There are no reports of "much stronger acceleration." What has been consistently reported is that the x51 will pull away slowly in the upper gears. This has not been reported to be a significant difference.There is a reported improvement in the sound of the motor and it is "freer revving" at high rpm's. It is 26 horsepower and a handful of footpounds of torque. What your 16K buys is exclusivity.

 

Neil Orton of Orton Performance did my ECU. His pal in Germany does the software, and supposedly it's pretty aggressive, but who knows. When I had it done, I definitely felt a difference. But the Plenum difference was equally, or perhaps more dramatic.

 

Hi Alex

There are actually 2 sets of results referred to in that thread!

The ones I was originally referring to were for a car owned by a guy with the nickname 'Speed'. This is the set with multiple runs before and after and shown on page 7. This guy just had the AWE (Headers, Cats, Mufflers). The tests were performed at AWE and show a 23.5BHP (wheels) increase.

The other set were for a car owned by a guy using the nickname 'Synergy' who was your customer. He is the one with the AWE/GIAC/EVO. His results are shown on page 3 and coincidentally gave him an increase of just over 23BHP (wheels) too.

 

Thanks. I am very happy with all my upgrades. Started with the Plenum and I was not disappointed.

 

I don't know if my experience will translate to the NA cars, but in my TT, there was a significant difference after I installed the plenum. I can't tell how much it helped versus the EVO boost recirculation valve I had installed at the same time, but I certainly have more torque and hp in low-to-mid range of the curve.

 

Here is my baseline dyno. I had a dyno done three years ago on another machine and they correlate very well. I am very happy with my stock car as it's higher than most cars with mods. I got 322 HP at the wheels and with 15% drive train loss. This yields 378 at the crank. I am being conservative with 15%.

 

My $0.02 ...

First of all let me qualify my perspective by saying that I am no expert at the design details of internal combustion engines. In my simple mind our engines are the equivalent of positive displacement pumps. They inhale air, mix it with fuel and exhale the byproducts of combustion. One of the key measures as to why some "pumps" perform better than others relates to their ability to quickly and efficiently fill the cylinder volume. Simply stated the more convoluted the intake path becomes, the harder it is for this to occur in an efficient manner and without detrimental losses. Logic tells me that any modification that allows the cylinder to "inhale" more efficiently should translate in better performing engine. The issue here for me is one of "how much better" and not if the IPD Plenum and smooth-bore intake pipes actually have a positive impact. For me the simple fact that a modified engine may rev-up faster than before the modifications were implemented does constitute a performance gain - is not all about HP/Torque gains. I remember spending endlesss hours polishing the case of my '79 911 SC 3.0 liter motor in an effort to reduce back pressure on the piston as it traveled downwards thinking that this was crazy, a waste of time and that I would never be able to tell the difference. Wrong. The engine probably retained the same HP ratings, but it moved up the tach like a monster wanting to swallow the redline.

All this is to say that I too will be anxiously waiting for the results of the dyno, but we should also consider what a dyno run will never tell us - the unmeasurable but noticeable improvement to our "pump's" breathing and its willingness to bring a grin to our faces.

 

Let me throw this out there. Do not take it as any indication of what our testing has actually revealed about the IPD plenum, just take it as a theoretical engine design discussion.

Intake tract tuning on a normally aspirated car has more of an impact on power output than on a forced induction car. In the modern era of engine design, very advanced software is used to do flow analysis on the intake, even on less advanced cars than a Porsche. In my humble opinion, the days of a manufacturer leaving a tremendous amount of power on the table through an obvious design flaw are long gone.

That does not mean that power can't be unlocked at the expense of another operation parameter, such as through a cold air intake that gives more power at the expense of more intake sound, or a performance software file that makes the car less tolerant of subpar fuel, or an exhaust system that eliminates EPA mandated cats and makes a louder sound.

But a component that has zero negative trade-offs in exchange for massive power gains is an INCREDIBLY rare find on any modern vehicle, especially on a highly engineered car like a 997S. I am not saying it is not possible, all I am saying is that the context is much different than days of yore.

Anyway, our results will be posted by early afternoon Eastern time today.

 

As always an insightful and knowledgeable post from Todd.

I think it's also fair to say that this is made all the more complex by the additional resonance valving Porsche uses between the 2 inlet manifolds. This is designed to give an intake 'Ram' effect at certain rpms (it used to be called 'Varioram' when it first appeared - do they still use that name)? I would hazard a guess that tinkering with another part of the intake plumbing (inboard of the throttle) would have a significant and unpredictable material effect on the effectiveness or otherwise of this system too.

 

Hey all, as this thread is coming to a climax i find it harder and harder not to chime in, finally i have broken and must add my humble opinion.
First off, just the thought of all of us eagerly awaiting the results of this test makes me smile, it means that most of us are in a great place in our life when this is whats important, kudos to all.
Second and more importantly, I purchased the plenum back when Ian UK first brought this thread up, since then i have recieved it, driven, and been smiling ever since, (approx 800 miles thus far) Whatever the improvement is, big or small, there is a definite improvement. For all who are only interested in doing minor engine mods (like me) i also added a BMC air filter from AWE which i think has also been able to add a more free flow to the system. Plus at the cost of 115 (which AWE was the cheapest) it is a smart move considering the price of the paper air filter which must be replaced periodically.
Lastly, I hope you all enjoy your cars as much as i am enjoying mine and dont treat them like garage queens. I have enjoyed your insight throughout the thread and thank you all for your opinions.
If anyone is on the NY/NJ run this weekend i would be glad show you the ease of install for this light mod.

 

Ok, time for the results.

I want to first give a short background on how we came about testing the IPD plenum.

The plenum has been a very popular modification, and there have been some very impressive power claims made about it. A few months ago, I contacted Greg at RSS to inquire about becoming a reseller for the product.

However, I made it clear that just like every other power product in our catalog, we needed to test it to be able to endorse it. I requested that he send us a plenum to test once we lined up a stock 997S, and if we were not satisfied that we could return it for a full refund within 30 days. Greg agreed to these terms.

The opportunity to test on a bone stock 997S occurred when dduncan delivered his car to us for modifications. With his permission, all this testing has been done. A big thanks to dduncan for volunteering his car.

Dduncan’s car is a 2007 997S with ~2500 miles on the odometer. The car is 100% stock.

Greg has been incredibly professional throughout this whole saga, and we have extended the same professional courtesy to him, sharing all results before making this post. In fact, when the first test did not come out as RSS expected, they wanted to ensure the plenum being tested was not somehow flawed, and overnighted a second one for us to test, which we did.

The political and monetary ramifications of this post are not lost on us. We know that we may make some enemies in the industry as this post has the potential to negatively affect sales of this part.

The only disclaimer I can add about this post is that testing was done only on one car, albeit with two plenums. Perhaps the results would be different when tested on another 997S, although no issues could be found with dduncan’s car to suggest that his car is not representative of the majority of 997S’s out there.


Onto the data:

Dyno testing was conducted on our Mustang AWD-500-SE chassis dynamometer. Our engineering director conducted all the data acquisition. Our technician conducted all the plenum swaps. Less than 2hrs would elapse between stock dyno pulls and plenum pulls in order to minimize ambient variables.

Ambient conditions on the first day of testing: ~65F ambient temp, 30.14 hg, 29% humidity

Ambient conditions on the second day of testing (second plenum): ~78F ambient temp, 30.06 hg, 26% humidity

Our standard cooling fans and placement were used as with all 997S product testing we do. The only difference between some tests posted on our site and these tests is a dyno software update over a year ago and a more accurate rpm sensor input to the dyno PC. All the same test variables under our control were kept consistent between the before and after dyno pulls.

Approx 30 total pulls were done with each plenum sent to us. Approx 7 pulls stock to establish a consistent baseline, and approx 23 pulls with plenum. After plenum install, we also did runs after an ECU reset via scan tool to ensure all adaptation issues were accounted for, as well as several key cycles and a couple hours of cooldown between some runs. As long as coolant temps and corresponding intake air temps were kept constant by careful testing protocol, our results were very consistent. Temps were monitored via scan tool, as they always are during modern Porsche power testing.


Here is a sheet comparing stock to the IPD plenum, second day testing:




Here is a sheet comparing plenum #1 to plenum #2. Second day testing was over ~10 degrees warmer than Tuesday, so overall power was a tad lower for all tests done yesterday:




Here is a sheet graphing the MAF output signal for stock and plenum. Units are lbs/min, and the stepped appearance of the curves is because of the output rate of the ECU through the OBD port:




Here is a sheet comparing 3 representative plenum #2 runs, in order to show consistency:




Here is a sheet comparing stock day 1 vs stock day 2:




Here is a sheet comparing 3 representative stock runs, in order to show consistency:





And finally, here are two sheets that we feel capture the common mistakes that dyno operators make, resulting in false positives. We have stressed to many clients how coolant temp monitoring during modern Porsche dyno testing is absolutely imperative to ensure test validity.

Even minor coolant temp deviation from full operating temp, whether higher or lower, has a tremendous impact on the ECU mapping. For example, if stock baseline testing was done while the car was not up to full operating temp, and then the plenum was swapped in while the car was still on the dyno, by the time the plenum was tested the car would be fully up to operating temp and massive whp deltas can be measured falsely.

We know that the far minority of dyno operators are monitoring coolant temp via scan tool on modern Porsches, and the ones that are not monitoring are greatly exposing themselves to false test results.







So there you have it.

I know this post will stir up a lot of controversy, and I want to go on record that our intention here was not to discredit any company or its products. We were testing for our own evaluation needs, but because testing was done on a customer’s car, the customer has asked us to publicly post the results.

Frankly, I am a bit uncomfortable about the whole matter. Not because I have any doubts about our data, but because our findings will fly in the face of a lot of other results out there. All I can offer as an explanation is that there is a strong possibility that other results posted out there were not done under such strict test conditions, and false positives were unintentionally recorded. We stand by our results 100%.

In closing, I must repeat that RSS has been extremely professional and accommodating from day one, and it would have been a pleasure and privilege to be actually able to endorse this product and add it to our catalog.

 

Interesting!

 

Before things get too far out of hand I just want to thank Dduncan and Todd/AWE for putting this much effort into the testing and for sharing their results with the community. It was clearly a lot of work and I especially appreciate the background information and insight into testing methodology.

Thanks.

 

Todd/AWE and dduncan, thank you for sharing this information, your thoroughness and your continued professionalism.

 

Thanks Todd. I think that, contrary to creating badwill, your unbiased post has enhanced your credibility within the owner community. I alluded to the "Hawthorne effect" previously (Google it if you are not familiar) and that is exactly what I think we have witnessed with the butt dyno reports.