about $35 and it weighs in at a hefty 4lbs. Granted we're turboed so it doesn't need to be too much, but hopefully soon we'll have a good enough tune that we can go do a sound test with our new decible meter.

[Davo]

A few years back we made our own muffler. Can't remember how much it weighed off the top of my head but it was pretty light and cost bugger all. The first time we tested it we found that we'd packed it with the wrong material and it all came out in a big dark cloud... We replaced it with the proper stuff (having a custom muffler makes it really easy to take apart and put back together) and it passed the noise test at the event.