Talk about some serious confusion...3 company's have come out with various exhaust mod's for the new 2009 Carrera/Carrera S. All 3 company's basline runs showing HP/TQ were vastly different and all claim different gains/losses and some contradict each other.

FABSPEED
Baseline on Dynojet........................339HP 273TQ
X Pipe w/ stock mufflers.................+13HP +23TQ
Side Muffler by-pass......................+17HP +24TQ

SHARKWERKS
Baseline on Mustang.......................309HP 244TQ
Center crossover w/ stock mufflers...+12HP +14TQ

AWE
Baseline on Mustang.......................345HP 289TQ
X Pipe w/ stock mufflers..................-6HP -4TQ...Yes AWE claims the X Pipe loses power
Center crossover w/stock mufflers.....+4HP +4TQ

Fabspeeds dyno testing shows power gains for the X-pipe and AWE shows a loss in power. From the pictures of the Fabspeed and AWE X Pipe they look the same but I wonder if there is some difference between these 2 products that is making the AWE lose power?

AWE and Sharkwerks both have simular center muffler by-pass crossover pipes keeping each exhaist bank seperate. However the power gain between th 2 company's are very different. This is mostly as I am told due to Sharkwerks useing a PDK car that has to be run on a 4 wheel drive dyno that is eating up some power. If we knew the absolute correction factors then the baselines might be closer.

The base line dyno runs are different with the Sharkwerks baseline vastly lower in power. I know dyno runs can differ due to weather, dyno operator, data input into the dyno computer and fuel but the Sharkwerks baseline is vastly different than both Fabspeed and AWE.

Now, wouldn't it be great if a car magazine like Excellence could possibly do an unbiased exhaust shootout and test all the above...on the same car, same dyno, same day?

 

Steve from IA did that five or six years ago with the 996 turbo. Seems like a good idea and pretty doable if someone volunteers their car, time and money into it.

 

We're all for it! I've chatted with Pete Stout from Excellence a few times about doing something similar with the 997 GT3. However, Excellence tends not to do product features, rather they do whole car features.

We'd love to see a qualified INDEPENDENT dyno do a shootout like you suggest. We've owned and operated a chassis dyno since 1999, so we have literally thousands of dyno runs under our belt, and we stand by our results 100%.

On a related note, I think a dose of common sense is needed here. Do you really think that Porsche would leave a huge amount of power on the table with just one of the three main components in their 997S system (other two being the header/cats and side mufflers)? The center rear muffler is doing minor sound absorption and is physically not presenting a huge restriction in our analysis.

As stated before, we do not think that competitors are necessarily knowingly presenting false data to the public, but it is our opinion that they are doing so unknowingly by not closely monitoring the vehicle with a scan tool while dyno testing. Currently, I think the only scan tools that can thoroughly monitor the fuel injection ECU on the 997.2 are the factory PIWIS and a proprietary tool made by GIAC. We own both.

Also, Sharkwerks saw much lower baseline numbers because they are using a PDK equipped car, which must be run in AWD mode to keep it happy. This automatically skews wheel hp lower as the RWD car is now having to exert power to turn the front rollers on the dyno in order to allow all four wheels to turn at once. We initially started our exhaust development work with a PDK car, but switched to a 6 speed because we felt it was just too abusive on the PDK car to expose it to hundreds of potential pulls that we always do during development.

 

Todd, I totally forgot that Sharkwerks is useing a PDK car. thanks for reminding me. i will add that to my post. I remember them telling us they had to run the PDK car on a 4 wheel drive dyno that ate up some HP/TQ.

 

Given that this thread was not started by a particular vendor, perhaps it is a good venue to start an open discussion between vendors regarding the technical merits of their various designs?

I'd like to discuss the theory and use of x-pipes for making power improvements.

X-pipes have been traditionally used on V8 engines. Many V8 engines have an un-even firing order, meaning that at times there are two exhaust pulses traveling down one side of the exhaust and no pulses traveling down the other side. The use of an x-pipe introduces a way for this uneven pressure to escape to the low pressure side of the exhaust system, effectively reducing backpressure and encouraging flow (resulting in a power increase).

The Porsche flat six has an even firing order, meaning that it does not suffer from uneven stacked pulses like in the example above. Cylinder firing alternates between banks of the engine. Therefore, there is no inherent "imbalance" in the 997 engine that can be easily relieved like which is present with a Ford 5.0.

However, x-pipe theory also includes the use of the venturi effect to produce a low pressure area in one bank of tubing via the energy from the pulse traveling down the opposite bank of tubing. If the geometry of the x is done properly, as the pulse crosses through the x, it "pulls" the pulse coming down the opposite bank by creating a low pressure zone ahead of it. You can see this effect off the car with a simple bench top demonstration using some sawdust and compressed air. Blowing compressed air into one inlet of the x can actually "suck up" sawdust placed at the opening of the other inlet. It does work.

Yet, there is an issue configuring this effect on the 997 engine, as the flow of exhaust comes in on "one side" of the x instead of split equally. One could argue that there is no "side" of an x as it is a symmetrical figure, but look at the pics below to see indeed the x on the 997 cannot be configured symmetrically.

The first pic would show how this venturi scavenging improvement could work if the exhaust flow entered at the red and green arrows (flow in the direction of the blue arrow):






However, on the 997, the flow is actually as in the picture below. Notice how the actual inlets must now head at each other instead of parallel to each other, resulting in a much less gentle "cross over", vs in the image above, when they finally meet:




Yet, this cross over does smooth out the tone a bit, and that effect alone is why we intend to offer this product. It does sound very nice.

Anyway, this is how we understand the x-pipe as applied to the 997. We welcome any discussion from competitors who may see a flaw to our design or theory.

 

Looking at Fabspeed's x-pipe, i think it flows a bit differently than the other available x-pipes, but I'd like them to explain how it works and what factors were taken into consideration during the design phase

 

This is precisely why we worked with the extremely knowledgeable experts at Stasis Engineering to avoid any possible issues. Having owned the car since September we've been playing/driving/testing on a daily basis to make sure we make something that works for most people in terms of sound, fit and design. The car performed flawlessly on their dyno (Same as yours I believe) every single time and there were zero transmission codes to boot. Nobody could ever question the way Stasis operate their dyno and they would have absolutely zero reason to skew results. We own the car and the product and they own the dyno. As you know as soon as you make a hardware change the ECU begins to switch up slowly between ignition maps when on the dyno and by run 8-9 it actually settles down and gives you the same results every time. Depending upon which run you choose to represent to represent will obviously show 4/6 (that was on run 2 after the change). IMHO it would be great if more shops also used independent dynos. As far as running in AWD mode and having lower results that is true but it's also an accurate representation of how a car with a PDK transmission will perform on a dyno and there are going to be a lot of people with these cars. We are not only able to monitor these cars on the dyno but also have software for these cars to boot hence we're in good shape. I also absolutely encourage/welcome anyone buying our part to dyno/test etc... It's too bad that you gave up on using/testing a PDK car because the resonance factor comes into play on that car with the way the revs end up sitting. We primarily designed something purely for aural pleasure but the fact that it picks up a few HP for us is a bonus. Had it made zero difference in that respect we would still use it on our car because everyone that's heard it, bought it etc... loves the sound just like we do. We wanted something that was legal here in California, wife-approved (for lack of resonance) and that we could also knowingly use at the track in favor of something else that was too loud or had cats that would disintegrate and get check engine lights.

 

I use a hi tech exhaust on my FF, it is complete with anti-reversion chambers, for a 1600 ford engine has the same effect as above.

REVERSION
REVERSION is the secondary pressure wave that travels back up the primary pipes and enters into the cylinder on valve overlap. As this pressure wave travels back up the pipe, it brings with it all the residual gases still left in the pipe. This is what contaminates the fresh intake charge. Enter in stepped headers and ANTI-REVERSION chambers, placed at strategic locations in the primary pipes. These methods are employed to tune the arrival of the exhaust wave and to diminish the effects of the high pressure in the pipes. The results are higher volumetric efficiency and more power.

Just some more useless input:-)

 

Fabspeeds X Pipe does have a slightly different shap to it. Also the Sharkwerks center muffler by pass cross over pipes are shaped different than AWE's as well.



I was speaking to someone about the 2009 Carrera exhaust options and this thread I created and the confusion and they brought up a good point I wanted to share here. By AWE comming out with an X Pipe and saying it loses power is like saying Fabspeeds X-Pipe looses power and hence discrediting Fabspeed because Fabspeed shows a power gain with their X Pipe. So why is AWE knowingly going on to sell a product that "looses" hp? I would not think anyone would buy the AWE X Pipe. That doesn't make any sense to me unless there motive is to discredit Fabspeed. AWE is selling it cheaper than Fabspeed's too.

I see that the aftermarket business is way more cut throat than I ever excpected.

 

Mdrums - some of your points are valid. There is so much inconsistency and dishonesty in this market, it is sickening. It has reached a point that my first reaction is to doubt what people say, until it is proven otherwise. I don't think that a US company can properly design an exhaust on a car as sophisticated as a Porsche in the short time frame quoted. Porsche engineers, (And that is a separate topic. Being a good mechanic or welder or machinist has NOTHING to do with your educational and experience background in math, physics, engineering, and chemistry that is necessary to truly understand what the hell you are doing when you bend a pipe 5 degrees to the right.) have been doing this for 60 years in a controlled environment with hundreds of models and checks and balances.

Am I saying they know it all? No. Am I saying it would take a hell of a lot to convince me you know a car much better than they do? Yes.

Finally, the most glaring point to all this is that most people on the forums will believe what they read and add further hype to this industry. The fact remains that it is very likely that in the pursuit of a company trying to add power by exhaust flow they can actually reduce it, as evidenced by AWE's x pipe. Kudos to them for reporting that they experienced a loss in power.

AWE, Sharkwerks, Fabspeed et al - In the 1st gen 997, the gases from the right bank of cylinders exited the left side of the car and vice versa (once it left the headers, came to the cats in the middle, then the muffler then the tips.)

In the 2nd gen 997, the gases from the right bank of cylinders exit the right side of the car as the center muffler is a sharp U turn so the exhaust coming in turns around and goes out the same side. Here are my questions purely for my understanding.

1. Why wouldn't Porsche have the gases run throught the center muffler similar to the previous gen and go in from the right, and exit the left. What are the advantages/disadvantages of maintaining the flow from left to right. The bypass systems you guys made are similar to the previous gen as they essentially cross over.

2. In the crossover design from AWE and Fabspeed, I would think that an open design (which I don't think most people understand that the center part is actually open) would not be as efficient as a bypass system. Furthermore, I think that a closed design crossover would be louder and more efficient and this would basically follow the design of the OEM center muffler without the baffling inside.

 

You need to go back and read some of the development posts the various companies have made in this forum about 997.2 exhaust products. We went on the record a few months ago that we had done extensive testing on x-pipe products with mid and rear engine cars, and had not seen success due to the angles of the tubing runs and how we intended to test again on this vehicle.

And as promised, we posted the results. So this was not some after the fact campaign to discredit a competitor. It was a free sharing of information gleaned from literally hundreds of dyno pulls and many, many hours of data analysis. And, as I stated previously regarding Gallardo work we did and also above, the x-pipe tends to make a very nice tone, which is what occurred on this car, too.

We have learned to "adjust" to the new Porsche aftermarket client demands. As we have seen from the sales of competitor products for other recent Porsche models, there are quite a few Porsche owners who want to buy products based on sound alone. They do not care as much or at all about any power data. However, we are not comfortable selling a product on sound alone, and with any product we are selling that can have an effect on power, we need to know exactly what that effect is and disclose it, whether good or bad.

 

And also for the record, I do not know if you noticed the massive price drop Fabspeed did recently on their version of this product. In reality, there is very little material and opportunity cost in this product. Even at the price we are selling it at, there is a nice margin. We feel our price is much more realistic for what goes into making this item.

 

amen

 

Mass, I am not sure...it is hard to read...but I think you might be confusing the crossover pipes that Sharkwerks and AWE have and the X-Pipe that Fabspeed and AWE have. If you are, let me explain that they are totally different. The crossover pipe like what AWE and Sharkwerks has do not conect the right side and left side exhaust flow...only the X pipes do. I hope this helps.

I do understand your question about why Porsche did not just have a straighter flow through the center muffler and why did they do U bends.

I suggested a center muffler design to these aftermarket companies so that there would be no U bends and the center muffler and the center muffler would actually be 2 mufflers in 1. Like you recall the left side exhaust would exit the right side of the car and visa a versa. This design would be more free flowing than the stock center muffler and would allow the removale of 50lbs side mufflers plus keep each exhaust bank seperate from each other. So far no one has run with this idea, maybe it's not a good idea but I'd like to test it out.

 

Todd/AWE, I have read those posts, read them many times, and totally understand that you believe in your testing that the X pipe does not work on a Porsche Carrera. On the other hand Fabspeed has tested the X Pipe and they believe it does work. I totally understand both companies stance on this. I am just openly talking about this on the forum.