Bigger Exaust Vs. Performance Muffler

[Greg McCall]

Can I get by with just a muffler addition on my Duramax ?
I have the Hot Juice but am serioulsly looking into a Tranny improvvement and maybe stacking boxes.
I see Michael T has added a performance muffler only and getting 13 second 1/4 mile passes. Using a cutout ?
Apparently the big exausts are more for long up hill pulling than 1/4 mile runs.
Any and all comments would be appreciated.

[TOYPULR]

Greg, I too have wondered about just upgrading the muffler... I see there are some that just take it out and straight pipe it with the stock exhaust and are happy with it, that's too loud for me. I was looking into the "Aeroturbine muffler" http://www.turboexhaust.com/diesel/index.html and I'm looking for anyone that might have tried it or knows someone that has. If I don't find anyone, I'm considering giving it a try... There specs look nice... My thoughts were that if I do get one, I would get the one for the 4" exhaust and adapt it to the stock pipe then if I thought it really needed the 4" then I could just get the pipe and still use this muffler... What muffler were you looking at?

Sss

[Greg McCall]

I have considered JKs 4" muffler and even a Flowmaster for diesels from Flowmaster's website. I would also be able to use it if I decided to later go with full exaust. I have even thought of an electric cutout and keep stock exaust.

Michael Tomac says he has only added the Flowmaster, though I suspect he took the Cat off.
I'm not big on noise, so I prefer the quieter muffler of equal performance.

[Amianthus]

Go for the full 4" exhaust. There are many more benefits to the larger exhaust than a muffler replacement alone can provide. I don't care what kind of "secret" design a muffler may have, there is just no performance comparison when you compare it to a full 4" (or larger) exhaust system.

As for the noise, find a muffler that suits your needs. I find a longer straight through muffler works pretty well. But if you must have it baffled (I wouldn't), there are a few choices out there that may give you satisfactory results. I run a 24" straight through design 4" muffler and am very happy with it. It's not near as loud as my un-muffled counterparts. Although, it will get your attention.

[mtomac]

My truck didn't come with a cat converter. I just replaced the stock muffler with a 3.5" in/out replacement Flowmaster has for the Duramax.

IMHO, with the squished stock downpipe a 4" exhaust & muffler offers little benefit compared to the stock 3.5" exhaust with a good flowing aftermarket muffler or no muffler at all on it.

I thought about using a cutout for truck pulling so I dropped the muffler and tailpipe and put an elbow on what was left of the stock pipe to point the exhaust down. Back when I was running the Hot Juice for truck pulling I would normally peg the 1500 degree EGT gauge for 5-8 seconds during a pull with the flowmaster muffler on the stock exhaust. With just the elbow on the stock pipe I pegged the gauge for 6 seconds during a pull on a shorter than normal track. After seeing that I figured the muffler wasn't causing enough restriction for me to worry about.

Now that I'm running comp boxes for pulling I'm pegging my 1500 degree gauge for 10-12 seconds during a pull. I'm seriously thinking about having CPmac build me a 4" downpipe like he has. Then I would go with a 4" exhaust and hopefully see some benefit from it.

[Greg McCall]

Thanks for the replies.
My Texas truck did not come with a Cat, and maybe there is a gain there. It seems the cutout is not worth much on a system that already has atleast a muffler addition.
It also seems unless your planning on making 400 plus HP (rear wheel) a muffler addition like Michael Ts would be okay.
However, I'm looking into buying a tranny upgrade and more HP, so maybe a well built downpipe and 4" exaust is what I need.
Only want to do this once. No patch work for me.

[ 08-29-2003, 06:24 AM: Message edited by: Greg McCall ]

[afp]

From what I understand, there is no HP gain with a freer flowing exhaust, just a drop in EGTs........... At least at the typical HP levels we're talking with this motor. maybe a 500 HP DMax would gain power with a bigger exhaust.

According to Magnaflow--who sells both mufflers and full exhausts for the DMax--the muffler is 75% of the restriction in the exhaust system (I have no CAT). I didn't have my gauges before I replaced the muffler, but there is a poster here who has done same thing I have--replace just the muffler--and he reported a 100-150 degree drop in EGTs.

Blaine

[Idle_Chatter]

Well, I replied a couple of times to this thread on Friday before we were "set back" on Saturday - so I'll post the previous information again. I installed a Magnaflow 4" straight-through stainless muffler in my stock pipes just like afp, and have been very happy with the results. I had my gauges in before the "mufflerectomy" and I saw EGTs go down 100-150 degrees across the board with the factory muffler out. Turbo spools up a bit faster and seems to peak at a couple of pounds more boost, too. Here are some searched threads and info on my install:

http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=3;t=005556

http://forum.thedieselpage.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=004826#000000

I bought mine on the internet from www.henschelandsons.com (http://www.henschelandsons.com) in Connellsville,PA. The muffler was the Magnaflow 14771 - $149.42, the adapters were 15441 - $22.33 each. I bought 4" band clamps from a local International truck parts supplier. The job wasn't so tough, I did it in my driveway without even jacking the truck. I cut the stock muffler outlet pipe as close to the muffler as possible with a chain cutter. This allowed me to get the muffler and inlet pipe out, as well as the tailpipe. I then cut off the stock inlet as close to the muffler as possible. This left "stubs" of stock pipe inside the factory hangers. A trial fit of the muffler and clamps indicated that the adapter/muffler combo was a bit too long for the gap vacated by the stock muffler, so I trimmed about 1" off the Magnaflow inlet and outlet and the same off the 3-1/2" sections of the adapters. The stubs were also oval due to both of them being in bends in the factory install. I rounded them back out for a better fit to the adapters with a 3-1/2" pipe expander tool. I then clamped the adapters to the Magnaflow and fit the three pieces back up under the truck. When I got it where I wanted it - in the factory hangers and the tip of the tailpipe supported on a floor jack, I tack welded the 3-1/2" end of the adapters to the stock pipes. Then I released the band clamps, brought out the three pieces, full welded the adapters to the pipes and put everything back. Whole job took about 4 hours.

Photos are in my PICS link under "mufflerectomy."

[a64pilot]

Amianthus,
The problem as I see it is there is no "full" 4" exhaust for the Dmax that I know of. They all use the stock down pipe. I was led to believe that without firewall modification a 4" wouldn't fit. That may be incorrect as apparently at least one member has made a 4" downpipe.

[DMAX Phil]

In the Summit catalog, they advertised a DMAX exhaust system for around $250 and as a separate line item, a turbo down pipe for another $150 or so. This was a four inch system.


Phil B.

[a64pilot]

Phil,
This is interesting. On page 337 in their "Diesel performance section" they list a turbo down pipe under Dynomax brand name, but don't specify the size.
Under their house name they claim a 4" turbo back exhaust system.
Does anyone know for sure if it actually is 4" from the turbo housing on, or is it really only after the stock down pipe like Banks and others.
If it is really 4" from the turbo housing on then $299.95 is one heck of a deal IMHO.

[mtomac]

after the stock downpipe like everyone else

[a64pilot]

Michael,
I was afraid so, seemed too good to be true.
Are you getting a 4" fabricated? will one fit without "clearencing" the firewall?

[mtomac]

actually it will be 3.5" which is better than the stock downpipe that is sandwitched down to 2.5"

[a64pilot]

If you find a source will you let us know. The stock downpipe being restricted, and funds availibility, have been what has been keeping me from an aftermarket exh.

[DMAX Phil]

Well, now I'm confused. It sure looks like a turbo down pipe, however, I am not yet "intimate" with the piping around the turbo. I found the Dynomax system with two 4" components advertised. One is the "turbo down tube" and the other is the "turbo intermediate tube." Both are 4" and both are in addition to their exhaust system for the DMAX.

Check the text out below, from RPMOutlet. They show the same picture for both items... but the price is different. Here is the URL:

http://www.rpmoutlet.com/duraexhaust.htm



01-03 Dynomax Turbo Down Pipe, 6.6L Duramax diesel Pick-Up, all models, all wheelbases
Now Duramax owners can enjoy greater benefits from our Exhaust Down Pipe. With the installation of our "Stainless Steel" downpipe, not only will you get an additional 12+ horsepower and 25+ lb-ft torque, your Duramax turbo diesel engine will also benefit from lower exhaust temperatures. These mandrel bent "Stainless Steel" downpipes not only give you more power but also helps the durability and longevity of your engine. Installs in less than 1 hour.
adds up to 1s4.4 RWHP hp

* 4" OD, mandrel bent, type 409 stainless, 15 gauge tubing
* Designed to mate directly to our performance exhaust system or to the OE exhaust
* Utilizes the OE hanger location for an easy installation
* Lowers back pressure at the turbocharger outlet to increase engine power and improve fuel economy
* Quick & Easy 2 Hour Installation
* Detailed Instructions IncludedPhil B.

[jcummins]

The pipe in the picture is not a downpipe, but the pipe that fastens to the downpipe.

[a64pilot]

Phil,
I'm with you, if they aren't talking about the pipe that connects to the turbo, then they are being so misleading then it amounts to lying.

[DMAX Phil]

Here's the word from their "technical support." At least it clears up what the "intermediate" pipe is.


Thank you for your inquiry for Dynomax Exhaust. We appreciate your interest in our products. In regards to your 2001 Chevy Silverado with the 6.6L Duramax Diesel, our #54194 turbo down pipe is a mandrel bent stainless steel pipe that will bolt to the cast iron elbow on the engine. To complete the kit, you will need the Ultra Flo kit #19375 for your 153" wb. This kit includes the intermediate pipe (goes between the down pipe and the muffler), Ultra Flo muffler, tail pipe, chrome spout, and hardware.

If you have any further questions, please feel free to contact our tech
line at the number below.

Thank You,

Lisa Kortz
Lisa Kortz
Dynomax Performance Exhaust
Installation Technician

Tech Line Number For a Dynomax Dealer Near You
1-734-384-7806 1-734-384-780

[a64pilot]

Phil,
It may have cleared it up for you, but what cast iron elbow on the engine? Gotta be the turbo right, or does she not know what she is talking about?

[mtomac]

You can be sure that NO ONE in the mass parts selling world is selling or will be selling a "downpipe" (clamps to the back of the turbo) for the Duramax unless they have a flexable line for the dipstick available as well for the Allison. The stock steel line and dipstick is in the way of a bigger downpipe. Not to mention it is a pain in the butt to get the stock downpipe off and just as big of a pain in the butt to replace it with a bigger one. It's not exactly a "bolt on" mod.

[a64pilot]

Michael,
I don't think they are either, but who knows, maybe? Wishful thinking I know. Just wish they wouldn't be so misleading. Was really trying to save someone some money before they bought something other than they were being led to believe they were getting. I really think these companies are being dishonest, maybe not legally, but it's enough to keep me from buying from them. Sometimes you get what you pay for, you know. ;)

[DMAX Phil]

a64 - What I meant to say was that the only thing they cleared up was what the "intermediate" pipe is. Hard to believe they are giving descriptions like the "cast iron elbow on the engine"... I'll buy what Michael is saying but I agree with you that they are either clueless or intentionally trying to deceive folks.


Phil B.

[Greg McCall]

Well...considering there is no improved downpipe, I will just add a muffler untill a downpipe is available.
Also has anyone revised the driver side exaust pipe restriction as JK shows on his site ? That seems like some HP robbing restriction.

Once last thought is my Turbo Buick is only running a 3" downpipe and makes well over 500HP.
However, EGTs are a little higher than what we may be comfortable with.