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PostPosted: February 20, 2008, 10:55 am 
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I'm about to put together the exhaust system for my build and want to be sure to meet the sound requirements at one of the tracks here in Ontario (Calabogie), which are the most restrictive from what I've seen. I'm going to be running a small block Chevy without cats, most likely an LT1 at this point. Hence, I think I've got my work cut out for me.

Most of the mufflers I've been reading about don't seem to be able to meet the tough restrictions at Calabogie, which I've posted below. Does anyone have any suggestions? I'm not sure if a 15" Long 5" round mufflers will be able to pass this test. The "Screening Test" it might pass, since the test is done behind the car, the side exit exhaust and the rear wheels might save me. However the on track test might be tough.

I have emails into Hooker about their reverse flow side pipes, as well as Flowmaster and others. One idea I have would be to run a collector muffler into a glass pack. Glass pack themselves don't do that much but when combined with the collector muffler might work.

Anyone have any suggestions?

Regards,

Paul

1. Screening Test - After a brief visual muffler check, a stationary test is undertaken. Sound levels will be measured 15 feet in front and behind the vehicle while the engine is revved at the maximum allowable rpm or the red line of the tachometer. The average should be no more than 100 dbA with no single reading over 104 dbA.

2. Pass-by Test - With the vehicle under full acceleration on the track, a reading will be taken from 50 feet. The maximum level allowed is 92 dbA. This level and standard is the most commonly used in North America and Europe and is where the entire industry is headed. Tests are valid for 9 months unless modifications to vehicle are made.

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PostPosted: February 20, 2008, 11:07 am 
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I ran into this at Laguna Seca with their 92dB limit. Fortunately I have room behind my mid-engine layout for the biggest Walker Dynomax muffler I could find.

My brother, OTOH, is building a Stalker and he's facing the same thing you are, that a Locost doesn't look nice with big mufflers. You can try tricks like having clamp-on turn-downs that you can point opposite the sound meter.

Of course, a Locost has tons of space for mufflers, but they'll be a big eye-sore on the street. For the track though, you can just install big-ass mufflers and remove them later. It certainly beats getting kicked off the course, or having to lift off the gas everytime you pass the sound station! I know how much that sucks, to have built the car, driven all the way there, then have to let off the gas with someone on your tail...

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PostPosted: February 20, 2008, 11:38 am 
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KB58 wrote:
I ran into this at Laguna Seca with their 92dB limit. Fortunately I have room behind my mid-engine layout for the biggest Walker Dynomax muffler I could find.

My brother, OTOH, is building a Stalker and he's facing the same thing you are, that a Locost doesn't look nice with big mufflers. You can try tricks like having clamp-on turn-downs that you can point opposite the sound meter.

Of course, a Locost has tons of space for mufflers, but they'll be a big eye-sore on the street. For the track though, you can just install big-ass mufflers and remove them later. It certainly beats getting kicked off the course, or having to lift off the gas everytime you pass the sound station! I know how much that sucks, to have built the car, driven all the way there, then have to let off the gas with someone on your tail...


Yes, nothing worse than getting sent home. As you can tell by the cage on my car, I intend to have some track fun with this car. ;) So it would suck if I get sent home. Oval shaped baffled mufflers just look like ASS on a Locost.

One idea would be to run the collector muffler, into a 14" long 5" round muffler and then cap the end with a Supertrapp. LOL, would look funny. How many mufflers does a car need? That would be 6 in my case. :shock:

Paul

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PostPosted: February 20, 2008, 2:42 pm 
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Ooooo, don't get me started about SuperTrapp "mufflers". They somehow mastered the rare engineering feat of achieving high back-pressure - with maximum loudness.

At that same Laguna Seca event, I had to remove all but 2-3 baffle plates for it to, um, STFU. Oh, and then a couple of the bolts in the end cap froze up and snapped off (even with antisieze). With it finally quite enough, the resulting back pressure was so great that it physically pushed the end-cap right out, stuffing and all. Never again will I use a SuperTrapp! Grrrrr :evil:

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PostPosted: February 20, 2008, 3:35 pm 
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Paul, you always have the option of bolting a couple turbos to it, that'll quiet things down by a good bit :twisted:

Kurt, IIRC the best "Laguna Seca special" exhaust sys tip should point down and to the left.

Moti

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PostPosted: February 20, 2008, 6:50 pm 
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Blackbird wrote:
Paul, you always have the option of bolting a couple turbos to it, that'll quiet things down by a good bit :twisted:

Kurt, IIRC the best "Laguna Seca special" exhaust sys tip should point down and to the left.

Moti


LOL, yeah, that would make it nice a drivable. ;)

Paul

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PostPosted: February 20, 2008, 7:47 pm 
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Mouahahaha! ;)

http://cgi.ebay.ca/82-92-Chevy-Camaro-Trans-AM-V8-T3-T4-TT-Twin-Turbo-kit_W0QQitemZ370024867583

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PostPosted: February 20, 2008, 8:55 pm 
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Well you could consider using Japanese motorcycles as an inspiration. Bikes with 1 litre plus motors and lots of horsepower have exhaust exits you could plug with your thumb. So it's doable without too much power loss. Having said this, I don't know what the insides of those mufflers look like.

For a regular muffler, I've noticed a few feet of pipe on the exit make a huge difference on the noise. So perhaps you could work up a setup where you add extra pipes for the track that reroute under the car behind the cockpit and exit under the rear. I saw someone here that had that setup for rear exhaust. The extra length and a couple of bends will help the noise. A small restriction at the end may also help noise, and with the extra pipe may not hurt performance that much.

Don't use overly large header tubes?

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PostPosted: February 20, 2008, 10:22 pm 
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Here are some photos of my American 7 with flowmasters.
I still need to build the covers.The covers will have a heat blanket built into it.The plan for the front pipe is a rap.
The sound level is very low.
Just a idea??[img][img]http://i257.photobucket.com/albums/hh232/schiada/LotusandBirds019.jpg[/img][/img]Image[img][img]http://i257.photobucket.com/albums/hh232/schiada/FirstRunLotus7022.jpg[/img][/img]

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PostPosted: February 21, 2008, 2:12 pm 
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I don't know the sound or quality of these pipes... But they look ok.

http://www.jcwhitney.com/autoparts/Prod ... 61/c-10101

Image

There are a few "round" mufflers out there, from like magna flow and it competators that might work, you might need 2 per side (or banks of Cyl's)


Edit here are some from Magna flow
http://www.magnaflow.com/02product/shop ... in&id=1438

Flowmaster
http://www.flowmastermufflers.com/outlaw.html

Borla
http://www.borla.com/products/product_m ... are|S-Type

They are pretty darn bin in some cases... But still retains the look.

Glass packs are allways a option?

Good luck and keep us posted.

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PostPosted: February 21, 2008, 5:56 pm 
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KENLUDE97 wrote:
There are a few "round" mufflers out there, from like magna flow and it competators that might work, you might need 2 per side (or banks of Cyl's)


Glass packs are allways a option?

Good luck and keep us posted.


Glass packs don't provide much in the way of muffling. Everything I've read has suggested they won't come close to what I need. Likewise most "straight trough" designs like Magnaflow, don't get the db reduction. I found the following forum post:

http://ls1tech.com/forums/showthread.php?t=113572

where they discussed the power and loudness of many mufflers (info below). This was originally posted from a Mustang forum, unfortunately that post no longer exists. So I'm not sure what engine, but will assume the 4.6 or 5.0.

As you can see on the muffler list below, at WOT, NONE of the mufflers would meet the sound requirements at the local track.

I did find another company, actually located in Canada, called DNA mufflers. They sell through Jegs/Sumitt etc. They don't use packing material in their mufflers, but a series of welded in sound diffusers. You can see it in this pic:

Image

Their website is http://www.dnamufflers.com and more information on the muffler can be found here http://www.rpmoutlet.com/pbb3.htm - They have sound clips on their website which gives their design promise. I talked to Randall from DNA, and while he couldn't be sure I would get 92db, owing to all the differences between engines, etc, they said that their muffler, on large displacement engines sounds deeper, but not much louder. They tested a Hummer from 8ft with a single muffler and seem to remember it being a little more than 92db. So a 50ft test, with tips that I can angle away from the sound meter and I might have something.

Whatever I come up with I'll test myself, I've got a SPL Meter at home.

Paul


1.Borla XS, 80db at idle, 90db at 2,000 rpm, 110db at WOT.
2.Hooker Maxflow, 80db at idle, 90db at 2,000 rpm, 120db at WOT.
3.Magnaflow, 82db at idle, 91 at 2,000 rpm, 114db at WOT.
4.Flowmaster, 82db at idle, 93 at 2,000 rpm, 115db at WOT.
5.Flowtech Warlock, 83db at idle, 92 at 2,000 rpm, 112db at WOT.
6.Dynomax UltraFlo, 83db at idle, 94 at 2,000 rpm, 113db at WOT.
7.Borla XR1, 83db at idle, 96db at 2,000 rpm, 118db at WOT.
8.Bassani Street, 83db at idle, 96db at 2,000 rpm, 120db at WOT.
9.Edelbrock RPM, 84db at idle, 93db at 2,000 rpm, 118db at WOT.
10.Bassani Real Street, 84db at idle, 96db at 2,000 rpm, MAX. (120+db).
11.Flowtech Afterburner, 86db at idle, 94db at 2,000 rpm, 115db at WOT.
12.Flowtech Terminator, 86db at idle, 94db at 2,000 rpm, 119db at WOT.
13.Hooker Aerochamber, 87db at idle, 94db at 2,000 rpm, 114db at WOT.
14.SpinTech, 87db at idle, 97db at 2,000 rpm, 116db at WOT.
15.MAC, 87db at idle, 98db at 2,000 rpm, 119db at WOT.
16.No Muffler, 91db at idle, 103db at 2,000 rpm, MAX. (120+db).

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PostPosted: February 21, 2008, 8:01 pm 
I'm using Yamaha R-1 Titanium mufflers - see a motorcycle wrecker near you! They're very quiet (you can't even hear a stock R-1 at 10,000 RPM+), and stay cool on the outside so a heatshield is not necessary. Stainless steel inlet pipe and clamp, as well. Might not work well enough for a large V-8, but should be great for anything smaller.

They can be expensive, though...new replacement cost is anywhere from $450-$900 each. I got two, used, one for me and one for my buddy, in like-new condition for under $100 each. 8)


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PostPosted: February 22, 2008, 3:35 pm 
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paulmon wrote:
I did find another company, actually located in Canada, called DNA mufflers. They sell through Jegs/Sumitt etc. They don't use packing material in their mufflers, but a series of welded in sound diffusers. You can see it in this pic:

Image

Their website is http://www.dnamufflers.com and more information on the muffler can be found here http://www.rpmoutlet.com/pbb3.htm - They have sound clips on their website which gives their design promise. I talked to Randall from DNA, and while he couldn't be sure I would get 92db, owing to all the differences between engines, etc, they said that their muffler, on large displacement engines sounds deeper, but not much louder. They tested a Hummer from 8ft with a single muffler and seem to remember it being a little more than 92db. So a 50ft test, with tips that I can angle away from the sound meter and I might have something.


I tried one of the larger DNA mufflers and it was louder than the brunt out Magnaflow that I took off. This is for a rotary powered car, it may work better on a piston engine. I ended up with a giant 7" dia, 30" long Dynomax turbo muffler. Got me down to 88dB, but not a clean look. You might want to try two mufflers in series, this is often done on rotary powered cars (which are known for being loud).


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PostPosted: February 22, 2008, 4:17 pm 
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They actually said their mufflers work with low frequency better, which goes to reason that it wouldn't work well on a rotary.

I'm going to give them a try, can always throw them on ebay if it doesn't work and/or add another in series.

Paul

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PostPosted: June 25, 2008, 5:49 pm 
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any update on the DNA's?

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