Lets hear some facts please, what is best and why? For my reference 416 Stroker TTI Headers and want to run to rear bumper 3" or 2.5" same question, pros or cons? I will be around 625-645 @ Crank on Horsepower.
X pipe H pipe or side by side
- Thread starter Hoophoop
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Lustle
Well-Known Member
H pipe - Lower end torque/power, deeper sound. The pulses will "run" into each other in the pipe. Helping reducing resonance. Think old school V8.
X pipe - High end gains. More horsepower overall. The pulses will "merge" better in the pipe. Causing a scavenging effect at higher RPMs. Think raspy newer high performance engines.
You can watch some shitstangs rev and compare x vs h in this video:
[ame="https://www.youtube.com/watch?v=lnI53sWqbcs"]X pipe vs H pipe REVS- Mustang GT - YouTube[/ame]
As for pipe size. 3". Don't even think of 2.5 at that kinda power. You'll choke it for sure. 2.5" is for around 400 horse. Read this: http://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/ The math holds up. 3" would be great on your setup.
X pipe - High end gains. More horsepower overall. The pulses will "merge" better in the pipe. Causing a scavenging effect at higher RPMs. Think raspy newer high performance engines.
You can watch some shitstangs rev and compare x vs h in this video:
[ame="https://www.youtube.com/watch?v=lnI53sWqbcs"]X pipe vs H pipe REVS- Mustang GT - YouTube[/ame]
As for pipe size. 3". Don't even think of 2.5 at that kinda power. You'll choke it for sure. 2.5" is for around 400 horse. Read this: http://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/ The math holds up. 3" would be great on your setup.
famous bob
mopar misfit
I went w/ 3.5" dual turn downs ( no room to go over the dana w/ the stock gas tank), I doubt very seriously that h, or x pipe would show enough, "if any" improvement at over 600h.p. probly not worth their weight !
ir3333
Well-Known Member
...can someone explain to me how a 6 inch piece of pipe can make horse power.
the exhaust can't get out any quicker.
the exhaust can't get out any quicker.
TrailBeast
AKA Mopars4us on Youtube
The idea is that one exhaust pulse pulls the next one coming, kind of like headers do.
roccodart440
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There are some good answers and links here
http://www.hotrodders.com/forum/x-pipe-h-pipe-215401.html
Bottom line, run an X or an H.
http://www.hotrodders.com/forum/x-pipe-h-pipe-215401.html
Bottom line, run an X or an H.
mguner
How many is too many?
I will try someday to post videos of my big block Duster in the burnout box both with and without the exhaust. The X and H pipe are both designed to promote scavenging from opposite side exhaust pulses, like supercharging by sucking on the exhaust. Without the X pipe I have to lay into the throttle for the burn out. With the X pipe and mufflers installed I have to feather the throttle to keep it off the red line! Better 60' with the X pipe too. I am running 3" pipe and my X is basically two 3" 90s with the cap of the bend cut off and welded together. Both H and X are designed to do the same thing but the X is more efficient. Before the X became popular I made U bent H pipes with the bend facing forward. This is what I still have on the 68 Dart and you will get nice low end improvements from a well designed crossover of either style.
ir3333
Well-Known Member
No matter where it goes,it will be trying to enter a pipe already full.
..if anything logic would say it will create interference.Aside from that
the exhaust can't get out any easier or quicker?
mguner
How many is too many?
And yet they work and have been documented to do so..... The alternating pulses create a vacuum on the side not firing so that the next cylinder in sequence has less resistance in the exhaust. A bit oversimplified but the basic idea.
ir3333
Well-Known Member
The same reason a 2 into 1 Harley runs stronger than 2 seperate
mguner
How many is too many?
Phreakish
Well-Known Member
It's NOT already full. It does not create interference.
Exhaust isn't a steady stream of gasses out of each cylinder. They're pulses. Only one cylinder at a time is huffing into those pipes. The gasses head for the exit - path of least resistance. A column of gasses has weight/mass, which gives it momentum. That means it takes work to slow it down. That's why when an exhaust valve closes, the column of air moving behind it toward the tail pipe is still 'sucking' on that valve - until the next one opens.
Having an H or X does two things - it allows the exhaust column on one side to 'suck' on the other. It also splits the escaping gasses into two sides, effectively cutting exhaust resistance in half. That's why the exhaust tone changes - it's effectively behaving as if the pipe diameters have been increased substantially. There's really no reason not to run one of some sort unless one simply cannot stand the sound of a cross-over style system or spend so much time at rpms where they're not adding much (sprint cars, for example) that the expense or maintenance headache (matter of access on some cars) isn't worth it.
It's not done by/for magazines or for exhaust manufacturers to sell more pipe - every major form of road racing uses them. Unless they're drinking the flowmaster koolaid too, huh?
ir3333
Well-Known Member
i can see two in to one pulling each other.
but 4 cylinders in each side should already be doing this.
..Larry Sheppard, (Mopars' head performance engineer for 25 years)
says an H pipe just quietens the system.
i'm no authority,just looking at what make sense.
mguner
How many is too many?
Just think of it like a Tri-Y with another Y down stream.
roccodart440
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An H pipe isn't a 2-1 system.
ir3333
Well-Known Member
i can see a Try-Y working if the single pipe is the correct size (tuned)
but an H is not 2 into one...it's 2 into 2 (or 4 in to 4 )
Phreakish
Well-Known Member
Some people just can't physics.. Even if it's 2 into 2, the 2 exhaust pipes are still carrying momentum of the exhaust gasses and applying an increased scavenging effect to all cylinders rather than 'waiting' on the same-side cylinders to do the work.
Run without one if you like, those that have them seem to see plenty of benefit and have timeslips and dyno sheets to prove it. Claim all the quotes you like, they don't change the numbers.
Run without one if you like, those that have them seem to see plenty of benefit and have timeslips and dyno sheets to prove it. Claim all the quotes you like, they don't change the numbers.
ir3333
Well-Known Member
i can't argue with those that have a proven increase.
I try to be objective and ask questions that will benefit everybody...
..it's all good!
I try to be objective and ask questions that will benefit everybody...
..it's all good!
mguner
How many is too many?
What may be a bit confusing is thinking about back pressure in the equation. The H or X is far enough up stream it is still more a factor of velocity and pressure differentials.
Phreakish
Well-Known Member
"back pressure" isn't a thing. It's a phrase, but it's not based on reality.
The notion of back pressure comes from the fact that lopping off exhaust or going to too large of an exhaust can lose low-end torque on some setups. The reason for this has very little to do with 'back pressure' and everything to do with momentum.
Short exhaust systems hold too little volume, larger volume = more mass = more momentum. The momentum of the gas stream is what causes the better scavenging.
Too large of an exhaust has to do with gases cooling off as they expand. A cooler charge has less volume, and will also move more slowly. As a result, momentum is also decreased by too large of an exhaust system.
This ignores pressure waves, by the way - that's a whole other ball of wax.
Having an H or X allows the momentum in the exhaust column to be applied to both sides of the engine. Effectively doubling the scavenging effect on any single cylinder in it's cycle.
It's most pronounced down low because the effect becomes overshadowed by other interactions in the intake manifold at higher revs.
Lustle
Well-Known Member
I'll maybe try to explain in a way that make's it a little easier to understand, without going too technical about scavenging and its effect on engine performance and how important it is to your system. Maybe even put a canadian twist on it for yah.
Think of your headers. Why do they work? Because they allow the "pulses" of the exhaust to not slam into each other when they reach the end of the runner. They merge like traffic on a highway. Everyone happy. Everything flows along nicely.
Now, think of the noble canadian goose. Why do they fly in a V? Because, the drag is reduced for each bird the farther back it goes right? Think of your exhaust as the same. Each pulse in front of it helps "pull" along the one behind it. Like our merging traffic, except as you merge you latch onto the vehicle in front of you and use less power to travel. While also pulling the vehicle behind you that just latched onto you.
This "pulling" effect, is scavenging. And will reach back into the cylinder itself through the exhaust valve. If it is strong enough and your exhaust is setup properly. On high end systems scavenging has been shown to help clear the cylinder of burnt exhaust gases, pull in more air/fuel (with proper cam overlap with the exhaust and intake open at the same time) and help the engine run better. If your exhaust and intake valves are open at the same time the exhaust will pull through the intake right? There is the vacuum from the exhaust helping to fill the cylinders. It can't do that if it is fighting itself. Merging the exhaust just amplifies that pulling effect. More pulses pulling more pulses. More cars pulling more cars. More geese pulling more geese.
If any of that makes sense.
Think of your headers. Why do they work? Because they allow the "pulses" of the exhaust to not slam into each other when they reach the end of the runner. They merge like traffic on a highway. Everyone happy. Everything flows along nicely.
Now, think of the noble canadian goose. Why do they fly in a V? Because, the drag is reduced for each bird the farther back it goes right? Think of your exhaust as the same. Each pulse in front of it helps "pull" along the one behind it. Like our merging traffic, except as you merge you latch onto the vehicle in front of you and use less power to travel. While also pulling the vehicle behind you that just latched onto you.
This "pulling" effect, is scavenging. And will reach back into the cylinder itself through the exhaust valve. If it is strong enough and your exhaust is setup properly. On high end systems scavenging has been shown to help clear the cylinder of burnt exhaust gases, pull in more air/fuel (with proper cam overlap with the exhaust and intake open at the same time) and help the engine run better. If your exhaust and intake valves are open at the same time the exhaust will pull through the intake right? There is the vacuum from the exhaust helping to fill the cylinders. It can't do that if it is fighting itself. Merging the exhaust just amplifies that pulling effect. More pulses pulling more pulses. More cars pulling more cars. More geese pulling more geese.
If any of that makes sense.
fratzog lover
Well-Known Member
[ame="https://www.youtube.com/watch?v=2crCWF5cmLk"]X-Pipe vs H-Pipe vs Factory Pipe - Ford Mustang V6 - Exhaust Flow Simulation - YouTube[/ame]
ir3333
Well-Known Member
here's another analogy...
pull in tight behind a tractor trailer on your favourite highway and he'll
actually pull you along to some extent.Now try to get in when they are
bumper to bumper...good luck!
These exhaust systems must be "tuned" and arbitrarily welding a pipe in
between somewhere?
pull in tight behind a tractor trailer on your favourite highway and he'll
actually pull you along to some extent.Now try to get in when they are
bumper to bumper...good luck!
These exhaust systems must be "tuned" and arbitrarily welding a pipe in
between somewhere?
Locomotion
Well-Known Member
The exhaust in the pipes isn't consistently "full". The exhaust is in pulses from each cylinder - "waves". So there are actual low and high pressure areas, but all moving pretty fast. The trick is to optimize the lengths and diameters of the headers, including and X or H additions in the system. Hold your hand to an exhaust pipe and you'll feel the pulses.
I put a 3" X-pipe and UltraFlo mufflers on my race car. It picked up between .05 and .10 over an open exhaust with collectors. I believe carb liked 1-2 numbers less jet as well after jetting was as good as I could get it with open headers. X pipe helped and those mufflers didn't hurt. I would think that 500+ HP would benefit more from a 3.5" exhaust.
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