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Kota Kid
Dodge Dakota
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9/20/2007
19:20:25
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 Subject: RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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My 4.7 2wd lost some low end grunt when I switched to the true duals, but it really pulls hard from 3500 up. Thats what I want though, on this truck any way on my 4x4, however I wouldn't do any thing to hurt that 318 punch off idle. Thats why I have a single in dual out Flowmaster and the cat removed on my 4x4, still has gobs of low end grunt and sounds quite aggressive. It claps almost as much as a 350 Chevy truck with Cherry Bombs.
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Kowalski
GenIII
9/21/2007
15:35:20
|  RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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I see there's a lot of misconceptions in this exhaust thread. The low end torque loss doesn't really have much to do with single or dual design; but is more dependent on proper pipe sizing. While you want pipes big enough to flow well, you need to keep the size small enough to maintain decent velocity for good exhaust scavaging in the cylinders. "eddy" is off base thinking that its harder to flow through larger pipes. It's easier, but because the exhaust flows easier it also flows slower - so you lose the scavaging effect. That's what kills low end torque.
Lead, follow, or get out of the way
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Kota Kid
Dodge Dakota
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9/21/2007
18:14:12
| RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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In a way it does have to do with the number of pipes because you are effectively doubling the size of the exhaust by doubling the number of pipes. Yes it would have the same effect if I had used a single 5in pipe instead of dual 2.5in pipes but 5in pipe isn't really feasable on a Dakota. Like I said before thats why all I did on my 4x4 is 3in pipe from the y-pipe to the muffler and dual 2.5in out under the bumper. Its all about where you want the power band to be when you design an exhaust system for power gains more than sound quality. Changing to true dual 2.5in pipes on my 2wd was done because I wanted to move the power band up a little, I don't haul anything except for a$$ down the 1/4mi. The higher power band also lets me take even more advantage of my 4.56 gears. All I did on my 4x4 is make it louder without costing me any power, its a pretty much stock 318 doing a bunch of work to the exhaust isn't a very good place to start to get power. I need to do some work to the intake side of the engine first maybee later I'll change the exhaust again when I need to go bigger or better.
Any way when this thread was started all the guy wanted to know was which would sound better Magnaflow or Flowmaster, I still vote Flowmaster. Been there, done that, sounds awesome!
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eddy
Dodge Dakota
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9/21/2007
18:54:49
| RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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" "eddy" is off base thinking that its harder to flow through larger pipes. It's easier, but because the exhaust flows easier it also flows slower - so you lose the scavaging effect. That's what kills low end torque."
How can an exhaust flow more easily and more slowly at the same time? What I was taught is that appropriately narrow pipes create a higher pressure environment which moves gases through faster and easier. Pipes that are too big slow the gases down. IF they're moving slower, then they're not getting out of the tips as easily.
Truth be told, I think we're pretty much saying the same thing but you're getting a bit wrapped up in semantics. Still comes down to the fact that the gasses don't get out as easily if the pipes are bigger than what is required by the rest of your setup, causing a loss of low end torque. Meanwhile this creates more top-end power since the engine is turning faster and pumping gases out at a higher rate, which makes up for the loss in scavenging effect caused by excessively big pipes.
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Kowalski
GenIII
9/22/2007
07:45:31
|  RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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eddy - we're not saying the same thing at all; especially since you don't seem to understand any of the basics of how gasses flow. I'll be happy to explain to you how an exhaust can flow more easily and more slowly at the same time - it is because the larger volume of the larger pipe will move a given amount of gas more efficiently than a smaller one. Let's say the smaller pipe has half the volume, for our example. To make up for the smaller size, the given amount of gas would have to flow twice as fast to get through the pipe.
You were either taught incorrectly, or didn't properly understand what you were being taught. This isn't a matter of semantics, but rather a misunderstanding on your part. you are still trying to claim that gases don't get out more easily if the pipes are bigger; and that is just plain wrong. The gasses do get out of the pipe more easily, and more slowly - and that costs you exhaust scavaging at the cylinder.
Kota Kid - No, it does not have much to do with the number of pipes "because you are effectively doulbling the size of the exhaust by doubling the number of pipes". That statement assumes incorrectly that a dual system should have the same size pipes; but a properly sized dual system should have smaller pipes than an idealy sized single so we keep the exhaust velocity high to get the scavaging effect at the cylinder. A single 5" pipe will flow much, much more than two 2.5" inch pipes. You clearly don't understand how to figure the area of a circle; or the volume of a pipe.
Lead, follow, or get out of the way
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yup
Dodge Dakota
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9/22/2007
09:28:23
| RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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"Any way when this thread was started all the guy wanted to know was which would sound better..."
Yup, so maybe some of you should have left it at that. Now a couple of you are trying to save face when you don't know what you are talking about ! Kowalski is right.
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wylman
Dodge Dakota
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9/22/2007
10:06:24
|  RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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I third Kowalski. How about putting it in layman's terms for those guys though. Think of it as back pressure. A single, larger diameter pipe doesn't allow enough back pressure (exhaust scavaging)Hence the lose of power. If you go with two pipes at the same diameter as the factory pipe......you get the same effect unless, you do something to create the same amount of back pressure. Usually achieved by going with mufflers that have an extra baffle or chamber. Another thing that will effect your power gain or loss, is the routing of the pipe. More bends makes it take longer to clear the exhaust. Straighter pipes make everything flow easier. On one of my past vehicles, ik stepped everything up as it went to the rear of the vehicle. I also ran the pipe it self as straight as possible, even going under the rear axle as to eliminate the bend in the pipe. Of course I only drove that car on the road. I also used a three chamber Flowmaster muffler and even added a big flat washer to the interior of pipe and set it at an angle to make sure I had the proper amount of back pressure. That is a trick we use on straight piped Harleys if we don't have a set of torque cones readily available. works pretty good....most of the time.
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DeereFarmer
Dodge Dakota
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9/23/2007
17:35:23
| RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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Well guys I got my exhaust done on Friday. I went with a SI/DO Flowmaster Origional 40 with 2.5" pipes, mandrel bent, and 4x18" stainless tips 45 degrees behind the rear tire. All i can say is I'm amazed. It is the best sounding truck ever, even with "just" the 4.7. My exhaust guy said to try the 2.5" pipes because that's what he likes. If I didn't like them he'd switch down to 2.25" for free. I haven't noticed any loss of power anywhere. It's just great. My girlfriend and I went to the local fair yesterday and I got tons of compliments and thumbs up. Even my girlfriend likes it now. I've set off two car alarms and have not been able to wipe the smile off my face. Now my neighbros might not like me Monday morning when I leave at 5:30AM, but oh well lol. I'm so happy with my decision and thanks to all of you guys.
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wylman
Dodge Dakota
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9/23/2007
18:34:01
| RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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Deerefarmer-As long as your happy, that is what counts. I mean, it is your truck. They have all those different exhaust configurations out there so we don't all have the exact same sound. Glad you like it.
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eddy
Dodge Dakota
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9/23/2007
18:50:31
| RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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OK got it. So exhaust gasses slow down in bigger pipes and move more slowly but exit the pipe more easily but in narrower pipes, they speed up but have a harder time getting out. Whatever you say. Makes perfect sense. I bow to your expertise. I hope your penis feels larger.
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Kota Kid
Dodge Dakota
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9/23/2007
20:09:41
| RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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I'm not trying to argue with Kowalski at all, I know hes right! I believe I said "IN A WAY it does have to do with the number of pipes." I didn't say it was solely base on number of pipes, I'm sure if you ran Honda sized pipe in a true dual application you probably wouldn't lose any torque, but frankly that looks down right silly and sounds like SH!T! I'm pulling off of what I personally know, which is on my truck with 2.5in mandrel bent true duals with an x-pipe and high flow cats and spintech mufflers it lost some low end power but gained at the top end, right where I need it with 4.56 gears. Kowalski just explained how that works.
DeereFarmer I'm glad you liked it like I said it was the exact same setup I had on my truck to begin with and its what I've got on my 318 4x4 now, and it is a sweet, sweet sound!
Hey wylman you heard anything else about that mudbog yet, I want to make sure I've got my 79 Bronco back on the road before then.
You guys would really hate the exhaust on this thing, its got 3in true duals through 14in long race 40 series flowmasters, but it sounds GOOOOOOOOOOOOOOOOD!!!!!!!!!
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wylman
Dodge Dakota
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9/23/2007
20:33:55
| RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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Kota Kid-I think it is supposed to be up and running the middle to the end of next March sooooo,you should have plenty of time to get Your Bronco together. I am working on getting another truck to run out there as well. I let you know for sure when I talk to my friend again. If you need any parts or anything for your Bronco, shoot me an email. I have a pretty good sized cache of Ford stuff stashed away.
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DeereFarmer
Dodge Dakota
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9/23/2007
20:52:21
| RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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You were dead right on that setup Kota Kid. It is honestly one of the best truck I've ever heard and that's not just because it's in my garage! I have gotten so many compliments and looks it blows my mind. When I had a FM 40 on my old Chevy nobody notcied, but put that bad boy on a Dodge and the heads turn!
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Kota Kid
Dodge Dakota
JOIN HERE
9/24/2007
19:41:11
| RE: 4.7L Exhaust. Magnaflow or Flowmaster?
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Sweet I should have my transmission back long before march, it better be done before october! Then all thats left is to get the new 400 4V in place of the original 351 2V. Already got the Powertrax Lock-Rite in the rear and am getting a Detroit Electrac for the front. Havn't got the 38x15.50 radial Ground Hawgs on yet either.
Check out my cardomain page I've got a picture of the Bronco on there too from when I first got it. It still looks the same just no hood, engine, or transmission at the moment.
http://www.cardomain.com/ride/2855458
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