While the mechanic was disassembling the engine on our 1993 U300 (DD 6V92TA) he noticed that the muffler had some holes in it, and said that it wouldn't pass a Texas vehicle inspection. We decided that it was more important for him to get the engine taken care of and replacing the muffler could wait. There have been several discussions about replacing the muffler with a resonator, but always on newer coaches.
What might be involved in such a project on my coach? I've been warned that the muffler is heavy. How heavy? How heavy is the resonator? What's the cost of a muffler and a resonator? I do have two hydraulic jacks and can easily build some sort of cradle to support the muffler, then lower it some if it is too heavy. Obviously, I'm not too concerned about damaging the old muffler while I'm in the process of replacing it.
Ideas?
Reply #226 and #237:
Resonator and muffler replacement (http://www.foreforums.com/index.php?topic=15111.msg206944#msg206944)
Texas inspections check for safety items-horn, brakes, lights, etc. No one climbs underneath or measures db's.
Have seen them check a bad muffler on a car or a pickup
but never on a big truck or a motor home, but the dealer
where he was having his work done was trying for a muffler
job, as well, I think.
Carter-
We changed ours out to a resonator two years ago and it has been great. It defiantly is a lot lighter. Our old muffler was huge and heavy, while the resonator is smaller and much lighter. Good luck!
Jeff
What brand of resonator does everyone suggest?
Most (including) me use Aero, search for other options on forum, lots of resonator threads
Used Aero on several coach's. Tried Jones Turbine on present coach, very similar to Aero but $50 cheaper.New Jones 5" TURBINE XL Truck Muffler Polished Stainless Steel 5050XL (http://www.ebay.com/itm/New-Jones-5-TURBINE-XL-Truck-Muffler-Polished-Stainless-Steel-5050XL-/291505487456?hash=item43df14be60:g:wpgAAOSwnDZUKxa1&vxp=mtr)
It's an easy and inexpensive DIY job on a U300 but if you live in the mountains like we do, the Jake (if you have one) would be louder in our neighborhood. I think Andy installed one on his coach so he might be a good person to ask on the noise difference.
U300 Detroits have a 5" exhaust pipe so the following will fit. About $170 in galv steel, $225 in stainless. Google (https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=big+rig+diesel+resonator&tbm=shop)
Pierce
We started with an Aero and changed to a Magnaflow. Found the latter to be much quieter without any perceived change in other factors.
Will my cat 3208T go faster or get better mileage?
Not sure, but it will sound cooler >:D
Gain 10 mpg and will need to watch for wheelspin when shifting into second.
Seriously, unless you are finally attuned to your coach, and keep good records of mileage. Probably not.
less back pressure - = either a tad better gas mileage, or a bit more power. But if you use the power - it will cost you gas - if you drive it the same way as before (in theory) you will have the same power at a slightly lower fuel burn.
For me, I noticed right away - much faster off the line - I suppose because turbo is spooling up against less resistance - that and the sound made it an easy decision for me - Again, search the forum threads - hundreds of posts out there on this topic - all from what to buy, how to install, etc.
I went from a rusted out muffler to a straight pipe with no resonator or muffler. Just five or so feet of pipe. Its loud outside but from the drivers position sounds wonderful. Didnt see any gains, but thats to be expected when the original pipe was no longer fully connected to the muffler.
Word of warning, if you drop the muffler on yourself, it hurts. Guess how I know. :/
This is not a good mod of you want to blend in. I always get a crowd of gawkers who want to hear all about my RV whenever I pull into a new campground. A common statement is "I knew this was something special when I heard it coming and saw those big chrome mirrors"
Tim noticed the same things
Quote"This is not a good mod of you want to blend in ?????"
Did this years ago and put in a basic steel resonator and love everything about it. It does make a difference and an added one is less heat under bed.
A no brainer.
JohnH
Faster spool up due to less back pressure equals less over-rich operating time (for mechanical injection engines) equals less pollution equals better fuel economy equals more hp generaly. Same goes for a BAHF air filter. Side effect on the exhaust may more noise. I have owned 2 vehicles that the WOT intake noise exceeded the the perceived exhaust noise.
BTW I'm pretty sure HD has a patent on how to convert gasoline to noise without the side effects of HP or performance.
I changed to a 4" diameter Aero muffler several years ago, mainly so I would have more room in that area for something else (AC compressor units). The difference between the Aero resonator and muffler is length. Made of polished stainless steel which discolors as soon as it gets hot. Weighs less than a muffler. My experience is that it makes a little bit more noise at idle, but is about the same at speed. The turbo does most of the muffling. I cannot tell any difference in power or economy, but there may be a little bit of improvement. If you have a jake brake, the Aero may not be suitable.
Jeff- my resonator is Donaldson, basic metal. I didn't need or want stainless under the coach. I like not having the heat in the bedroom after running and turbo spools up faster and a little more boost at top end also.... ^.^d
I agree with Michelle in reply #9 "We started with an Aero and changed to a Magnaflow. Found the latter to be much quieter"
I installed the Magnaflow because Brett W posted that it is favoured in Cat diesel websites he monitors because it is quieter.
I am not sure why most folks here seem to prefer the Aero, but do know from experience that the noise level is highest with pipe, then Aero resonator, then Aero muffler, then quietest with Magnaflow.
The Aero muffler (not resonator) has internal ports which Aero claims reduces back pressure using a venturi effect. I do not know if it actually works, but do know that it does change the sound.
What model Magnaflow? The website doesn't like 1993 Foretravel.
For the Detroit get the biggest one probably 5". Detroits flow a boatload of exhaust cfm because they are 2 stroke. At full load iirc it's around 2900 cfm so about 240 mph air out the pipe. use slash tip instead of straight tip at the outlet.
Have heard before that slash tip is better for flow, but wonder why?
Andy 2 is the only forum member I know who did this change on a coach just like yours (except the year: his is a 1992 but I think it has the identical muffler layout). Here's his post on it with pictures: Resonator install (http://www.foreforums.com/index.php?topic=25762.msg204718#msg204718)
It appears you need to select a resonator that is not too long if you do an install like his.
the slash tip allows the air to exit in a straight line uninterupted while the round pipe allows a hollow pattern of air that rolls over itself thereby not exiting the pipe cleanly. I made the end of mine like a "flatterned sine wave" so the decibels are low but the effect is actually "sucking" the fumes out as well as being blown by pressure. This gives me about a 3.5% more efficient engine and better fuel economy.
JohnH
I used the MagnaFlow 12771. It is 4" in, 4" out, and 4" bore straight through the center. My exhaust pipe from turbo outlet to muffler is 4", and my tailpipe downstream of muffler is 5". I used a 4" to 5" adapter from muffler to tailpipe. It's a dirty D.I.Y. job, but not technically difficult.
7" ROUND 12771 (https://www.magnaflow.com/products?partNumber=12771)
Has to do with the velocity pressure loss based on exit area and poor exit conditions of the straight pipe creating more turbulence and more resistance. Slashed elbow that you see on otr trucks is good also. 6v92 Detroit 2 stroke engines are flowing 2X amount of exhaust of a four stroke (all other factors being equal, which they are not, hence the term boatload). Donaldson has charts showing expected peak flows. Ultimate may well be a bellmouth exit in the low pressure zone on the back of the coach giving a couple of pounds of free boost while reducing vehicle areodynamic rear drag.
Four stroke racing Motorcycles use three steps in the tubing diameters as it leaves the head. More even power. More peak power, more torque
Chuck,
Before I ask this question, I admit that I did not do well in my Fluid Dynamics course:
What is the advantage to using a 5" tailpipe when all of the other pipes are only 4"?
Thanks,
Trent
Don't know about Chucks case, on on my isc 350, turbo out is 4 inch, then to a 4 to 5 inch adapter, into exhaust can then 5 inch to chrome tip at back.
When brother Dave was living , he and I tried to figure out how to do this on my coach . Physically it is doable but that is where it stops . Just too involved with all the computer sensors with the particulate filter mess . It is EPA from here to China and back , expensive and complex . Wow , makes me wonder about some of this stuff . This can be done . There is a business in Pittsburg Pa. that can do this . They specialize in the computer programing and that is exactly what is needed . They can take this engine to 850 HP as well , but the tranny can't take that much , so I'll just leave it alone for now . ::) ::) ::) Brad Metzger
1. Big tailpipes are more bad@ss than small tailpipes...this is a known fact...just look at all the "real" trucks you see rollin' coal on the superslab.
2. Big tailpipes
always make you go faster, regardless of what kind of engine you have.
3. The only thing better than one big tailpipe is DUAL big tailpipes!
Oh, and there is one other reason why I have a 5" tailpipe: Our coach came to us that way, and I re-used the existing tailpipe. 8)
Brad- I have read many good things about Pittsburg Power, but it comes down to how many coach bucks you want to spend to get more power vs how many miles can you go by spending the same coach bucks on diesel and going out to play with your toys and friends.
I do have a resonator but not all the power and stuff you have on your newer coach, so as Dave always said, " do what makes you happy." I love that saying and try to use it every day- thank you Dave.
I disagree that the transmission cannot take the extra horsepower. Unless you are trying to do Hole Shots leaving the starting line under WOT I do not feel you will ever achieve the torque levels needed to destroy your transmission. Once the Unit is in motion I would find it hard for you to ever reach a point where you were at or over the MAX torque rating for your trans.The thing about High Horsepower diesels is they do not have to work as hard to achieve the same results. With a good ECM program You can see a MPG increase as well as making the unit more pleasurable to drive. My 12.7 Series 60 Detroit is putting just shy of 600 hp to the ground seen on a dyno.It was 430Hp which might have been 350 to the ground before I made changes. I have to watch water temp and know when to back out of it,but the truck is a pleasure to drive and I am less stressed at the end of my day than I would have been fighting a underpowered rig all day long. The programs that Pittsburg Power and other places custom tailor to your application actually allow the engine to breath and operate more efficiently. Your Right Foot is attached to your wallet also and common sense will keep you from destroying the entire package. This is not something you would do if you had multiple drivers in your Rig. Same goes for a guy with a big truck like myself. I am the one that drives it every week, I pay the bills,etc. A employee would not care about taking care of the rig so the standard factory safeties are there to protect your engine. Common Sense has to be Used!! JMO 8)
Chuck, put in a fake 5" pipe coming out the other rear corner. Cool!
For serious hp gains add red stickers, along with the fake outlet. Other colors may well result in a hp loss.
In reply #21 kb0zke asked: What model Magnaflow?
In 2011 I installed a MagnaFlow 14774 $200 polished SS muffler, 5 in, 5 out, 30 long, 7 OD body. The Magnaflow 12774 is the same muffler which is cheaper because it is not polished. I found the 14774 (polished) on sale for less then the unpolished one.
About the HP and the tranny . Allison states that 650 HP is max for my model . I agree with you on it staying together , just sort of gave up on the unnecessary need of it . I'll just suffer along with what I got .But ---I sure do have it on my brain . Brad Metzger
Long ago the Allison guys allowed Foretravel to use a 277hp/840 torque 6v92 in the original unihomes in 1988.
Trans was rated for 780 torque.
Allison allowed this because of the light weight of the coaches.
I had so many customers complain about the 277 hp rating that there buddies teased them that THERE motorhome had 300hp(cat) that at the unihome seminar on Oct 87 in Nac I met the Detroit and Allison guys and asked if they could change the rating to 300hp.
They looked at each other and looked at their pocket specs and said that was fine as it lowered the torque to 820.
Side by side racing the 277 pulled the 300 noticeably. Two coach lengths to 60?
Fitted the resonator and wrapped with heat tape the help the dash ac , happy with results . Feels less choked, spins up more freely. Just seat of pants assessment.