Straight Pipe Woes

Every Muffler I bought had a baffle and by no means was just straight thru, they all had the little holes and the goofy looking funnel type thing at the bottom end. Now these were just off the shelf ordinary fleetguard mufflers.

The one resonator I had, had no baffle but did have the holes.... So thats why I'm asking the question.

My thinking, and I could be wrong, would be that the muffler with a baffle and holes would be much more restrictive than a resonator with holes and no baffle...

Am I missing something?

 

My BIL has a 2001 Freightliner with factory 6NZ 550. Couple of years ago, he put 7" straights, then couple of weeks later he realized how the straights only sounded good if you were faaaaar away from the truck, and REALLY sucked if you were inside the cab. Joking with him, I told him not to call me if his engine was running. He mounted two of those short resonators under the cab, then pulled them off, saying it raised his EGTs, and made his floor too hot. He still has the straights mounted, but has offered them to me more than once. I have TWO under sleeper mufflers mounted on my 2004 W900, and that is about the only way I think 7" straights would sound good.

 

My 2001 W900 had the cab mounted vertical mufflers. When they began rusting at the bottom, I removed them, and began to mount two of the Donaldson (I think) brand replacement. You could look straight through the 5' opening- no baffles or restriction except on the 5" perimeter inside the muffler. They were actually louder than the rusted mufflers I removed!

 

Ok But I still don't get how a straight thru muffler/resonator will cause you EEGT's to be higher than running a baffled muffler?

Thats all I'm really asking...

I thought all KW mufflers, on the newer ones, 2000 and up had the muffler mounted under the cab?

 

They do...This one has me scratcin' my head. There's no room for a side mounted muffler on a W900, Unless it's possibly a day cab but every day cab I've seen had the same under the truck muffler that I have!

I always try to get the quietest muffler possible on my truck because I don't like all the racket!
I had a resonator on it for a couple'a months and hated it so I tossed it in the dumpster and put on a new muffler.
Everyone told me that the muffler was gonna rob power and fuel mileage but I haven't noticed any change exept that I got rid of the noise!

 

Have a 900 areodyne with the stupid muffler arrangement under the cab(KW must have worked very hard to come up with that system). Bought the Bruce muffler and had a local guy alter it to fit my truck(wet system, etc in way).Alittle deeper, louder noise but i can live with it. It is ok setup, but when time comes for replacement i will have my local guy make the complete muffler setup. It will be near perfect and im sure outlast the truck.
Now to instigate. Have a W/S with 5EK. Had one elbow rot/break off few weeks ago and driving it home thought it felt "peppyer". At first figure it was in my head because extra noise made it sound like a big truck. But boost gauge showed extra 2-3 pounds of boost while it was "open".But cant stand the noise so it is quiet again with loss in boost.
So let the beatings begin....

 

I went on the Donaldson site and did some reading exhaust systems have changed a lot in a short time. The old resonators were different than the new ones. They now only reduce the decibel reading by 2, hardly worth the effort. The new silent partner mufflers, have baffles and bell shapes internally to quiet the noise with a minimal of restriction. The maximum I saw was 3 inches of mercury, 40 inches of water, that is not much.

 

I drove a new 80 Western Star starting September of 1980 back and forth to the west side, its muffler was under the truck, I never notice it to cause no problem whatsoever, I enjoyed my time driving that truck & I liked the twin stacks without a muffler.

 

Hi OSB: Nothing against the muffler being under truck if it is a decent system. Take a peek under a KW sometime and you will shake your head.
Exhaust goes in and out same end of muffler. Looks like one restrictive SOB.

 

Corn binder been doing that for awhile too. I know it's expensive to replace also.