How free is too free? (exhaust)
#11
01-22-2008, 09:54 PM
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RE: How free is too free? (exhaust)
Firslty, Iceman, thank you for the compliments, kickass. Although, here is my only question. To me, it seems like 2.5" just isn't that big of a deal if it's only part of the exhaust. Lets say he runs a 2.5" in/out cat, and then that system and but up directly into that right? Originally, when I had just my magnaflow cat (3" in/out), and super 44 installed (3" in/2.5" out) I lost no horsepower, I gained quite a bit. To me, he will be running an even more modest set-up than that, and I think that truck can handle it, especially if he runs an intake and the fastman. I don't agree it being 2.5 true dual, but I think for a 318, which isn't a small engine by any means, can handle a piece of the exhaust having 2.5" duals. What is your thought on that? Again, thank you for the compliments on the truck man
#12
01-22-2008, 10:57 PM
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RE: How free is too free? (exhaust)
ORIGINAL: Silver_Dodge
I think 2.25" duals is the right size on a 5.2, or else 2.5" single, but that is just my opinion. I'm changing my single exhaust to 2.5" from the 3" I currently have, so I can't imagine running dual 2.5" pipes on a 5.2 unless it is built. Just my opinion.
I think 2.25" duals is the right size on a 5.2, or else 2.5" single, but that is just my opinion. I'm changing my single exhaust to 2.5" from the 3" I currently have, so I can't imagine running dual 2.5" pipes on a 5.2 unless it is built. Just my opinion.
Let me know how the 3" to 2.5" swap goes. My stock exhaust is 3" that knuckled down to 2.5" at the cat and muffler. I thought that was pretty dumb as the high pressure created by shrinking at the cat and muffler was lost as soon as the pipe got bigger again. I figured DC just did it to keep the mufflers and cats as the same part # for all the 2nd gens. I think the larger piping was the reason DC claimed more HP in the 2001 ram 5.2 and 5.9 than in previous years.
I have thought about going shorty headers with 1 1/2" primaries ceramic coated to keep the heat/velocity up. I might try to see what I can find in a y pipe that is ceramic coated as well to keep the exhaust hot until it passes thru the cat.
Wonder why nobody makes 2.75" piping and accessories? Seems like that might be the sweet spot for moderately tweaked vehicles.
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01-22-2008, 11:02 PM
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RE: How free is too free? (exhaust)
Ok here comes the math; volume of a cylinder = pi*r^2*h now if we use a constant for h, say 48 inches, and we use two different radia (2.5 & 2.25) we can calculate the volume change between the two systems.So in that section of 4 foot pipe the volume of the 2.5 is 235.62 cu. in.and thevolume of the 2.25 is 190.85 cu. in. If we go ahead and multiply that by two we get 471.24 cu. in. and 381.7 cu. in. respectfully. Now we can see that the volumetric difference between dual 2.5 in. pipe and dual 2.25 in. pipe is 89.54 cu. in. Thats a pretty good difference volume wise. Hope that helps you understand the difference even a quarter of an inch can make. And please someone check my math its been awhile, and if I'm just being an idiot you can say that too. [8D]
#14
01-22-2008, 11:06 PM
RE: How free is too free? (exhaust)
"To reduce additional backpressure, the OEM exhaust tubing can be replaced with mandrel-bent tubing of the same size or one size up from the OEM. As a general rule, you can enlarge the pipe diameter of your OEM exhaust system by 1/4 to 1/2-inch to increase your horsepower. However, any additional increase in pipe diameter is likely to decrease your performance; specifically, low end torque."
That is a direct quote from thelinktoMagnaflow. Why waste timetheorizing when certified professionals tell you what you need to know??? [/b]
That is a direct quote from thelinktoMagnaflow. Why waste timetheorizing when certified professionals tell you what you need to know??? [/b]
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01-22-2008, 11:06 PM
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RE: How free is too free? (exhaust)
ORIGINAL: ICEMAN_CH
...............
grrrrrrrr
1st no such thing as to free flowing. End of story.
2nd The most impotant thing to remeber is exhaust velocity. If your exhaust is sized to big then the exhaust slows down and cools wich means it is harder to get out of the exhaust pipt meaning less engine power. Ideally the entire exhaust would be heat wrapped to avoid any heat loss.
3rd 20DodgeNeon has a sick sounding truck and I'll be running a system almost exactly like his minus the cat. However technically 2.5 duals are a tad to big for the 5.9. They are way to big for a 5.2. Again end of story don't argue with me 20DodgeNeon I'm not starting a fight I think you know what your doing and your truck sounds great but, the fact is 2.5 is to big for the 5.9. I went with 2.5 because I'll be getting into heads, cams and possibly stroking the motor. Just because it sounds cool dosen't mean it's doing a good job.
4th 2.25" pipes will be perfect for the 5.2 and will leave you plenty of room to grow. If you want to run one pipe then go 2.5". If your going to run true duals you might be able to get away with 2.25 but, you would have a ton or room to grow and would have to do a ton of mods so you might want to go one size down.
5th This is extremly important if you want to gut the cat then you need to put a pipe in place of it and wrap that pipe with the cat so that it looks like it is still there. While gutting the cat does add power putting a pipe in place of it will definetly add power.
6th this is the last one. for all of you who think backpressure is real try this. Install a system that is to big so that you can feel the loss. Now kink like he asked about and let me know how much more power you loose. Thats about as dumb as running the exhaust into your intake.
...............
grrrrrrrr
1st no such thing as to free flowing. End of story.
2nd The most impotant thing to remeber is exhaust velocity. If your exhaust is sized to big then the exhaust slows down and cools wich means it is harder to get out of the exhaust pipt meaning less engine power. Ideally the entire exhaust would be heat wrapped to avoid any heat loss.
3rd 20DodgeNeon has a sick sounding truck and I'll be running a system almost exactly like his minus the cat. However technically 2.5 duals are a tad to big for the 5.9. They are way to big for a 5.2. Again end of story don't argue with me 20DodgeNeon I'm not starting a fight I think you know what your doing and your truck sounds great but, the fact is 2.5 is to big for the 5.9. I went with 2.5 because I'll be getting into heads, cams and possibly stroking the motor. Just because it sounds cool dosen't mean it's doing a good job.
4th 2.25" pipes will be perfect for the 5.2 and will leave you plenty of room to grow. If you want to run one pipe then go 2.5". If your going to run true duals you might be able to get away with 2.25 but, you would have a ton or room to grow and would have to do a ton of mods so you might want to go one size down.
5th This is extremly important if you want to gut the cat then you need to put a pipe in place of it and wrap that pipe with the cat so that it looks like it is still there. While gutting the cat does add power putting a pipe in place of it will definetly add power.
6th this is the last one. for all of you who think backpressure is real try this. Install a system that is to big so that you can feel the loss. Now kink like he asked about and let me know how much more power you loose. Thats about as dumb as running the exhaust into your intake.
First wanted to take a second and say thanks for all of the input asI just now had a chance to sit down and take a look at things. I'd also like to say sorry ICEMAN_CH as I have seemed toticked you off a bit with my use of words. In response to your "there is no free flowing, how else do I describe what im talking about w/o saying in that sort of way? Just curious. Also my use of the word backpressure is in the same sense. I know where you are coming from, but if you say backpressure, even an average n00b can pick up on it. Just some food for thought.
After posting, I have done some more thinking. As 20DodgeNeon00 I believe is trying to say, does the 2.5" pipes really make that much of a difference as far as past the muffler? I mean, lets look at it this way. How many people dump their exhausts right out of the muffler. If you had the same si/do, it would be like running dual 5"+ tips (i mean there is no limit really). While the exhaust isnt running through pipe anymore.... does that really matter. Now no one jump down my throat here because I asked if it mattered, I mean think about it at least. I would resort back to a si/si, but for one i like the dual setup, and for two the whole reason i would want this kit is because its mufflerless minus the resonator tips that act as the muffler. If i could find a legit mufflerless exhaust such as this, then by all means, but if not, ... guess I would want this. Basically I've never messed with a high flow cat. I didnt want to have it flowing too free as to lose a lot of torque (sorry ICEMAN_CH). Well thanks for taking your time. As always it is greatly appreciated.
Thanks again,
pcfixerpro
#16
01-22-2008, 11:08 PM
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01-22-2008, 11:11 PM
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#18
01-22-2008, 11:12 PM
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RE: How free is too free? (exhaust)
ORIGINAL: xskylinedx
Ok here comes the math; volume of a cylinder = pi*r^2*h now if we use a constant for h, say 48 inches, and we use two different radia (2.5 & 2.25) we can calculate the volume change between the two systems.So in that section of 4 foot pipe the volume of the 2.5 is 235.62 cu. in.and thevolume of the 2.25 is 190.85 cu. in. If we go ahead and multiply that by two we get 471.24 cu. in. and 381.7 cu. in. respectfully. Now we can see that the volumetric difference between dual 2.5 in. pipe and dual 2.25 in. pipe is 89.54 cu. in. Thats a pretty good difference volume wise. Hope that helps you understand the difference even a quarter of an inch can make. And please someone check my math its been awhile, and if I'm just being an idiot you can say that too. [8D]
Ok here comes the math; volume of a cylinder = pi*r^2*h now if we use a constant for h, say 48 inches, and we use two different radia (2.5 & 2.25) we can calculate the volume change between the two systems.So in that section of 4 foot pipe the volume of the 2.5 is 235.62 cu. in.and thevolume of the 2.25 is 190.85 cu. in. If we go ahead and multiply that by two we get 471.24 cu. in. and 381.7 cu. in. respectfully. Now we can see that the volumetric difference between dual 2.5 in. pipe and dual 2.25 in. pipe is 89.54 cu. in. Thats a pretty good difference volume wise. Hope that helps you understand the difference even a quarter of an inch can make. And please someone check my math its been awhile, and if I'm just being an idiot you can say that too. [8D]
#19
01-22-2008, 11:16 PM
#20
01-22-2008, 11:17 PM
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RE: How free is too free? (exhaust)
ORIGINAL: pcfixerpro
That displays the volume of gas, but how do you take into account for restrictions? Yes the tube may fill up with more gas.. heck more hot gas right which aparently is needed for an effective system acc. to ICEMAN_CH. How do you take the cat into play? It just means the tubes before are going to be filled up. Same as between the cat and the muffler. I assume that gas will fill the extra space, but then after the muffler its home free. I know you guys understand this more than I do, but I like to look at many different angles. Lets say if i increased the size of the cooling system hoses from the heater core. There is more volume to fill, but extra liquid occupys that extra space. Maybe that wasnt a good example.
ORIGINAL: xskylinedx
Ok here comes the math; volume of a cylinder = pi*r^2*h now if we use a constant for h, say 48 inches, and we use two different radia (2.5 & 2.25) we can calculate the volume change between the two systems.So in that section of 4 foot pipe the volume of the 2.5 is 235.62 cu. in.and thevolume of the 2.25 is 190.85 cu. in. If we go ahead and multiply that by two we get 471.24 cu. in. and 381.7 cu. in. respectfully. Now we can see that the volumetric difference between dual 2.5 in. pipe and dual 2.25 in. pipe is 89.54 cu. in. Thats a pretty good difference volume wise. Hope that helps you understand the difference even a quarter of an inch can make. And please someone check my math its been awhile, and if I'm just being an idiot you can say that too. [8D]
Ok here comes the math; volume of a cylinder = pi*r^2*h now if we use a constant for h, say 48 inches, and we use two different radia (2.5 & 2.25) we can calculate the volume change between the two systems.So in that section of 4 foot pipe the volume of the 2.5 is 235.62 cu. in.and thevolume of the 2.25 is 190.85 cu. in. If we go ahead and multiply that by two we get 471.24 cu. in. and 381.7 cu. in. respectfully. Now we can see that the volumetric difference between dual 2.5 in. pipe and dual 2.25 in. pipe is 89.54 cu. in. Thats a pretty good difference volume wise. Hope that helps you understand the difference even a quarter of an inch can make. And please someone check my math its been awhile, and if I'm just being an idiot you can say that too. [8D]
I'm getting a little tired but think of it like this; Iceman was saying that you want velocity, now if you have a larger volume the gasses expand to fill that volume and lose velocity. Its like cutting down your intake runners, when you do that it lowers the runner volume but increases the velocity for more power. Man I think thats right but I'm going to bed so feel free to correct me.
Oh and dude, no ones haten. I'd be happy as hell if his truck pulled harder than mine cause its not a competition.