Engine/Transmission (1998.5 - 2002) Has anyone insulated their downpipe?

[Seed Guy]

Our mercedes diesel uses a double walled down pipe to reduce noise. I have been brainstorming what would work to wrap it in to keep heat and noise in the pipe where it belongs. Anyone done this? Or know what might work?

 

[Ncostello]

Cant speak for ISB pickups but its common practice on custom cab (cab over engine) fire trucks to keep heat and noise out of the cab where the firefighters ride. Our KME has the pipe on its ISC wrapped all the way from the turbo down to the muffler with an exhaust brake right behind the turbo. Now if we could just replace the direct drive fan with a Horton it would actually be quiet. That thing makes it sound like your sitting next to a steam turbine.

 

[n7gxz]

I've wrapped my 4" down pipe with 2" wide header wrap. I did reduce the tinny sound especially when the E-brake comes on.



Kevin

 

[Mark Craig]

Down Pipe

Morning,



We have had a number of customers wrap their down pipes with Header wrap on both the 24 valve and the new common rail engine exahust systems they purchased from us. They have called us back and claimed a decent noise reduction and cooler underhood temps etc. Most fo them felt it was worth their time effort and cost. FYI!



Mark

DPPI

 

[AKDrifter]

What's header wrap and where do you get it? Paul

 

[Scooby]

Try JEGS or Summit (on the web) - you can get the header tape from either one. - it's basically a roll of thick, heat resistant cloth-like tape.

 

[Ncostello]

Header wrap is available through places like Summit Racing. It looks like a white weave material... kinda like kevlar fabric. Comes in a roll and goes on like duct tape. Just overlap it I think. I've seen it in thicknesses of about 1/8" or so. Very heat resistant. In fact on the ISC, I can touch the pipe near the turbo without it burning me. Its warm but not hot.

 

[nbr1trucker]

exhaust wrap

Hi guys, was just wondering---could you use header wrap to wrap exhaust under the cab to cut down on the noise from having a straight piped truck, and keep the noise out of the cab. tia Ian

 

[drawson]

I have my down pipe wrapped, because after the Piers HX-40 the new down pipe came too close to the firewall. As far as noise reduction there is some but it isn't alot.

 

[Mtngoat]

Would the header wrap hold in moisture when the pipe cools and cause rust problems?



Robin

 

[jandtjil]

Another source of header wrap is Hamilton Marine

http://store.hamiltonmarine.com/index.htm

I just purchased some extremely heavy 3" from them, great price!

unfortunately they do not stock the stainless fasteners or high temp silicone spray.



JJ

 

[Lsfarm]

Downpipe mods

I had used header wrap on my factory downpipe early in my noise reduction experiments. There is some reduction, but not a huge one. Pretty much as described above as a reduction in the 'tinny' sound.



After experimenting with several variations of factory downpipe expanding into a 4" system with various mufflers, I finally decided to go with a full 4" system from the turbo back.



The system I used has 16Ga steel pipe, and there was a noticable increase in the background 'hum or drone' from the thinner steel pipe. I did not take the time to install header wrap on the new system.



The first experiment to reduce this new exhaust pipe noise was to replace the downpipe to muffler pipe [the horozontal section] with a heavy wall 12Ga. pipe. There was a noticable change in the overall noise level, mostly when under heavy acceleration.



There was still a lot of noise under heavy throttle, and it was really annoying me. My truck was about 2-3DB quieter at 80 mph than at 70 mph. There is a definite engine generated hum or ressonance at around 1900 RPM [70mph] in my truck.



So about a week ago, I pulled off the downpipe [4" bare steel, no headerwrap] and added a second layer of steel to it to make it as much as possible a double walled pipe.



I took a length of 4" 14GA pipe, and slit it lengthwise. This allowed me to open up the slit with expanding pliers and slip cut-to-length pieces over and past the downpipe's bends and kinks. . I then clamped the second layer down tight against the inner pipe and used a MIG to weld it in place. I was not able to double wall the bends in the pipe, or the cone shaped section where the pipe expands from the turbo to the 4" pipe.



I reinstalled the much heavier downpipe again without header wrap, just to see what changes in noise this mod had produced.



Well the 'tinny' sound is mostly gone, so I consider the experiment a success. I can't really measure any huge reduction in sound pressure [decibels], but I don't hear that annoying background hum or drone anymore, and the 1900 rpm range doesn't stand out as much as before.



Next I will wrap the downpipe and horizontal section up to the muffler with header wrap, and see what difference this makes.



If you want to shop around for header wrap, GSI sells various widths, lengths and weights of this product, I would describe it as a woven fiberglass tape. The type I bought is 2" wide and about 1/8" thick. www.soundstop.com TDR members get a 15% discount on most GSI products, a 30% discount on the 1/2" soundstop foam.





Greg L. The Noise Nazi