Why are exhaust brakes loud?
11-14-2002, 12:02 AM
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Why are exhaust brakes loud?
Ok, I'm full of questions and that one probably sounds completely ridiculous!<br><br>I am wondering this though.<br><br>My concept of the exhaust brake is that it shuts off the flow to the exhaust, thereby increasing back-pressure.<br><br>For some reason, it seems to me as if cutting flow to the exhaust system should make things *quieter* since it is pretty much the reverse with everything that increases flow.<br><br>What am I missing here?
11-14-2002, 12:22 AM
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Re:Why are exhaust brakes loud?
Hmmm... I must be thinking of the wrong thing.<br><br>I assumed that is what is going on when you hear a big-rig going down a grade that sounds like a whoopie cushion on steroids?<br><br>Sean
11-14-2002, 12:43 AM
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Re:Why are exhaust brakes loud?
On a big rig you are hearing an ENGINE RETARDER which is very different than an exhaust brake. As you mentioned, an exhaust brake is just an obstruction in the exhaust system, a retarder floats the valves on the power stroke. An exhaust brake provides back pressure, a retarder uses the compression stroke to slow down by robbing the power stroke. Similar results, very different methods. Retarders are rarely seen on engines with smaller displacement than 10 liters, and are never seen on engines with hydraulic lifters. When you hear a loud one it is usually on a rig with no mufflers. The rapid fire popping is the retarder, the diesel roar is the lack of mufflers.
11-14-2002, 12:55 AM
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Re:Why are exhaust brakes loud?
Mine is not loud out of the exhaust tip, but it does make noise under the hood. It's basically a hissing sound which I assume would be excess pressure being released. The brake sure does work nicely though.
11-14-2002, 01:10 AM
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Re:Why are exhaust brakes loud?
Jack, you are the first person I've seen so far that has an auto and an exhaust brake.<br>Could you tell me what the ins and outs are for using/installing on an AT?<br><br> 
<br><br>Sean
<br><br>Sean
11-14-2002, 09:22 AM
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Re:Why are exhaust brakes loud?
I just finished putting on my new PacBrake yesterday. I love it! The sound is more than a hissing sound on mine. Of course, the 4" exhaust makes a difference too. Mine sounds like the exhaust tone was just turned up a notch when it engages. There is some hissing noise but there's a rumble in the background. I figure that the exhaust gas going through that little hole in the butterfly makes the velocity high and changes the sound. I'm amazed at how good it works.
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11-14-2002, 10:58 AM
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Re:Why are exhaust brakes loud?
My Pacbrake is louder when in use, both at idle, and when the brake is actually braking. I have an auto tranny also. To use an exhaust brake, you have to have a way to keep your torque converter locked up, and also you should have a heavier duty torque converter and valve body. If you use one on a stock tranny, you will tear things up. I have a DTT equipped transmission, and I love it. I also have the DTT SmartController that keeps the TC locked up then the e-brake is in use.
11-14-2002, 11:18 AM
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Re:Why are exhaust brakes loud?
Yes, Jack, I have it on almost all the time. My installer tells me that I should turn it off when the roads get slick, though. I guess that it tends to want to make the rear end pass the front on the snow and ice. [undecided] Also, I find when I turn the e-brake off, I get annoyed that I have to use the brake pedal so much.
11-14-2002, 05:40 PM
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Re:Why are exhaust brakes loud?
[quote author=DPG link=board=4;threadid=7018;start=0#66769 date=1037294295]<br>Also, I find when I turn the e-brake off, I get annoyed that I have to use the brake pedal so much.<br>[/quote]<br><br>That's cause your lazy. 
11-14-2002, 06:17 PM
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Re:Why are exhaust brakes loud?
[quote author=BigBlue link=board=4;threadid=7018;start=0#66909 date=1037317238]<br>[quote author=DPG link=board=4;threadid=7018;start=0#66769 date=1037294295]<br>Also, I find when I turn the e-brake off, I get annoyed that I have to use the brake pedal so much.<br>[/quote]<br><br>That's cause your lazy. <br>[/quote] <br><br><br><br><br> OUCHHH. That'll leave a mark.
<br>[/quote] <br><br><br><br><br> OUCHHH. That'll leave a mark.
11-14-2002, 06:56 PM
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Re:Why are exhaust brakes loud?
[quote ]Also, I find when I turn the e-brake off, I get annoyed that I have to use the brake pedal so much.<br>
11-15-2002, 12:50 AM
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Re:Why are exhaust brakes loud?
Jack, I agree about the e-brake. You learn to get used to it. What exhaust temps do you have at idle. I have questioned BD about my temps going to 900 and 1100 degrees. they say my backpressure is set to high ???. I am set in the middle of the specs the give. Please let me know. Thanks Kelly