x and h pipes

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Well although I've been driving for some 30 years now, I never really got into exhaust work. I see these comments and pictures of x and h pipes and I start wondering what the purpose is. I recently bought a 63 Dart 4 door with a slant 6 225 pushbutton auto. Been thinking about putting in a 318 and going with dual exhaust. What is the reasoning behind using an h or x pipe and is it something I should think about when I swap engines? Does it make a difference if I swap trannies to a 4 speed on what exhaust I can/should use?
 
The biggest reason for using them is it will allow the use of a less restrictive (louder) muffler and keep the noise level to acceptable levels. If they are positioned exactly right they will help with power but its not a huge amount.

I had a car with duals and glass paks an it was all together to loud and the sound was pretty raunchy under WOT. I installed an H-pipe cross over and the change in the sound level and quality of the sound was dramatic.
 
Im Going To Do The Flowtech System From Summit Wit The Xpipe, And The Un- Corking Plate That After The X Pipe, On A Pretty Warmed Up Street 340 Solid Cam Motor, What 3inch Mufflers Should I Use?? The Cheaper The Better For Me ,im On A Budget,i Was Looking At Summits Mufflers, Or Hush Thrush Turbo??????? Anybody??
 
ANY X-pipe is going to increase your torque and horsepower - 20 - 25 ft lbs of torque (minimum), 10- 20 hp gain ! And for an added bonus, a better deeper throaty sound, - an will improve your gas mileage !!!! It's a win - win situation. Especially for the buck factor. No old Mopar should be without one, especially if you have a 'hopped up' street Mopar !!! You have to get into the 21st century.
 
I would disagree with that statement. I wnet from 2.25" dual exhaust with straight through glass pak mufflers to a 2.5" system with an x-pipe and Flowmaster mufflers.

By the butt dyno I did not feel any difference in power but the sound level is low at cruise with no interior resonance. This is an ~ 370 HP 360.

I just can't see a 20-25 ft-lb increase in torque by just adding the x-pipe.
 
dgc333 said:
I would disagree with that statement. I wnet from 2.25" dual exhaust with straight through glass pak mufflers to a 2.5" system with an x-pipe and Flowmaster mufflers.

By the butt dyno I did not feel any difference in power but the sound level is low at cruise with no interior resonance. This is an ~ 370 HP 360.

I just can't see a 20-25 ft-lb increase in torque by just adding the x-pipe.
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Just going on the 3 or 4 articles in the Mopar mags and Hot Rod rag, that I've read - and personal experience. (dyno pulls, et's slips). I'll try to find the articles, and post . Of course alot of other factors have to be considered - horsepower, size of complete exhaust. tailpipes, etc, etc. If you have a lot of bottled up horsepower/torque, there should be a noticable difference. :-D:-D
 
i have no before and after numbers but after i went to an X-pipe i had to jet up the primaries 2 sizes. at the track the car ran exactly the same with the full exhaust as it did opened up. something is definatley working in that exhaust.
 
The answer I got when I asked a friend who is a custom exhaust builder, before I had my dual stainless built was that there is a slight gain in HP and torque due to the better flow and less back pressure, both will somewhat lower the tone of the exhaust. The "H" is what he recommended for street and the odd strip run. The "X" is better used in high rev application, ie highway driving with 4:10 gears.

Hope this helps.
 
340butterduster said:
The answer I got when I asked a friend who is a custom exhaust builder, before I had my dual stainless built was that there is a slight gain in HP and torque due to the better flow and less back pressure, both will somewhat lower the tone of the exhaust. The "H" is what he recommended for street and the odd strip run. The "X" is better used in high rev application, ie highway driving with 4:10 gears.

Hope this helps.
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That makes no sense because all new V8 powered cars have X-pipe systems and cruise below 2500 RPM on the highway (75 MPH). I think a lot of the power improvement has to do with the build of the engine itself; Mopar Action got around 20 extra HP at the rear wheels switching to an X-pipe system but that was on their 700 HP 496 wedge-powered '69 Road Runner (Project Bold Beeper).
 
340butterduster said:
The answer I got when I asked a friend who is a custom exhaust builder, before I had my dual stainless built was that there is a slight gain in HP and torque due to the better flow and less back pressure, both will somewhat lower the tone of the exhaust. The "H" is what he recommended for street and the odd strip run. The "X" is better used in high rev application, ie highway driving with 4:10 gears.

Hope this helps.
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i don't agree with that. the H or X are perfectly at home on the street at any rpm. the H will equalize the pressure from side to side. the X will equalize the pressure plus help scavenge the exhaust because one cyls. exhaust will actually help pull the next cyls. exhaust out of the cyl. when that exhaust valve opens . that make sense?
 
abodyjoe said:
i don't agree with that. the H or X are perfectly at home on the street at any rpm. the H will equalize the pressure from side to side. the X will equalize the pressure plus help scavenge the exhaust because one cyls. exhaust will actually help pull the next cyls. exhaust out of the cyl. when that exhaust valve opens . that make sense?
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Yes

That's the reason when I installed the X that my exhaust got quieter...scavenging was helped out.
 
It appears I was mis-understood, or did not explain it very well. Basically what I tried to say was that Both the "H" and the "X" will be a benifit in the flow and a slight gain in power due to the better flow and equalized pressure.

The "X" system compared to the "H" is relatively the same except in the higher RPM range, the "X" is better (slightly) than the "H", again due to the flow.

That is why todays cars have factory "X" system, they are higher revving engines from the factory. It is not unusual to see factory engines rev. above 7,500 rpm easily, compared to our older pushrod V8's and head design that need work to get in that range.

Having said this, I'm not saying that the "X" is not good in the lower ranges, but it's cheaper and easier to do an "H" system, if you are not going to be benefitting from it.

I used the highway/4:10 gears for an example of high rpm.

Sorry for the inconvenience this may have caused.
 
Im lucky enough to have before and after numbers that also support the articles Ive read.Both H and X pipes are good and are big improvements over std duals,an H-pipe will have more low end torque in the lower rpm range compared to an x-pipe,but after that the x-pipe takes over on tq and h.p..The X pipe gives you more overall power throughout the range,I have personally seen a car pick up 1 1/2 tenths going from a H to X with no other changes to the exhaust,running mid 11s and shifting at 6,700and as abody said the carb needed rejetting.I wouldnt even run std dual pipes on a performance car after seeing/feeling the inprovement of an H or an X pipe,for me though I will run an X when ever possible.
 
Here is data from our test a few years ago. Note sound levels with and without X.
About 75% were lower with the X.
Air flow is also something to note. For folks that like the chambered muffler sound, you can see they tend to be louder and on top of that, they do not pass near as much air as straight through mufflers, and it makes sense of course, why that is. When you compare the numbers though it is eye opening.
Look, even the old 1965 Corvair Turbo muffler is quieter and flowed more air than some of today's favorites. It is easy to see why they worked so well compared to stockers.
Tom

silentpower2.JPG


silentpower.JPG
 
VOETOM that is great information!

The Flowmaster 40s suck at air flow. The Dynomax "Ultra Flo" and "Welded Ultra Flo" show excellent numbers.
 
how well would a glasspack like purple hornies or cherry bombs flow compared to something like the ultra flows? i know the ultra flows would probably outflow em, but are they atleast better than 2 chambers?
 
I put an X-pipe on out 70 Dart 318, I noticed a difference. I ran 2 1/4 duals with flowmaster style mufflers. I also have a one on my 340 Satellite, I like em!
 
MSH, we tested a lot of glass packs and the non louvered ones flow a lot of air but as soon as you get into the cheaper ones, yep, the rate is less.

You can't go by only the air flow rate for sure but there definitely is a good correlation between excessive back pressure and reduced performance of the engine at higher speeds. Exhaust is not a smooth flow but we see a good trend between high back pressure (low flow rates) and less than perfect performance.

On powerful engines, it makes a big difference; on less powerful ones, not as much.

With the X instead of an H, we saw reduced back pressure at the engine which will let you run more restrictive mufflers (quiet or loud, take your pick) with less performance degradation. I use it for sound control, others might use the X to let them run loud nasty sounding ones. :):) The X gets rid of more resonation in most cases too, depending upon the muffler, engine's power, and length of pipes and how the mufflers and pipes mount.

Does this make sense?
Tom
 
some good information...thank you for sharing it
 
VOETOM said:
MSH, we tested a lot of glass packs and the non louvered ones flow a lot of air but as soon as you get into the cheaper ones, yep, the rate is less.

You can't go by only the air flow rate for sure but there definitely is a good correlation between excessive back pressure and reduced performance of the engine at higher speeds. Exhaust is not a smooth flow but we see a good trend between high back pressure (low flow rates) and less than perfect performance.

On powerful engines, it makes a big difference; on less powerful ones, not as much.

With the X instead of an H, we saw reduced back pressure at the engine which will let you run more restrictive mufflers (quiet or loud, take your pick) with less performance degradation. I use it for sound control, others might use the X to let them run loud nasty sounding ones. :):) The X gets rid of more resonation in most cases too, depending upon the muffler, engine's power, and length of pipes and how the mufflers and pipes mount.

Does this make sense?
Tom
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Tom Hand by chance?
 
Why yes, Tom Hand, son of Jim, owner of the 11.50 4100 pound Pontiac wagon that we did all the muffler tests on!
Tom
 
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