3 muffler configs today

[sootie007]

So I am new to Jeeps and the first mod I have done is changed the exhaust...today I tried 3 different setups with mufflers I had lying around....

First config 3rd cat removed from system , factory long case muffler and stock tail pipe exiting out the back stock location .....over the last 3 weeks I lived with this setup....was a tad louder than stock, barely discernable BUT netted surprising 8-13% fuel mpg increase....I know I know its illegal but it was holding the truck back, I could actually feel it (blarg) and I do 325 miles a week so I need every bit of mpg I can get .... best tank was 18.85 mpg up from 16.44 mpg originally . Front 2 cats still in place .

I had an IMCO chambered muffler lying around, medium size fully welded case ,3 chamber (FLowmaster ripoff) 2.5 " in, out, dumped with a short turndown right before the rear end ...WOW WAAAAY LOUD at startup it took me 10 seconds to decide it was waaaay to loud for me ..big time annoying burble at idle ...I didnt even cruise around to see the interior resonance ...sounded just like an over the top annoying import just like an 80's MONZA exhaust note...YUCK.

decided to see what a straight pipe sounded like...YIKES ..alot louder than I thought it would be with the 3.7 ....burbles,snarls, pops in the pipes etc when you rev it...way loud.

Then I switched to a cheapie 2.5 inch Summit Racing Turbo ...its a medium size case 2.5 in 2.5 out, $25 rolled edge case muffler ..I ran it again with a short turndown tip coming right off the mufflers exit pipe- before the rear end.... .....sounds great .....low rumble at idle to 1800 in the cab ...again its heard in the cab above stock db BUT not annoyingly bad at all then it kind of subsides from 1900-2500 and gets a little quieter at cruise inside it seems which I love ....BUT if you get on it - it will come alive and get a tad louder inside - sounds like a nice V8 "factory" sports car muffler tone...for me I think its the best compromise. ...update just went through a drive thru and it was louder than I thought with the windows down but sounds great idling and inside its not overly obnoxious like a constantly droning flowmaster at cruise. I have owned 50 series FM's in my hot rods over the years and at cruise they can be annoying- this Summit Racing Turbo isnt. Hopefully I will pickup a tad MPG too. Will post a video on You tube tomorrow of this sound and update my MPG after a few tanks to see if it netted anything. I am really enjoying the Jeep so far ......I have been a hot rod and drag race car guy primarily for the last 30 years and wanted a change hence the Jeep ....

Update here is the link...its doesnt sound well as the cameras microphone is too tinny...it sounds like a diesel in the video ...... the in cab video is also there which unfortunately the base in the cab doesnt come through the video either...oh well I posted it anyway . J

http://www.youtube.com/watch?v=AUMHaqGqSLM

http://www.youtube.com/watch?v=nln1Hm5BAR4

 

[HoosierJeeper]

Can't wait for a vid!!!

 

[sootie007]

I bought a MAGNAFLOW P/N 1640 33 inches overall 2.5+ inlet outlet straight through design. Its the biggest straight through they make I believe which is what I wanted (quiet). I am coming off of a summit turbo 2.5 inch muffler. Which had a little too much rumble-resonance at idle to 2k rpms for me . This sucker is big at almost 3 ft long....it is totally quiet at idle inside with just a hint of a burble coming up through the floor The Summit turbo you could definitely hear through the floorboards at idle to 2k then it quieted. I have heard the Magnaflows change a little after the first week of driving so we shall see if it gets louder at idle. I can feel a difference when you get on it to accelerate it just feels freer revving and additionally a hint of more power coming off idle not much though. Its not running cooler temp wise going from the factory gauge. When you get on it - it has a nice tone which can be heard but again the sound is lower db wise up through floor boards than the turbo sounded. I love it so far..... super quiet but has freed up a little more power. Will give an update next week when the internal packing has settled or burned through ...I will also update my MPG post thread for a few weeks following this installl. This is a gigantic muffler which muffles very well but is a straight through design ...I think if you want a little more sound go for the smaller cross sectional case and also to tuck it up in the chassis-mine is still installed higher than the rear end and off roading isnt in my plan ..this one is big at 6 inches across.. The mufflers end pipes are flared and accept 2.5 inch pipe inside them...the case is 27 inches long , 6 inch cross section with 3 inch stubs on each end or 33" total length single in single out .....

Update well after about a week running on it - it has gotten a little louder as others said . Not obnoxious but definitely louder...from idle to 2k you can hear it almost on par with the turbo that was on there before ........mileage updates to come later ...... . J

 

[sootie007]

Update ..about 10-11 days in - this muffler is getting louder ...will let you know when it stops getting louder.....its still not too obnoxious but its no longer dead quiet at idle...its still not as loud as the turbo muffler at idle but it has picked up db from say 1000-2000 but still is under the turbo mufflers noise levels at those rpms....I am just curious when the Magnaflows finally settle down and stop getting progressively louder. I tried getting a video for you guys but my cameras microphone just sounds too tinny and in person sounds nothing like the video so why bother posting. J

 

[Dave]

Sootie, so far it seems like a compromise between to loud and too quiet......maybe just right?

Dave

 

[sootie007]

Yes Dave as long as its stops now and doesnt keep getting louder this ones a keeper ! J

 

[tour96se]

is this with or without hte cat?

 

[sootie007]

No 3rd cat.

 

[Ry' N Jen]

The muffler on our Jeep is about ready to be replaced.
The rest of the exhaust system looks to be in good condition.
However, I am not one to just replace a muffler and then 3-6 months later needing to replace the rest of the exhaust system.
So I'm going to let this muffler run it's course and when it is truly baked, I'm thinking of spending the cash and having a true dual exhaust system installed by a shop I've been dealing with for the last 26 years.

My question though... Is...

This 3.7 liter V6 engine requires back pressure to maintain the low end torque.

What type of mufflers should I be considering?
Or should I just keep a single outlet at the "Tail pipe"?

Seems a little ass backwards to have only one tail pipe with a "Vee" configuration engine!
I'm used to V8 power!

 

[sootie007]

I have run the following modified setups and comments over the last 2 months .....

stock exhaust..it is what it is ..nice and quiet but plugged up only, not great acceleration at speed ..... 16.4 mpg

Removed 3rd cat , stock muffler and tailpipe.....best mileage with this setup by about 1 mpg -solidly in the high 17,- high 18 mpg range , felt slightly held back when trying to accelerate from say 45mph up. Torque difference - I cant really feel it.

Removed 3rd cat , summit Turbo 2.5" dumped at rear axle -no tailpipe....tad better acceleration , mileage slightly down by about .5 mpg - .75 mpg from no 3rd cat / stock muffler ..too loud inside for my taste from idle to 2k ...

Removed 3rd cat , 27 inch long by 6 inch wide round Magnaflow straight though dumped at rear axle -no tailpipe....engine feels freer revving, "happier" at cruise 70 mph , slightly / tad peppier,,,BUT mileage is slightly down over the turbo muffler and stock muffler even though its a straight through design......the torque difference again isnt noticeable to me .......J

 

[Ry' N Jen]

In all honesty, I don't care about fuel economy. Within reason of course!
I don't want to loose any torque in the low end.

 

[ridenby]

Took third cat out,thrush glasspac,stock tailpipe,seems to like this setup.

 

[tour96se]

we had a 14whp gain over the stock catback on my SVT contours 2.5L v6...not sure why our 3.7 would lose hp/tq