Muffler & Resonator Install w/Empirical Results

[Unforgiven]

My components:



Left to right are 3.5" ID to 4" ID adapter, 4" ID to 5" ID FTE Resonator, 5" OD short pipe, 5" ID Pittsburgh Power muffler, 5"OD 68 degree bend, 5" rain flap. Sorry for the shadows in pic.



Inside view of the resonator. It's a right-hand corkscrew like a sea shell surrounding a straight-through core.



Inside the assembled, welded muffler stack including the 68 degree tip. Notice there is quite a direct path through the stack to minimize back pressure.



This is where I cut off the stock exhaust



Yes, I know. It's hideous! This summer I am making a Crew Cab out of the truck. When I do this, I'll relocate the muffler stack behind the Crew Cab. That will also lower it about a foot or so. This is a very temporary setup.

I used the 68 degree mandrel-bent pipe as the tailpipe tip to make the gasses exhaust out, up, and back all at the same time. That way the sound is carried up and away from the cab.



There's the flapper flapping away while I'm enjoying being a passenger for a change.



It doesn't look bad from inside the cab. Still, It's a little top-heavy for now. Notice the paint scraping from the mirror bracket as the truck vibrates over the dirt roads. It doesn't move much, just enough to bother me. I tend to be a perfectionist. But for now ... good enough.



Now for the meat and potatoes ... empirical results. Be patient. It'll take me a few minutes to upload the pics & edit. I think you will find the data useful.

 

[Unforgiven]

900 RPM Idle Results

I bought a dB meter just for this project. Curiosity was killing me beforehand.

All of this is at 900 RPM idle. Also note, this is my "quiet" Deuce. The other truck is substantially louder!

Pics are self-explanatory. No muffler is on left. Mufflered is on the right.



Driver's seat before & after



Passenger's seat before & after



5 feet away



10 ft




Note, sound is logarithmic. For example, going from 80 dB to 90 dB is an increase of 10 in intensity. Likewise, going from 90 to 100 dB is also a factor of 10. So an increase/decrease from 80 to 100 dB is a difference of intensity of 100!

For simplicity, roughly every 3 dB equates to a doubling of the sound intensity. 83 dB is 2x more intense than 80 dB. So even a change of a few dB is really enormous.

Human hearing does not respond linearly to intensity. An 83 dB sound may not "sound" twice as loud to the human ear. But intensity-wise it is.

Osha starts requiring hearing protection at 90 dB for extended periods of time.

Anyway, back to the results:

 

[Unforgiven]

1500 RPM Idle Results



Driver's side at 1500 rpm's



Passenger side.



5'



10'



15'

 

[Unforgiven]

900 RPM at 20'



1500 RPM at 20'



Driving at 50 mph driver's side



Driving at 50 mph passenger's side



50 mph passenger side with window down

 

[EXITNOONE]

please post part #'s.

thank you

do you have any decibel measurements ?

 

[Unforgiven]

Summary of results

900 RPM Idle:

Driver 87.1 dB reduced to 83.1 dB
Passenger 86.9 dB reduced to 83.8 dB
5' 85 dB reduced to 84.4 dB
10' 81.8 dB reduced to 79.7 dB
15' 78.5 dB reduced to 77.1 dB
20' 76.5 dB reduced to 74.6 dB

1500 RPM Idle:

Driver 88.6 dB increased to 89.6 dB
Passenger 90.9 dB reduced to 83.8 dB
5' 90.7 dB reduced to 88.1 dB
10' 88.2 dB reduced to 84.4 dB
15' 86.9 dB reduced to 82.0 dB
20' 83.4 dB reduced to 82.5 dB

50 MPH Driving:

Driver 100.0 dB reduced to 95.8 dB
Passenger 99.6 dB reduced to 97 dB




Qualitative Results:

You can have a conversation in the truck now.
It is still loud. But you don't have to shout.

Ear muffs are not necessary anymore, unless it's a really long trip.

Still not quiet enough for a radio.

Most of the cab noise is now coming from the floorboard & firewall. This is mainly due to valve-train & drive train sources.

That incessant GGGRRRRRRR droning resonance is completely gone!

Pedestrians on the sidewalk no longer jump in shock when you drive by.

No noticeable change in engine power.

The truck is much more comfortable to drive. It's not quiet, but much, much better than before.

 

[Unforgiven]

please post part #'s.

thank you

do you have any decibel measurements ?

Quiet Performance Classic 51.5 universal stack muffler - Pittsburgh Power - High performance diesel


https://store.ftediesel.com/home/viewPrd.asp?idproduct=41&idcategory=8

Exhaust Elbow 68-Degree 5" OD/OD

Exhaust Rain Cap 5"

 

[oddshot]

Thank you for this VERY comprehensive test.

It would be useful to see a number of exhaust systems done in this same manner for comparison.

You are correct. It is about butt ugly.

Maybe a little paint would serve to blend it all in.

oddshot

 

[Flyingvan911]

Nice results. That is a huge muffler!

 

[usmc320]

Thanks for the detailed results. I would like to muffle my deuce in the future. That thing is massive though.

 

[EXITNOONE]

UNFORGIVEN- thank you very much !!!

i'm going to try to get decibel measurements with my stock m35a3 muffler and post them soon.

i like the thinner profile of the aftermarket mufflers and have been considering one for my a3.

it all comes down to the decibel comparison.

 

[mktopside]

UNFORGIVEN- thank you very much !!!

i'm going to try to get decibel measurements with my stock m35a3 muffler and post them soon.

i like the thinner profile of the aftermarket mufflers and have been considering one for my a3.

it all comes down to the decibel comparison.

After I cut out the EGR tube from mine, I noticed how tiny the hole in the bottom of the A3 muffler really is.... I might be replacing mine also.

 

[EXITNOONE]

MKTOPSIDE- i'm glad you tried the egr tube removal. i just noticed your thread on the m35a3.net site about it.

i haven't driven my a3 since removing the egr tube (been repainting the truck inside and out and almost done) but i would like to get a serious quantitative side by side comparison of the stock a3 muffler decibels vs. the aftermarket mufflers the a2 guys are using.

so as soon as i can measure on my a3 i'll post it so we can compare to unforgiven.

 

[mktopside]

MKTOPSIDE- i'm glad you tried the egr tube removal. i just noticed your thread on the m35a3.net site about it.

i haven't driven my a3 since removing the egr tube (been repainting the truck inside and out and almost done) but i would like to get a serious quantitative side by side comparison of the stock a3 muffler decibels vs. the aftermarket mufflers the a2 guys are using.

so as soon as i can measure on my a3 i'll post it so we can compare to unforgiven.

Yea, I was blown away after looking at it!! Glad you made it over!

 

[Tinwoodsman]

Unforgiven, Where did you get the flapper?

 

[Unforgiven]

The rain cap is from Airflow. I'm sure it's just a generic flapper for agricultural equipment. The good thing is that even at a 68 degree angle it opens & closes without problems. If not, I would have had to modify the counterweight.

Exhaust Rain Cap 5"


Pittsburgh Power has a shorter version of the muffler. If I were keeping the exhaust in the stock location I'd have opted for that one instead. But since I'm crew-cabbing the truck this summer I got the longer muffler. I plan to run a different pipe from the turbo along the frame rail to the back of the crew cab. It will look much more natural then.

For now I just wanted the truck quieter without much work.

Keep in mind that 3 dB of change is 2x the sound intensity. So the sound level at 50 mph dropping from 100 dB to 95.8 dB means that it dropped by more than half! Not bad for a one-day weld & bolt temporary mod.

Soundproofing the firewall, floorboard, and weatherstripping will definitely cut much of the road noise out as well. I won't do that until the crew cab is finished.

 

[ftballman125]

Good results, and thanks for the documentation! Here's a chart indicating safe decibel exposure levels... even with your muffler/resonator, it'd still be wise to wear ear protection...

Dangerous Decibels How Loud is Too Loud?

 

[kc5mzd]

I used a auger type insert from Jegs in mine and it worked good. I like it because it fits inside the stock tube and doesnt require any cuting or welding.

 

[islasaero]

read this please!

Soundproofing the firewall, floorboard, and weatherstripping will definitely cut much of the road noise out as well. I won't do that until the crew cab is finished.[/QUOTE]

I would go for a thick spray-on sound and heat deadening materials from secondskinaudio.com . Check Them out. I've used the sticky mats before, but, they dont conform to the surface very well. You have to be cutting the sound mats to shape too, which takes a lot of time. Its easier to spray on!And will cost about the same!! Trust me on this, I've been there!!

 

[maxim]

http://www.steelsoldiers.com/deuce-...apa-muffler-will-really-quiet-truck-down.html