H vs. X
H-pipe vs X-pipe
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Junior User
Joined: Oct 2003
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From: College Station, TX
H-pipe vs X-pipe
Can anyone can tell me why a X-pipe is better than a H-pipe? My motorhead buddies all seem to think this is true, but they can't tell me why except to babble about scavenging. Any reason I should spend more money on the X-pipe?
Post Fiend
Joined: Feb 2001
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From: Missouri
The purpose of any type of cross over is scavenging. The H - pipes scavenge some but the x pipes scavenge much better due to the fact that the 2 pipes are crossing paths completely.
Scavenging is when the exhaust flow from one pipe pulls gasses from the other pipe. Kind of like canadian geese flying in a V pattern.
Okay the goose thing might not be the best description but you should have the idea.
Scavenging is when the exhaust flow from one pipe pulls gasses from the other pipe. Kind of like canadian geese flying in a V pattern.
Okay the goose thing might not be the best description but you should have the idea.
Logistics Pro
Joined: Jan 2002
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From: suburban atlanta
I don't think there is significant difference between a H form and an X form as long as they are cross-connected. Two single, non-connected pipes, on the other hand, will act and sound like two big 4-bangers, because that is what the exhaust is. The 'standing waves' in the exhaust can form vacuum and pressure spots based on rpm, so *where* the crossover or joining is down from the exhaust manifold can have a difference in performance, but anything is better than nothing when it comes to the sound...
tom
tom
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Joined: Dec 1999
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From: Copley, OH
There are imbalanced exhaust pulses in each bank of a V-8. By bringing the exhausts together at a common point and crossing them, the X pipe allows slightly better scavenging by allowing the center 2 cylinder pulses from one bank to phase in with the outer 2 pulses from the other. The difference is very small, usuallly less than a 5 HP gain at peak over an H pipe. The H pipe typically produces slightly more mid-range torque, again nothing to write home about.
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From: Monterey bay area
The H pipe helps balance the exhaust pulses from each bank....
increasing the siphon effect called scavenging....
The H pipe has to travel through at least 90 degress in order to be effective
while the x pipe has a direct shot at balancing the pulses....
So this would make the X pipe much more efficient overall.
Plus the X pipe sounds so cool.
increasing the siphon effect called scavenging....
The H pipe has to travel through at least 90 degress in order to be effective
while the x pipe has a direct shot at balancing the pulses....
So this would make the X pipe much more efficient overall.
Plus the X pipe sounds so cool.
Posting Guru
Joined: Apr 2000
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From: Pryor
Have you ever stood near the highway when a semi came by at about 70 mph??? When it goes by, you dang near get sucked in behind it. That is similar to the way an X-pipe works. As the exhaust gasses from one bank rush through the X, they create a relative vacuum for the opposite exhaust pipe, pulling exhaust from that side proximal to the X. This makes X's better than H's. Theoretcally, H's will allow you to gain back some of the hp lost to backpressure in an exhaust system, whereas X's can even gain hp beyond what you would have by not having an exhaust at all as each bank helps the other. Of course all this stuff doesn't apply too much to full exhaust systems with mufflers. They choke off the power bad enough that neither can gain very much and the actual difference between the two in actual applications is minimal.
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Joined: Oct 2003
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From: Fort Lauderdale, FLORIDA
There's a guy named Lois Ott that makes X pipes for Porsche 928's....they are gaining **30 hp** with these!
It would be easy to mount this part on nearly any sort of vehicle equipped with dual exhausts.
The Ott design isn't a true X...it is actually a pipe section where the dual exhausts "kiss", with a large oval window between them. This causes a suction effect in one pipe as a pair of exhaust pulses race past in the other pipe....while not increasing drag at all. Ott has a website- no affiliation on my part.
N!
It would be easy to mount this part on nearly any sort of vehicle equipped with dual exhausts.
The Ott design isn't a true X...it is actually a pipe section where the dual exhausts "kiss", with a large oval window between them. This causes a suction effect in one pipe as a pair of exhaust pulses race past in the other pipe....while not increasing drag at all. Ott has a website- no affiliation on my part.
N!
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