Why are Flowmaster mufflers bad on a diesel? I would like to see dyno numbers or some other data to support this idea. I believe member "maynard3" uses a flowmaster muffler on his truck with good results.

 

I have one on my 98 12 valve, I love the sound and as you can see by my numbers, it does me right!! I think the only problem is that a "chambered" muffler can/will fill up with particulate over time.

 

If your worried punch a small hole in the end of the muffler for water and soot to blow out of (just like the stock muffler has) This will allow stuff to blow outa it. I do agree the only reason baffeled mufflers aren't recomended as soot will build up and not blow out. However that raises the same question with the kitty, those I'm sure will build up also. To each his own.

 

Correct and that is why the third injection event in your engine is done, it's purpose is to heat up the Cat and keep it clean. Hence the reason you do NOT want to remove it on your 05

Baffled mufflers are a bad idea for a Diesel because they ARE restrictive. You want FLOW not a choke point

 

That restriction thought is interesting, I will test it at the next dyno day, I have the straight pipe to muffler thing down to 3 minutes or less!!

 

Remove the third injector sequence or the cat?

 

The cat, you don't want to remove the cat

 

I doubt you will see much difference on the dyno unless you really pushing major HP, but if that were the case, you would likely as not have a muffler to remove anyway.

The real difference will be in EGT's

 

Remember the turbo "spins" the exhaust gasses so a chambered muffler may interupt the swirl of the exhaust gasses.

 

How can user "Maynard3" run 368/718 with a flowmaster if it is so restrictive? He runs part# 53553 which is a 3.5" offset inlet/outlet that matches up to the stock 03/04 exhaust. I used to run a flowmaster 40 series muffler on my 1998 1500. It was so ridiculously loud with a high flow cat that I have a hard time believing that it was restrictive. Does anyone have data about EGTs dyno numbers, or mileage?

 

Flowmaster mufflers "sound" good on many, many vehicles. And they have a great marketing system. But they do not "flow" like straight thru mufflers such as Dynomax, Borla, MBRP or others of similar design.

 

Well, I made a big mistake this week.

A friend of mine (member coalbucket) and I attended another diesel truck club's Christmas Party at Florence, KY December 10th. He has a 2005 Dodge RAM 2500 CrewCab 4x4 six shooter w/CTD. He had his truck straight-piped some time ago.......after the party was over, we were about 8 or 10 miles south of Florence on I-75 South and I decided to give him a call to swap out trucks for the remainder of the trip. We switched, and after driving it about 60 or 70 miles at interstate speeds, I **thought** I'd like mine straight piped. I rounded up two 45* elbows and a 3.5" to 4.0" increaser and went to a well known muffler shop in London, KY. Tuesday to have the work done. The trip back from London to home (no interstate) wasn't too bad, but I already kinda disliked it. One trip to Lexington, KY from my house this week (about 57 miles one way, 30 miles of I-75) was more than enough for me. The drone of my 305/555 straight piped CTD at 2000 rpm & above is enough to make me wanna pull my hair out ! This is even worsened by running the Juice w/Attitude on 3, 4, or 5. Talking to my wife and/or 4 year old is about like this . We use my truck for all of our vacations (Myrtle Beach, SC and Florida) two to three times per year. There's no way I'd last on a long trip in this thing ! At least I discovered this way before I'd remotely considered stacks !

One good thing about the situation.....I requested the guy at the muffler shop to remove my Flowmaster #53553 in such a way that I could re-install should I decide that the straight-piped route not end up being for me......thankfully, he did and I'll be back sometime before my next long trip (if not sooner) to have it re-installed.

As for the performance aspect of it, I have noticed a slight seat-of-the-pants reduction in lower rpm power / torque. I've read over on the TDR (I'll post a link after I find the thread) that the HPCR's need some back pressure to prevent them from spooling too fast and then de-fueling.

The muffler was only slightly blackened inside (normal in my opinion) from the 28 months or so that it's been on the truck.....nothing even remotely appeared to be building up inside the muffler as far as exhaust soot goes. Cruising EGT's with the Flowmaster and straight-piped are virtually the same given any level selected on the Juice w/Attitude. I only noticed a very slight reduction in the time required to let my truck's EGT's hit 300* F before shutdown while straight-piped.

If anyone has seen an OEM 3rd GEN muffler inside, don't knock a Flowmaster until you've seen the inside of a Flowmaster.

Here's the link to the TDR article from 04/13/2004 :

http://www.turbodieselregister.com/f...03728#poststop

Greg