Muffler

[Venturer]

Instead of a large muffler, my Exec has what looks like a resonator. The pipe going in is 5" in diameter. The body is about 8 -9" in diameter and approximately 20" long. It all looks OEM, but wonder if it's just a good aftermarket replacement. The exhaust tone is louder at idle, although it's not noticeable in the cab at highway speeds. However it sounds like a semi when using the Jake brake. I would not be able to use the Jake in residential areas.  Is this the standard setup for the 06 500 ISM in the Executive or has a former owner modified it??    

Edited March 23, 2024 by Venturer

[Just Jim]

I don't think so.  Mine is several years older, but nothing like you describe.  I'm not long away from needing to replace mine... thinking maybe a straight pipe.  LOL

[timaz996]

If they did it was a good way to go. Turbos don't like back pressure. I put in a straight though muffler about 18" long. It also helps the EGT to stay cooler.

[Chargerman]

That muffler is not the original. I have the same coach and the muffler is oval with offset inlet and outlet. Had to fabricate a complete setup for mine two years ago from the turbo back. 

[Mroock]

Changed My huge oval to a Walker straight thru heavy duty.  I made it easy to remove to service everything on the side of Engine.  A little louder on highway, But runs great.

[Paul J A]

 Reducing back pressure is an easy thing to do with obvious performance results. I had a 525 ISX in a 07 Executive i did the following changes to the intake and exhaust components. I replaced the OEM air cleaner with one from AFE, which had a washable filter element and more CFM capacity, same micron spec. Next i replaced ALL the pleated intake hose with rubber fittings and aluminum tubing from intakehoses.com. That's what truckers use. Got rid of all the air friction in the intake. Next was a resonator to replace the muffler from dynaflexproducts.com. Largest MFG. of class 8 truck exhaust components in the U S A. Did not like that so i went straight pipe. . Here is a picture of the results on a screen shot of my Aladdin system. Performance was great and my average CRUISING MPG went up. I cruised at 1350-1400 RPM, 61-62 MPH.

[Venturer]

What fuel economy did you get prior to your mods?

[birdshill123]

Washable filters can kill a diesel engine. We use a lot of air and you can end up dusting your engine

[Paul J A]

11 hours ago, birdshill123 said:

Washable filters can kill a diesel engine. We use a lot of air and you can end up dusting your engine

Bruce ; Maintain the components that require that will provide the results you want.  Neglect is self induced.

On 3/24/2024 at 2:37 PM, Venturer said:

What fuel economy did you get prior to your mods?

Doug ; Cruise  was  6.2  MPG  over 7900 miles.  The increase in CFM's and straight pipe was amazing.

Accelerating thru 1st, 2nd, and 3rd was great on the X way entrance ramp. Climbing elevations too. 

Edited March 26, 2024 by Paul J A

[Venturer]

Other than the smoother intake and exhaust pipes, Mine should be similar. I've also added the Ugly Fix. I can tell the engine is more responsive and the boost stays at 46 when under load. My only concern is not knowing the EGT on a long pull. To counter that concern, I intend to keep the RPMs near 2000 when conditions warrant it. I might install a Pyrometer in the future just to be certain.  The ISM sure has more pull than the 450 ISL of my former Bus but gets about the same economy overall and no more DEF. 😎  

[birdshill123]

There used to be a fellow who posted in a few forums. He was an engineer who specialized in filtration. Worked for Cat and then Cummins.

 He was against all of those washable  filters. He did not like to open up your filter housing as it can spread dust into the system. What really would help is a larger filter.  But in most rv applications there is no room for a larger filter.

[Ivan K]

I have K&N reusable filters on go-fast gasoline cars that need a lot of air at near 8k RPM and aren't meant to last for ever but would not dare to put them on my diesels. After few washes I could almost see through them.

[cbr046]

I use an oiled "sock" over my oiled motorcycle filters.  It saves a lot of dust from getting to the filter.

My shop vac has a foam filter that goes over the paper filter.  No, I don't oil it . . .

It'd be sweet if someone made a similar sock to go over the RV paper air filter.  The right density wouldn't interfere with airflow.  Might not be able to oil it . . . . but imagine peeling it off, washing then re-installing it for extended filter intervals.  The inner air chamber never gets exposed. 

- bob