As I just shelled out on new cats I cannot get plenum this month so if you`ll get it anytime soon - try to do dyno run prior and post install, it would be quite interesting to see what will your results show.

 

I always have to ask... if the power gains can be so significant with something as simple as this device... why didn't all the Porsche engineers think to do it?

Matt

 

With your thinking why does Porsche have so much different models? Why don't they make the 3.6L 997.1 Carrera 415HP like the 997.1 GT3, they basically have the same engine It would not leave any room for performance upgrades such as X51 package Upgrades & options always cost more money

Porsche has changed the engine on the new Turbo from 3.6L to 3.8L and also added DFI, and all they could squeeze out this new engine is only 13HP? I don't think so... Every car manufacturer limits the power of their cars to some level

If Porsche sold the 997.1 Carrera S with X51 package already installed on it for the base Carrera S price, why would anyone pay more for the GT3? Why does a 997.1 Carrera and a Carrera S have different Headers? The header design on a 997.1 Carrera is better than a 997.1 Carrera S!!! You are paying $10K more for an "S" and Porsche detunes the engine?

All this is a basic marketing strategy

Sinan

 

I wonder if one will take stock plenum apart - does it have a center wall inside to separate left side air stream from right side? How does it chamber looks like inside?

The only practical difference I see from stock is that RSS has somewhat like V shaped back wall which supposedly reduces internal turbulence of incoming air stream and splits it more evenly with less slowdown for both intakes while stock design just smashes incoming air stream at perpendicular back wall. So basically to remedy that problem all one needs to do is to bend back wall of stock plenum inside or put insert there to alter internal chamber shape.

Having rss plenum made from metal should not actually give any benefits and even contrary to that should reduce performance compared to plastic chamber as metal will heat up passing air stream more effectively than plastic.

Why Porsche does not change plenum design is a good question - perhaps they are not concerned about any turbulence related issues in intake. Back from carburetor ages it actually was one of major tune-ups - to work on chamber, polish it and provide as smooth transitions as possible for intake streams, but it never actually resulted in amount of gain claimed for this plenum alone and that is really only part of this topic that puzzles me much - to separate hoax from truth.

And as it was stated before - dyno runs are very subjective things, as simple change as having first run done on hot engine and other runs done on totally cold engine in 2 hours after install of that plenum will easily show terrific power gain that has nothing to do with plenum by itself. There are many parameters there on those runs that cannot be just assumed by default. Ideal dyno run would be to do it on taken off engine in conditioned room with stable temperature and humidity after exactly same warming up time from been dead cold - but who here can do such a stunt? Probably no one.

 

Again trying to avoid raking too much muck here, but it strikes me that the comments about the questionable value of these dyno runs seem odd.
For some months many have asked to see some form of dyno measures on the plenum piece. In this thread, we finally have a chance to see one and no sooner does it appear than many start questioning the validity of the run, and dyno comparisons at all.
I accept that science experiments require great rigor, repeatability, and the observation and minimization of any and all exogenous factors not germane to the experiment. And in this case, the tests seem to be pretty close to a practical ideal. Same car, same day, same dyno. Allegedly nothing changed but the part. Yes, there is a 2-3 degree ambient air difference (if I'm reading it properly), the unknown fluid/engine temperature thing, and the really unknown impact of ECU learning.
What I can't determine from all this is whether dyno's are now useless. They clearly cannot be used to compare independent runs on different cars and dynos. Too many variables. But in an experiment like this one, with as many factors remaining constant or nearly so, if this sheds no light on real metrics, then we're all sunk.
Still, I accept that repeating the experiment, by an independent, with a similar 'before and after' is vital to know that there is no manipulation going on here.
Oh, and I guess I should add that I have no business or personal relationship with the folks representing this part, nor do I have any particular interest at this time in purchasing one.

 

I will let you know if I do this, but my first priority is X51 headers, window tint, and clear side-markers.

 

Well, good luck with your mods, it is totally understood.

BTW I just exchanged emails with service manager in dealership I use, asked his opinion about this plenum install warranty-wise and actually did not get anything negative from him so far, he says he will check with his crew, he sort of did let me know even if anything may happen because of ay aftermarket part - they do not make a federal case out of it.

ECU mods as he added later are strictly forbidden and there is no way for them to perform warranty as all specs are shot. I wonder now - does flashing back softronic original file leave any traces in ECU or does not?

 

Factors were not varied during testing and were controlled as reasonably as possible during the runs. Fact is, you can list +100 more factors but none of which would be statistically significant in contributing to the +HP gains in the data presented. It can certainly be complex to obtain sound data if efforts aren’t taken to keep them controlled and level-set. So, that’s why the aftermarket automotive industry is composed of intelligent individuals who know the importance of effectively controlling these influences and conducting baseline runs to level-set these factors under real-time conditions at final use. There’s no foul-play, several of us were there that day as SME’s including the owner of the vehicle and didn’t detect any lurking factors that could have compromised the data. Please refrain from providing assumptions on the temperature of the engine prior to the runs as you were not there. However, we can state that prior to doing any initial runs the vehicle sat for a longer period of time allowing for the dyno operator to get setup than the plenum installation time itself. Suggesting that testing be conducted in a lab or cleanroom environment can be conducted and the plenum would likely produce more +HP gains. But we know very well we could care less about what happens in the lab and certainly value more about what happens in the real world.

 

I don't know about Softronic specifically, but I have experience with OBDII tuning on BOSCH ME7 for my other non Porsche car and flashing between stock and tune was virtually undetectable by the dealer. Never had any issues. All they do is version verification and check for fault codes anyway.

 

Well, will see, if I will need to ever use warranty. Softronic sort of claims their 'untuned' file is an original Porsche file so it has same original control sums and all signatures so PIWIS should read it as if it was there always.
Better proof would be of course to find if anyone from here actually went to dealer with re-flashed untuned file and passed PIWIS checks with flying colors. that would give some confidence.

 

I appreciate this information and as a matter of fact I never questioned authenticity of your (and other) reports - I was mostly speculating about possible technical reasons behind those numbers.
I also agree that it really seems plenum makes a difference. I still cannot say I understand the magnitude of that difference, but if it does happen - well, it is nice to know. Plus it is simple enough mod to do, why not then.

 

The only thing I can add here is that, after looking over the shoulder of my local tech (non Porsche dealer but factory trained and using a third party PIWIS emulator running on a tablet - very cool by the way) while he reset a CEL that occurred after my EVOMS filter came loose (!), I did see that everything (EVERYTHING) had a date/time stamp. Thus I suspect that the 'flash date' of the ecu will not be back at the 'born date' of the car if you reflash back to factory. Not sure anyone would notice or care, but it will likely be there.

 

Well, as I read about this new PIWIS performs automated control sum check so if anything does not add-up it will flash and scream, sort of, plus it does it at any connection to your car.

It made me remember that my aftermarket local shop has PIWIS as well, would be interesting to stop by and see what will it show up.

 

They had to change the plenum on the X51 kit as the intake manifolds are completely different. The non X51 intake manifolds uses a dual plane type with a valve while the X51 intake manifold foregoes this. The plenum on the X51 kit still has the "T" in it though.Dave

 

Looks like an independent dyno to me...BBK is a Mustang shop...did a lot of business with BBK in my time when I was into Mustang SVTs.For those of you who dont know BBK they are into US built muscle and dont dally into Porsche aftermarket.Dave