ADVANTAGE OF X PIPE vs H PIPE vs TRUE DUAL?
03-23-2009, 08:26 AM
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ADVANTAGE OF X PIPE vs H PIPE vs TRUE DUAL?
Was just wondering if anyone could give me some insight on the advantages and disadvantages of an h pipe vs x pipe vs true dual on the z.i currently am running aam 3" true dual with aam hf cats and i feel like i should have gained more performance than i got out of it.my car is na,would i be better off with the x pipe of a stillen exhaust? Any insight or help would greatly be apreciated.also other mods include aam reflash,plenum spacer,pop charger.was looking at jw cams and or headers.i know for the money i spent i could have went fi,but whats done is done ,so ill continue the na route for now.any advice on a solid next performance mod would also be apreciated.car put down 248 to the wheels on aam dyno and best et of 13.7 at 103mph on 20" wheels and street tires.thanks.anXious to here from you.
Last edited by kylerumsey; 03-23-2009 at 08:47 AM. Reason: SPELLING
03-23-2009, 10:15 AM
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the difference is:
true dual is two seperate exhaust pipes ran all the way.
the h-pipe is used to help equal the back pressure on both sides of the exhaust (its still dual)
the x-pipe is the same but is much better at equalizing the pressure. (still dual)
hope i explained that where you can understand it.
true dual is two seperate exhaust pipes ran all the way.
the h-pipe is used to help equal the back pressure on both sides of the exhaust (its still dual)
the x-pipe is the same but is much better at equalizing the pressure. (still dual)
hope i explained that where you can understand it.
03-23-2009, 11:44 AM
#7
Each pipe of your dual is 3"? Wow.
Having two pipes that aren't connected = worst.
Having two pipes that feature a H pipe = better.
Having two pipes that feature a X pipe = best.
As to why or as to why you think that's not the case is a subject you can research.
Having two pipes that aren't connected = worst.
Having two pipes that feature a H pipe = better.
Having two pipes that feature a X pipe = best.
As to why or as to why you think that's not the case is a subject you can research.
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03-23-2009, 01:06 PM
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There's a big misconception about the intended function of the X-Pipe versus the H-Pipe.
The H-Pipe does balance out the pressures and slightly helps start the scavange effect on the next exhaust pulse. But it's most effective use when properly placed and sized is for it's tuning function. Sound waves enter the tube changing to a specific frequency that was found to be a problem. Prehaps a droaning noise at highway speeds. With the correct placement in the system and correct inside diameter, sound waves entering the tub shift to the problem frequency. When like frequencies collide, they cancel.
The power comes from opening up the exhaust. A slight add comes from the scavenge effect but ultimately the H-pipe is to counter the noise from opening up the exhaust.
The X-Pipe on the other hand is more effective in sound cancellation. By forcing the exhaust streams to collide, some sound frequencies are cancelled. (In a much larger range than the H-Pipe.) You would think the two exhaust paths colliding would cause more backpressure. In reality, the exhaust flow mass follows the path down the same side. (Bending around the inside of the X.)
The sound frequencies cross paths of the exhaust. Cancellation of like frequencies occur even though the mass of the exhaust flow hits and deflects into the same side pipe.
This is all assuming WOT condition or near full mass flow rate. At lower flow rate, the X-pipe does make the low frequency idle sound a little irratic. Something desireable in a Mustang or Corvette. But a Cadillac wouldn't care for it.
This is used as a band aid in tuning high performance vehicles to meet the legal pass-by requirements. Something that is difficult to do on a car like the Viper Roadster or Corvette.
The X-pipe idea was tried on the Viper roadster but ultimately they used the H-pipe design. If you've ever seen the OE system on a Viper Roadster, the exhaust exits the headers, enters an un-Godly hot converter that I have seen damage body panels and melt basalt packing back into a crystal solid. It runs down the side of the car into the main muffler and then to the rear axle. Then it turns to the opposite side and hits the H-pipe which is over the axle and exits out before the axle on the opposite side of the car. If it were not for the Pass-By requirements, this would be an easy design.
Designs like this and the birth of the X-pipe all stem from the need to meet the requirement. Again, the X-pipe just allows the exhaust to be opened up more while tuning out undesireable frequencies. It's ability to "add" power is a debate most drawn up by aftermarket marketing managers. Everyone loves a gadget.
The H-Pipe does balance out the pressures and slightly helps start the scavange effect on the next exhaust pulse. But it's most effective use when properly placed and sized is for it's tuning function. Sound waves enter the tube changing to a specific frequency that was found to be a problem. Prehaps a droaning noise at highway speeds. With the correct placement in the system and correct inside diameter, sound waves entering the tub shift to the problem frequency. When like frequencies collide, they cancel.
The power comes from opening up the exhaust. A slight add comes from the scavenge effect but ultimately the H-pipe is to counter the noise from opening up the exhaust.
The X-Pipe on the other hand is more effective in sound cancellation. By forcing the exhaust streams to collide, some sound frequencies are cancelled. (In a much larger range than the H-Pipe.) You would think the two exhaust paths colliding would cause more backpressure. In reality, the exhaust flow mass follows the path down the same side. (Bending around the inside of the X.)
The sound frequencies cross paths of the exhaust. Cancellation of like frequencies occur even though the mass of the exhaust flow hits and deflects into the same side pipe.
This is all assuming WOT condition or near full mass flow rate. At lower flow rate, the X-pipe does make the low frequency idle sound a little irratic. Something desireable in a Mustang or Corvette. But a Cadillac wouldn't care for it.
This is used as a band aid in tuning high performance vehicles to meet the legal pass-by requirements. Something that is difficult to do on a car like the Viper Roadster or Corvette.
The X-pipe idea was tried on the Viper roadster but ultimately they used the H-pipe design. If you've ever seen the OE system on a Viper Roadster, the exhaust exits the headers, enters an un-Godly hot converter that I have seen damage body panels and melt basalt packing back into a crystal solid. It runs down the side of the car into the main muffler and then to the rear axle. Then it turns to the opposite side and hits the H-pipe which is over the axle and exits out before the axle on the opposite side of the car. If it were not for the Pass-By requirements, this would be an easy design.
Designs like this and the birth of the X-pipe all stem from the need to meet the requirement. Again, the X-pipe just allows the exhaust to be opened up more while tuning out undesireable frequencies. It's ability to "add" power is a debate most drawn up by aftermarket marketing managers. Everyone loves a gadget.
03-23-2009, 04:06 PM
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There's a big misconception about the intended function of the X-Pipe versus the H-Pipe.
The H-Pipe does balance out the pressures and slightly helps start the scavange effect on the next exhaust pulse. But it's most effective use when properly placed and sized is for it's tuning function. Sound waves enter the tube changing to a specific frequency that was found to be a problem. Prehaps a droaning noise at highway speeds. With the correct placement in the system and correct inside diameter, sound waves entering the tub shift to the problem frequency. When like frequencies collide, they cancel.
The power comes from opening up the exhaust. A slight add comes from the scavenge effect but ultimately the H-pipe is to counter the noise from opening up the exhaust.
The X-Pipe on the other hand is more effective in sound cancellation. By forcing the exhaust streams to collide, some sound frequencies are cancelled. (In a much larger range than the H-Pipe.) You would think the two exhaust paths colliding would cause more backpressure. In reality, the exhaust flow mass follows the path down the same side. (Bending around the inside of the X.)
The sound frequencies cross paths of the exhaust. Cancellation of like frequencies occur even though the mass of the exhaust flow hits and deflects into the same side pipe.
This is all assuming WOT condition or near full mass flow rate. At lower flow rate, the X-pipe does make the low frequency idle sound a little irratic. Something desireable in a Mustang or Corvette. But a Cadillac wouldn't care for it.
This is used as a band aid in tuning high performance vehicles to meet the legal pass-by requirements. Something that is difficult to do on a car like the Viper Roadster or Corvette.
The X-pipe idea was tried on the Viper roadster but ultimately they used the H-pipe design. If you've ever seen the OE system on a Viper Roadster, the exhaust exits the headers, enters an un-Godly hot converter that I have seen damage body panels and melt basalt packing back into a crystal solid. It runs down the side of the car into the main muffler and then to the rear axle. Then it turns to the opposite side and hits the H-pipe which is over the axle and exits out before the axle on the opposite side of the car. If it were not for the Pass-By requirements, this would be an easy design.
Designs like this and the birth of the X-pipe all stem from the need to meet the requirement. Again, the X-pipe just allows the exhaust to be opened up more while tuning out undesireable frequencies. It's ability to "add" power is a debate most drawn up by aftermarket marketing managers. Everyone loves a gadget.
The H-Pipe does balance out the pressures and slightly helps start the scavange effect on the next exhaust pulse. But it's most effective use when properly placed and sized is for it's tuning function. Sound waves enter the tube changing to a specific frequency that was found to be a problem. Prehaps a droaning noise at highway speeds. With the correct placement in the system and correct inside diameter, sound waves entering the tub shift to the problem frequency. When like frequencies collide, they cancel.
The power comes from opening up the exhaust. A slight add comes from the scavenge effect but ultimately the H-pipe is to counter the noise from opening up the exhaust.
The X-Pipe on the other hand is more effective in sound cancellation. By forcing the exhaust streams to collide, some sound frequencies are cancelled. (In a much larger range than the H-Pipe.) You would think the two exhaust paths colliding would cause more backpressure. In reality, the exhaust flow mass follows the path down the same side. (Bending around the inside of the X.)
The sound frequencies cross paths of the exhaust. Cancellation of like frequencies occur even though the mass of the exhaust flow hits and deflects into the same side pipe.
This is all assuming WOT condition or near full mass flow rate. At lower flow rate, the X-pipe does make the low frequency idle sound a little irratic. Something desireable in a Mustang or Corvette. But a Cadillac wouldn't care for it.
This is used as a band aid in tuning high performance vehicles to meet the legal pass-by requirements. Something that is difficult to do on a car like the Viper Roadster or Corvette.
The X-pipe idea was tried on the Viper roadster but ultimately they used the H-pipe design. If you've ever seen the OE system on a Viper Roadster, the exhaust exits the headers, enters an un-Godly hot converter that I have seen damage body panels and melt basalt packing back into a crystal solid. It runs down the side of the car into the main muffler and then to the rear axle. Then it turns to the opposite side and hits the H-pipe which is over the axle and exits out before the axle on the opposite side of the car. If it were not for the Pass-By requirements, this would be an easy design.
Designs like this and the birth of the X-pipe all stem from the need to meet the requirement. Again, the X-pipe just allows the exhaust to be opened up more while tuning out undesireable frequencies. It's ability to "add" power is a debate most drawn up by aftermarket marketing managers. Everyone loves a gadget.
you're the man!...my exhaust guru!
03-24-2009, 06:25 AM
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You will need to have the Y-pipe completely redone. Including relocation of the flex joint. For ease of adjusting the system and durability, I'd recommend two small flex joints instead of one large one. I found when installing this that the ridged Y-pipe, center assembly and tails left no ability to adjust the system. Had there been flex joints on both sides fo the Y, then I could eek out a degree or so allowing me to center the tailpipes better on the bumper.
If you're going to do the X pipe, then have a muffler shop make individual pipes right and left instead of a Y. Keep small flex joints one on each side. It's your option if you want to flange the connection to the X pipe or weld the two pipes and the X together. Less flanges = less system weight, cost or leaks.
In my honest opinion, if you are running with test pipes or HFCs, the system needs muffler volume to keep the rasp down. The main mufflers and submufflers are OK. I'm not sure the X-Pipe will do as good of a job as the center resonator. However, the X should flow better. I would consider looking into two bottle type resonators and make a true dual exhaust from front to back.
If you are stock running cats, then the X-Pipe would be fine to use instead of the bottle resonator. Post up pics if you do it.
03-24-2009, 07:51 AM
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You will need to have the Y-pipe completely redone. Including relocation of the flex joint. For ease of adjusting the system and durability, I'd recommend two small flex joints instead of one large one. I found when installing this that the ridged Y-pipe, center assembly and tails left no ability to adjust the system. Had there been flex joints on both sides fo the Y, then I could eek out a degree or so allowing me to center the tailpipes better on the bumper.
If you're going to do the X pipe, then have a muffler shop make individual pipes right and left instead of a Y. Keep small flex joints one on each side. It's your option if you want to flange the connection to the X pipe or weld the two pipes and the X together. Less flanges = less system weight, cost or leaks.
In my honest opinion, if you are running with test pipes or HFCs, the system needs muffler volume to keep the rasp down. The main mufflers and submufflers are OK. I'm not sure the X-Pipe will do as good of a job as the center resonator. However, the X should flow better. I would consider looking into two bottle type resonators and make a true dual exhaust from front to back.
If you are stock running cats, then the X-Pipe would be fine to use instead of the bottle resonator. Post up pics if you do it.
Thanks for the info. I'm running test pipes and headers along with the greddy evo2. There is some nasty rasp around 3000 rpm that I want to get rid of. So basically you're saying weld two resonators to two straight pipes and mate it to the rest of the exhaust system? Correct me if I'm wrong but I believe the center resonators are hollow and don't really function?
Last edited by AUS10TAT10US; 03-24-2009 at 07:58 AM.
03-24-2009, 09:25 AM
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Thanks for the info. I'm running test pipes and headers along with the greddy evo2. There is some nasty rasp around 3000 rpm that I want to get rid of. So basically you're saying weld two resonators to two straight pipes and mate it to the rest of the exhaust system? Correct me if I'm wrong but I believe the center resonators are hollow and don't really function?
Regarding the two small mufflers, they are definately not empty. That small section weighs a ton so I suspect it's a straight through tube wrapped with a layer of stainless wool around the tube. The rest of the muffler volume is probably filled with Advantex roving fiberglass or Basalt wool. (The Japanese muffler manufacturers love Basalt for some reason.) So definately leave them in there.
Also, just to be safe, check the clearance between the driver's side over the axle pipe and the differential. The diff has a piece of casting sticking up that was hitting my Greddy system. I adjusted the best I could and in the end made a flat section in the pipe to gain the clearance. Also check clearance below the exhaust between the resonator and the sheetmetal crossmember.
03-24-2009, 10:01 AM
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Ok thanks, ya I had a rattle by the resonator and crossmember and had to put spacers on to clear it. How much do you think it should cost to weld in two resonators in the y-pipe to make it a true dual? I may have to do this.
03-24-2009, 10:23 AM
#17
I've gone that route before. My advice is keep the original "x-pipe" that came with the greddy exhaust. Then have the shop fabricate a new x-pipe: two straight pipes with resonators, with or without an x-pipe in there. Hacking up the original will just make it more difficult to sell later on. Trust me.
03-24-2009, 11:05 AM
#19
Phreakdout:
While I agree with your assements regarding the sound portion of these items, I disagree with your conclusions about the performance aspects. Hot Rodders have been debating the characteristics of H / X / no crossovers for many years. Although specific applications may differ, the general consensus is that some type of cross over is better than nothing and the X is probably superior to all.
http://www.pontiacstreetperformance....p/exhaust.html
http://www.carcraft.com/techarticles...ion/index.html
There are probably tons more examples but this is what I've found with a quick google.
While I agree with your assements regarding the sound portion of these items, I disagree with your conclusions about the performance aspects. Hot Rodders have been debating the characteristics of H / X / no crossovers for many years. Although specific applications may differ, the general consensus is that some type of cross over is better than nothing and the X is probably superior to all.
http://www.pontiacstreetperformance....p/exhaust.html
http://www.carcraft.com/techarticles...ion/index.html
There are probably tons more examples but this is what I've found with a quick google.
03-24-2009, 04:33 PM
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What I've read from multiple sources and tests is that a properly tuned H pipe will slightly outperform an X pipe in the lower RPM range, while the X pipe will outperform the H pipe in the upper RPM range, which means the X pipe will make more power.
What I've experienced on my Mustang is that H pipes have a lower pitched mean muscle car sound while the X pipes are a little quieter, eliminate some droning, and sound more refined, although the comment about odd sounds at time also fits.
My 350Z with Stillen headers, Berks, and Bassani definitely has some rasp, which kicks in just below 3000 RPM, and never really goes away all the way to redline. It sounds great until the rasp kicks in....but the exhasut does work great.
Dual 3" pipes for a 350Z NA are oversized unless you're running extremely radical cams, and would hurt your torque production in the lower RPM's, but leave your top end power unaffected. That loss of torque would hurt your quarter mile times.
What I've experienced on my Mustang is that H pipes have a lower pitched mean muscle car sound while the X pipes are a little quieter, eliminate some droning, and sound more refined, although the comment about odd sounds at time also fits.
My 350Z with Stillen headers, Berks, and Bassani definitely has some rasp, which kicks in just below 3000 RPM, and never really goes away all the way to redline. It sounds great until the rasp kicks in....but the exhasut does work great.
Dual 3" pipes for a 350Z NA are oversized unless you're running extremely radical cams, and would hurt your torque production in the lower RPM's, but leave your top end power unaffected. That loss of torque would hurt your quarter mile times.