Several people on this forum have warned me that modifying a 6.5 is addictive. This came as no surprise to me as I have modified every vehicle that I have ever owned.

It started in high school with an '80 jeep cj5 on 33" tires. By the time I was in college I needed longer distance transportation. I bought an '80 camaro with t-tops and the 3.8L motor. Got it for $600. I started with a little bondo....before long I had stuffed in a 350 motor and had lifted the sagging car 2" with aftermarket springs.

After the camaro, I bought a '93 Ford F250. It used to be completely stock. I went from stock to 36" to 38" tires, now it's on 44" tires...that's my daily driver...

My affliction has now affected my family life.

I found this forum when I got online to find information as to why our 6.5L Suburban overheated while towing a light trailer. Well truth be told, that's my wife's daily driver... :rolleyes:With that said, I just installed 4" exhaust on it yesterday. It's somewhat louder inside than it was with the stock exhaust. I haven't cranked down all the clamps yet because I need to make a new rear hanger- the hangers that came with the kit were useless.

I'm considering wrapping the entire exhaust ith header wrap. Does anyone else think this will help with the interior noise? Will this rot out the new exhaust? Also, should there be any difference in the interior noise after simply tightening all the exhaust clamps?

By the way, yes I can really hear the turbo whistle. It sounds great! But there's too much interior noise for a family car.:eek: Any help for interior noise control will be appreciated.

Thanks all for your continued support:o:

Perhaphs the right muffler would dampen that exhaust note enough.

As with any addiction, a 12 step program and a support network. We are here for you, brother. Of course, you can never be 'cured', just helped. :)


I'd look into a different muffler. Wrapping the exhaust in header wrap will only promote corrosion, and wont help alot with the noise.

Most aftermarket exhausts lean towards the noisy side, a better muffler will help.

Tim

If you are ambitious, you could apply a good car audio sound deadener to the floor pan. Makes a huge difference.

My Banks muffler is about the same, noise wise, as the stock one. I'm installing a new Kennedy system soon. Banks sells a 4" muffler for trucks (my Suburban muffler is 3") that I bet would fix your noise problem, yet provide better flow. They don't list it separately, but if you talk to them, they will sell you a muffler by itself.

Joi,

Best of luck with that.. I am still waiting for my damn system to SHIP! UPS still says "Billing Info Received" http://www.dieselplace.com/forum/images/smilies/frown.gif You win.

hi, my name is bowtie65 and i have been an addict for 10 years now. it all started when i removed my snokle and could breathe. then came the banks power,the 3'' exhaust and then 4". where will it end!

bowtie, what do you think of the interior noise with your 4" straight thru exhaust vs. the 3" banks exhaust....I'm getting a ton of vibration inside the suburban... not to mention unbearable amounts of heat from my wife for sawzalling off a working quiet factory exhaust!!:smashfrea

joi, i did not have a banks exhaust. i had a 3" straight thru and i just changed it to a 4" st.thru. opening it up made a big difference power wise and noise wise. before it sounded more like a muscle car with a turbo muffler. now it purrs like a kitten, unless you really spool it up. then it is insane. the turbo whistle is unbelievable. check out my thread titled (whipped out the big 4") and you"ll understand. :cool2:

I looked under the hood tonight and figured out a couple things:


1. It's still loud :D

2. There's a substantial amount of exhaust noise that get's transfered through the air filter box. When I was reinstalling the air filter box at 9:45 pm Sunday night, I saved myself some time by not installing the boot that connects the box to the fender opening. I put my ear up to the opening of the air filter box with the engine idling. It sounded like I had my ear next to the factory tail pipe.

I don't remember if it was Quantum Mechanic or Turbine Doc that said that about 70% of the exhaust noise gets bounced back off the turbo. Where does this noise go??? I'd say that more than a small amount radiates through to the impeller side of the turbo and back through the intake box.

This weekend's project is to add paint-on sound dampener to the floor of the sub and to the inside of the air filter box. I'm also going to re-install the widget that connects the air filter box to the fender.

:rolleyes: .....still telling the Mrs. how bad the factory exhaust was for the sub (:D )

joi, know what i did when my wife complained about diesel noise? bought her a dodge intreped and told her she is not allowed in my truck anymore. it's a diesel and it is noisy no matter what. i see you have made no mods yet. don't plan on any at all if you let her in your ride. if you modify a diesel the end result is noise. the trick is to tell her you will get much better milage and save lots of money so that she can go shopping with all the extra money you will have now. ha ha ha i love that one. she does'nt even question my truck fund any more.

OR you could just shut the window, Thats all I have to do to make it quite in my cab. OH yea I also limit the amount of time I spend with any women in my truck's cab:blahblah:if you know what I mean? :exactly:

joi, In my experience with car audio I found that a good sound sheet type asphalt deadener like those made by Dynamat, Rockford, Scoche etc worked alot beter than any of the liquid types. That being said, I haven't tried a liquid type sound deadener for about 6 years, mostly because I wasn't impressed with the results when I did try them. The sheet types are very easy to apply and alot less messy too. The place that the liquid types are good for are those really awkward out of the way places that you can hardly reach (in between body panels etc) so you can get some sort of deadener on them. I think you will see alot better results with a good sheet type. Anyway, just my 2 cents.

If you turn the radio up, other noises tend to fade away.

Dynomat is where its at!

Noise doesn't go away it's still there the turbo changes the frequency of it, saying 70% gets knocked back probably not the best way to quantify it, comparison should have been stock NA engine no muffler vs turboed engine no muffler apples to oranges difference turbo equipped noise will be less,

turbo to turbo with & without muffler, mufflered one will be less, several no muffler turbo guys say straight pipe is tolerable to those inside the cab; neighbors aren't none too happy, I have a muffler on mine neighbors will tolerate cold diesel clatter as that is nature of the beast, get real mad tho if I take my sawz all to vehicle pipes and cut out mufflers, I get by with my Bronco 2 straight piped as I tow it to the woods for 4wd and don't run the neighborhood with it much.


I looked under the hood tonight and figured out a couple things:


1. It's still loud :D

2. There's a substantial amount of exhaust noise that get's transfered through the air filter box. When I was reinstalling the air filter box at 9:45 pm Sunday night, I saved myself some time by not installing the boot that connects the box to the fender opening. I put my ear up to the opening of the air filter box with the engine idling. It sounded like I had my ear next to the factory tail pipe.

I don't remember if it was Quantum Mechanic or Turbine Doc that said that about 70% of the exhaust noise gets bounced back off the turbo. Where does this noise go??? I'd say that more than a small amount radiates through to the impeller side of the turbo and back through the intake box.

This weekend's project is to add paint-on sound dampener to the floor of the sub and to the inside of the air filter box. I'm also going to re-install the widget that connects the air filter box to the fender.

:rolleyes: .....still telling the Mrs. how bad the factory exhaust was for the sub (:D )

Hey, you're not making that one up.

Firefighter, thanks for the input. I already have the paint on dampener from Quietcar. If that doesn't do it, I'll try dynamat or equivolent. As a side note, I'm a builder and we use a self adhesive product along eaves and valleys called "ice and water shield". It has a granular surface, but it's very flexible and much less expensive than dynamat. Ever heard of it? What are your thoughts?


As far as keeping the Mrs. out of the truck......well it's Her daily driver.... anybody want to tell her to stay out of it for me??:eek:

:muahaha:......

I found sound deadener on e-bay from a co. called fatmat. their web site has all kinds of graphs showing that it is equal or better than dynamat for 1/3 the cost which becomes significant when trying to cover the inside of a full size vehicle.

As to wrapping the exhaust, I have also considered doing this but was waiting until the completion of 4" exhaust install. This can also be found cheap on ebay and jcwhitney.
:rockit:

Joi, I think I know the stuff you are talking about, but to be honest have never tried it. The key is going to be the density and weight of it though. As far as I know, all the sound deadeners are asphalt based sheeting with a sicky back and I would imagine that this stuff is also asphalt based. Does it have any smell to it? That might be a concern if it does. I always use a heat gun to apply mine and it is way more plyable and seems to stick better too. Seeing as you probably have a bunch of that stuff lying around, I'd put it down in conjunction with the liquid stuff you have. What could it hurt? And besides...more is always better.....right?!):h

yes, more is better....can't say that enough. Yeah the stuff does have an odor to it, but then again so does tar paper. I used tar paper under the hardwood floors in my house, but my house doesn't smell like tar paper.

I'll try the goop first, deal with the air filter box and if it's not good enough, then it's time to roof the floor of the truck...

hopefully next post will be about what I've done, not all my I'm gonnas...
:grd:

Well I didn't put any ice and water shield on the floor of the sub. I'm not sure that I'm going to need to. I did apply the liquid sound dampener to the passenger side floor.

The snorkel was removed by the previous owner. I enlarged the opening of the tube that connects the air filter box to the fender. I didn't make any modifications to the outlet side of the box. I also applied more sound dampener to the entire inside of the air filter box. The truck is definitely quieter now, but still slightly louder than stock.

I also installed a K&N air filter. (which by the way, comes with a self adhesive gasket that gets applied to the air filter housing lid. They also give you grease to complete the seal.) The truck quieted down slightly with the k&n.

Bottom line is that between the 4" exhaust and the K&N, the truck has more power using much less throttle. When it was stock, I could floor it up a hill and it would not excellerate, it would just hold the same speed. Now, on the same hill, I give it throttle and it accellerates. I did try flooring it up the hill, it sped up some, but nothing record setting. I'm most happy about the strong accelleration with limited throttle.:D

I'm still determined to beat this interior noise issue. I have to make better exhaust hangers than the ones that I whipped up when I did the late night install (the ones that came with the kit are absolutely useless) . Turns out the exhaust touches the cross member:o: ....this be noisy.