Hedman makes both H and X pipe kits, yet on their site they say that the X will make more hp and trq than the H pipe. They make money by selling either
http://www.hedman.com/pages/XTREME-SCIENCE.html

 

X pipe scaveges and balences pressure as the engine goes through its firing order. H pipe primarily only balences pressure to equate uneven exhaust lengths and such. Like FAST LS1, you have to image it in pulses, or time slices. The summation of all the slices together yeild the constant flow. The idea is that the vaccuum effect works it way up the pipe and helps pull the exhaust out of the cylinder when the E valve is open. Futhermore, depending on what kind of cam LSA you have, it can help to draw in more air through the intake port. Just tmy theory.

 

Let's not be silly here...if the "H" pipe was the hot ticket then NASCAR would never use an "X" pipe!

 

Very true

I found another article showing the benefits of an x-pipe.
https://ls1tech.com/forums/generation-iii-external-engine/134259-interesting-x-pipe-setup-carcraft-article.html

 

Last time I checked NASCAR wasn't racing LS1's. The engineers at GM utilize a H pipe on their flagship LS1 powered vehicle.......the Vette.

 

The exhaust requirements for an LS1 are no different than any other pushrod motor so the same general technical principals apply here. When are people going to realize that there is nothing magically or unique about modifying an LS1???

 

So if we're to believe that theory then we should all just buy a Vette and be done with it since that's the way GM engineered it and therefore it must be perfect, right? Looks like these same bunch of engineers also designed locking steering columns, PCV's that hardly function, pushrods that bend, timing chains that break, oil pump relief valves that stick, etc.

No, the truth is that every factory engineered part is a compromise and the Corvette exhaust system is no exception. Many tests have been done (Hot Rod did a good one a few years ago) and in most every case I've seen the results show that an X is slightly superior in performance.

 

ill keep my ypipe

thanks jrp

 

me too!

 

OK. If there is proof that the X is slightly better, I'll buy it. Who's got some good hard scientific #'s. I doubt it's more than 1-2 HP, 1-2 ft/lbs.

John B, that is a sarcastic post to the fellow who wanted to use NASCAR as proof. HMMMMMMMM, those cars are designed to be full out ***** to the wall for several hundred laps.......not really a valid comparison to a sreetable F body.


Fulton 1, no I don't mean that either. I just want to see some proof. None of us would modify our cars if all the components from the manufacturer were the best.....right.........Sorry, my sarcasm doesn't seem to be that noticeable online.

 

Direct quote from Hedman who sells both H and X pipes.
"The traditional H-Pipe equalizer allows some of the excess pressure to bleed over the “quiet side” of the exhaust system, resulting in some low and mid-range torque improvements. At high RPM’s however, the gases cannot bleed across the H-Pipe fast enough to help power significantly. Hedman’s X-TREME equalizer pipe splits the flow in the crossover junction so the pressures on both banks will be equal and pulse free after the crossover, regardless of the RPM. Volumetric efficiency and power are therefore improved at all engine speeds."

http://www.hedman.com/pages/XTREME-SCIENCE.html

It may only be 2-3rwhp/trq but most people will put either an H or X pipe on their true dual setup. I think most would rather have more hp/trq since they are virtually the same price on a custom setup.

 

lol, i cant believe you guys are still argueing about which is better. on the average joe blow setup the difference would be negligible. if you have an X setup there'd be no sense switching to an H setup and vise versa.

 

you'll find the most on this on mustang sites like stangnet.com and so on. They all have true duals. From what i was told is that x-pipes give you more peak power while the h pipe is better for low end. since the ls1 is a peak power motor, or it can pull a crap load peak i would look into an x-pipe. Only problem with x-pipes on f-bodies is ground clearance. An h pipe is mainly for equalizing exhaust pressure while an x-pipe makes more of a pull system.

You have to think of where x-pipes were devised from, nascar, where the rpms are always high.

 

Good job everyone, I love a good debate, unfortunatly for the H-pipe team I am going with the X pipe, thanks for all the input my exhaust is going on in the morning total cost:

Dynomax bullets: $80
X pipe: $40
3" exhaust dumped at axles and labor:$120

TOTAL for true duals-$240

Used Mac headers bought from CamminBeaSSt-$150 to my door

Grand total Headers and true duals $390

 

The Hot Rod testing that I referenced earlier can be found in the October 2000 issue (article entitled "Passing Gas - Exhaustive Research" by Terry McGean, pp 60-63).

Engine used for this test was 350 SBC, 9:1 compression, aluminum 23* Trick Flow heads with 2.02/1.60 valves and a Comp 236/236, .490/.490, 110 cam. Intake was Edelbrock Performer RPM and Demon 750 carb. Headers used for the H v. X testing were Hooker 1-5/8" LT's. Engine was tested out of the car with 3" dual exhaust and Flowmaster 3-chamber mufflers. X-pipe used was Dr.Gas X and the crossover portion of the exhaust built by Spintech.

Here are the results:

RPM / H-pipe hp / H-pipe tq | X-pipe hp / X-pipe tq

3000 / 219.3 / 384.0 / 231.2 / 404.7
3100 / 226.9 / 384.5 / 235.3 / 398.7
3200 / 239.4 / 392.9 / 242.6 / 398.2
3300 / 249.5 / 397.1 / 252.0 / 401.0
3400 / 260.5 / 402.4 / 262.1 / 404.9
3500 / 269.7 / 404.6 / 271.2 / 406.9
3600 / 280.1 / 408.6 / 280.5 / 409.3
3700 / 291.3 / 413.4 / 290.3 / 412.1
3800 / 302.8 / 418.6 / 300.3 / 415.0
3900 / 311.9 / 420.1 / 308.6 / 415.6
4000 / 321.1 / 421.6 / 317.4 / 416.7
4100 / 331.6 / 424.8 / 326.9 / 418.8
4200 / 342.4 / 428.2 / 337.0 / 421.4
4300 / 352.0 / 429.9 / 345.7 / 422.2
4400 / 358.4 / 427.8 / 352.9 / 421.2
4500 / 361.5 / 421.9 / 358.7 / 418.7
4600 / 365.1 / 416.9 / 363.7 / 415.2
4700 / 370.3 / 413.8 / 369.5 / 412.9
4800 / 377.1 / 412.7 / 375.8 / 411.1
4900 / 382.3 / 409.8 / 380.1 / 407.4
5000 / 385.1 / 404.5 / 381.8 / 401.1
5100 / 386.7 / 398.3 / 381.1 / 392.5
5200 / 387.8 / 391.7 / 381.5 / 385.3
5300 / 389.1 / 385.6 / 384.0 / 380.5
5400 / 389.3 / 378.6 / 387.7 / 377.0
5500 / 390.7 / 373.1 / 391.9 / 374.3
5600 / 393.7 / 369.2 / 395.6 / 371.0
5700 / 396.6 / 365.4 / 400.0 / 368.6
5800 / 398.9 / 361.2 / 402.9 / 364.9
5900 / 397.3 / 353.7 / 401.2 / 357.2
6000 / 391.2 / 342.5 / 394.8 / 345.6

As you can see the X-pipe showed significant gains below 3400RPM and above 5500RPM. Max delta was at 3000RPM where the X made 11.9hp and 20.7ft-lb tq more than the H-pipe system. The H-pipe showed a stronger mid range with max delta of 6.3hp and 7.7ft-lb tq at 4300RPM.

 

What do you think the gains would have been over a y-pipe on that same test??

 

Well, since my car is a street driven A4 with a Vig 3200 and I have a lead foot. The H is better for me... more power in the 3700-5400 RPM range( where I spend most of my playtime). I guess the X is better if your a hardcore 1/4 mile drag racer.


Thanks for posting up some scientific valid #'s.

 

Here's another test with "hard numbers" that shows the x gains over the H at all rpm's for both trq and hp.

http://www.magnaflow.com/05news/magazine/05racepgs.htm