muffler

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muffler

August 18, 2010, 06:27:35 pm

just wondering if anyone with an 8.3 mechanical (325 hp) has swapped out the muffler for a aero
turbine muffler or is even running a straight pipe? any comments on increased performance, m.p.g. or noise?

Re: muffler

Reply #1 – August 18, 2010, 08:53:45 pm

Wayne,

Don't expect any performance gain unless you've seriously powered up your 8.3.

Re: muffler

Reply #2 – August 18, 2010, 09:35:38 pm

Dave,

I wonder if anyone has done this and what improvement in mileage they noted?

Jim
2002 U320

Re: muffler

Reply #3 – August 18, 2010, 10:24:05 pm

Hello;
My engine is ISC 8.3
I removed the stock muffler and played with a few different setups. My goal was to see how much the stock system hampered airflow through the engine, if any.
The stock system has several turns in the piping. I eliminated almost all , four inch stainless steel flex approx 42" long into a 4" to 5" increaser into a 5"x 36"long chrome turn down. Was a little loud at idle, so I installed some ceramic fiber. Just right sound at idle.
The engine now spools up faster BUT the big advantage was the long hills around Cinn. Oh. are now a easy pull AND a lot less heat ,I think the MPG went up 5%.
Mind you I am not in any way abusing or hot rodding , just wanted to have the engine breath easier with less heat.
Anyone need a stock muffler cheap?

Re: muffler

Reply #4 – August 19, 2010, 12:12:47 am

Quote from: Wayne Macauley – August 18, 2010, 06:27:35 pm

just wondering if anyone with an 8.3 mechanical (325 hp) has swapped out the muffler for a aero
turbine muffler or is even running a straight pipe? any comments on increased performance, m.p.g. or noise?

Wayne,
I am about to do this on my 8.3 (325 HP) mechanical.
I have significant corrosion (through wall) on the original muffler and the outlet piping (both of which were only aluminized material) and on the final chrome exhaust extension. The turbo outlet flex piping and the 30 degree elbow into the original muffler are both 304 SS and they are still strong and sound.
I had a chance to purchase an AERO 4040XL Resonated Performance Diesel Muffler for $75 some time ago and I have subsequently rounded up the additional pieces that I need to make a fully 304SS system including the exhaust extension.
I have seen two AERO mufflers, both on larger diesel SOB's with 5 inch exhausts, but I couldn't tell that the engine sound or note was anything other than stock at either idle or load. Both owners professed a 5% (+) improvement in mileage over the long term (one had about a year's worth of data and the other had over three years of data behind their claims).
I'm more interested in just improving engine breathing flow (a 4 inch AERO Muffler eduction design = a straight 5 inch pipe, in terms of restriction forces), reducing exhaust system weight and I know that I can vastly improve the hanger design as well.
I do have a couple of questions:
I noticed recently (viewed from the bottom) that the exhaust manifold valley between the front and rear three cylinders has a 2.5 inch (or so) surface crack dead center in the valley. It is obviously not a through wall crack in that there are no exhaust plume discolorations of the metal surrounding the surface crack.
Has anyone else seen anything similar?
Should I replace the exhaust manifold now or would it likely go a long time before progressing to through wall?
I'd appreciate any insights that you may have.
Neal

Re: muffler

Reply #5 – August 19, 2010, 01:33:24 pm

I've got an ISC 350 (99 U-270), and had the exhaust manifold crack all the way through. The crack was 1/32+" wide, and leaked plenty, wouldn't let the turbo spool up much, lots of black smoke out the tailpipe. Had it replaced about a year ago at Cummins Gillette, WY. The manifold was s 2-piece design (maybe all 8.3's are 2-piece?), and I had them replace both pieces. No idea if or how long there was a surface crack, but I would get it replaced, since it will seriously cut your power down if it gets as bad as mine. Apparently Cummins 8.3's have a history of exhaust manifold cracks, and the replacement is a revised design.

Re: muffler

Reply #6 – August 19, 2010, 08:50:04 pm

Quote from: Dave Katsuki – August 19, 2010, 01:33:24 pm

I've got an ISC 350 (99 U-270), and had the exhaust manifold crack all the way through. ................ Apparently Cummins 8.3's have a history of exhaust manifold cracks, and the replacement is a revised design.

Thanks Dave,
On the '98 8.3 mechanical, the manifold is all one piece.
Cummins is advising me that the surface crack is not necessarily urgent and could very well go quite a while (maybe years) before cracking through-wall (I need to keep an eye on it for change). But Cummins is also advising me that it is entirely unpredictable. Cracking in this exact location is apparently quite frequent and common on my engine. I'll have to find out if the new manifold is of an improved design. They didn't mention anything about that.
The quoted manifold is about $485. The other parts bring the parts total to about $775 (includes an improved thermostat and housing and gasket). Labor, based on the appearance of my manifold bolts, is about 5 hours. Of course, grubbing out broken manifold bolts could quickly double that.
Did you have any broken manifold bolts or other upsets in your replacement process?
Neal

Re: muffler

Reply #7 – August 19, 2010, 09:54:17 pm

I had one or two break on my 93 while replacing it - at the front by the coolant filter. The new C8.3 manifold is no different. With a good install it should last 10 to 15 years. They warp, then break and/or blow the gaskets...

Re: muffler

Reply #8 – August 19, 2010, 11:06:56 pm

Cummins did not have to drill out any bolts but noted that one was "hard to remove." Total for the replacement of the 2 piece ISC manifold and associated gaskets & hardware was $825. Cummins said that the two piece ISC manifold design was to address warping and cracking, but apparently it doesn't completely do that...

Re: muffler

Reply #9 – August 19, 2010, 11:22:08 pm

RE: "grubbing out broken manifold bolts could quickly double that"

Remove broken exhaust manifold bolts: The champion of methods for removal of stubborn broken bolts is to drill them out, using a left hand drill bit and a reversible drill. (The good quality, variable speed, 3/8" models, which produce good torque at low RPM, work best.) As always with drilling holes, drill a small "pilot hole" first, then drill a larger hole through the broken fastener. (It's easier to drill centered and straight by using a small drill first, but be careful not to break the small drill!) Most bolts come out before the hole drilling operation is finished. (Then there is no need for "easy-outs," which sometimes break off in the drilled hole and make matters worse.)

Keenserts are better than Helicoils for an new threaded hole.
http://www.newmantools.com/kee.htm

Re: muffler

Reply #10 – August 19, 2010, 11:22:09 pm

RE: "The manifold was s 2-piece design (maybe all 8.3's are 2-piece?)"

Earlier Cummins C8.3 engines use a one-piece exhaust manifold and cannot be changed to the later two-piece manifold.

Re: muffler

Reply #11 – August 20, 2010, 06:46:42 pm

neal
can't help you with the cracked exhaust manifold, mine seems to be fine. my stainless
exhaust tip was rusted and the flex from the turbo is totally rotten but my muffler is in
good condition.
anyway to make a long story longer, I pulled everything off, from the turbo back, and I
am going to run straight pipe all the way, without any flex. if there is too much
noise I might insert an aero muffler. I don't really expect any increase in performance,
power or anything else for that matter, but I just like messing around. let us know how
your modification works out.

that's tulip

Re: muffler

Reply #12 – August 20, 2010, 08:24:15 pm

Wayne;
You should have some flex to absorb the movement and vibrations of the engine.....lest you may damage $$$$ the turbo. Old diesel mechanics chime in,,,,

Re: muffler

Reply #13 – August 20, 2010, 08:28:51 pm

gary
thanks, I did not know that. I will use some flex.

Re: muffler

Reply #14 – August 20, 2010, 09:28:26 pm

For sure, some turbo's do not have a heavy mounting, meaning the exhaust is directly off the turbo flange, weak and fragile.

Look to see if the turbo has a heavy mounting with casting bolted to the engine after the hot side turbine.

If not use flex and some hangers.

Have not looked at the ISM setup yet, if it has the heavy mounting, I would run the 5" exhaust pipe out the corner with a resonator (Walker makes them), directly out the corner, maybe no hanger, would need to see how it works out.

That is the method used on my MCI with Detroit Diesel 8V-92, worked great.
FWIW
Dave

Re: muffler

Reply #15 – August 24, 2010, 08:29:18 pm

neal
did you go ahead and install your new exhaust?
I have stripped my exhaust system from the pipe that exits the turbo all the way back.
I was reading gary's install of his straight pipe and it sounds like (gary, correct me if I am
wrong) he ran 42 inches of flex off of the turbo downpipe to a 5 inch adapter and then 5
inches the rest of the way back.
my question is, will going to a 5 inch after running almost 4 feet of 4 inch make any
difference, other than the fact that you will have a big honken 5 inch tip out the back, that
off course will look good.

Re: muffler

Reply #16 – August 24, 2010, 08:45:46 pm

Wayne;
I was trying to replicate what the original setup was .My coach had a short piece of 4" flex(for vibration) then a couple of elbows then a increaser to 5" into the muffler.
I believe that the increase to 5" will cause a low pressure area thus helping to draw the gases from the engine. I am no expert but have worked with air flow and racing applications for a lot of years. It really lets the whole system breath easier. The old saying"can't eat , can't poop",,,,"can't poop , can't eat". In this case I believe the coach has enough cool intake air,but I feel the poopin end needed help. It sure made my coach a lot happier especially on the climb up the hills.

Re: muffler

Reply #17 – August 24, 2010, 09:06:18 pm

gary
thanks, I am going to the truck store tommorrow and start to buy the necessary pieces.
I think I will start with the 42 inches of 4 inch stainless flex and the 4" to 5" inch adapter and
a few torctite clamps.
If I need a hanger for the flex, do I need a special hanger or take any precautions to avoid
damaging the flex. the way it was before, it ran straight into the muffler and was fairly
rigid. also, not being a U-320 do I need a bigger hole in the back to accommodate proper clearance for a five inch exhaust tip?

Re: muffler

Reply #18 – August 24, 2010, 09:52:09 pm

Wayne;
I did not need a hanger for the flex,but I used two hangers on the 32 inch (?) rigid turndown pipe,as I recall.
My 1999 295 had a 5" tail pipe and the hole was OK. Your application may vary.
My experience with "straight pipes" is that you may need a resonator to stop droning(sp) that is why I used ceramic fiber in the first 12" of the 5"turndown pipe,,,kinda like a old school glas pack. If you want you can use a 5050xl and shorten the turndown pipe (pprox$120) the xl is about 8" diameter will work fine,,,,but keep it away from the air intake duct (plastic) and A/C condenser system.
I was in a time restraint or I would have used the 5050xl,,,still may change it.
The measurements may be different on your application.
Good Luck mellow sound.....BRRrrrrrr.

Re: muffler

Reply #19 – August 25, 2010, 01:47:24 pm

Wayne,
I haven't installed mine yet - I'm waiting to work with my son (great welder) on a new hanger for my 4040XL AERO (I feel obliged to use that 4 inch AERO because I purchased it so inexpensively). I should have looked for a deal on a 5050XL, but I didn't think it through thoroughly enough.
My exhaust tip opening would definitely have needed increasing if I had gone to 5 inch diam. downstream of the flex. The tailpipe must have 3/8 inch or more clearance or it would be both a heat and a body contact problem.
I agree with Gary 100% on the need for less restriction in our exhaust. Our 8.3 intake system and air filter seem to be sized for an M11 but our 4 inch exhaust is very restrictive, by comparison, when it doesn't need to be. I also agree with Gary on the need for a resonator of some sort to prevent "thrumming" or "droning".
Going to a 5 inch system "after the turn to go aft" makes great sense. Flow restriction forces are cumulative, like resistors in series. So a relatively short 4 inch section is still going to be a restriction but overall, there will be a big improvement over the original muffler and the 4 inch "total system" restrictions.
I'm using urethane isolation hanger grommets and all 304SS components, including a polished 304SS tailpipe and (3) cab brackets for hangers where I can properly isolate and suspend the weight of the system from the frame.
My original turbo flange outlet turn-down, original flex and the 30 degree elbow into the original muffler were all 304SS and they are in excellent condition (I'll replace the flex anyway to an improved, lower flow restriction type). Everything after that, starting with the muffler, was just aluminized or zinc plated and those components are thoroughly rotted, from the inside out as well as from external corrosion.
The original hanger design has more than a hundred pounds of mass suspended from a single 5/16 inch bolt, so that can be improved.
I'll try to document my changes with some decent photos.
Good Luck with your changes.
Neal

Re: muffler

Reply #20 – August 25, 2010, 02:00:00 pm

I will get going on a muffler mod as soon as someone addresses a question on back pressure, is there any consequences to a mod on a 99 320 450hp as to back pressure required for proper engine operation? thanks jc

Re: muffler

Reply #21 – August 25, 2010, 04:40:55 pm

JC,
The less back pressure the better with any turbo engine, Any length exhaust pipe will work fine. For the ISM engine, it uses the 5" pipe, do not make it smaller, that would be restrictive.
Dave

Re: muffler

Reply #22 – August 25, 2010, 08:37:51 pm

Cheapest 5050XL I found: 169.00, 5050 even sheaper...
http://www.ourdealsrock.net/AeroExhaust.aspx

Quote

On 8/25/2010 1:47 PM, Neal Pillsbury wrote:
Wayne,
I haven't installed mine yet - I'm waiting to work with my son (great welder) on a new hanger for my 4040XL AERO (I feel obliged to use that 4 inch AERO because I purchased it so inexpensively). I should have looked for a deal on a 5050XL, but I didn't think it through thoroughly enough. My exhaust tip opening would definitely have needed increasing if I had gone to 5 inch diam. downstream of the flex. The tailpipe must have 3/8 inch or more clearance or it would be both a heat and a body contact problem.
I agree with Gary 100% on the need for less restriction in our exhaust. Our 8.3 intake system and air filter seem to be sized for an M11 but our 4 inch exhaust is very restrictive, by comparison, when it doesn't need to be. I also agree with Gary on the need for a resonator of some sort to prevent "thrumming" or "droning". Going to a 5 inch system "after the turn to go aft" makes great sense. Flow restriction forces are cumulative, like resistors in series. So a relatively short 4 inch section is still going to be a restriction but overall, there will be a big improvement over the original muffler and the 4 inch "total system" restrictions. I'm using urethane isolation hanger grommets and all 304SS components, including a polished 304SS tailpipe and (3) cab brackets for hangers where I can properly isolate and suspend the weight of the system from the frame.
My original turbo flange outlet turn-down, original flex and the 30 degree elbow into the original muffler were all 304SS and they are in excellent condition (I'll replace the flex anyway to an improved, lower flow restriction type). Everything after that, starting with the muffler, was just aluminized or zinc plated and those components are thoroughly rotted, from the inside out as well as from external corrosion. The original hanger design has more than a hundred pounds of mass suspended from a single 5/16 inch bolt, so that can be improved. I'll try to document my changes with some decent photos.
Good Luck with your changes.
Neal

Neal Pillsbury
'98 U270, WTFE, 36' Extreme, Build #5336
'03 Odyssey
'04 Gold Wing
'07 Featherlite 24'
Exeter, NH & LaBelle FL

Re: muffler

Reply #23 – August 28, 2010, 10:44:35 pm

I finished the install of the 5 inch straight pipe, on the 325 mechanical today.
there is definitely a little growl that wasn't there before, but even increasing
the rpm didn't seem to upset anybody in the hood. I will be going for a little
run in about 10 days, so I am looking forward to see if there appears to be
any more ponies that were being held hostage by that big freaking muffler.
I will comment on any change in mileage when we make our annual pilgrimage
south to yuma in october.

Re: muffler

Reply #24 – October 25, 2010, 04:54:55 pm

'98 U270 Replacement Exhaust System:

Well, we finally got the new (4") exhaust system finished (8.3 mechanical, 325 HP).
Thanks to my son, the installation all went smoothly and the finished product is a thing of beauty. I took many pictures along the way and have tried to assemble a few of them into a slideshow that is compatible with Foreforums. I'll get them into a Foreforums album, with a little help from Steve or Barry. In the meantime, I've provided a Picasa link below.

We learned a few things along the way but I'm really pleased with how this project turned out.
We haven't traveled far with the coach yet, but the exhaust tone and note of the new system seem to be even better than I had hoped for. There are more detailed notes in the Picasa slideshow.
Best Regards to All,
Neal
http://picasaweb.google.com/pillsna/DropBox?authkey=Gv1sRgCPjuhuHTiuWa4gE#slideshow

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