Review: GIAC Stage 2 91 Oct vs. Cobb Stage 2 91 ACN
10-04-2015, 04:08 AM
#1
Drifting
Thread Starter
Review: GIAC Stage 2 91 Oct vs. Cobb Stage 2 91 ACN
Car: 991 Turbo S
Bolt-on: Europipe exhaust with 100 cell cat.
Software: GIAC Stage 2 91 Octane (for 3 months), Cobb Stage 2 91 Octane ACN (Present)
Ok, I had the GIAC Stage 2 software tune installed by Sam at By Design about 3 months ago. I wanted a true ecu tune, and not some piggy back plug-in and at the time, GIAC was the only game in town. I want to start off by saying that all of my previous turbocharged cars (996, 997.1, 997.2) have been tuned by GIAC and there is no doubt in my mind that GIAC does great work. Their tune was always very smooth and very reliable.
So ever since the Cobb Accessport came out for the 991 Turbo S, I have been following their progress carefully. I have read their blogs and I have studied all of the dyno plots that been released in the past couple of weeks. I have to admit, I was very intrigued by the power that they are claiming from their tune. To be absolutely honest, I was very skeptical. I mean, how can the numbers be that much different between the two tunes? Some of the numbers are as much as 90-100ft/lbs of torque (in favor of the Cobb).
So I called up Sam and started asking him a series of questions regarding the Cobb tune. I wanted to buy the Cobb unit and try it out, but Sam made his best attempt to persuade me not to do it, as I currently have the GIAC Stage 2 and he does not want to add more fuel to the fire in the on-going debate between Cobb vs. GIAC. Still, I persisted and Sam had Cobb overnight the Accessport to my house the very next morning. Sam even dropped by my house to hook up the power outlet to my car’s battery and teach me how to use the unit. I told Sam that as we were uploading the 91 ACN Stage 2 tune to my car, that if I didn’t like the Cobb tune or if I can’t feel the difference compared to the GIAC, I am going ask for a full refund and reflash back my GIAC Stage 2.
Installation was a breeze on the Accessport as advertised and the whole process was finished in about 10 minutes from start to finish. Sam helped me customized the gauge section and showed how to data log. The next day (I wasn’t able to drive the car on the day we flashed it), I hooked up the Accessport, and went out for a drive. A few things that is very apparent on the Cobb Stage 2 compared to the GIAC Stage 2 within 2 miles of driving:
1. There is a bigger power surge between 2700rpm to 3500 rpm on the Cobb than the GIAC. This took me totally by surprised, because the amount of power difference in that rev range is very obvious and noticeable. It took me about 10 minutes to get used to it because the power comes on so strong and so quickly.
2. There is definitely more torque across the power band with the Cobb tune (especially between 3000-5000rpm). Top end is slightly more powerful than GIAC, but not by the same margin as in the lower rpm. Power remains more consistent in the Cobb, where the GIAC feels softened up after 6000rpm.
3. When you floor the throttle in 6th or 7th gear and engage overboost, the boost gauge is always pegged at 17psi whereas in the GIAC, you would hit 17psi momentarily and it will be reduced at 16psi. I do not know why GIAC does this, but Cobb doesn’t and it’s always pegged at the full boost.
4. Between 1500 to 2300rpm, the throttle response on the GIAC is better calibrated than the Cobb. Basically, before the turbo kicks in, I like the throttle response better on the GIAC.
5. There is more turbo whooshing sound in the Cobb tune than the GIAC. I think this is the by-product of the Cobb tune working and engaging the turbo much harder and earlier than the GIAC.
6. I have not dyno the car and I don’t really intend to because there have been so many posts on this side of the topic and I wanted to post my real world driving experience. Based on my seat of the pants, I would conservatively guess that the Cobb tune is about 50-60ft/lbs more across the power band.
Some additional interesting notes:
- I did 2 LC on the Cobb and it produced 1.31g and 1.32g on my stock PZero tires. The best number I got with GIAC was 1.29g. So it’s not a big difference.
- On the Accessport, the maximum actual boost recorded was 38.2psi and the target boost was at 40.4psi. Subtracting the atmospheric pressure of 15psi, you get the actual boost (24.2psi actual and 25.4psi target). However, this does not mean Cobb is running at this boost level all the time. I noticed that when I floor it, the boost will come on at 24.2psi and tapper off at around 21-21.5psi throughout, which is what they advertised.
So here it is guys, my first hand experience between the Cobb and the GIAC software and my unbiased, although very unscientific, review between the two. Am I a Cobb believer now, you bet I am! Do I think GIAC is bad in any way? Of course not! It’s still a very good tune, but I think GIAC needs to go back and find more power. As Cobb have shown, there is more power to be extracted from the car and it can be done very smoothly and safely.
Bolt-on: Europipe exhaust with 100 cell cat.
Software: GIAC Stage 2 91 Octane (for 3 months), Cobb Stage 2 91 Octane ACN (Present)
Ok, I had the GIAC Stage 2 software tune installed by Sam at By Design about 3 months ago. I wanted a true ecu tune, and not some piggy back plug-in and at the time, GIAC was the only game in town. I want to start off by saying that all of my previous turbocharged cars (996, 997.1, 997.2) have been tuned by GIAC and there is no doubt in my mind that GIAC does great work. Their tune was always very smooth and very reliable.
So ever since the Cobb Accessport came out for the 991 Turbo S, I have been following their progress carefully. I have read their blogs and I have studied all of the dyno plots that been released in the past couple of weeks. I have to admit, I was very intrigued by the power that they are claiming from their tune. To be absolutely honest, I was very skeptical. I mean, how can the numbers be that much different between the two tunes? Some of the numbers are as much as 90-100ft/lbs of torque (in favor of the Cobb).
So I called up Sam and started asking him a series of questions regarding the Cobb tune. I wanted to buy the Cobb unit and try it out, but Sam made his best attempt to persuade me not to do it, as I currently have the GIAC Stage 2 and he does not want to add more fuel to the fire in the on-going debate between Cobb vs. GIAC. Still, I persisted and Sam had Cobb overnight the Accessport to my house the very next morning. Sam even dropped by my house to hook up the power outlet to my car’s battery and teach me how to use the unit. I told Sam that as we were uploading the 91 ACN Stage 2 tune to my car, that if I didn’t like the Cobb tune or if I can’t feel the difference compared to the GIAC, I am going ask for a full refund and reflash back my GIAC Stage 2.
Installation was a breeze on the Accessport as advertised and the whole process was finished in about 10 minutes from start to finish. Sam helped me customized the gauge section and showed how to data log. The next day (I wasn’t able to drive the car on the day we flashed it), I hooked up the Accessport, and went out for a drive. A few things that is very apparent on the Cobb Stage 2 compared to the GIAC Stage 2 within 2 miles of driving:
1. There is a bigger power surge between 2700rpm to 3500 rpm on the Cobb than the GIAC. This took me totally by surprised, because the amount of power difference in that rev range is very obvious and noticeable. It took me about 10 minutes to get used to it because the power comes on so strong and so quickly.
2. There is definitely more torque across the power band with the Cobb tune (especially between 3000-5000rpm). Top end is slightly more powerful than GIAC, but not by the same margin as in the lower rpm. Power remains more consistent in the Cobb, where the GIAC feels softened up after 6000rpm.
3. When you floor the throttle in 6th or 7th gear and engage overboost, the boost gauge is always pegged at 17psi whereas in the GIAC, you would hit 17psi momentarily and it will be reduced at 16psi. I do not know why GIAC does this, but Cobb doesn’t and it’s always pegged at the full boost.
4. Between 1500 to 2300rpm, the throttle response on the GIAC is better calibrated than the Cobb. Basically, before the turbo kicks in, I like the throttle response better on the GIAC.
5. There is more turbo whooshing sound in the Cobb tune than the GIAC. I think this is the by-product of the Cobb tune working and engaging the turbo much harder and earlier than the GIAC.
6. I have not dyno the car and I don’t really intend to because there have been so many posts on this side of the topic and I wanted to post my real world driving experience. Based on my seat of the pants, I would conservatively guess that the Cobb tune is about 50-60ft/lbs more across the power band.
Some additional interesting notes:
- I did 2 LC on the Cobb and it produced 1.31g and 1.32g on my stock PZero tires. The best number I got with GIAC was 1.29g. So it’s not a big difference.
- On the Accessport, the maximum actual boost recorded was 38.2psi and the target boost was at 40.4psi. Subtracting the atmospheric pressure of 15psi, you get the actual boost (24.2psi actual and 25.4psi target). However, this does not mean Cobb is running at this boost level all the time. I noticed that when I floor it, the boost will come on at 24.2psi and tapper off at around 21-21.5psi throughout, which is what they advertised.
So here it is guys, my first hand experience between the Cobb and the GIAC software and my unbiased, although very unscientific, review between the two. Am I a Cobb believer now, you bet I am! Do I think GIAC is bad in any way? Of course not! It’s still a very good tune, but I think GIAC needs to go back and find more power. As Cobb have shown, there is more power to be extracted from the car and it can be done very smoothly and safely.
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MovingChicane (12-12-2021)
10-04-2015, 06:15 AM
#2
Burning Brakes
Thanks for the really detailed review. One of my friends on another forum who has the Cobb Stage 2 has told me identical comments on the Cobb to your numbers one and four.
On Stage 2 pre ICs and Stage 2 plus my GIAC tune did the same thing -- reducing boost at higher RPMs. This is consistent with what GIAC wrote on another forum in response to my concerns about heat soak -- that with stock intercooling, to keep intake air temps in he safe zone the tune aggressively reduces power. Now at Stage 2 plus with Champion ICs I don't feel that.
We will see which tune makes more power at the upcoming October events. Your report of more torque with Cobb at least seat of the pants seems consistent with some of the Dino runs although. I'm still skeptical of a 100 foot pound difference in torque between GIAC and Cobb with the same hardware. If that torque difference reported by Cobb owners on the Dyno proves to be true in the real world the Cobb Stage 3 with ByDesign Intercoolers should be blowing my car away and the Cobb Stage 2 cars with stock ICs should be about even with my car on October 7 at our private Atco Dragway rental (for which we are expecting perfect weather and members here are invited to race).
Your review is really really good and consistent with what my friend reported in terms of there being a big power surge in the same place in the rev range as you did (which plenty of people will like and find thrilling) and the throttle response not being as smooth in the lower half of the rev range as he expected. My friend has never had GIAC on his 991 Turbo S so he couldn't report on a comparison between the two. He did feel that his car on Cobb stage two felt about the same speed seat-of-the-pants as my car when it was GIAC stage 2.
On Stage 2 pre ICs and Stage 2 plus my GIAC tune did the same thing -- reducing boost at higher RPMs. This is consistent with what GIAC wrote on another forum in response to my concerns about heat soak -- that with stock intercooling, to keep intake air temps in he safe zone the tune aggressively reduces power. Now at Stage 2 plus with Champion ICs I don't feel that.
We will see which tune makes more power at the upcoming October events. Your report of more torque with Cobb at least seat of the pants seems consistent with some of the Dino runs although. I'm still skeptical of a 100 foot pound difference in torque between GIAC and Cobb with the same hardware. If that torque difference reported by Cobb owners on the Dyno proves to be true in the real world the Cobb Stage 3 with ByDesign Intercoolers should be blowing my car away and the Cobb Stage 2 cars with stock ICs should be about even with my car on October 7 at our private Atco Dragway rental (for which we are expecting perfect weather and members here are invited to race).
Your review is really really good and consistent with what my friend reported in terms of there being a big power surge in the same place in the rev range as you did (which plenty of people will like and find thrilling) and the throttle response not being as smooth in the lower half of the rev range as he expected. My friend has never had GIAC on his 991 Turbo S so he couldn't report on a comparison between the two. He did feel that his car on Cobb stage two felt about the same speed seat-of-the-pants as my car when it was GIAC stage 2.
10-04-2015, 01:26 PM
#3
Drifting
Thread Starter
On Stage 2 pre ICs and Stage 2 plus my GIAC tune did the same thing -- reducing boost at higher RPMs. This is consistent with what GIAC wrote on another forum in response to my concerns about heat soak -- that with stock intercooling, to keep intake air temps in he safe zone the tune aggressively reduces power. Now at Stage 2 plus with Champion ICs I don't feel that.
We will see which tune makes more power at the upcoming October events. Your report of more torque with Cobb at least seat of the pants seems consistent with some of the Dino runs although. I'm still skeptical of a 100 foot pound difference in torque between GIAC and Cobb with the same hardware. If that torque difference reported by Cobb owners on the Dyno proves to be true in the real world the Cobb Stage 3 with ByDesign Intercoolers should be blowing my car away and the Cobb Stage 2 cars with stock ICs should be about even with my car on October 7 at our private Atco Dragway rental (for which we are expecting perfect weather and members here are invited to race).
Your review is really really good and consistent with what my friend reported in terms of there being a big power surge in the same place in the rev range as you did (which plenty of people will like and find thrilling) and the throttle response not being as smooth in the lower half of the rev range as he expected. My friend has never had GIAC on his 991 Turbo S so he couldn't report on a comparison between the two. He did feel that his car on Cobb stage two felt about the same speed seat-of-the-pants as my car when it was GIAC stage 2.
I was very skeptical about the power gains that I have seen on the Cobb dyno plots and I'm still not sure about the 100ft/lbs of difference. If I were to guess from my seat time is that there is about 50-60ft/lbs of difference because it is very noticeable across the power band.
More driving and more data logging next week. Then Sam at By Design to help me create a custom tune just for my car with the Europipe exhaust! Hopefully we will find a few more ponies and torque along the way
