So I was bored tonight and decided to gut the stock muffler. Took about 3 hours. Figured you guys would enjoy the pictures, although for some reason my camera wouldn't load the "final product" pic (exhaust ready to install back on to truck) on to the computer. There's also a pic of my welder: Unfortunately I didn't have any gas to MIG weld with, so the welding was done with flux-cored wire.

Driving Impressions: Not as loud as a straight pipe, but similar EGT's. Very quick turbo spool up and throttle response... No drone on the highway running 70.

Dan

I have a stupid question. Would it not have been easer to just put in a chunk of pipe?

...and miss this,,, what are you crazy?):h

I have a stupid question. Would it not have been easer to just put in a chunk of pipe?

"Thinking outside the box" and doing things like this is how new mod.'s are discovered. Who knows, by doing this he may have inadvertently discovered that gutting the muffler put less backpressure on the muffler bearings, which in-turn may have lowered the air temperature moving across the canooter valve thus improving MPG's by 5+ per gallon.

That wasn't the case this time, but if at first you don't suceed, try try again :)

:funnypost
:rolleyes: does lowering the EGT's accross the canooter valve :think:really help get better MPG's?:confused:

:duh:

ag4gt: I have already put in a chunk of pipe about, uh, 3 times using 3in, 3.5in, and 4in pipe. All created too much of a drone on the highway for me and didn't like it, so as I said stated in my first post "I was bored and decided to gut the muffler".

Luckily I did because it sounds sweet, the turbo sings like crazy and it's not loud at all, plus it keeps the EGT's in check... I think that's mostly because I replaced the muffler bearings and lubed the EGT actuator reducer, which in turn reduced back pressure on the exhaust filter so it doesn't clog up as fast):h

Seriously though, after looking at the inside of a stock muffler, no wonder it is so restrictive. It has more holes and channels than a 2 cent whore:eek:

Dan

ag4gt: I have already put in a chunk of pipe about, uh, 3 times using 3in, 3.5in, and 4in pipe. All created too much of a drone on the highway for me and didn't like it, so as I said stated in my first post "I was bored and decided to gut the muffler".

Luckily I did because it sounds sweet, the turbo sings like crazy and it's not loud at all, plus it keeps the EGT's in check... I think that's mostly because I replaced the muffler bearings and lubed the EGT actuator reducer, which in turn reduced back pressure on the exhaust filter so it doesn't clog up as fast):h

Seriously though, after looking at the inside of a stock muffler, no wonder it is so restrictive. It has more holes and channels than a 2 cent whore:eek:

Dan
Is this on an LB7 or an LLY? I would like to reduce EGT's without making it to loud or increasing the drone. Give the dealer one less thing to void warranty over. May be something that I can afford....

Well this mod fit my needs to a "T". I wanted lower EGT's quicker turbo spool up and not as loud as a straight pipe, or any drone... and it does exactly that, without having to spend a dime doing it!

This is for an LB7, I'm sure you could do the same for an LLY and make that variable vane turbo really sing.

Dan

Cool. Any time you get to play with the welder is good.
With the muffler still there it gives it a chance to resonate and cancel out some of the loudness. I think anyway. When I gutted the glass packs on my 76 truck it was loud, but not as loud as having pipe there instead. Plus then it has a muffler on it you can point at if you get asked.

ag4gt: I have already put in a chunk of pipe about, uh, 3 times using 3in, 3.5in, and 4in pipe. All created too much of a drone on the highway for me and didn't like it, so as I said stated in my first post "I was bored and decided to gut the muffler".

Luckily I did because it sounds sweet, the turbo sings like crazy and it's not loud at all, plus it keeps the EGT's in check... I think that's mostly because I replaced the muffler bearings and lubed the EGT actuator reducer, which in turn reduced back pressure on the exhaust filter so it doesn't clog up as fast):h

Seriously though, after looking at the inside of a stock muffler, no wonder it is so restrictive. It has more holes and channels than a 2 cent whore:eek:

Dan
I was worried when I saw this post that you may have forgotten about the muffler bearings and the EGT actuator reducer:badidea: . Glad to see you have it all under control.:thumb: <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>

Dan, you are missing the grease zerk for the muffler bearings. I put mine about 3 inches over from the rear exhaust outlet.

Also, looks like ya need some 285s on that truck to bring out the chrome wheels and nerf bars ;)

Only a fellow member of the AAAA could use the internal forces to come up such a plan.


I thought about the idea of gutting the sound reduction device, but after much debate went another route.;)
http://www.kydtr.com/coppermine/albums/userpics/10195/normal_5-1-2.JPG (javascript:;)

Nice stacks coalbucket, I want some... which is next on my agenda!

Dan

<raises hand<RAISES hand>>
Question:
Can someone explain the flow of the stock muffler from those pics?? As in what purpose do the "smaller tubes" play in the grand scheme of things?? Exhaust comes in the 3.5" openning, then does the exhaust "leak" from all the holes in the pipe into the smaller ones?? Sorry, I stared and stared at the pic and just couldn't figure it out.
Sorry for the seemingly elementary question... :o:

Bob

I see you got your stacks in, Coalbucket. Looking good:ro)

Hey Coalbucket, got any pics from the side of the truck with the stacks? very nice though.

I found this:

http://auto.howstuffworks.com/muffler.htm

Thanks ag4gt!

What is the smallest diameter pipe that the exhaust gas must go through inside the stock muffler?

I was told several years ago that inside the stock muffler, the 3 1/2 diameter exhaust pipe necks down something around 2 inches. Your the first person that has posted that they actually took the stock muffler apart. Neat idea.

Well guys, I've had a couple of days now to drive this thing around and here's what I've found...

As I stated in my first post, I noticed lower EGT's, quicker turbo spool, etc... The thing I am really amazed about is how QUIET this setup is, I don't quite understand. I imagine that the whole inside area of the muffler is acting like a resonator and cancelling out a lot of the sounds. The loudest thing about this setup is the turbo whine, I even had my girlfriend drive it while I stood in the driveway to hear it accelerate away from me and holy smokes, the turbo whine is piercing! The best part I like about it is there is no drone at any speed, it feels like a really free flowing exhaust without all the noise.

Anyway, I really like this setup and will probably keep it, but I am experimenting with some 4" pipe to make my own turbo back exhaust so I don't have to spend lots of money on one.

Dan

Hey Coalbucket, got any pics from the side of the truck with the stacks? very nice though.
I will get some more as soon as I can wash it, too much dust right now.
http://www.kydtr.com/coppermine/albums/userpics/10195/normal_5-1-1.JPG (javascript:;)

Straitdiesel,now you tell us! I cut mine all apart and gutted it this morning hoping to get some noise and now you say it's quite.:mad: All that work to cut it off and put in a strait pipe.

oops, sorry about that!

Did you get the straight pipe in? I love the sound of a straight pipe around town, but on the highway there is too much drone in the cab... I think that might have a lot to do with the fact that I have a regular cab, who knows though.

Dan

No problem,just some experience.I just cut the pipe off right in front of the muffler.I haven't gotten a piece of pipe to put in there yet.I found a place that sells them but they want $45 for a 33" piece of pipe.

go to any junk yard or steel yard, they should have a piece of pipe you can cut to length for cheap.

Dan

Straitdiesel, did you weld it back up using mild steel wire? I think this is just what I'm looking for.

I just used standard wire.

Yes, I welded it back up using mild steel wire, more specifically I used .035 Innershield NR-211-MP... If I were to do it again, I would go with a thicker wire because it's a butt weld and in some places there was a big gap to weld... unfortunately my local Lowe's only has .035 so that's what I used.

Dan

If you were to attempt to use a stick welder as I have, what rods would you use? I'd like to do that to mine.

depends on what type of stick welder you have... I had a Lincoln AC-225 stick welder and used the Fleetweld 180's (E6011)... they worked the best, especially if your muffler is rusty... the 180's are basically an all-purpose, easy arc stick.

Dan

Thanks, I have a box of 6011. I'll try it this week if I get time.

This is probably a stupid question but is the outer shell of the muffler stainless? Got some .030 308 wire in my Blue welder that has nothing better to do than make my turbo spool up faster ):h

"I love to weld, I'm just no good at it!"