Need to quiet down exhaust

[Mattchu60]

I finished up my C10 build this winter. Out on the road, its clear the exhaust is a lot more than I was hoping for. The setup I have is a swapped 5.3, with cast camaro manifolds dumping into a 2.5" exhaust, then X-Pipe, dual Dynomax super turbo mufflers after the x-pipe.

I have some strait runs between the manifolds and the beginning of the X-pipe, but limited space around around the pipe. I think I could fit a shorter glasspack muffler in that space (maybe a 20-22" long one). I'd leave the super turbos in of course.

Any other ideas I can consider? I need a very compact muffler, there's probably only a few inches around the pipe of room. Traditional muffler will not fit. I want to kill the highway drone noise to a point where I barely hear it.

[The Rocknrod]

You fell into the more is better trap. I'm going with 2.25" exhaust, enough for the small block. AcampoDave,a member here also added resonators at the end of the exhaust before the rear bumper. http://67-72chevytrucks.com/vboard/s...d.php?t=792007

[AcampoDave]

Originally Posted by The Rocknrod

You fell into the more is better trap. I'm going with 2.25" exhaust, enough for the small block. AcampoDave,a member here also added resonators at the end of the exhaust before the rear bumper. http://67-72chevytrucks.com/vboard/s...d.php?t=792007

I've done an awful lot to get a smooth quiet ride. The link that Rocknrod posted above is one example. Besides the resonators at the end of the tailpipe I aso have Vibrant Ultra Quiet resonators https://www.summitracing.com/parts/vpe-1140?rrec=true before the mufflers. Even though I started the thread about 1/4 waves, you'll get to the part where I abandoned that idea and went for the Ultraquiet resonators. They helped a lot but a while later I wanted it even quieter which is where the bottle style units got added. Also as I mentioned the quieter you go the more you notice. For instance, I have a manual tranny and the hole in the floor for the Hurst shifter is, by necessity, rather long for the throw of it. Even that was addressed with a proper shift boot made out of a padded material. I also noticed my intake and carb made a lot of noise with a open element air filter. I changed to one I made, which is open only in the front. That was also a noticeable improvement.
As Rocknrod Said "the more is better trap" i fell into it with a desire for quietness. Dont hesitate to ask me if you have any questions about the stuff I did.

[AcampoDave]

I also experimented with hoodliner which you can read about here: http://67-72chevytrucks.com/vboard/s...d.php?t=808418

[AcampoDave]

And here is where I did the Noico that MikeC recommended. http://67-72chevytrucks.com/vboard/s...d.php?t=814233

[Mattchu60]

Thanks for the replies! It sounds like a resonator is the way to go. Does it matter if it goes before the mufflers or after? I see some folks putting them right before the exhaust tips.

[sweetk30]

Do you have carpet or rubber floor mat kit and full insulation pad ? This will make a big change .

And were is your exits for the pipes ? If they stop under the body even with turn down tips it will be a LOT worse and you need to get them out the back or near the rear sides .

And factory tends to put resonators before the muffler mid way from engine and muffler .

[AcampoDave]

Originally Posted by Mattchu60

Thanks for the replies! It sounds like a resonator is the way to go. Does it matter if it goes before the mufflers or after? I see some folks putting them right before the exhaust tips.

Vibrant website says it doesn't matter. Edit: I should say...Vibrant website used to say it doesn't matter. I was trying to remember their wording on that, it was something like "designed for mid pipe or after muffler installation....etc"
Anyhow, it prompted me to look it up and now they simply don't seem to say.

[Mike C]

Do you have room for the 20" case DynoMax mufflers? I assume you have the 14" case mufflers? If you do have the 14's, swapping in the 20's only adds 6". Do you have tailpipes? That will go the furthest to eliminate drone and noise over everything else.

[Mattchu60]

Thanks for all the replies folks. You guys asked for some info on the interior, so heres what I have.

Dynamat on the floorboards, back wall and ceiling. Also a layer on the door skin and on the inside "side" of the door shell (under the panel side). I have new GM door seals (they still make them!), and also added the extra 2nd door seal. I have new carpet with mass backing material. I also have carpet on the back wall.

I have the longer (20" case) super turbos installed.

THe drone is not awlful, but its there and bothers me. After my original post a few days ago I found I had a few holes that were not plugged in the cab (factory cab had power windows and i removed the wire harness but failed to plug the holes, i have manual windows now). I installed the plugs that the noise inside has dropped some.

I can still hear the exhaust drone but not as terrible now. It would get annoying on a longer drive for sure.

I'll look at resonators. I have space right after the manifolds (as originally mentioned) but i also could install them right before the exhaust tips it looks like as well.

I appreciate all the information provided already!

[whitedog76]

Just FYI, my Trailblazer has the resonator before the turn down on the tailpipe. Late model Hemi trucks do too, so a resonator may be effective regardless of where it's located.

[AcampoDave]

Are your exhaust maifolds old? I was a bit surprised by how warped my old ramhorns actually were. The machine shop guy showed me the pattern on the mating surface after the first run on the machine and it was half planed and still half nasty. He had to let it cool off and go for another round. He said the other one was 2/3rds as bad as the first. When I put them on, (no gaskets) the reduction in noise prompted me turn right around and do my other truck. I just test drove it this morning, and the result is the same as the first. A noticeable reduction of noise at idle and upon normal acceleration. I also noticed it upon deceleration too. At highway speed however, the change was less noticeable due to the wind noise.

[Myself]

I can tell you my personal experiences with exhaust and resonators. BEFORE the muffler helps quiet down more, AND helps rid the bumblebee sound on 4 & 6cyl, the raspy pops on a V8. Just an overall smoother, quieter tone. On trucks, and especially SUV's, try to get the mufflers as far back as possible. Duals with free flowing mufflers directly under the passenger compartment on an SUV make a TERRIBLE drone at certain RPM's. Resonators AFTER the mufflers still help quiet and smooth out the tone but not NEAR as much. For example a 4 cylinder car with a free flowing muffler will still have that fart can popping when letting off the throttle going downhill, It's just a bit quieter, not as raspy.....VS BEFORE the muffler where those noises go away almost completely.

[AcampoDave]

Originally Posted by Mattchu60

Thanks for all the replies folks. You guys asked for some info on the interior, so heres what I have.

Dynamat on the floorboards, back wall and ceiling. Also a layer on the door skin and on the inside "side" of the door shell (under the panel side). I have new GM door seals (they still make them!), and also added the extra 2nd door seal. I have new carpet with mass backing material. I also have carpet on the back wall.

I have the longer (20" case) super turbos installed.

THe drone is not awlful, but its there and bothers me. After my original post a few days ago I found I had a few holes that were not plugged in the cab (factory cab had power windows and i removed the wire harness but failed to plug the holes, i have manual windows now). I installed the plugs that the noise inside has dropped some.

I can still hear the exhaust drone but not as terrible now. It would get annoying on a longer drive for sure.

I'll look at resonators. I have space right after the manifolds (as originally mentioned) but i also could install them right before the exhaust tips it looks like as well.

I appreciate all the information provided already!

Could you please post a bit more info regarding the added 2nd door seal? I do remeber the early 60's trucks had those and I think I'd like to do that on my later 60's doors. I'm wondering if you used the seals for the early doors or if you know of something better. I did already convert my cabside seal to the push on style and I gotta say, those are pretty sweet.

[Mattchu60]

Heres the link for the seals:

https://www.soffseal.com/ss-9352

I put them on my last truck and it did seem to help with the wind noise a bit.

[AcampoDave]

Originally Posted by Mattchu60

Heres the link for the seals:

https://www.soffseal.com/ss-9352

I put them on my last truck and it did seem to help with the wind noise a bit.

Thanks, even though my application is 1964, it looks like they would still work.
Just peel and stick, large flange up?

[Mattchu60]

Yes, they are a peel and stick install. Pretty easy/fast. The "flanges" are up - with the small one against the door shell, and the larger one contacts the cab when the door is shut.