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mr rhoades
Dodge Dakota
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11/02/2006
20:41:31
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 Subject: single or dual?
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Hello,
I love this forum as it has a lot of good info on pretty much anything I would want and everyone seems to have a good grasp on performance concept, etc. My question is: I have a stock 4.7 with a magnaflow dual exhaust. It feels as if I have lost some low end power. Would it be better to stick with a single out exhaust? I believe it's a 3inch pipe with 3.5 tip. Thanks!
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Anthony
Dodge Dakota
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11/02/2006
21:23:06
|  RE: single or dual?
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what size are the pipes now?? I have a Magnaflow dual exhaust on my 4.7 and I gained low end torque.
With the previous 3" cat-back system I had, I lost low end torque.
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mr rhoades
Dodge Dakota
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11/02/2006
21:40:39
| RE: single or dual?
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I believe the pipe is 3 inches and the exhaust tip is 3.5
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GraphiteDak
GenIII
11/02/2006
21:41:14
| RE: single or dual?
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mr rhoades, do you have DUAL exits after a single muffler? Or duals all the way from the engine?
I haven't lost much from my true duals.
And duals after the muffler shouldn't really effect anything at all. But I think fake duals is pointless anyway...
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mr rhoades
Dodge Dakota
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11/02/2006
21:43:50
| RE: single or dual?
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Bah I should have specified. Dual exits not TRUE dual. I read where it MAY hurt my low end with this feature and should stick with single out. I haven't actually Dyno'd my truck for proof on this...although it would be nice
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Anthony
Dodge Dakota
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11/02/2006
22:26:07
| RE: single or dual?
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What's the size of the pipes on your duals????
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Mattson
Dodge Dakota
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11/02/2006
22:45:13
| RE: single or dual?
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On the 4.7 engine, much bigger than 2-1/4 to 2-1/2 and the exhaust loses velocity and inertia. This reduces scavenging, which reduces perceived power, especially low in the RPM band.
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Kowalski
GenIII
11/03/2006
07:50:33
| RE: single or dual?
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Good point by Mattson, some of the others have hinted at this. It really comes down to proper pipe sizing. A properly designed single can flow as well on the street as dual. Guys tend to favor the true duals as this does away with the restritive y-pipe; but a properly designed single that has also done away with the y-pipe will flow just as well. The best dual design incorporates an x-pipe, connecting the 2 sides for better scavenging by including the scavenging effect of the other side of the engine.
Lead, follow, or get out of the way
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mr rhoades
Dodge Dakota
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11/04/2006
09:20:20
| RE: single or dual?
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Do you think it would be better if I purchased the single-out muffler and just stuck with one pipe rather than the dual? I would really like to NOT have to purchase another cat back system and reduce the pipe size...but any input is appreciated. Thanks for all the responses!!
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trucky
Dodge Dakota
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11/04/2006
23:31:33
| RE: single or dual?
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i think single all the way is better...most peeple do duals for the look and sound not so much performance. remember that in dual the exhaust has to fight its way to each tube and 'decide' where to split. in a single it doesnt even matter and its breathes better. im not even gonna bring up backpressure cuz that will start a long drawn out argument
just know that single is probly better
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Kowalski
GenIII
11/05/2006
07:29:58
| RE: single or dual?
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A properly sized single system is neither better or worse than a properly sized dual system with an x-pipe. While it may take some energy for us to make decisions, no such energy is required in gas (or fluid) dynamics. Wether gas or fluid, the medium will take the path of least resistance; I'm sure he means well but the previous post is bad science.
Lead, follow, or get out of the way
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99dakrt
Dodge Dakota
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11/07/2006
04:06:34
| RE: single or dual?
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Use the money that you would spend on another exhaust system for another power gaining modification like a cold air intake and a chip. You will gain your power back and maybe a little extra. Just my $.02
~Rob
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Bucket
GenII
11/07/2006
11:17:56
| RE: single or dual?
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I agree with 99dakrt,2 mufflers 2 pipes 2 tips 2 repairs later on.... what a pain,when i got my JBA headers installed i had the Muffler shop make a bigger Y pipe and add a high flow cat to my already new Gibson cat back set-up,sounds great no problems.one pipe one muffler one cat one fix.Use the extra dough for another mod not another muffler.
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dakota5.2
Dodge Dakota
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11/07/2006
15:21:49
| RE: single or dual?
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DakRT has a good idea with the single and add the extra money somewhere else on a performance mod.
... If the dualed pipes are 3 in., it's too big a diameter.
Good Luck
D5.2
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GraphiteDak
GenIII
11/07/2006
16:43:22
| RE: single or dual?
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I went HUGE with 2 1/2" duals from the manifolds back. No x pipe for now. Didn't seem to loose any power. And I would notice when towing.
The pipes are FULL LENGTH thogh going all the way out the rear.
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Anthony
Dodge Dakota
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11/07/2006
22:37:09
| RE: single or dual?
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Graph,
With 4.56 gears it would be hard to notice any loss in your low end, with your dual 2.5" pipes.
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Hmm
Dodge Dakota
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11/08/2006
18:45:10
| RE: single or dual?
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Do Not Get An X-Pipe for your Truck. An H-Pipe would Work Much Better for it.
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GraphiteDak
GenIII
11/08/2006
18:46:02
| RE: single or dual?
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From the get go, yes that would be true.
But in high gear climbing grades I would still have noticed.
I think FLOW and SCAENGING is more important than thinking in BACKPRESSURE.
On these stock engines, I'd say running a full length exhaust would be important rather than Donkey D!cking the pipes down in front of the rear axle.
I'm still waiting to get some materials and the balls to try some full length headers.
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Kowalski
GenIII
11/08/2006
19:15:10
| RE: single or dual?
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I hope everyone realizes GD was responding to Anthony and not not Hmm; who posted just a minute before him. GD - while I would have expected better sizing at lower rpms with 2 1/4 pipes, didn't you also do the exhaust mod before the gear change ? Not sure if I'm remembering that correctly...
Hmm - either your new, or you don't usually post under that name - I'm not aware of any science that would suggest an H-pipe would be better than an X-pipe - in face I'm pretty sure X-pipes were inttoduced as an improvement over the H-pipe balance design. Posting under a different screen name than usual would seem to suggest you're not that sure of your info; or not ready to back it up. Care to comment ?
Lead, follow, or get out of the way
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GraphiteDak
GenIII
11/08/2006
22:20:11
| RE: single or dual?
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Thanks for saving me Kowalski!!!! I was responding to the gear swap question.
Hmm must have been typing at the same time as me.
Too bad this forum has no darn EDIT feature!
Or I could go back and fix things like that.
Some day I'll make an x-pipe and cut it in to test out any difference next time I tow.
Towing always seems to be the best way to notice any changes from mods.
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Anthony
Dodge Dakota
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11/08/2006
23:14:26
| RE: single or dual?
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Only real difference that I gathered from an X vs H pipe, is sound. People say the X pipe flows better and makes more power, but I haven't found any solid proof. And a H pipe produces better sound than a X pipe. Again this is up in the air.
With a true dual setup a balance pipe is a must.
A lot of people say you need backpressure to keep your torque. You don't want backpressure, what you want is velocity "flow". You want to create a vacuum effect to suck the exhaust gases out of the motor.
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