| Author | Message | ||
| Bob Wies (Ncbob)
Rating: N/A |
While in CHI, picking up our MC5A last week, I was shown and Aero Turbine muffler by the seller. Cool! He's and old street rodder and plans to use one on his 8V92. Love the music these Detroits play. But, my first concern is about back pressure being too light for an 8V71 Detroit. I'm going to need a new muffler in the not too distant future so I was wondering if anyone has tried anything but the standard replacement muffler on a DD. I know they can get awfully snotty without enough back pressure and don't breathe right with too much. Comments appreciated. NCbob | ||
| Doug Wotring
Rating: N/A |
muffler not needed for a DD | ||
| JR
Rating: N/A |
Yep. I agree with Doug. All that I've read indicates DD 2 strokes don't need mufflers. They are for noise control only. Best, JR | ||
| Buswarrior (Buswarrior)
Rating: N/A |
Out of curiosity, not to be contrary... Back when the exhaust cross-over pipe on my 8V71 rotted off at the flange and started leaking badly, the engine power dropped off remarkably. I would have thought it would have at least been unnoticeable, or improved, but it sure didn't. Thoughts? happy coaching! buswarrior | ||
| T. (Bluegrass)
Rating: N/A |
I was under the assumption that to gain ft-lbs and HP you were supposed to open up the exhaust and also use less fuel while you were at It. Tony | ||
| Dallas Farnworth (Dal300)
Rating: N/A |
Back when I was a wee young thing, we always took off the mufflers and added 5" straight stacks. It worked so well, you could get flame out of the stack. It was really cool looking. Until I was headed up Snoqualmie with a load of hay. The boss didn't understand the toasted stuff. Anyway, back to reality, The 318's need some back pressure, such as provided by the 4" exhaust pipe. But all that's needed is about 4-6'. After that, it doesn't matter a whole lot. But remember, if you are on dry grass, the muffler is a spark arrester also. Dallas | ||
| Doug Wotring
Rating: N/A |
fLXIBLE fLEXLINERS HAD 6-71 WITH NO MUFFLER FROM FACTORY | ||
| Cliff (Floridacracker)
Rating: N/A |
Guys, I am really curious about this subject. I know I need to replace my muffler this year and am trying to figure out alternatives. I have an 8v71 and a new (not nos) is going to run me around $800+. I have thought about building a Y where the pipes went into the muffler and either adding a small diesel truck muffler or now what about straight pipes. How loud are one of these with straight pipes? Comments! Cliff | ||
| Buswarrior (Buswarrior)
Rating: N/A |
Hello Cliff, On the loudness, do not rely on a test in the yard by revving the motor. You want an under load, on the road, full fuel trial. My Freightliner hardly burbled in the yard with the pipes disconnected, but boy, you should have heard it on the road!!! happy coaching! buswarrior | ||
| Steve N. (N4rsn)
Rating: N/A |
Comming home from Florduh, in March, I was passed by an MCI that was doing about 75,on 75, I could hear it when his front was at my rear. (I am driving my 4106). It was sooo loud, but It sounded sooo good. I LOVED IT. He had about 4" of about 5" pipe out the back. I never saw him again, but, I will remember the sound. (music) Steve | ||
| Doug Wotring
Rating: N/A |
I have a muffler that may suit your needs L26" 15"x10" oval 5.25" inlet and outlet. on the same end make me an offer...cannot determine what it is for...... it's brand new | ||
| FAST FRED Rating: N/A |
"I will remember the sound. (music)" G. Gordon Libby has a great CD of a WW11 Messershmit, supercharged fighter on take off. A headset and a 100W sound amp should take care of your delights , with out the horrors of the Harley crowd , with 4 mile megaphones. Your right to swing your arms about ends BEFORE my nose! Your "right" to noise ends BEFORE my ears! Or so one would presume Good Listening, FAST FRED | ||
| Jack Conrad (Jackconrad)
Rating: N/A |
Cliff, A friend has an MC-7 with dual exhaust (custom built by him). Each exhaust manifold goes to a small resonator and then up a vertical chrome plated stack on the out side rear corners of his bus. You can hear him a mile away when he takes off. A fellow busnut was following him and had to back off because of the noise level when following closely. Jack | ||
| TomNPat
Rating: N/A |
I've heard that the turbo on a detroit reduces the sound considerably. So if the 71's aren't turboed, they might be pretty loud without a muffler. Our 92 has a muffler and is quieter than Dodge and Ford pickups. Bus Warrior, is your engine turboed? If so, loss of exhaust volume before the turbo could affect performance. TomNPat | ||
| John MC9 Rating: N/A |
No exhaust sound dampening and a Jake brake in use..... Flames leaping from the exhaust pipe..... oh yeah... This is gonna' do busnuts a world of good, PR-wise... | ||
| Gary Carter Rating: N/A |
I gutted the muffler on our 4106. A freind was following me in the hills of east TN. Said everytime I hit it hill it sounded like a pack of Harley's. | ||
| JR
Rating: N/A |
My 6V92T muffler is gutted and the bus isn't noisy. The muffler body is intact, just a big can. I disassembled the muffler to repair a damaged tailpipe and found that the cat converter was 1/4 sooted up. Removed the cat core, and the rest is just a can. I was afraid it was going to be loud, but it isn't. The turbo chops the sound waves so no resonance...at least not within the normal operating range. JR | ||
| John MC9 Rating: N/A |
Gotta' listen to it whilst goin' thru a tunnel! (or from behind it while it's being driven) I have a hole in mine.. I didn't think it was loud, until I went thru an underpass with my window open.. | ||
| Buswarrior (Buswarrior)
Rating: N/A |
Hello TomNPat. Nope, no turbo. Maybe something to do with it being out of balance, more back pressure on the side that stayed together? Who knows? happy coaching! buswarrior | ||
| JW Smythe (Jwsmythe)
Rating: N/A |
As far as performance goes, as long as your engine is big enough, you generally get more power with as little restriction as possible, both at the intake and exhaust end. Race cars run large open exhaust, only adding mufflers for tracks that require it. As a few other people said already, the DD's do fine with no muffler. Turbos do add some restriction, but compensate nicely by the pressure they provide. Most mufflers do provide some protection as flame arrestors. In most gas engines, you shouldn't see any flames beyond the collector of the headers. You'll see them if you only have exhaust manifolds and no or short pipes. This will burn your exhaust valves. The backpressure provided by the pipes take care of this. The flame is usually just excess fuel, and can be tuned out. I know diesels are different in this respect, and frequently have unburnt fuel passing out the exhaust. You can't exactly advance or retard the spark timing.  Exhaust pressure balance is VERY important on gas engines, and I have to assume just as important on diesels. For performance cars, the collectors are usually adjustable for your setup. People generally buy headers that are tuned by the aftermarket manufacturer. Some performance cars with true dual exhaust, factory or otherwise, sometimes have a H pipe connecting the two exhaust pipes to provide a consistant pressure. If you don't have a turbo, or have two turbos, you could probably get away with independant dual exhaust pipes of equal length. If it has two turbos, you'd need to make sure both pipes were equal distant to the turbo and equal distant to the exhaust tip. One turbo would provide mis-matched pressures, and cause trouble. Generally, I'd say be polite and keep the muffler stock. John MC9, ya.. When I drove my RTS home (6v92 turbo), I had the front door open, as well as my toll window. It was hot out, and I was dying without them open. I passed under a few bridges at full throttle, max RPM's, and an indicated 65mph (it still has city gears). It wasn't too loud, but it did make a very loud pleasant scream under the bridges. I'll be happier when it's not redlined all the time. My trucker friend says it's fine as long as I don't try to adjust the governer. Some truckers run at red-line all the time, depending on their equipment and the route. He's done a lot of interstate driving, but is now doing in-state driving for a local company. | ||
| Geoff (Geoff)
Rating: N/A |
To me there is nothing less impressive than a bus with loud exhaust. A bus is supposed to represent comfort and refinement, not noise competition for Harleys and kids' cars with Yakimoto exhausts. | ||
| Cliff (Floridacracker)
Rating: N/A |
OK, Lets recap what we know: A DD 2 stroke CAN run without a muffler It will be loud under load. The odds are you will cause a PR problem, Attract the noise police(FF), or look unrefined. The difference between Music and Noise is still an individual opinion(unless regulated by Law) In the end I will either repair or replace my muffler. I like the sound of my Detroit, but within reason. Cliff | ||
| Larry D Baker (Lbaker4106)
Rating: N/A |
I have had one on my 4106 for a year. Engine runs good with no notice of lower power. With the replacement muffler and a new air filter I picked up about a half mile per gallon. It is noisey when you step on it but I can tell if I start to get into it too much while on the road. I made my own exaust pipe to take the muffler. | ||
| Bill Gerrie (Bill_gerrie)
Rating: N/A |
A friend of mine has an "Aero Turbine " on his bus and as he was passed by truckers coming home from Texas he heard them comment on the CB "boy is that bus loud". It is a 6V92TA. Food for thought. Bill | ||
| FAST FRED Rating: N/A |
"You'll see them (flames)if you only have exhaust manifolds and no or short pipes. This will burn your exhaust valves" A more common danger with short or straight stacks is warping the exhaust valves on rapid cooldown. The muffler system provides some protection to the entry of large volumes of cold air. A short stacked coach might wish to idle for 2 min to help get the exhaust valves to cool down. FAST FRED | ||
| Jarlaxle Rating: N/A |
Many old non-turbo diesels would pop flames out of the stacks...common enough to be mentioned in a song. I've seen it a couple times. | ||
| Marc Kirby Rating: N/A |
4-Strokes - The turbo cuts the noise, so I've always run them without a muffler. Performance makes a dramatic improvement as a result. 2-Stokes - First thing I did when I got my 8V-92T was to remove the muffler. Oh my gosh, what a mistake. 2 stokes are some kind of noisy even behind the turbo. The muffler that was on the bus was some little thing that had been drug a time or two and I wanted a new one anyway. Found some company up north that custom builds mufflers. Just supply them info on engine, dimensions, and .... the'll build what you want. I forgot the price, but around $200 or so. I had them build mine with an outlet on each side so when I piped it up...I've got dual exhaust. |