[markstertt]

In a previous post I asked about quiet performance mufflers and pretty much narrowed it down to Dynomax super turbo or Walker quiet flowSS in a large size can, single outlet. My exhaust guy says he'll do either 3" or 2.5" tailpipe w/muffler for $170 but if I want him to wack off the end of the Y and put on a better 2" to 3" collector then do 3" all the way it'd run about $250. Both sound pretty reasonable to me, here's the question for an '04 4.7L 4x4 DAk QC:

With only mods planned being a set of HO cams and moddified TB plumbing to modded air filter box lid(larger) & an sct tune is there really anything to be gained or lost by going to 3" ex. pipe all the way with my few mods? Bottom to midrange is what I would hope to increase. My impression from searching is the general concensus is that the 4.7L engine likes 3" plumbing, is this in all cases, regardless of mods or lack of? Thanks, Mark

 

[SPC. Brinkmeyer]

what about this setup i got it at the exhaust pix thread http://www.dakota-durango.com/forum/showthread.php?t=132935&page=3
im sure he has the 360 but could be an idea for you

here's mine. dual 3" all the way.

edit: but instead of having it dump you could run it out the back or whatever

 

[xxxxxxxxxspshultz]

I would go with a single 3". This will keep most of your low end torque but give you a little more up top when pulling a load up some big hills. I had a 2008 Dodge Dakota 4.7L and had a single 3" done with a custom y-pipe. I lost just a tiny bit of low end torque but gained more in mid-range and upper RPM's.

 

[Hurley]

There is everything to gain from the 3" diameter. I would honestly look into something like a flowmaster y-pipe (or other brand, ~$40-45) that is pre-fabricated. The pre-fabbed y-pipes will have a much better fit/finish/design, and will cut down on the overall system losses due to restrictions/etc.

 

[FastQC4.7]

There is everything to gain from the 3" diameter. I would honestly look into something like a flowmaster y-pipe (or other brand, ~$40-45) that is pre-fabricated. The pre-fabbed y-pipes will have a much better fit/finish/design, and will cut down on the overall system losses due to restrictions/etc.

Magnaflow makes a cheap 2.5 dual to single 3" prefabricated Y-pipe that works great. The stock 4.7 Rams had a single 3" exhaust, hemi sized catalytic converters, and the larger, but still restrictive hemi Y-pipe.

 

[Craigslue]

More info on a 2.5 to 3" y pipe. Our trucks only have 2" before the Y. A Y pipe from a Ram will fit our trucks? What year Ram? What about the cats?

 

[FastQC4.7]

More info on a 2.5 to 3" y pipe. Our trucks only have 2" before the Y. A Y pipe from a Ram will fit our trucks? What year Ram? What about the cats?

On my brothers 03 Dakota we installed JBA headers that have ~2.25" collector openings on them. We borrowed a set of spare 2.25" flanges that came off my junkyard 5.7 hemi. We stayed 2.25" for about 2" on each side of the truck, the piping was bumped to 2 1/2" mandrel bent, into a Magnaflow pre-made 2.5" dual in single 3" out Y into a single 3" exhaust.

I am almost certain the Ram Y will not fit, but I was using it for reference that some 4.7s use a 3" exhaust stock.

 

[Kingst3r]

Single 3 inch, dual 2.5 inch

 

[Kingst3r]

what about this setup i got it at the exhaust pix thread http://www.dakota-durango.com/forum/showthread.php?t=132935&page=3
im sure he has the 360 but could be an idea for you


edit: but instead of having it dump you could run it out the back or whatever

Whos set up is this?

 

[SPC. Brinkmeyer]

bryanrt360... its a quote from his post in that thread... i wonder if a setup like that in like 2.25 would help out my 3.7dak cuz its a turd lol im thinking of maby doing a remote turbo and if i do i would probly put it where the x pipe is

 

[gocartone]

More info on a 2.5 to 3" y pipe. Our trucks only have 2" before the Y. A Y pipe from a Ram will fit our trucks? What year Ram? What about the cats?

People use the step ups to make it work on our stock Y pipe. I think I might end up doing this for my truck, I just bought exhaust for my car that came with a 3" cutout welded in that I'm taking out (Borla adjustable, it has a spot for the cutout on it already not sure why they welded one in) and putting on my truck. I figure I already have the cutout, all I need to do is buy the 2.5-3" Y and cut a chunk of pipe out before the 3rd cat (or cut it out completely, but that would make the cutout all but pointless as I have a CB Extreme muffler). For the whole size thing, I would say go for 3" as it isn't going to be mandrel bend 3".

 

[addicted2blue00]

the y pipesare what is the restriction on our exhaust, better y pipe and single 3" would be good and may have a lil better low end torque, dual 2.5" with x pipe will let the motor breath nicely, far as quiet muffler if you really dont mind droppin some money flowmaster now has a "hush" muffler but its $100+. ill be doin my exhaust when my motor is redone which itll be a heads/cam 360 so ill be goin with a dual 2.5" from the mid-length headers to a x pipe -the x pipe lowers the sound from 2-6 DBs- back to a set of 18" round magnaflow mufflers

 

[markstertt]

Thanks for all the ideas, due to costs, I will look into modifying the exit of the existing Y to open it up and then run 3" the rest of the way back and see how she goes. I think this is about the best I can do for now...Mark

 

[gocartone]

I would just replace it with the 2x 2.5 to 3" y-pipe(just the Y, not the whole manifold to Y). Everyone says that is the worst part of the exhaust, making a wider opening after that isn't going to help a whole hell of a lot and they are only like $30 for the y-pipe, say $60 total to get two adaptors welded on so it will work with the stock y-pipe

 

[Tiresmoke]

I would just replace it with the 2x 2.5 to 3" y-pipe(just the Y, not the whole manifold to Y). Everyone says that is the worst part of the exhaust, making a wider opening after that isn't going to help a whole hell of a lot and they are only like $30 for the y-pipe, say $60 total to get two adaptors welded on so it will work with the stock y-pipe

So you're thinking this http://www.summitracing.com/parts/MPE-10778/ Will weld up to stock stuff just fine? Sure the spacing and everything will be correct?

 

[Hurley]

So you're thinking this http://www.summitracing.com/parts/MPE-10778/ Will weld up to stock stuff just fine? Sure the spacing and everything will be correct?

more like this one from flowmaster. The magnaflow y-pipe doesnt really have an efficient design

 

[FastQC4.7]

I have two of the Magnaflow Ys and they work better than the Flowmaster version, not to mention the Magnaflow is stainless.

This is the Ram Y-pipe and the Dakota 4.7 is even worse!!

 

[Hurley]

I have two of the Magnaflow Ys and they work better than the Flowmaster version, not to mention the Magnaflow is stainless.

This is the Ram Y-pipe and the Dakota 4.7 is even worse!!

Are you certain that they work better? I'd beg to differ based on actual design theory and the fact that the high-quality guys make them in the same fashion as the flowmaster.

http://lmgtfy.com/?q=merge+collector

 

[FastQC4.7]

Are you certain that they work better? I'd beg to differ based on actual design theory and the fact that the high-quality guys make them in the same fashion as the flowmaster.

http://lmgtfy.com/?q=merge+collector

Don't you think if I have run them both, that I have track times that show the Magnaflow did marginally, but measuerably better.

 

[Hurley]

Don't you think if I have run them both, that I have track times that show the Magnaflow did marginally, but measuerably better.

Over how many runs? Were they consistent enough to actually show a difference created from the power delivery, and not your driving? I cannot imagine changing such a minimal (and singular) variable being changed and documented over a series of track runs. It's hard enough to get verifiable data on a dyno.