I know a lot of forum members have been anxiously awaiting our 997TT exhaust system (we've gotten a ton of e-mails), so here is an update.

We took delivery of our development car almost a month ago, and rapidly put on some break-in miles to ensure that our data during testing remained accurate. We did not want power to vary just because the engine was breaking in.

Meanwhile, we mocked up a system based on measurements we took and on correspondence with BorgWarner technical. The VTT turbos on the 997TT are run near 95% of maximum efficiency at stock redline boost levels, and BorgWarner expressed concern with pushing the turbos past their current high rpm boost levels. Apparently, the ECU is not able to control the turbos when they are pushed that hard, and wild overboost can happen.

We reached what we considered to be a proper break-in point last week, and began our data acquisition on our chassis dynamometer of the actual stock performance characteristics, such as backpressure, boost production and wheel power numbers. We also documented stock sound volume levels, and recorded stock sound tone. This is how we approach all our exhaust system development.

Now for the numbers...

Here is a stock boost mode dyno sheet showing our first muffler prototype vs the stock muffler:




Here is the muffler test in overboost mode:



We're quite pleased so far with the power results!


Even more interesting, is how the boost is affected by the new muffler.

Stock boost mode:




And a close up on the lower rpms showing initial boost ramp up:



Notice that with our prototype design, we are able to improve boost ramp up but at least 100rpms, not to mention allowing the turbos to actually produce more boost than stock (which is a main contributor to our power gains down low).


Here is overboost boost testing:




And a close up of lower rpms range:



Again, we were able to improve boost ramp up, though not as drastically as when in stock mode.


Some specs on our current prototype:

3.5" inlets to 200cell German metal cats, 3" primary tubing, 2.5" tailpipe outlets. Backpressure is 50% of stock. 304SS, 14 and 16 gauge thickness. OEM tips can be reused. Fully modular like our 996TT system.

We also incorporated a balance pipe to clean up the sound tone a bit, though the two cans are able still to be separated.

Road testing will be done now for several hundred miles to evaluate the sound qualities, and then our next prototype power testing will happen next week. We plan on testing the power effects of the balance pipe, as well as the effects of 3" tailpipe outlets.

Because of our intensive R&D with this system, it may be a month or so until we are ready to ship our first orders. However, we are firm believers in doing thorough testing of all our products before releasing them to the public. It may cause us to come to market later than some competitors, but any extensive R&D program takes time. In the long run, we have found that it results in happier users!

Any questions, please feel free to ask. I hope to have some sound clips up by early next week.

I will be leaving the office early today to attend Mike's wedding in Virginia. A perfect road test opportunity!

 

So the car is making 455 AWD hp bone stock? I thought it made like 42X bone stock on another thread?
?

 

If you look at the bottom of the sheets it says run 1 is with the mufflers, and run 2 is stock. So it was 455 with the mufflers, and 440 whp stock. Still pretty high. Maybe they disconnected the drive train. usually a 14% correction factor is for RWD. On a Mustang dyno that would be huge hp.

 

We have an AWD chassis dyno, so no need to disconnect drive axles. Keep reading for more info.

Our first dyno testing yielded around 420whp, but as break in continued, we topped out at 440whp.

To be perfectly honest, our 1.14 correction factor is a very rough estimate.

We really prefer not to make any concrete claims regarding crank horsepower when measuring with a chassis dyno.

But we always get the question: "so what it is making at the crank?"

We offer a loose correction factor based on the assumption that the factory crank power numbers are accurate.

However, in this case, if we assume a 480 crank hp with a measured 440 wheel hp, that results in a correction factor of 1.09 (480/440), which equals roughly 8% drivetrain losses ( (480-440)/480 ).

An 8% loss on an AWD car does not sit well with us, so we picked a 12% loss as a more realistic correction factor.

This sort of hazy math is a perfect example of why crank corrected chassis dyno numbers should be taken with a grain of salt.

Anyway, it is interesting to see the progression of AWD turbo Porsche wheel power numbers:

stock 993TT ~303 whp
AWE/GIAC tuned K24 993TT ~400 whp

stock 996TT ~355 whp
AWE/GIAC tuned K24 996TT ~500 whp

stock 997TT ~440 whp

All the above tests were done on our Mustang AWD-500-SE chassis dyno with the same dyno settings, and done on multiple cars (except the 997TT) to establish data validity.

So either the factory has been way overrating some of the cars, or the opposite is true (more likely).

Therefore, we'd have to conclude that the 997TT is making in reality 500 hp+ at the crank bone stock.

Or our 997TT is a freak.

 

Really impressive..

Todd any problems with CE lights etc.?

on my former 996TT the first exhaust i tried(not yours) after some "hard" laps at the Mugello circuit,make the CE lights on,and they must change a cat converter becouse "burn out"..in reality they change me the complete exhaust becouse was in one piece..and i'm worried to have the same problem now..

have you got a supplier in Europe?

thanks
Ciao
Dario

 

I always thought the 996TT was somewhat underrated at 415 hp based on the 116 mph trap speed, but these awhp numbers from the 997TT makes the former seem like a dog! While there will be endless debate over whether they sandbags their hp ratings or just build incredibly efficient drivetrains or both, the only metric that really matters here is the power measured at all four wheels. Hats off to Porsche for building such phenomenal powertrains. Just when you think they've used up all their tricks they pull another rabbit out of the hat!

 

I think it has to do with the break in as well. we all known Porsches are much faster after breaking them in.

 

440 awhp stock is some serious power. Makes 11.7's and 120+ mph trap speeds seem very realistic.

 

If you are talking a 14% correction factor for an AWHP dyno that sounds like a way understatement, and Porsche is incredibly conservative with their #'s. Usual correction factors for an AWD dyno is in the 20%-25% range. With RWD dynos I have seen from 10%-18%.

 

That will probably sound nice, and the power gains look to be solid.

 

Not at this time, and we are quite confident we will not have any issues.


Our 996TT muffler system uses a US manufactured metal core catalyst, and we put several days of track use and many thousand miles of street driving on them before releasing the muffler in 2003. To date, we have been very pleased with their overall reliability in terms of matrix integrity and their ability not to set off a check engine light. The ability for our mufflers to make big power and also keep the check engine light off is our main claim to fame.

However, the 997TT uses an 800 cell per square inch catalyst from the factory. We already have extensive experience with making exhaust systems work on cars that came with these new low emissions cats, as the very latest VWs and Audis also have them. We initially tested our VW and Audi systems using the same 300 cell metal core cat used on our 996TT system, but after a few hundred miles a code would be logged and a check engine light would come on.

We then tried two US cats with a different coating formula, but these too were not able to keep the CEL off. We then went to the same cat manufacturer that VW, Audi, and Porsche use, and the problem was solved.

These German made Emitec core cats are quite expensive, but seem to be the only real solution to keeping the CEL off on cars originally equipped with the new 800 cell cats.

So far we have logged nearly 1000 miles on our 997TT muffler prototype with no cat issues or CELs, which does not surprise us.

However, if indeed there ever was an issue with one of our cats, they are able to be replaced separately from the rest of the exhaust system. Our systems for the 996TT and 997TT are completely modular.


We do have a few distributors in Europe. Please visit this page on our site:

http://awe-tuning.com/pages/info/AWE...map_europe.cfm

Any other questions, let me know.

 

A 1.14 correction factor is actually trying to correct for a 12% drivetrain loss:

If we assume that the crank power is more like 500 hp, then there is 60hp lost through the drivetrain. 60/500 is ~12%. It's just easier to provide a multiplication factor instead of telling people to divide. 500/440 = ~1.14

Anyway, I agree with you that even 12% loss is a bit low for what you should see on an AWD car. But if we assume a 20% loss, then the 997TT is actually making 550 crank with 440 wheel hp measured.

I am not sure Porsche is underrating their motors to that extent!

So the question may be: are our dyno settings off, causing our wheel power numbers to read too high?

Well, if that is the case, then these same settings are causing the 993TT and 996TT numbers to read too high, also (we regularly calibrate our dyno, so we know it has been consistent in its measurement).

Which brings us back to the point that it is a *very* grey area when you start to make assumptions on crank power based on wheel power.

But everyone's doing it.

 

Thanks,really clear!

 

did you experience any Check Engine Light with this header and exhaust mod?

 

We have several thousand miles on our prototype and have had no issues with Check Engine Lights. Nor do we expect to have any, as we are using a German Emitec 200 cell metal core cat, which is the only aftermarket one that we have found to keep the light off on cars that originally came with 800 cell cats from the factory.

We have completed road and dyno testing, and we are building jigs for the system today.

We are quite pleased with the power and sound results. By working with different balance tube configurations, we have been able to increase whp gains to 20, while still keeping the volume civilized!

Pics and videos coming.