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J-Pipe Comparison Test: ATLP vs RV6 vs XLR8 ** Inconclusive!

  • Posted: 10-23-2012 10:37 AM
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PLEASE NOTE: The results of this test were INCONCLUSIVE. Each successive pipe tested produced more power than the last, even when the first one was dynoed again last. Please read the entire posting and don't make judgements based on the graphs alone. There is a much more accurate and informative test here: ATLP, XLR8, and RV6 J-pipes tested together. ATLP V2-R debut!

We just got back from Church Auto Testing, where we did another round of J-Pipe shootouts yesterday. Some may recall the last shootout we did involved only the RV6 V3 and ATLP V2 designs, and that the ATLP while showing favorable performance above 4000 RPM, gave up some torque to RV6 in the lower RPMs. The car tested was a Base model TL with a 3.2L engine and a manual trans.

Of course, we were also testing prototype revisions of the new ATLP V2R pipe which has been in the works.

Eager to get more data and urged on my the ever-anticipating Acurazine community, coupled with an relatively extraordinary dyno report on the XLR8 V2 pipe, we finally made our way back. The parts we brought with us this time were an ATLP V2 pipe with optional Race pipe cat delete, an RV6 V3 J-pipe, and an XLR8 V2 J-pipe (both of the latter with integrated cat-deletes as part of the design). We also had the latest revision of the V2R pipe. The car this time is a larger displacement TL Type-S with a 3.5L engine and manual transmission. As before, this car retained it’s standard primary converters but was equipped with an ATLP exhaust cat-back.

What we learned yesterday was both startling and a little depressing. What we learned was there are more variables involved in testing parts for the TL than we imagined before. Unfortunatly, we got caught up chasing numbers that led us in circles.

The main goal of this test was not to see which pipes gain more power over stock, since we do know that all the pipes gain power. The main idea where was to see how the pipes compare to eachother. We know that dyno testing is really a game of relativity, and therefore bragging about specific numbers really is somewhat of a losing point. However when comparing parts to eachother, a dyno can be revealing as to what changes in parts make to the performance of the engine.

Here was our first dyno chart to share:

It is important not to take this first chart for face value, as I will explain after I outline the observations we made. In this chart we are comparing the ATLP combo (yellow), the RV6 (purple), and XLR8 (red). The pipes were tested in that order as well, with each one showing more power than the last. The main thing we were surprised to see was not so much the the ATLP was down on lower RPM torque compared to the RV6, but that it did not best the RV6 in the upper ranges as it had the last time. We saw considerably more top end with the ATLP in the previous test. We were not sure how to explain this. Also, we were initially impressed with the performance of the XLR8 part. While we did expect this pipe to have a good balance of high and low end, it definitely outshined the others everywhere. Also, it was more consistent. But therein lies what would ultimately be the undoing of the test…

Here is the second dyno chart:

At the end of the day, still somewhat curious as to why the ATLP performed so much less than the others, we put it on the car and did another run with it juuust to see if the lackluster performance was a fluke or not. Actually, we did five runs with it and got the same thing every time. The solid red line is the ATLP dominating the other two at the end of the day (the XLR8 line is dashed in this chart rather than solid). The ATLP pipe suddenly jumped a whopping 10+ ft-lbs right around 3600 RPM, and for there on up it literally leapfrogged the competitors.

What gives?

The problem lies within the car. The 04-08 TLs have a newer generation of computer in them which is constantly changing variables around, making dyno testing of this nature (just swapping parts around to see what they do) practically impossible to make any sense out of. In earlier runs the computer was definitely functioning differently than at the end of the test. Add to this, our tester told us they were pretty mild with diving their car; they never really rev out past 5000 or so RPM. The car was used to driving slow basically and when it was asked to make power it didn’t know how until we flogged on it for 4 hours. This explains why as the day went on we made more and more power. Unfortunately, limited by time (and money) we had to cut it off before doing another round of tests on each pipe.

Even with that point aside, with the ignition timing constantly moving around, back-to-back comparisons are literally impossible to rely on. The result of this, in my mind, is that ANY dyno charts shown for an 04-08 TL (and I am sure many other car this applies to as well) are definitely to be called into question. And this has nothing to do with the integrity of the test itself or the people involved, because the one main variable at work is something that to this point is relatively uncontrollable: the car’s computer.

However all is not lost. We will be back at the dyno with a programmable computer to lock in a base map tune, and that will allow us to see which pipe makes what power and how. This likely won’t happen until the first quarter next year. Until then, I am afraid it is still a bit of a guess as to what part really is the best one for making low or high range power. Even the information we got in the past has to be question to a degree.

V2R update: While we do have to bring into serious question all of the numbers this day, we do have reason to believe that the V2R prototype we tested certainly is capable of making more power than the others in this test. We feel confident that with a locked basemap we will be making more power than the others here, while having a lighter, stronger part with top notch fabrication.


Any updates?
02-18-2015 11:20 PM at 11:20 PM
I've only recently been informed about a j-pipe upgrade. When I have saved the money I am very interested in doing it for my '09 Accord Coupe. I see that this was posted in October of '12. Have you made any final decisions on the results?
Administrator Note:
Hi there, we definitely have. Please find this latest dyno test we've done:
11-09-2014 05:52 PM at 5:52 PM
I am always willing to sacrifice some power for build quality and fitment of the product. Which pipe was the best pipe to buy for quality of the engineering of the pipe? RV6 has less welds and with the flex pipe it would seem like it would last longer.

[MrHeeltoe]: All of the pipes have shown to have similar reliability. There have been isolated flex failures on all pipes, and the 304 stainless pipes are more prone to cracking. Ultimately, the RV6 does not show to us an particular advantage over the others in either power or reliability.
01-22-2014 08:35 AM at 8:35 AM
im not a good as you guys with cars but why didnt you just put the car into open loop? wouldn't the computer run consistent? i mean it was just for a comparison. if im wrong sorry. :)
MrHeeltoe: Good question! We really didn't have the ability to monkey with the car's computer much.
Jose L Frias
11-15-2013 07:39 PM at 7:39 PM
Yeah, thanks for taking the time spent (money as well), because not that much information is out there for either Acura/Honda TL or Accord v6.
Carlos Vittini
05-30-2013 02:23 PM at 2:23 PM
Thank you for taking the time and spending the money necessary to do this comparo!
Fu$&ing A
04-17-2013 07:20 PM at 7:20 PM
Really, 941 people can view their Dynos but don't comment ? WTF

Thank you Heal Toe for doing this. It is very informative and helpful. I appreciate your work/ Research into the product your retail !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Most companies don't give two $hits.

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