Hi Chris,

Cargraphic Exhaust:
Subjective: felt no change, other than faster pooling.
Objective: no test was done as I did not have Durametric yet to do before and after.
For others reading this (not Chris): even though there is no power gain with exhaust in a stock car, if you are going to mod the ECU, you do need an after-market exhaust to improve flow. In other words, power gain with an exhaust is more for a car with modded ECU.

GIAC:
Torque (for others reading this: in typical dyno, torque gain is an indication of power gain in lower RPM, 3500 rpm or so):
1. By dyno at GIAC facility17%
2. By Durametric at home 30% (GIAC versus Stock, both in Sport Mode)
I believe GIAC guys were happy with the result of this curve (large gain with very large flat plateau).
Horsepower (indication of power gain at higher RPM, 6000 rpm or so):
By dyno at GIAC facility: had problem with clutch slip and curve looks funny at top end as a result, 8% gain. Even without clutch slip, I don't expect much more than 10% with a stage 2.

It's all in the little prints in dyno graph below. Hope this helps - are you trying Durametric cable or something?

 

 

Gotcha

 

Wow, was a bit surprised by your observation and then see that there were no comments in this thread. Installing a Cargraphic loud on my car I immediately noticed several things. The throttle response is definitely improved. Noticeably faster response, almost like a lightweight flywheel compared to stock. Faster spooling indeed! Well, that means more boost at lower RPM. With the same throttle input as before, you get boost when stock there was no boost yet. So, for the same throttle input, more power. On the top, slightly more psi as well (1 psi on my car). The exhaust is much more than beautiful noise, response is better and the power comes on more quickly. What is the bottom line? LESS TURBO LAG!

 

Clearly, his clutch is slipping, bc those numbers should be about 450 at the wheels with a stage 2 turbo. The exhaust alone will ad 20hp do to flow and backpressure reduction alone. That you should feel in faster spool up.
A bone stock 997tt will lay down about 385hp at the wheels.

 

Conrad, Ok, power gain with exhaust alone, this is going to be very interesting discussion - I am game. :-) We have same exhaust and of course I would be happy to agree with your observation, since it shows how good my Cargraphic exhaust is. But... let me be devil's advocate and ask you this question: I believe and trust your subjective sensation, but how about if I say "prove it to me" with real objective data and not seat-of-the-pant sensation? Subjective data is nice of course, but it is subjected to bias, error, placebo effect, etc. This is why the big boys on this forum prove their high power engine mod with 60-130 times and not how fast the car "feels."

There are 4 ways to provide objective data of power gain:
1. Vbox time: for the "big boys," not going to show with exhaust gain. Bottom of the line.
2. Dyno: MUST have before and after data, by third party, in other words, one of us, and not the vendor. I am well aware that every exhaust manufacturer has beautiful dyno graphs showing about 20 hp gain with exhaust. Have you seen one done by one of us? (Actually I know of one such comparison and will talk about this later.)
Regarding dyno (for anyone new to dyno and ECU mod): a single dyno is of not much use as settings of dyno could be manipulated to yield different numbers. You need one before, and one after change, done under same condition, to do a valid comparison. It is the percentage *change* and the shape of the dyno curve that are important.
3. Durametric: I would love for us to start collecting data with Durametric. When I had my Cargraphic install I wasn't "advanced" enought to think about doing this.
4. Track time: not going to show with exhaust gain. This is another true bottom of the line.
Again, being the devil's advocate, let me ask, which one of the above 4 has been done with Cargraphic?

The topic of power gain with exhaust is actually even more complicated when you think about it. Dyno, Vbox, Durametric, etc., are ALL full-throttle test that shows all out push. But, how often are we at full throttle? What if an after-market exhaust loses torque at lower RPM, when the engine acts more like a naturally aspirated engine (no boost)? So... partial throttle test anyone? How?

 

Hey buddy, I'll entertain. This is NOT a seat of the pants observation. There is a boost gauge on the dash, however inaccurate it may be.
You even mentioned the turbos "spooling" faster. Well, that is more boost earlier. I would only say that this does NOT necessarily translate into more power, but it does translate into noticeably better response and less turbo lag. This cannot really be measured, however the stock versus plus exhaust dyno curves all seem to show not only more peak power, but increased power and torque lower in the RPM band.

Hmm, I thought nearly EVERY exhaust mfg brags about increased power and torque - often with before and after dyno runs. Little doubt you add more power and torque with just an exhaust - is that a question? How MUCH power and torque is certainly debatable, I won't enter that debate or suggest "my exhaust is worth 30 hp" or some such conclusion. I have no idea. But I don't care that much either. Okay, I realize you find that any of these dyno runs could be manipulated, but I don't think any tuner would disagree that you get power gains from an exhaust. This is particular ONLY to this car really - perhaps other turbo cars are similar, I don't know.

Compared to almost countless BMW exhausts that were merely sound boosters, it was really amazing to add an exhaust and actually get a power gain. Of course you get more with a tune, but even the exhaust has proven quite worthwhile.

 

SharkWerks promotional material for the Cargraphic Loud exhaust:


For those of you wanting a louder exhaust the Cargraphic 997TT "loud" exhaust is the defacto choice. The design of this system combines all of the power associated with a precision built aftermarket sport exhaust system with the sound quality discriminating Porsche owners expect and your 997TT deserves. The Cargraphic system offers a pure, clean, crisp sound while maintaining a quiet interior cabin without any annoying resonance. The muffler canisters are engineered sound chambers that utilize different cavities and air channels to reduce sound. Additionally, the included heat shields act as additional sound barriers while reducing radiant heat like the OEM system. This is the ultimate exhaust system that offers it all and will make the perfect addition to your Porsche 997 Turbo.

Features
HP Gain: ~30
TQ Gain: ~30

-Dyno tested ~21 HP / ~30 TQ increase with no other modifications
-MASSIVE 70mm piping throughout
-Accepts the OEM Porsche 997TT tips
-Incorporated the highest quality 200 cell European sport catalysts
-Easy bolt on installation
-Allows operation within OBD2 parameters
-Offers a fine balance of power and sound with only some resonance
-Aggressive sound!

 

Conrad,

1 "Spool faster with exhaust": I actually agree with you on this, but my emphasis was that on this forum, to be credible to the seasoned veterans here, we have to PROVE it. Looking at the boost and think that it spool faster is not enough.
There is a way to check spool speed, and that is through Durametric. I actually have checked the spool speed with GIAC tune (will post on that thread later), but not with the exhaust, and as mentioned several times, would love to see anyone else check out the numbers with after-market exhaust.

2. Dyno for exhaust: Yes I know of the gains posted by vendors, incl. CG. But... what about third party check? I know of only one dyno done by third party for 997 Turbo, by a member here (dkreid..), with a reputable exhaust, under similar conditions before and after. Unfortunately he never did publish the graphs, but to best of my knowledge, it actually shows no gain at high rpm, and minor loss at lower rpm. All this means is that it would be nice to have some third party numbers to confirm that 20-30 hp we see often. And nowadays with Durametric, it's a no brainer simple test for anyone about to install an exhaust.

 

Simple. If you agree with spools faster, then that translates to more boost earlier, which means more power sooner. And no question, less turbo lag. That is worth the price itself.

 

Back to back 1/4 mile runs would be better that 60-130 IMHO.
Back in 07, IA motorsports had a vid showing a a stock 997tt on the dyno, immed followed by a fabspeed install, gained 21 hp, same car, 2hrs later, cool stuff!

 

Pardon my ignorance on this issue....But how do you get the gain using Durametric? What do you data log and how do you calculate...or point me if it is somewhere else? I have been interested in finding boost too with Durametric, but the various threads have just confused me a bit

Thanks,
DC

 

Thanks C. Good data.

 

DC, no problem. As far as gain calculation, very easy: the run is a third gear WOT run on safe empty track. Cruise at 2000 rpm, then bam, gas pedal all the way down and do not let go until rev limiter cuts in. You could do run in 4th gear but remember now you have to be at the track because that will take you to 130 mph or so.

The data you are looking at is Engine Load. In my case,
in Stock Sport mode, the engine load is 172, and
in GIAC Sport mode, the engine load is 222
so GIAC/Stock=222/172=1.29, a 29% gain.

I love Durametric but still am keeping an open mind about it as we learn more from more people reporting their findings. For example, the gain compared to my Dyno run at GIAC is different: on the GIAC dyno the gain was only 17% (still a very big gain, but not 29%). I don't know how and why this difference arises (could be operator's error (me), could be the way the runs are done with GIAC dyno run being done in 4th gear, etc., etc.). Nevertheless, Durametric's huge advantage is it could be done at home, by anyone of us, so we could spy on our vendors.

Durametric is fascinating new frontier and I would like to see more of us doing it to gather data. For the guys about to install exhaust or ECU, remember you have to measure Durametric BEFORE and after install. Data is worthless if you just measure after-the-install as there is no reference.

 

Besides engine load, the other parameter that would be of interest is boost pressure. I mean, tuners pay special attention to AFR, timing, IAT, EGT, etc., but that their problems :-), for us amateurs and for these low power measurements, boost and engine load are of interest.

As you could see from my conversation w/ my friend ryem3 above, one interesting question is, does boost goes up with an after-market exhaust only (without ECU tune)? It's possible but I don't know. The answer is again, easily obtainable in Durametric.

I would also point out another interesting point, that from the shapes of the curves I have charted, it appears to me Engine Load approximates the torque curve, rather than the power curve (hp). No big deal, "horsepower sells car, torque wins races." :-)