2.25" vs. 2.5" X-Pipe?

[TiAgX5]

The vid demonstrates the scavenging operation of the X-pipe when only one side is moving exhaust gasses (out of phase), this will ONLY happen thru the RPM/throttle position/load range with equal length tubing upstream. The X5 has about 2' more exhaust length from the left cyl bank to the X-pipe vs the right cyl bank, this will cause some RPM/throttle position/loads to deliver the pulses in phase.

I'm all for everyone modding to personal taste, I just point out the flaw when it's passed off as a "performance enhancing mod".

[KyleNatolix5]

I did it for the loud factor. Reading all this info convinced me that i had no clue what i was doing and took a shot in the dark. The end result was successful, im the neighborhood alarm clock

[Ricky Bobby]

Originally Posted by bcredliner

If we consider horsepower and reduced noise the X pipe is always effective as it always reduces noise and never decreases HP.

I know this is a big boy v8 thread but for someone like me who might want a bit smoother exhaust flow, and a slightly different tone to the stock exhaust this is why I would personally do an X pipe on my 3.0.

So from what I gather here the x pipe should be installed as far forward as possible to the factory mounting flanges of the factory resonator for best performance?

Without spending 1400 on aftermarket mufflers for increased sound which I don't really want anyway, I'd rather just do an X pipe and delete the factory resonator if I'm able to do so with no ill effects and a couple hours of time at the shop installing it.

[bcredliner]

Originally Posted by TiAgX5

The vid demonstrates the scavenging operation of the X-pipe when only one side is moving exhaust gasses (out of phase), this will ONLY happen thru the RPM/throttle position/load range with equal length tubing upstream. The X5 has about 2' more exhaust length from the left cyl bank to the X-pipe vs the right cyl bank, this will cause some RPM/throttle position/loads to deliver the pulses in phase.

I'm all for everyone modding to personal taste, I just point out the flaw when it's passed off as a "performance enhancing mod".

The video is only to show that an H pipe has little to no scavenging capability.

I spoke with Magnaflow tech. He didn't come across as an expert though he didn't hedge or sound like he was making stuff up so he might have been. He said there is an insignificant difference in the scavenging performance with equal or unequal tubes from the exhaust manifolds.

Per the X-pipe information I have wadded through my take is a performance exhaust system designed from the manifold to the exhaust exit to maximize scavenging capabilities of an X-pipe will result in better performance than if it is not included. How much depends on a specific application and it is a small compliment to the rest of the system. Other than that it is a shot in the dark that will sound better.

[TiAgX5]

Here's Lingenfelters data on H-pipes, page 132. Lingenfelter has spent thousands of hrs dyno testing.......

John Lingenfelter on Modifying Small-Block Chevy Engines: High Performance ... - John Lingenfelter - Google Books

Additional torque below peak torque RPM with no loss of HP. Just what you want on a streeted SUV.

John Hennessey tested X-pipes on the Jeep SRT V8 (same unequal length exhaust config as the V8 X5s) and found there was a power loss across most of the operational RPM range. X-pipe was tossed.

[bcredliner]

Originally Posted by KyleNatolix5

I did it for the loud factor. Reading all this info convinced me that i had no clue what i was doing and took a shot in the dark. The end result was successful, im the neighborhood alarm clock

Great shot!

[bcredliner]

Originally Posted by Ricky Bobby

I know this is a big boy v8 thread but for someone like me who might want a bit smoother exhaust flow, and a slightly different tone to the stock exhaust this is why I would personally do an X pipe on my 3.0.

So from what I gather here the x pipe should be installed as far forward as possible to the factory mounting flanges of the factory resonator for best performance?

Without spending 1400 on aftermarket mufflers for increased sound which I don't really want anyway, I'd rather just do an X pipe and delete the factory resonator if I'm able to do so with no ill effects and a couple hours of time at the shop installing it.

Yes, the closer to the exhaust manifold the better but not between the exhaust manifold and O2 sensor. If sound is your only goal it won't matter where you install the X pipe. However, I would try to find a place to put it before the mufflers as you may get some performance benefit. The X-pipe results in a different sound than the H-pipe. The H-pipe results in a lower sound, toward a American muscle car sound while the X-pipe change is more toward the exotic car sound. You can find some comparisons on Youtude.

[Ricky Bobby]

I think just the X-pipe alone would give me the slight tonal change in the exhaust that I would be looking for, and be a little more free-flowing than factory resonator.

No need for increased loudness (it is a 3.0), and the only way to achieve that is either deleting or replacing with aftermarket mufflers. Too much work for me lol.

[bcredliner]

Originally Posted by TiAgX5

Here's Lingenfelters data on H-pipes, page 132. Lingenfelter has spent thousands of hrs dyno testing.......

John Lingenfelter on Modifying Small-Block Chevy Engines: High Performance ... - John Lingenfelter - Google Books

Additional torque below peak torque RPM with no loss of HP. Just what you want on a streeted SUV.

John Hennessey tested X-pipes on the Jeep SRT V8 (same unequal length exhaust config as the V8 X5s) and found there was a power loss across most of the operational RPM range. X-pipe was tossed.

Everything I have posted I noted as the general consensus of current information or it might, could, may or may not deliver a particular result of horsepower and/or torque.

The older the articles I found the more likely there were several schools of 'expert' conclusions. There are still anecdotal 'expert' counterpoints or particular applications that don't hold true to the general consensus. I am not going to challenge the findings of Lingenfelter or Hennessey. I have read other similar test findings from reputable organizations.

It is important to note the Lingenfelter article is about conclusions drawn in 1996 derived from a small block Chevy. It could well be that the H-pipe delivered in that particular application. The X-pipe was not a consideration then. This following are their current offerings: Akrapovic Stainless Evolution Exhaust ZO6 ZR1 Corvette 2006-2012 - Lingenfelter Performance Corsa Camaro SS Stainless Steel Cat Back Exhaust 6 Speed AT 2010-2013 - Lingenfelter Performance While neither look like the X-pipe pictured in this thread, both merge the two sides to equalize the exhaust and contribute to scavenging.

I assume this article was before X-pipes were a factor. Meaning, there is no comparison where Lingenfelter might conclude--don't bother with and H-pipe if performance is the goal.

The phrase you mention read-- additional torque was at or below peak torque. That doesn't mean to you the gain is very near peak torque? If that was the case, per my chevy small block days, the torque peak was at 3500 to 4000 RPMs and wouldn't be usable normal street driving for me.

The majority of current findings are that the H-pipe measured performance benefits are within the range of dyno error or the variables in other conditions that impact torque and horsepower from one dyno run to the other. As I mentioned in previous posts, results vary per the application. Since an H-pipe does equalize the exhaust the Lingenfelter testing base may be one of those applications that the H-pipe is a performance benefit. On the other hand the increase in exhaust velocity or scavenging via a H-pipe is very little to none so my guess any increase was very small.

I have not seen the Hennessey information you reference. Does it say the unequal length was the reason they scrapped the X-pipe? The impact on X-pipe performance with unequal exhaust lengths from the exhaust has been a specific question I have asked. Both performance exhaust makers clearly said it does not. The exhaust is still equalized and the level of scavenging does not change.
The following is the current SRT8 exhaust offering which includes and X-pipe but not the components that would be unequal length: MagnFlow Stainless Steel Cat-Back System Performance Exhaust | 2006 - 2010 Jeep SRT-8 Parts & Accessories | Hennessey Performance

I think the only conclusions of this discussion that is worthwhile is that either route will change the sound, the X-pipe will very likely result in an improvement of how long it takes from point A to point B and how you get the best performance may be different for a 3.0, 4,4, 4.6 4.8 and also different depending on what engine mods or exhaust system mods one has already done.

IMO,if you want the biggest improvement of A to B performance of a X5--reduce the back pressure rather than a H,Y,X or whatever pipe. That was the first thing we did in the good ol' days. It still holds true for the vast majority of applications, the X5 not being a part of the few where it is detrimental.