4" Single or 3" dua exhaust
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From: Fort Worth, TX
4" Single or 3" dua exhaust Right now I'm debating on two different exhaust systems to use for my ride. I currently have a 3" flow master exhaust system that is holding me back 70rwhp and 84rwtrq (see dyno graph) Setup is a 427LSX with LS7 heads, smallish cam in my 01' TA. I'm looking to maximize the power output of my exhaust, as I'm sure as it sits even with the 3" cutout open, I'm still losing power.
I'm currently struggling with two options:
Option one, build my own 3" true dual system utilizing two Magnaflow Mufflers 12619 at the back. This will be a full dual exhaust, no dumps, with the mufflers on each side at the rear of the vehicle, exiting to 3.5" corsa clone tips. I am thinking about x-pipe, and doing this by utilizing a second 2-1 merge welded to the end of the ARH y-pipe. See the picture attached that illustrates what I'm talking about.
My main concern with the x-pipe is the center will be 3", will this be a restriction to the exhaust? Or will it be a non-issue?
The other option would be to just run a single 4" exhaust system with a 4" elec cutout ready to be opened up. Not sure on the muffler selection, but would probably just run a 2-1 merge at the over the axle portion of the exhaust (4" inlet - 2x3" outlet) and run the same muffler selection like above.
Both systems would cost about the same for me, which one would make more power?
Thanks for any help in advance!
I'm currently struggling with two options:
Option one, build my own 3" true dual system utilizing two Magnaflow Mufflers 12619 at the back. This will be a full dual exhaust, no dumps, with the mufflers on each side at the rear of the vehicle, exiting to 3.5" corsa clone tips. I am thinking about x-pipe, and doing this by utilizing a second 2-1 merge welded to the end of the ARH y-pipe. See the picture attached that illustrates what I'm talking about.
My main concern with the x-pipe is the center will be 3", will this be a restriction to the exhaust? Or will it be a non-issue?
The other option would be to just run a single 4" exhaust system with a 4" elec cutout ready to be opened up. Not sure on the muffler selection, but would probably just run a 2-1 merge at the over the axle portion of the exhaust (4" inlet - 2x3" outlet) and run the same muffler selection like above.
Both systems would cost about the same for me, which one would make more power?
Thanks for any help in advance!
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From: Webb City, MO...out in the garage
I'm doing single 4" on my 454. i've got 2" Kooks headers with 3.5" collectors. i'm going to run 3.5" pipe off the headers into a 3.5"x4" Flowmaster Merge collector with a 4" bullet muffler shortly thereafter, dumped. it will weigh less and flow better than just about anything. From what i've seen and read, that Y-merge is the only thing flowmaster does right. I love their single chambers too, but i'd NEVER run one of their catbacks on anything i own.
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How does the 4 inch have more volume than 2 3inch pipes? The Area of the pipe for the first, Area=pi*radius^2, is 4*pi ....each of the two pipes is 2.25*pi, so you multiply that by 2, and it is 4.5 pi for the cross sections of both. Also with two straight pipes there will be less bends = more flow, right? If both pipes are equal length then the same volume is there for the four inch and the 2 3 inch pipes. I am not trying to be rude here, just wondering how it works, please do not leave negative comments.
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From: Webb City, MO...out in the garage
One thing that must also be taken into account is a properly designed Y-Merge will scavenge so efficiently that the Y-pipe setup will outflow the TD's all day long, and Flowmaster's Y-Merge is nicely designed, hence my reasoning for my setup.
Exhaust In building my TA, I wanted true duals also.
I bought a 3" X pipe and had 2 flowmaster over the axle pipes.
Finding someone to make it up was impossible in the Kansas City area. Everyone said impossible, but I'm sure it is if someone wants to tackle it.
With ARH 1 7/8 headers and 3" Y to a 4" outlet, I went with a Mufflex 4 inch Magnaflow. Fit like a glove.
I bought a 3" X pipe and had 2 flowmaster over the axle pipes.
Finding someone to make it up was impossible in the Kansas City area. Everyone said impossible, but I'm sure it is if someone wants to tackle it.
With ARH 1 7/8 headers and 3" Y to a 4" outlet, I went with a Mufflex 4 inch Magnaflow. Fit like a glove.
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From: Fort Worth, TX
In building my TA, I wanted true duals also.
I bought a 3" X pipe and had 2 flowmaster over the axle pipes.
Finding someone to make it up was impossible in the Kansas City area. Everyone said impossible, but I'm sure it is if someone wants to tackle it.
With ARH 1 7/8 headers and 3" Y to a 4" outlet, I went with a Mufflex 4 inch Magnaflow. Fit like a glove.
I bought a 3" X pipe and had 2 flowmaster over the axle pipes.
Finding someone to make it up was impossible in the Kansas City area. Everyone said impossible, but I'm sure it is if someone wants to tackle it.
With ARH 1 7/8 headers and 3" Y to a 4" outlet, I went with a Mufflex 4 inch Magnaflow. Fit like a glove.
Is anyone able to find a 4" 2-1 collector?
Last edited by Haans249; Nov 7, 2009 at 08:18 AM.
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Yea, i know they have it, and that the muffler blows. That's part of the reason why I'm probably leaning away from it. I don't want to have to purchase the whole deal, and then spend another 700 on a cutout, mufflers, piping, labor on top of the 600 it already costs.
Dual 3" with Borla XR1's right before the axle. If you dont dump it (no turn down), it wont drone nearly as bad. A single 4" will either have to be louder to move the same airflow or will have to go over the axle and lose it's *** in a rear mount muffler.
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That's about what I figured, just wanted to see what everyone thought. I would be more partial to the 4" but it's just not quite what I need as far as setup and would just cost too much to setup right. Plus I already have the panhard relocation setup and perfect piping already for it. I'll post up a new thread with what I had used for it as I'll have a stainless system for under 1000 all the way out the back! Pm sent.
Yes the 4" set up will yeild more power thru the band. Exhaust will flow thru the most unrestrictive pipe so even if you have two 3" pipes it still must travel in a smaller pipe. The 4" setup is the way to go. I had mine built by my roll cage fabricator who actually built the y pipe as a true 4" (let me know if you want pics), instead of a y pipe to a 4" set up. And I run my 4" all the way to a rear muffler and exit pipe at the bumper. Sounds cleaner, quiter, and makes more power than my old tru dual and dumped set up.
Get a y pipe that has the merge collector as a true 4" set up
Get a y pipe that has the merge collector as a true 4" set up
I just installed a set of ARH headers on my SSS and went with the dual 3" into single 4" with the Flowmaster Y. I used a Hooker Maxflow center in/out 4" muffler dumped in front of the axle and it's actually quieter than the stock exhaust with a drop in flowmaster muffler at idle and part throttle. It does scream at WOT but thats when I actually want it to be loud. I know this is in a truck and not a car but the sound is SWEET! Also if you look at the test in the FAQ section here you will see the Hooker Maxflow was the 3rd most power and the 2nd quietest. I think it's very overlooked for power and sound...it actually flowed the same as strait pipe in the test!
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From: AUSTIN TX
I sure am confused by some of the exhaust facts/recommendations in this thread. For one, unless there is a formula for exhaust flow that I am unaware of, the dual 3" has more area for flow than a single 4" (14.13 sq in to 12.56 sq in), secondly the dual 3" has much more surface area than the single 4" (18.84 inches to 12.56 inches) which from what I have always heard may not be beneficial in helping with the scavenging affect of the headers, but once the exhaust gasses get downstream that additional surface area causes the exhaust gasses to cool and condense which means even less exhaust size is necessary for the same flow. So in theory at least, not only would the dual 3" flow more to begin with, but the gasses would cool more as well meaning that the difference in flow values would only increase the farther back the exhaust went. Of course the downside will be the dual will be much heavier, may be more complicated to route, and lastly may be overkill for the op's situation.
Not to steal the thread, rather add to it. Here's the system I'm running, its a one-off piece and it probably more then I need currently.
Its tight against the driveshaft only when the suspension isn't loaded. Its actually almost 2" away when loaded.
There's also a DMH 4" cutout now about 10" down the Y pipe.
Something like this could be what your looking for. On your CI, you would benefit from this 4". On my current 6.0, I don't think its helping that much. Your looking at a pretty major HP increase just from exhaust, But, lots of money tied up here with Kooks, DMH 4", and a fabbed 4" though.
Its tight against the driveshaft only when the suspension isn't loaded. Its actually almost 2" away when loaded.
There's also a DMH 4" cutout now about 10" down the Y pipe.
Something like this could be what your looking for. On your CI, you would benefit from this 4". On my current 6.0, I don't think its helping that much. Your looking at a pretty major HP increase just from exhaust, But, lots of money tied up here with Kooks, DMH 4", and a fabbed 4" though.
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I sure am confused by some of the exhaust facts/recommendations in this thread. For one, unless there is a formula for exhaust flow that I am unaware of, the dual 3" has more area for flow than a single 4" (14.13 sq in to 12.56 sq in), secondly the dual 3" has much more surface area than the single 4" (18.84 inches to 12.56 inches) which from what I have always heard may not be beneficial in helping with the scavenging affect of the headers, but once the exhaust gasses get downstream that additional surface area causes the exhaust gasses to cool and condense which means even less exhaust size is necessary for the same flow. So in theory at least, not only would the dual 3" flow more to begin with, but the gasses would cool more as well meaning that the difference in flow values would only increase the farther back the exhaust went. Of course the downside will be the dual will be much heavier, may be more complicated to route, and lastly may be overkill for the op's situation.
I'll start pricing out some 4" stainless piping. Anyone have any good sources for this type of exhaust pipe thats a killer price?
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This is what I have to work with so far...
Two SLP intermediate 3" stainless pipes. They will plug right into the 2-1 3" collector I'll get to put on the end of the y-pipe. Then all i need is the tubing from that point and the mufflers. I already have the corsa clones as well. So far I have only about 45 dollars in that piping. The rest of the piping would cost me about 300. So thats about 380 total for the pipes.
Now, if I could get an idea as to how much 4" piping would be?
Two SLP intermediate 3" stainless pipes. They will plug right into the 2-1 3" collector I'll get to put on the end of the y-pipe. Then all i need is the tubing from that point and the mufflers. I already have the corsa clones as well. So far I have only about 45 dollars in that piping. The rest of the piping would cost me about 300. So thats about 380 total for the pipes.
Now, if I could get an idea as to how much 4" piping would be?
Last edited by Haans249; Nov 12, 2009 at 08:56 PM.
wow that custom 1 off system looks like the y pipe is choking the crap out of that system. and think of the gas flow in a pipe as exhuast will flow together instead of gasses seperating. my fabricator put it this way. Exhaust gasses dont seperate so if it can flow in the least restrictive direction which would be the largest pipe. all i know is i made more power with 4" instead of my old 3" dumped setup and i moved from a 10 bolt to a 9".