X-pipes and H-pipes Add Effortless Horsepower
X-pipes and H-pipes Add Effortless Horsepower, but Which is Best for Your Rail?
Don’t let the glorious Bow Tie horsepower idiot you. Firing eight cylinders every ninety degrees in a 1-8-4-3-6-5-7-2 sequence is an inherently chaotic endeavor. Since the mass of the counterweights and flywheel mask this violence by smoothing out the power delivery of the crankshaft, it’s effortless to leave behind that eight individual combustion events are going down every seven hundred twenty degrees of crank rotation. Alternating the firing order inbetween the left and right bank of cylinders means that there is often a substantial difference in harass pressure inbetween each bank. The result—at any given moment—is a traffic jam of harass molecules in one bank of cylinders when minimal backpressure exists in the opposite bank. While this recurring screenplay reduces engine efficiency and horsepower, the solution is as effortless as integrating a balance pipe into the harass system.
Adding a balance pipe is like downloading Google Maps for your harass. As combustion gases travel out of the header collector and into the intermediate pipe, if their progress slows down due to backpressure, a balance pipe redirects them to a less congested flow path. “The name ‘balance pipe’ should be a clue as to why X- and H-pipes work so well,” Don Lindfors, Director of Harass R&D at PerTronix Spectacle Products explains. “Just like the name suggests, they help to balance the flow inbetween all the cylinders. Beyond that, they can even help with scavenging by having cylinders from the opposite bank of the engine create a negative wave to increase the overall flow of the harass.”
In terms of both spectacle and price, balance pipes are so effective that GM has been installing them for decades on Corvettes and more recently on fifth-gen Camaros. Best of all, balance pipes can be added to any existing dual harass system. Before busting out the Sawzall and welder, however, there are many significant factors to consider, such as the spectacle difference inbetween X- and H-pipes, where to place them in the harass tract, cost, and potential horsepower and torque gains. Granted that balance pipes are rather plain devices, but there’s far more to the science behind how they work than their appearance suggests. To get the inwards scoop, we hit up the industry experts Blane Burnett of Hooker Headers, Don Lindfors of PerTronix, and George Rumore of Stainless Works.
Balancing the harass pressure from bank to bank is just one of the many ways an X- or H-pipe improves overall harass flow. With a conservative factory camshaft, the harass seemingly flows out the tailpipe in one continuous stream. In reality, however, harass flaps travel in pulses, which become much more noticeable as camshaft duration increases. Consequently, reducing the detrimental effects of these pulses can positively influence horsepower and torque. “A balance pipe serves two distinct functions. Very first off, it takes the left and right banks of an engine’s harass and provides a crossover point to equalize flow from side to side,” Blane Burnett of Hooker Headers explains. “Secondly, balance pipes sleek out uneven harass pulses. Any given engine generates low- and high-pressure harass pulses due to the effects of the firing order. As these low and high pulses stir downstream through the harass piping, they travel at different speeds. Having an harass crossover helps draw these pulses out into a more balanced pattern, which ultimately improves engine output. A nice side benefit is that crossovers also decrease in-cabin harass drone.”
Albeit X- and H-pipes perform enormously well for a minimal investment in time and money, both suggest unique properties that make one more suitable than the other depending on the application. “The two largest differences inbetween an X- and an H-pipe are sound and power. Generally, the X-pipe will produce a more high-pitched harass note, making a car sound more exotic, whereas an H-pipe gives a deeper tone with more of a traditional hot rod sound,” says George Rumore of Stainless Works. “As for the difference in power build up inbetween the two, it is very minimal. The X-pipe will usually make anywhere from two to four more horsepower than an H-pipe. The slight horsepower difference comes from the way the X-pipe creates a venturi effect, which helps pull the harass gases out of the cylinder quicker. Overall, the main difference is sound rather than spectacle, meaning there are no pros or cons. It’s simply a matter of individual preference.”
In addition to differences in sound and horsepower, both X- and H-pipes affect different parts of the powerband as well. According to PerTronix’s Don Lindfors, the basic configuration of both styles of crossovers lend a clue as to why this is the case. “An H-pipe tends to make more of a difference at lower rpm, while-X pipes will increase power more at higher rpm. As you can imagine, just by looking at each configuration, in the H-pipe the harass has to make a acute 90-degree turn, while the X-pipe offers a smoother transition,” he says. “The X-pipe creates much more of a scavenging effect. That said, it is significant to prevent the X-pipe from necking down too puny or flow can be hampered. Both an X- and an H-pipe will slick out the separated sound of the cylinders, while an X-pipe tends to blend all eight cylinders together more.”
For all-out power, X-pipes seem to be the winner, but H-pipes boast several advantages as well. “H-pipes typically suggest enlargened backpressure compared to an X-pipe, which nets an increase in low-end torque. They are also more tunable because they suggest more options in terms of the length of the crossover, the diameter of the tube, and the size and location of the transfer crevice,” Blane Burnett explains. “As a simpler design that takes up less space, H-pipes have more options as to where on the harass system the crossover section can be placed. While spectacle is a large consideration when designing an harass system, vehicle packaging is also a meaty factor. Depending on the application, an X- or an H-pipe might suit the chassis better, but an H-pipe certainly offers more options as to where it can be placed.”
01. Gen III/IV small-blocks, like this 840hp LS7 built by the School of Automotive Machinists, utilize a slightly different firing order (1-8-7-2-6-5-4-3) than past Chevy V-8s. Unlike a Mouse or Rat engine where adjacent cylinders on the same bank fire one right after the other, the revised firing order ensures that each combustion event alternates inbetween each bank of cylinders. In theory, this should help even out the variation in harass pressure from bank to bank.
02. X-pipes are essentially two mandrel arches sliced open along the long radius to create an oval opening, which are then welded together. The openings create a seamless path for harass to travel from one bank to the other.
03. In contrast to an X-pipe, harass must negotiate a series of 90-degree turns in order to stir from one side of the harass system to the other in an H-pipe. The resulting increase in backpressure isn’t necessarily a bad thing, since it boosts low-end torque. Stainless Works laser cuts its X- and H-pipes to ensure optimal flow without any obstructions at the center union.
04. A-bodies were never designed to accommodate an X-pipe, but the transmission tunnel serves as an ideal location due to its proximity to the header collectors. This location also provides slew of ground clearance.
05. Installing an X-pipe is simply a matter of connecting the dots. Once the front portion of the “X” has been welded to the collector pipes, the rear portion of the “X” can be connected to the intermediate pipes.
06. The radius of the two halves of pipes that comprise the “X” typically range from forty five to ninety degrees. The broader the radius of the arches, the tighter the space they can fit inwards. Even underneath the taut restricts of a C5 Corvette, wide-radius arches make it possible to fit an aftermarket X-pipe with room to spare.
In addition to differences in sound and horsepower, both X- and H-pipes affect different parts of the powerband as well. According to PerTronix’s Don Lindfors, the basic configuration of both styles of crossovers lend a clue as to why this is the case. “An H-pipe tends to make more of a difference at lower rpm, while-X pipes will increase power more at higher rpm. As you can imagine, just by looking at each configuration, in the H-pipe the harass has to make a acute 90-degree turn, while the X-pipe offers a smoother transition,” he says. “The X-pipe creates much more of a scavenging effect. That said, it is significant to prevent the X-pipe from necking down too puny or flow can be hampered. Both an X- and an H-pipe will sleek out the separated sound of the cylinders, while an X-pipe tends to blend all eight cylinders together more.”
For all-out power, X-pipes seem to be the winner, but H-pipes boast several advantages as well. “H-pipes typically suggest enlargened backpressure compared to an X-pipe, which nets an increase in low-end torque. They are also more tunable because they suggest more options in terms of the length of the crossover, the diameter of the tube, and the size and location of the transfer slot,” Blane Burnett explains. “As a simpler design that takes up less space, H-pipes have more options as to where on the harass system the crossover section can be placed. While spectacle is a large consideration when designing an harass system, vehicle packaging is also a giant factor. Depending on the application, an X- or an H-pipe might suit the chassis better, but an H-pipe certainly offers more options as to where it can be placed.”
With driveline and chassis components to contend with, figuring out the positioning of the balance pipe on the harass system could very well be determined by wherever space is available. That said, each engine and harass system combination has one specific spot where the balance pipe works best, albeit the importance of this positioning is up for debate. “The placement of X- or H-pipe is most effective when placed somewhere around eight to eighteen inches from the end of the collectors,” says Don Lindfors. “Moving it around can shift the torque peak slightly, but not enough to make a real-world difference. Usually, the available space under the car will end up dictating exactly where the X- or H-pipe will end up.” Blane Burnett of Hooker Headers concurs, stating “There is a sweet spot that exists for the integration of X- or H-pipes, and those gains will be noticeable. Whether or not you can achieve that particular design will always vary from vehicle to vehicle, and requires extensive testing.”
Due to the staggering spectacle benefits of balance pipes, many aftermarket header-back harass systems include an integrated X- or H-pipe. Consequently, for those in the market for a accomplish harass system, adding a balance pipe is a click of the mouse away. For the hoards of hot rodders out there that already have an aftermarket harass system, balancing out that dual harass system is just as effortless. There was a time when X- and H-pipes had to be custom-built from scrape with sections of straight tubing or U-bends. Fortunately, that’s no longer the case, as aftermarket companies such as Hooker, Stainless Works, and PerTronix all suggest universal X- and H-pipe kits that can be lightly integrated into any existing dual harass system. All it takes is some basic cutting and welding abilities and a duo of hours of spare time.
07. Crossover pipes are typically placed directly after the collectors (bottom). On the factory C5 harass (top), however, GM elected to position it at the very back of the intermediate pipes. Albeit the exact reasoning why this is the case is unclear, it reinforces the notion that having a crossover pipe somewhere on the harass system is better than having no crossover at all.
08. Ideally, the crossover tubing of an H-pipe shouldn’t be any smaller than the harass tubing it’s connected to. In certain applications, enhancing the diameter of the crossover pipe can yield significant gains in horsepower.
09. Flowtech’s universal Warlock X-pipe is built from mandrel-bent 16-gauge aluminized steel and includes four sets of cut-to-fit gams and extension tubes to fit virtually any application. For those that aren’t handy with a welder, the kit also comes with U-bolts and flared collectors. They’re even available with optional harass cutouts for the ultimate in flow.
Ten. The easiest way to add an X-pipe to any car is by installing a accomplish harass system that already has an X-pipe in it, like this header-back system for a second-gen Camaro from Hooker. The unique form of the “X” is made possible by Hooker’s universal crossover pipe that permit for custom-made inlet and outlet angles.
11. Sometimes it’s much lighter to package an X-pipe underneath a car if the inlets and outlets can be set at different angles. Hooker now offers universal stamped stainless steel crossovers that are essentially X-pipes without any preconfigured inlets and outlets. This gives fabricators almost limitless plasticity in setting the angles of the pipes exactly how they want them.
12. On a typical 400-horsepower street car, adding an X-pipe or an H-pipe to an existing dual harass system can add 7-12 hp. A smoother harass note and diminished interior resonance are added bonuses.
X-pipes and H-pipes Add Effortless Horsepower
X-pipes and H-pipes Add Effortless Horsepower, but Which is Best for Your Rail?
Don’t let the glorious Bow Tie horsepower idiot you. Firing eight cylinders every ninety degrees in a 1-8-4-3-6-5-7-2 sequence is an inherently chaotic endeavor. Since the mass of the counterweights and flywheel mask this violence by smoothing out the power delivery of the crankshaft, it’s effortless to leave behind that eight individual combustion events are going down every seven hundred twenty degrees of crank rotation. Alternating the firing order inbetween the left and right bank of cylinders means that there is often a substantial difference in harass pressure inbetween each bank. The result—at any given moment—is a traffic jam of harass molecules in one bank of cylinders when minimal backpressure exists in the opposite bank. While this recurring screenplay reduces engine efficiency and horsepower, the solution is as effortless as integrating a balance pipe into the harass system.
Adding a balance pipe is like downloading Google Maps for your harass. As combustion gases travel out of the header collector and into the intermediate pipe, if their progress slows down due to backpressure, a balance pipe redirects them to a less congested flow path. “The name ‘balance pipe’ should be a clue as to why X- and H-pipes work so well,” Don Lindfors, Director of Harass R&D at PerTronix Spectacle Products explains. “Just like the name suggests, they help to balance the flow inbetween all the cylinders. Beyond that, they can even help with scavenging by having cylinders from the opposite bank of the engine create a negative wave to increase the overall flow of the harass.”
In terms of both spectacle and price, balance pipes are so effective that GM has been installing them for decades on Corvettes and more recently on fifth-gen Camaros. Best of all, balance pipes can be added to any existing dual harass system. Before busting out the Sawzall and welder, however, there are many significant factors to consider, such as the spectacle difference inbetween X- and H-pipes, where to place them in the harass tract, cost, and potential horsepower and torque gains. Granted that balance pipes are rather ordinary devices, but there’s far more to the science behind how they work than their appearance suggests. To get the inwards scoop, we hit up the industry experts Blane Burnett of Hooker Headers, Don Lindfors of PerTronix, and George Rumore of Stainless Works.
Balancing the harass pressure from bank to bank is just one of the many ways an X- or H-pipe improves overall harass flow. With a conservative factory camshaft, the harass seemingly flows out the tailpipe in one continuous stream. In reality, however, harass swings travel in pulses, which become much more noticeable as camshaft duration increases. Consequently, reducing the detrimental effects of these pulses can positively influence horsepower and torque. “A balance pipe serves two distinct functions. Very first off, it takes the left and right banks of an engine’s harass and provides a crossover point to equalize flow from side to side,” Blane Burnett of Hooker Headers explains. “Secondly, balance pipes slick out uneven harass pulses. Any given engine generates low- and high-pressure harass pulses due to the effects of the firing order. As these low and high pulses budge downstream through the harass piping, they travel at different speeds. Having an harass crossover helps draw these pulses out into a more balanced pattern, which ultimately improves engine output. A nice side benefit is that crossovers also decrease in-cabin harass drone.”
Albeit X- and H-pipes perform enormously well for a minimal investment in time and money, both suggest unique properties that make one more suitable than the other depending on the application. “The two thickest differences inbetween an X- and an H-pipe are sound and power. Generally, the X-pipe will produce a more high-pitched harass note, making a car sound more exotic, whereas an H-pipe gives a deeper tone with more of a traditional hot rod sound,” says George Rumore of Stainless Works. “As for the difference in power build up inbetween the two, it is very minimal. The X-pipe will usually make anywhere from two to four more horsepower than an H-pipe. The slight horsepower difference comes from the way the X-pipe creates a venturi effect, which helps pull the harass gases out of the cylinder swifter. Overall, the main difference is sound rather than spectacle, meaning there are no pros or cons. It’s simply a matter of individual preference.”
In addition to differences in sound and horsepower, both X- and H-pipes affect different parts of the powerband as well. According to PerTronix’s Don Lindfors, the basic configuration of both styles of crossovers lend a clue as to why this is the case. “An H-pipe tends to make more of a difference at lower rpm, while-X pipes will increase power more at higher rpm. As you can imagine, just by looking at each configuration, in the H-pipe the harass has to make a acute 90-degree turn, while the X-pipe offers a smoother transition,” he says. “The X-pipe creates much more of a scavenging effect. That said, it is significant to prevent the X-pipe from necking down too petite or flow can be hampered. Both an X- and an H-pipe will slick out the separated sound of the cylinders, while an X-pipe tends to blend all eight cylinders together more.”
For all-out power, X-pipes seem to be the winner, but H-pipes boast several advantages as well. “H-pipes typically suggest enlargened backpressure compared to an X-pipe, which nets an increase in low-end torque. They are also more tunable because they suggest more options in terms of the length of the crossover, the diameter of the tube, and the size and location of the transfer crevice,” Blane Burnett explains. “As a simpler design that takes up less space, H-pipes have more options as to where on the harass system the crossover section can be placed. While spectacle is a large consideration when designing an harass system, vehicle packaging is also a fat factor. Depending on the application, an X- or an H-pipe might suit the chassis better, but an H-pipe certainly offers more options as to where it can be placed.”
01. Gen III/IV small-blocks, like this 840hp LS7 built by the School of Automotive Machinists, utilize a slightly different firing order (1-8-7-2-6-5-4-3) than past Chevy V-8s. Unlike a Mouse or Rat engine where adjacent cylinders on the same bank fire one right after the other, the revised firing order ensures that each combustion event alternates inbetween each bank of cylinders. In theory, this should help even out the variation in harass pressure from bank to bank.
02. X-pipes are essentially two mandrel leans sliced open along the long radius to create an oval opening, which are then welded together. The openings create a seamless path for harass to travel from one bank to the other.
03. In contrast to an X-pipe, harass must negotiate a series of 90-degree turns in order to budge from one side of the harass system to the other in an H-pipe. The resulting increase in backpressure isn’t necessarily a bad thing, since it boosts low-end torque. Stainless Works laser cuts its X- and H-pipes to ensure optimal flow without any obstructions at the center union.
04. A-bodies were never designed to accommodate an X-pipe, but the transmission tunnel serves as an ideal location due to its proximity to the header collectors. This location also provides slew of ground clearance.
05. Installing an X-pipe is simply a matter of connecting the dots. Once the front portion of the “X” has been welded to the collector pipes, the rear portion of the “X” can be connected to the intermediate pipes.
06. The radius of the two halves of pipes that comprise the “X” typically range from forty five to ninety degrees. The broader the radius of the leans, the tighter the space they can fit inwards. Even underneath the taut restricts of a C5 Corvette, wide-radius leans make it possible to fit an aftermarket X-pipe with room to spare.
In addition to differences in sound and horsepower, both X- and H-pipes affect different parts of the powerband as well. According to PerTronix’s Don Lindfors, the basic configuration of both styles of crossovers lend a clue as to why this is the case. “An H-pipe tends to make more of a difference at lower rpm, while-X pipes will increase power more at higher rpm. As you can imagine, just by looking at each configuration, in the H-pipe the harass has to make a acute 90-degree turn, while the X-pipe offers a smoother transition,” he says. “The X-pipe creates much more of a scavenging effect. That said, it is significant to prevent the X-pipe from necking down too puny or flow can be hampered. Both an X- and an H-pipe will slick out the separated sound of the cylinders, while an X-pipe tends to blend all eight cylinders together more.”
For all-out power, X-pipes seem to be the winner, but H-pipes boast several advantages as well. “H-pipes typically suggest enhanced backpressure compared to an X-pipe, which nets an increase in low-end torque. They are also more tunable because they suggest more options in terms of the length of the crossover, the diameter of the tube, and the size and location of the transfer crevice,” Blane Burnett explains. “As a simpler design that takes up less space, H-pipes have more options as to where on the harass system the crossover section can be placed. While spectacle is a large consideration when designing an harass system, vehicle packaging is also a big factor. Depending on the application, an X- or an H-pipe might suit the chassis better, but an H-pipe certainly offers more options as to where it can be placed.”
With driveline and chassis components to contend with, figuring out the positioning of the balance pipe on the harass system could very well be determined by wherever space is available. That said, each engine and harass system combination has one specific spot where the balance pipe works best, albeit the importance of this positioning is up for debate. “The placement of X- or H-pipe is most effective when placed somewhere around eight to eighteen inches from the end of the collectors,” says Don Lindfors. “Moving it around can shift the torque peak slightly, but not enough to make a real-world difference. Usually, the available space under the car will end up dictating exactly where the X- or H-pipe will end up.” Blane Burnett of Hooker Headers concurs, stating “There is a sweet spot that exists for the integration of X- or H-pipes, and those gains will be noticeable. Whether or not you can achieve that particular design will always vary from vehicle to vehicle, and requires extensive testing.”
Due to the terrific spectacle benefits of balance pipes, many aftermarket header-back harass systems include an integrated X- or H-pipe. Consequently, for those in the market for a accomplish harass system, adding a balance pipe is a click of the mouse away. For the hoards of hot rodders out there that already have an aftermarket harass system, balancing out that dual harass system is just as effortless. There was a time when X- and H-pipes had to be custom-built from scrape with sections of straight tubing or U-bends. Fortunately, that’s no longer the case, as aftermarket companies such as Hooker, Stainless Works, and PerTronix all suggest universal X- and H-pipe kits that can be lightly integrated into any existing dual harass system. All it takes is some basic cutting and welding abilities and a duo of hours of spare time.
07. Crossover pipes are typically placed directly after the collectors (bottom). On the factory C5 harass (top), however, GM elected to position it at the very back of the intermediate pipes. Albeit the exact reasoning why this is the case is unclear, it reinforces the notion that having a crossover pipe somewhere on the harass system is better than having no crossover at all.
08. Ideally, the crossover tubing of an H-pipe shouldn’t be any smaller than the harass tubing it’s connected to. In certain applications, enhancing the diameter of the crossover pipe can yield significant gains in horsepower.
09. Flowtech’s universal Warlock X-pipe is built from mandrel-bent 16-gauge aluminized steel and includes four sets of cut-to-fit gams and extension tubes to fit virtually any application. For those that aren’t handy with a welder, the kit also comes with U-bolts and flared collectors. They’re even available with optional harass cutouts for the ultimate in flow.
Ten. The easiest way to add an X-pipe to any car is by installing a accomplish harass system that already has an X-pipe in it, like this header-back system for a second-gen Camaro from Hooker. The unique form of the “X” is made possible by Hooker’s universal crossover pipe that permit for custom-made inlet and outlet angles.
11. Sometimes it’s much lighter to package an X-pipe underneath a car if the inlets and outlets can be set at different angles. Hooker now offers universal stamped stainless steel crossovers that are essentially X-pipes without any preconfigured inlets and outlets. This gives fabricators almost limitless plasticity in setting the angles of the pipes exactly how they want them.
12. On a typical 400-horsepower street car, adding an X-pipe or an H-pipe to an existing dual harass system can add 7-12 hp. A smoother harass note and diminished interior resonance are added bonuses.
X-pipes and H-pipes Add Effortless Horsepower
X-pipes and H-pipes Add Effortless Horsepower, but Which is Best for Your Rail?
Don’t let the glorious Bow Tie horsepower loser you. Firing eight cylinders every ninety degrees in a 1-8-4-3-6-5-7-2 sequence is an inherently chaotic endeavor. Since the mass of the counterweights and flywheel mask this violence by smoothing out the power delivery of the crankshaft, it’s effortless to leave behind that eight individual combustion events are going down every seven hundred twenty degrees of crank rotation. Alternating the firing order inbetween the left and right bank of cylinders means that there is often a substantial difference in harass pressure inbetween each bank. The result—at any given moment—is a traffic jam of harass molecules in one bank of cylinders when minimal backpressure exists in the opposite bank. While this recurring script reduces engine efficiency and horsepower, the solution is as effortless as integrating a balance pipe into the harass system.
Adding a balance pipe is like downloading Google Maps for your harass. As combustion gases travel out of the header collector and into the intermediate pipe, if their progress slows down due to backpressure, a balance pipe redirects them to a less congested flow path. “The name ‘balance pipe’ should be a clue as to why X- and H-pipes work so well,” Don Lindfors, Director of Harass R&D at PerTronix Spectacle Products explains. “Just like the name suggests, they help to balance the flow inbetween all the cylinders. Beyond that, they can even help with scavenging by having cylinders from the opposite bank of the engine create a negative wave to increase the overall flow of the harass.”
In terms of both spectacle and price, balance pipes are so effective that GM has been installing them for decades on Corvettes and more recently on fifth-gen Camaros. Best of all, balance pipes can be added to any existing dual harass system. Before busting out the Sawzall and welder, however, there are many significant factors to consider, such as the spectacle difference inbetween X- and H-pipes, where to place them in the harass tract, cost, and potential horsepower and torque gains. Granted that balance pipes are rather ordinary devices, but there’s far more to the science behind how they work than their appearance suggests. To get the inwards scoop, we hit up the industry experts Blane Burnett of Hooker Headers, Don Lindfors of PerTronix, and George Rumore of Stainless Works.
Balancing the harass pressure from bank to bank is just one of the many ways an X- or H-pipe improves overall harass flow. With a conservative factory camshaft, the harass seemingly flows out the tailpipe in one continuous stream. In reality, however, harass swings travel in pulses, which become much more noticeable as camshaft duration increases. Consequently, reducing the detrimental effects of these pulses can positively influence horsepower and torque. “A balance pipe serves two distinct functions. Very first off, it takes the left and right banks of an engine’s harass and provides a crossover point to equalize flow from side to side,” Blane Burnett of Hooker Headers explains. “Secondly, balance pipes slick out uneven harass pulses. Any given engine generates low- and high-pressure harass pulses due to the effects of the firing order. As these low and high pulses budge downstream through the harass piping, they travel at different speeds. Having an harass crossover helps draw these pulses out into a more balanced pattern, which ultimately improves engine output. A nice side benefit is that crossovers also decrease in-cabin harass drone.”
Albeit X- and H-pipes perform utterly well for a minimal investment in time and money, both suggest unique properties that make one more suitable than the other depending on the application. “The two thickest differences inbetween an X- and an H-pipe are sound and power. Generally, the X-pipe will supply a more high-pitched harass note, making a car sound more exotic, whereas an H-pipe gives a deeper tone with more of a traditional hot rod sound,” says George Rumore of Stainless Works. “As for the difference in power build up inbetween the two, it is very minimal. The X-pipe will usually make anywhere from two to four more horsepower than an H-pipe. The slight horsepower difference comes from the way the X-pipe creates a venturi effect, which helps pull the harass gases out of the cylinder swifter. Overall, the main difference is sound rather than spectacle, meaning there are no pros or cons. It’s simply a matter of individual preference.”
In addition to differences in sound and horsepower, both X- and H-pipes affect different parts of the powerband as well. According to PerTronix’s Don Lindfors, the basic configuration of both styles of crossovers lend a clue as to why this is the case. “An H-pipe tends to make more of a difference at lower rpm, while-X pipes will increase power more at higher rpm. As you can imagine, just by looking at each configuration, in the H-pipe the harass has to make a acute 90-degree turn, while the X-pipe offers a smoother transition,” he says. “The X-pipe creates much more of a scavenging effect. That said, it is significant to prevent the X-pipe from necking down too puny or flow can be hampered. Both an X- and an H-pipe will sleek out the separated sound of the cylinders, while an X-pipe tends to blend all eight cylinders together more.”
For all-out power, X-pipes seem to be the winner, but H-pipes boast several advantages as well. “H-pipes typically suggest enlargened backpressure compared to an X-pipe, which nets an increase in low-end torque. They are also more tunable because they suggest more options in terms of the length of the crossover, the diameter of the tube, and the size and location of the transfer slot,” Blane Burnett explains. “As a simpler design that takes up less space, H-pipes have more options as to where on the harass system the crossover section can be placed. While spectacle is a large consideration when designing an harass system, vehicle packaging is also a ample factor. Depending on the application, an X- or an H-pipe might suit the chassis better, but an H-pipe certainly offers more options as to where it can be placed.”
01. Gen III/IV small-blocks, like this 840hp LS7 built by the School of Automotive Machinists, utilize a slightly different firing order (1-8-7-2-6-5-4-3) than past Chevy V-8s. Unlike a Mouse or Rat engine where adjacent cylinders on the same bank fire one right after the other, the revised firing order ensures that each combustion event alternates inbetween each bank of cylinders. In theory, this should help even out the variation in harass pressure from bank to bank.
02. X-pipes are essentially two mandrel arches sliced open along the long radius to create an oval opening, which are then welded together. The openings create a seamless path for harass to travel from one bank to the other.
03. In contrast to an X-pipe, harass must negotiate a series of 90-degree turns in order to stir from one side of the harass system to the other in an H-pipe. The resulting increase in backpressure isn’t necessarily a bad thing, since it boosts low-end torque. Stainless Works laser cuts its X- and H-pipes to ensure optimal flow without any obstructions at the center union.
04. A-bodies were never designed to accommodate an X-pipe, but the transmission tunnel serves as an ideal location due to its proximity to the header collectors. This location also provides slew of ground clearance.
05. Installing an X-pipe is simply a matter of connecting the dots. Once the front portion of the “X” has been welded to the collector pipes, the rear portion of the “X” can be connected to the intermediate pipes.
06. The radius of the two halves of pipes that comprise the “X” typically range from forty five to ninety degrees. The broader the radius of the arches, the tighter the space they can fit inwards. Even underneath the taut restricts of a C5 Corvette, wide-radius arches make it possible to fit an aftermarket X-pipe with room to spare.
In addition to differences in sound and horsepower, both X- and H-pipes affect different parts of the powerband as well. According to PerTronix’s Don Lindfors, the basic configuration of both styles of crossovers lend a clue as to why this is the case. “An H-pipe tends to make more of a difference at lower rpm, while-X pipes will increase power more at higher rpm. As you can imagine, just by looking at each configuration, in the H-pipe the harass has to make a acute 90-degree turn, while the X-pipe offers a smoother transition,” he says. “The X-pipe creates much more of a scavenging effect. That said, it is significant to prevent the X-pipe from necking down too puny or flow can be hampered. Both an X- and an H-pipe will slick out the separated sound of the cylinders, while an X-pipe tends to blend all eight cylinders together more.”
For all-out power, X-pipes seem to be the winner, but H-pipes boast several advantages as well. “H-pipes typically suggest enlargened backpressure compared to an X-pipe, which nets an increase in low-end torque. They are also more tunable because they suggest more options in terms of the length of the crossover, the diameter of the tube, and the size and location of the transfer fuckhole,” Blane Burnett explains. “As a simpler design that takes up less space, H-pipes have more options as to where on the harass system the crossover section can be placed. While spectacle is a large consideration when designing an harass system, vehicle packaging is also a thick factor. Depending on the application, an X- or an H-pipe might suit the chassis better, but an H-pipe certainly offers more options as to where it can be placed.”
With driveline and chassis components to contend with, figuring out the positioning of the balance pipe on the harass system could very well be determined by wherever space is available. That said, each engine and harass system combination has one specific spot where the balance pipe works best, albeit the importance of this positioning is up for debate. “The placement of X- or H-pipe is most effective when placed somewhere around eight to eighteen inches from the end of the collectors,” says Don Lindfors. “Moving it around can shift the torque peak slightly, but not enough to make a real-world difference. Usually, the available space under the car will end up dictating exactly where the X- or H-pipe will end up.” Blane Burnett of Hooker Headers concurs, stating “There is a sweet spot that exists for the integration of X- or H-pipes, and those gains will be noticeable. Whether or not you can achieve that particular design will always vary from vehicle to vehicle, and requires extensive testing.”
Due to the tremendous spectacle benefits of balance pipes, many aftermarket header-back harass systems include an integrated X- or H-pipe. Consequently, for those in the market for a accomplish harass system, adding a balance pipe is a click of the mouse away. For the hoards of hot rodders out there that already have an aftermarket harass system, balancing out that dual harass system is just as effortless. There was a time when X- and H-pipes had to be custom-built from scrape with sections of straight tubing or U-bends. Fortunately, that’s no longer the case, as aftermarket companies such as Hooker, Stainless Works, and PerTronix all suggest universal X- and H-pipe kits that can be lightly integrated into any existing dual harass system. All it takes is some basic cutting and welding abilities and a duo of hours of spare time.
07. Crossover pipes are typically placed directly after the collectors (bottom). On the factory C5 harass (top), however, GM elected to position it at the very back of the intermediate pipes. Albeit the exact reasoning why this is the case is unclear, it reinforces the notion that having a crossover pipe somewhere on the harass system is better than having no crossover at all.
08. Ideally, the crossover tubing of an H-pipe shouldn’t be any smaller than the harass tubing it’s connected to. In certain applications, enlargening the diameter of the crossover pipe can yield significant gains in horsepower.
09. Flowtech’s universal Warlock X-pipe is built from mandrel-bent 16-gauge aluminized steel and includes four sets of cut-to-fit gams and extension tubes to fit virtually any application. For those that aren’t handy with a welder, the kit also comes with U-bolts and flared collectors. They’re even available with optional harass cutouts for the ultimate in flow.
Ten. The easiest way to add an X-pipe to any car is by installing a finish harass system that already has an X-pipe in it, like this header-back system for a second-gen Camaro from Hooker. The unique form of the “X” is made possible by Hooker’s universal crossover pipe that permit for custom-made inlet and outlet angles.
11. Sometimes it’s much lighter to package an X-pipe underneath a car if the inlets and outlets can be set at different angles. Hooker now offers universal stamped stainless steel crossovers that are essentially X-pipes without any preconfigured inlets and outlets. This gives fabricators almost limitless plasticity in setting the angles of the pipes exactly how they want them.
12. On a typical 400-horsepower street car, adding an X-pipe or an H-pipe to an existing dual harass system can add 7-12 hp. A smoother harass note and diminished interior resonance are added bonuses.