I think Commander 47 is confusing exhaust velocity with back pressure. It true that you can have too large an exhaust pipe. The example of blowing through a straw vs a paper towel tube is a good example. You'll push more air through the paper towel tube (no back pressure) but the velocity of the air leaving the tube will be low compared to the straw. In an exhaust system that low velocity translates to little or no scavenging. It's like a large amount of low pressure air moving over a paint gun pick up tube. You'll move a lot of air but you won't pick up any paint. According to Commander 47's theory putting restrictions in your exhaust stream would produce more horsepower. I think we all know that is not correct.

 

or a potato with a hole drilled in it

where do people come up with this nonsense?

 

There is a lot of information on exhausts .. The Borla guys and others if you notice always bench make against an open exhaust pipe.

Hot rod did a test , used 1 3/4 primary tubes and 2.5 and 3.0 exhaust on a 383sbc

The 3 inch proved to create more power .. Not a boat load but an average of 5hp and 5tq .. They also add if you add an x pipe the gains may be more . .

 

Ahh, and so it begins....laugh all you want. Your ignorance is showing.

This quote from Magnaflow:

"To reduce additional backpressure, the OEM exhaust tubing can be replaced with mandrel-bent tubing of the same size or one size up from the OEM. As a general rule, you can enlarge the pipe diameter of your OEM exhaust system by 1/4 to 1/2-inch to increase your horsepower. However, any additional increase in pipe diameter is likely to decrease your performance; specifically, low end torque.

 

All an H or X pipe does is affect noise.

They can impede exhaust by adding extra bends into the exhaust cycle. The extra bends rob horsepower.

The babble about "balancing" the exhaust pulses, and "evening" out the exhaust is just babble. They are talking about noise, not performance.

Exhaust is a lot like Carburettors, a lot people think bigger, more etc is the way to go. Often it is not.

As is quoted below from Car Craft and Magnaflow, a straight through route is better for horsepower. Both Magnaflow and Flowmaster agree that the X and H pipes serve no real power benefit.

"The common H-style crossover is good at balancing sound pulses between the two halves, but does little to promote scavenging because the exhaust gases tend to follow the path of least resistance, which is straight through each pipe rather than taking the 90-degree turn through the H-pipe into the other half of the system. In an X-pipe system, however, where the two sides of the system intersect, the gasses have no choice but to intermingle as they pass through the junction. This promotes improved scavenging effects by smoothing out uneven exhaust pulses from the engine’s firing order. It also helps quiet down the exhaust, resulting in a mellower, less raspy tone. According to Magnaflow, the faster acceleration of the gasses through an X-pipe causes them to flow in a linear fashion parallel to the walls of the tubing rather than tumbling. This “laminar” flowing gas is much quieter than tumbling gas, resulting in an exhaust tone up to 8 decibels quieter than a traditional H-pipe."

Read more: http://www.carcraft.com/techarticles...#ixzz2s7SQH3HS

 

Hey Commander 47

2½-INCH 3-INCH
RPM TQ HP TQ HP TQ HP
2,700 385 198 390 200 +5 +2
2,900 400 221 404 223 +4 +2
3,100 418 247 424 250 +6 +3
3,300 427 268 437 274 +10 +6
3,500 433 288 435 290 +2 +2
3,700 430 303 428 301 · ·
3,900 423 314 419 311 · ·
4,100 421 328 417 326 · ·
4,300 426 349 429 351 +3 +2
4,500 440 377 446 382 +6 +5
4,700 455 407 463 414 +8 +7
4,900 461 430 471 439 +10 +9
5,100 462 449 473 460 +11 +11
5,300 459 463 470 474 +11 +11
5,500 453 474 463 485 +10 +11
5,700 445 483 454 493 +9 +10
5,900 438 492 444 499 +6 +7
6,100 431 501 433 503 +2 +2
6,300 422 506 424 508 +2 +2
6,500 407 504 411 509 +4 +4
Peak 462 506 473 509 +11 +11
Average 432.8 381.0 437.9 385.7 +5.1 +4.7

Well I will be kind and not call you any names , but here is car crafts actual tests with a 383 SBC 2.5 vs 3.0 exhaust.

At all the IMPORTANT rpm ranges it is double digits more power. And only falls off at 6k most likely as a result of cam choice. From the test rpm up it built tq and hp faster IT DID not reduce power in any way shape or form as you want to suggest...

They also added if am H or X pipe was properly placed you could possibly expect more Gaines.

 

Again, no arguments or name calling. I do not dispute the figures above.

But like I said in my second post, to realize those kinds of gains a person really need to know which system is best for that engine. A pro can tell that.

A person that thinks they can take a stocker and start bolting on 3 inch pipes is probably not going to realize those gains above. And if you have a computer it will definitely hurt performance until addressed.

As for the X and H pipe: " They also added if am H or X pipe was properly placed you could possibly expect more Gaines"

Operative word is "possibly". The X and H pipes were originally added to quiet the car. Not improve it. They also have some sort of smog application that eludes me.

The H and X pipes also mask problems you may have on one side of your engine. That is part of the "evening" of the pulses.

True duals are the way to go for more power. We AGREE on that. Heck, my car has a 4 inch pipe on each side after the headers

My noise and flow is controlled by baffles. And to be honest, it probably robs two or three ponies. I believe the long tube headers make up for that somewhat though because they scavenge each cylinder longer.

I would suggest taking out the H pipe on the sweet 3 inch system and turn it into a "True Dual" system. JUST MY 2 cents. Then again, it may not have the sound you want.

For anyone not wanting "true" duals, an X pipe along the stock right side of the frame cross member opening will probably work great.

This will save the OP a lot of extra work. (my original point)

 

The H was standard on my Super cobra jet 429 2.5" Factory system.. The point of it is to aid in scavenging the pulses from one bank to the other. It is not simply a noise reducer.
The only reason the article said possibly was not because they see an x pipe as a noise reducer but because placed correctly it has a purpose in the exhaust system.


H- and X-tubes for dual exhaust--
H-tubes balance the backpressure between the two sides of your engine, and even out the complex pressure waves that are flying around in the pipes. The result is enhanced low-end torque, better overall performance, and better sound.
Why?
With a V8, there are always two cylinders on each side of the engine that fire within 90 degrees of each other. On a small-block Chevy, the firing order is 1-8-4-3-6-5-7-2, and the cylinders are numbered from front to back down the crankshaft. Odd numbers on one side and even numbers on the other. A cylinder fires every 45 degrees of crankshaft rotation.
So by looking at the firing order, you can see that cylinders 4 and 8 fire 45 degrees apart on one side. Then later, cylinders 5 an 7 fire 45 degrees apart.
This creates a high-pressure pulse that inhibits smooth flow and makes for a "choppy" exhaust sound. H-tubes and X-pipes equalize this pressure pulse, smoothing out exhaust flow and sound, thus helping your torque output. X-pipes do a better job of this than H-pipes, because there is no distance separating the pipes with an X. But some cars, like my 'Bird, have no way to fit an X underneath.
H-tubes should be at least 3/4 the size of your exhaust pipes, and located in the "hot" area of the pipes behind the header outlets. To find that hot area, one suggestion is to spray a line of ordinary white paint down the pipes after the headers, and go for a good run. Install the H-pipe somewhere in the area where the paint burns off the pipes, equal distance from each header collector. Use the same technique to determine where to place an X-pipe.

 

H is standard on almost all new performance GM cars from the factory

 

Wow! This thread started with a guy who wants to buy the exhaust system off my '79 and asked if it would fit his '80.

 

OK, so let's get back on track. Short answer: no. Long answer: yes, if you make some mods. Next question!

Scott

 

Seems like I kinda said that to start with... but maybe that's just me.

 

I was basically paraphrasing you, Casey. Casey Jones, eh? Ya know, we used to sing a marching song about you when I was in the Army. If even half the stuff in that song is true, you're a helluva guy!

Scott

 

Dont be a buzz kill Scottyp99 ,,, Bahahahahahahaha

 

This post above should be titled "How to compare Apples to Oranges." The Carcraft article was comparing open headers to an H pipe and and X pipe set up. In other words it is totally pointless for this discussion. The OP and everyone else in this thread are talking about adding an H or X pipe to an exhaust system, not running open headers. You provided a lot of information that has nothing to do with this discussion.

 

I really don't want to confuse anyone with facts. Your minds are made up.

X and H pipes are the fad of the day.

Many many new cars today do not use X or H pipes. Neither does NASCAR, NHRA, F1 or any other performance car.

None of the muscle cars from the 60's use them.

If you feel better using one, then rock on

Seems to me if even 1 horsepower could be gotten from adding an X or H pipe, the racers would do it. They don't, because there are no gains. (Unless you are trying everything to minimize losses from cats and other stuff.)

My new 2013 Expedition has a two in and One out. All the pipes are 3 inch, even from the motor. I have gobs and gobs of torque.

If you have invested in an X or H pipe to smooth out your pulses, then you will want to jump all over the Tornado Turbulator to go with it. Pulse in, and pulse out: (also have one for a carb)

Tornado is a turbine shaped device, which creates a vortex or swirling effect to the engine. The result is improved airflow into the engine combustion chamber, causing a more efficient mixture between air and fuel resulting in more power and fuel efficiency.

 

Again you are talking around the subject. The OP was talking about modifying an older car with dual exhausts. Headers only, not true duals, racing and what your new car has on it has nothing to do with the issue. And since he needs an exhaust system and not open headers your Carcraft article was totally irrelevant. The issue is will an X pipe or a Y pipe improve performance compared to a simple dual exhaust system: everyone except you says yes. I appreciate this thread because it caused me to do some research and confirm somethings and debunk other things that had assumed about X and Y pipes. It also confirmed for me that someone who ignores the facts and sticks to their own assumptions will not be convinced when presented with solid evidence to the contrary.

 

BTW, I hope you were joking about the tornado tabulator:

"Intake turbulators

By placing a magically shaped piece of metal in the intake system of your car's engine, you can use the powerful force of a tornado to improve your fuel mileage. Sorry but wrong again.

These devices simply create an extra choking effect in your vehicle's air intake system and that's been proven to actually *reduce* fuel efficiency, sometimes quite dramatically. The fact is that the mix of air and fuel entering your car's engine is already extremely turbulent by the time it is ignited. Trying to add extra turbulence achieves absolutely nothing except making it harder for your engine to breathe.

And yes, scientific tests have proven that they simply don't work.

These intake turbulators are marketed under many names but perhaps the most well-known (and reviled) is the Tornado.

More stuff to avoid!"

 

If you really want to increase performance, you need a Turbo Encabulator.


Scott

 

Finally some irrefutable facts.