How noisy is your TJ really?

Tigerman said:
I was wondering why your numbers were around 8 to 10 dB higher. Awesome data :) The great thing is that the differences between your own readings are very consistent and inline with the rest of the sample data. The question I have is where exactly the sound getting through to the cabin? The firewall and the floor in the front or primarily through the rear passenger wheel well and the muffler?
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I’m hoping to have time to test the various locations, my gut feeling for mine is primarily firewall.

The data will be useful when deciding on an approach. Initially I was considering lizard skin inside (because I don’t like the idea of moisture being trapped between a dynamat like application), but if I/we can determine the specific spots that would be fantastic to save the headache.
 
rasband said:
I’m hoping to have time to test the various locations, my gut feeling for mine is primarily firewall.

The data will be useful when deciding on an approach. Initially I was considering lizard skin inside (because I don’t like the idea of moisture being trapped between a dynamat like application), but if I/we can determine the specific spots that would be fantastic to save the headache.
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I think I am going to go a little further and install a series of microphones in the Jeep in different locations. I have something like 12 spare microphones left over from a project and a microphone data hub module. Once I collect the data, I will create a 3D model of the Jeep with rough dimensions and color the different sections based on the sound level. Would be pretty cool I think to visually see this.

Cheers
 
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Chris said:
Awesome idea for a thread! Whenever I get my TJ back I'll have to test this out. I've always suspected a large amount of the noise was coming from the engine itself. It would be nice if someone made some sort of underhood installation. Maybe pair that with some sound deadening material on the firewall itself. I'll bet you could reduce some of the noise drastically!
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I would love to do that when I get a new carpet kit, maybe like a sound/ and heat shield


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Tigerman said:
I think I am going to go a little further and install a series of microphones in the Jeep in different locations. I have something like 12 spare microphones left over from a project and a microphone data hub module. Once I collect the data, I will create a 3D model of the Jeep with rough dimensions and color the different sections based on the sound level. Would be pretty cool I think to visually see this.

Cheers
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It would be interesting. I wish I had that much spare time.
 
Nicholas said:
I would love to do that when I get a new carpet kit, maybe like a sound/ and heat shield


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I intend to do it when I get my Jeep back from the shop. It should make a noticeable difference.
 
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Tigerman said:
I think I am going to go a little further and install a series of microphones in the Jeep in different locations. I have something like 12 spare microphones left over from a project and a microphone data hub module. Once I collect the data, I will create a 3D model of the Jeep with rough dimensions and color the different sections based on the sound level. Would be pretty cool I think to visually see this.

Cheers
Click to expand...

Please share, that’ll be awesome to see!
 
jjvw said:
I'm driving around this morning and trying the app out.

Engine off 49-51db.
60db parked at idle.
78db at 3000rpm parked in neutral.

Today I have the hard doors with the windows rolled up. Some highway driving at 60mph. No rear windows. I haven't seen anything louder than 78db.
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To add to my data...

78-79db at 75mph

There were a couple brief spikes into the low 80s, but I didn't notice what caused them. Ambient noise is my best guess. The Jeep noise is pretty steady and consistent.
 
Just had a thought. The engine noise we are hearing is mostly the fan. It's cold enough in most places that our fan clutches are not fully engaging.

Will the noise increase in the summer?
 
jjvw said:
Just had a thought. The engine noise we are hearing is mostly the fan. It's cold enough in most places that our fan clutches are not fully engaging.

Will the noise increase in the summer?
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Good point. That fan on the 4.0 is ungodly loud... Imagine if you replaced with with a slim electric mounted fan how much quieter the engine would be!
 
Chris said:
Good point. That fan on the 4.0 is ungodly loud... Imagine if you replaced with with a slim electric mounted fan how much quieter the engine would be!
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If only a fan swap was that easy without creating other problems.
 
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jjvw said:
If only a fan swap was that easy without creating other problems.
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When I bolt on that Magnum Powers supercharger we'll find out. Since it has it's own crank pulley and an independently driven serpentine belt, it requires you put in a slim electric fan (which it includes). Supposedly there are no problems with them. Dave installs them all the time and has never said anything bad about them.

I wouldn't be doing it to be honest, but it's required with this supercharger.
 
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Numbers are with hardtop, full doors and BFG MT's

37 with engine off.
51 at idle.
66 at 35 mph
70 at 40 mph
75 at 50 mph.
 
lxxtsy said:
Numbers are with hardtop, full doors and BFG MT's

37 with engine off.
51 at idle.
66 at 35 mph
70 at 40 mph
75 at 50 mph.
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Comparing to mine you have slightly less noise both when engine is off and idle, but significantly more noise when driving. Where is the additional noise coming from? My tires are BFG A/T K02.
 
this is a great thread, very interesting. I'll post mine as soon as I can - probably this weekend. I have soft top with half-doors. curious to see what my numbers are.
 
4L-35” MTRs-Soft top-Manual Trans-No Carpets-No Muffler- hard doors.

Idle running- 65
Coasting- 73
Under norm load- 80
Highway under load- 85-87

Cool app, thanks!:clap2:
 
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Tigerman said:
Comparing to mine you have slightly less noise both when engine is off and idle, but significantly more noise when driving. Where is the additional noise coming from? My tires are BFG A/T K02.
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Squeaky back seat, rattling door handle, no carpets, manual transmission to name a few things
 
TrailYacht said:
4L-35” MTRs-Soft top-Manual Trans-No Carpets-No Muffler- hard doors.

Idle running- 65
Coasting- 73
Under norm load- 80
Highway under load- 85-87

Cool app, thanks!:clap2:
Click to expand...
Wow, I must say your numbers are higher than mine by a lot. 10 dB noise difference is perceptible by human ear as twice as loud or twice as quiet.
Here is a cool video for reference:
 
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Tigerman said:
Wow, I must say your numbers are higher than mine by a lot. 10 dB noise difference is perceptible by human ear as twice as loud or twice as quiet.
Here is a cool video for reference:
Click to expand...

Awesome vid! :clap2:

I would imagine the lack of muffler and interior is the obvious culprit lol
 
Listening to that video, a 5db change is where you can actually hear a difference. That should give you a good (+,-) of difference between everyone's readings. I'll tell you one thing, the transfer case is a noisy piece, so don't forget about that area.
 
BFG MT's KM2 33x12.5R15, 42RLE Hard top, Full hard door, Full carpet, Flow Master, App used=NIOSH SLM

Windows Up
Engine off - 28
High Idle - 60
Idle - 53
30 mph - 68
70 mph - 85
Windows Down
Idle - 58
30 mph - 80
70 mph - 95
 
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