Excellence features GT3
09-29-2013, 03:25 PM
#1
Race Car
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Excellence features GT3
Latest edition has a lengthy technical piece on the GT3.
David Donahue has a driver's perspective that nails the issue of "who likes/dislikes PDK and why".
David Donahue has a driver's perspective that nails the issue of "who likes/dislikes PDK and why".
10-11-2013, 12:47 AM
#2
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Well, I just bought my first ever copy of Excellence magazine to read about their views on the 991 GT3. Basically, there are 2 articles: one is a long piece revealing many specs and technical details written by Ian Kuah, while the second shorter one is a "driving impression" by David Donahue.
The first article is extremely well written and provides insights and explanations from Andreas Preuninger and others on the development of the 991 GT3 that I have not read from anywhere else. Some highlights for me include:
- One of the development goals for the new engine was to ensure revving to 9000rpm with complete reliability over the life of the engine, which means over 100,000 miles before needing a rebuild. There is lot of detail in the article to list all the features of this engine to reach this goal.
- We all know that the GT3 engine is about 44lbs (20kg) lighter than the Carrrera 9A1 engine, which significantly helps to improve the polar moment of inertia for a rear engine car. But this weight savings is completely offset by the higher weight (44lbs/20kg) of the PDK-S box. However, the gearbox sits very low and is in line with the rear wheels, ahead of the engine, which means that extra weight is transferred forward to result in better weight distribution and handling, even though the engine/gearbox combo is not lighter than before.
- Because the PDK-S gearbox is partnered with a dual-mass flywheel, the extra weight of the unit is definitely felt when the throttle is blipped in neutral (even though the flywheel is already 10% lighter than the Carrera's). There is a comment that because of this, the 991 GT3's engine does not possess the racecar feeling of super light internals and the more aggressive revvng that the previous RS 3.8 and RS 4.0 models had with their single-mass flywheels.
- PDK-S is worth 4.0 seconds per lap on the Ring; Timo Gluck set the benchmark Ring laptime of 7 min 25 sec; the shift speed of the PDK-S was benchmarked against the Carrera Cup cars' sequential gearbox with near instant gearshifts.
- The new electro-hydraulically controlled variable locking differential, which replaces the previous mechanical LSD, is a major reason for the increased cornering speeds. In addition to providing the exact amount of correct locking by each of the driven wheels for any given situation under load, it also runs as an open differential on the over-run and under braking, which aids turn-in. The partial locking of the previous mechanical LSD under braking contributed to some understeer when entering a turn.
- During high speed endurance testing at Nardo, they discovered another advantage of the rear wheel steering system (in addition to the well documented increased cornering agility and stability): there was more even tire wear......the rear tires stayed cooler on track, stabilizing at a higher level of performance, resulting in better laptimes.
- They worked closely with Michelin on a bespoke "N0" version of the Pilot Sport Cup 2 for the GT3.
- Why 20" wheels?......1) visual reasons as the 991 had such huge wheelwells, 2) lower profile tires deliver better transient response as long as the suspension is optimized and 3) the 20" wheels actually lighter than the previous 19" wheels from the 997 GT3.
The first article is extremely well written and provides insights and explanations from Andreas Preuninger and others on the development of the 991 GT3 that I have not read from anywhere else. Some highlights for me include:
- One of the development goals for the new engine was to ensure revving to 9000rpm with complete reliability over the life of the engine, which means over 100,000 miles before needing a rebuild. There is lot of detail in the article to list all the features of this engine to reach this goal.
- We all know that the GT3 engine is about 44lbs (20kg) lighter than the Carrrera 9A1 engine, which significantly helps to improve the polar moment of inertia for a rear engine car. But this weight savings is completely offset by the higher weight (44lbs/20kg) of the PDK-S box. However, the gearbox sits very low and is in line with the rear wheels, ahead of the engine, which means that extra weight is transferred forward to result in better weight distribution and handling, even though the engine/gearbox combo is not lighter than before.
- Because the PDK-S gearbox is partnered with a dual-mass flywheel, the extra weight of the unit is definitely felt when the throttle is blipped in neutral (even though the flywheel is already 10% lighter than the Carrera's). There is a comment that because of this, the 991 GT3's engine does not possess the racecar feeling of super light internals and the more aggressive revvng that the previous RS 3.8 and RS 4.0 models had with their single-mass flywheels.
- PDK-S is worth 4.0 seconds per lap on the Ring; Timo Gluck set the benchmark Ring laptime of 7 min 25 sec; the shift speed of the PDK-S was benchmarked against the Carrera Cup cars' sequential gearbox with near instant gearshifts.
- The new electro-hydraulically controlled variable locking differential, which replaces the previous mechanical LSD, is a major reason for the increased cornering speeds. In addition to providing the exact amount of correct locking by each of the driven wheels for any given situation under load, it also runs as an open differential on the over-run and under braking, which aids turn-in. The partial locking of the previous mechanical LSD under braking contributed to some understeer when entering a turn.
- During high speed endurance testing at Nardo, they discovered another advantage of the rear wheel steering system (in addition to the well documented increased cornering agility and stability): there was more even tire wear......the rear tires stayed cooler on track, stabilizing at a higher level of performance, resulting in better laptimes.
- They worked closely with Michelin on a bespoke "N0" version of the Pilot Sport Cup 2 for the GT3.
- Why 20" wheels?......1) visual reasons as the 991 had such huge wheelwells, 2) lower profile tires deliver better transient response as long as the suspension is optimized and 3) the 20" wheels actually lighter than the previous 19" wheels from the 997 GT3.
10-11-2013, 01:04 AM
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At the end of the second article, there is a short piece entitled "What PDK Means to You".
The writer described 3 schools of thought on PDK
1) The Enthusiastic Newcomers: people are new to the sport or just haven't mastered the heel-toe downshift or shifting in general; they enjoy driving like any car fan, but can't reach their ultimate potential in a manual car.
2) The Diehard Traditionalists: people who not only love to drive but love the whole process; they enjoy the "control" aspect; they enjoy the "exclusivity" of having the skill to master driving with 3 pedals.
3) The Phlegmatic Thrill Seekers: people who can heel-toe without a thought and therefore do not get huge satisfaction from doing it; they enjoy the driving experience just like the other 2 groups, but don't get all worked up about the process; they tend to look at new approaches and evaluate them at face value.
Which one are you?
The writer described 3 schools of thought on PDK
1) The Enthusiastic Newcomers: people are new to the sport or just haven't mastered the heel-toe downshift or shifting in general; they enjoy driving like any car fan, but can't reach their ultimate potential in a manual car.
2) The Diehard Traditionalists: people who not only love to drive but love the whole process; they enjoy the "control" aspect; they enjoy the "exclusivity" of having the skill to master driving with 3 pedals.
3) The Phlegmatic Thrill Seekers: people who can heel-toe without a thought and therefore do not get huge satisfaction from doing it; they enjoy the driving experience just like the other 2 groups, but don't get all worked up about the process; they tend to look at new approaches and evaluate them at face value.
Which one are you?
10-11-2013, 01:21 AM
#4
Rennlist Member
But interesting that this feature, PTV Plus, has recently disappeared from the 991S Technical Specs overview listing on Porsche's site, although still fully explained in the "Features/Chassis" section. Marketing!
10-11-2013, 02:09 AM
#5
Well, I just bought my first ever copy of Excellence magazine to read about their views on the 991 GT3. Basically, there are 2 articles: one is a long piece revealing many specs and technical details written by Ian Kuah, while the second shorter one is a "driving impression" by David Donahue.
The first article is extremely well written and provides insights and explanations from Andreas Preuninger and others on the development of the 991 GT3 that I have not read from anywhere else. Some highlights for me include:
- One of the development goals for the new engine was to ensure revving to 9000rpm with complete reliability over the life of the engine, which means over 100,000 miles before needing a rebuild. There is lot of detail in the article to list all the features of this engine to reach this goal.
- We all know that the GT3 engine is about 44lbs (20kg) lighter than the Carrrera 9A1 engine, which significantly helps to improve the polar moment of inertia for a rear engine car. But this weight savings is completely offset by the higher weight (44lbs/20kg) of the PDK-S box. However, the gearbox sits very low and is in line with the rear wheels, ahead of the engine, which means that extra weight is transferred forward to result in better weight distribution and handling, even though the engine/gearbox combo is not lighter than before.
- Because the PDK-S gearbox is partnered with a dual-mass flywheel, the extra weight of the unit is definitely felt when the throttle is blipped in neutral (even though the flywheel is already 10% lighter than the Carrera's). There is a comment that because of this, the 991 GT3's engine does not possess the racecar feeling of super light internals and the more aggressive revvng that the previous RS 3.8 and RS 4.0 models had with their single-mass flywheels.
- PDK-S is worth 4.0 seconds per lap on the Ring; Timo Gluck set the benchmark Ring laptime of 7 min 25 sec; the shift speed of the PDK-S was benchmarked against the Carrera Cup cars' sequential gearbox with near instant gearshifts.
- The new electro-hydraulically controlled variable locking differential, which replaces the previous mechanical LSD, is a major reason for the increased cornering speeds. In addition to providing the exact amount of correct locking by each of the driven wheels for any given situation under load, it also runs as an open differential on the over-run and under braking, which aids turn-in. The partial locking of the previous mechanical LSD under braking contributed to some understeer when entering a turn.
- During high speed endurance testing at Nardo, they discovered another advantage of the rear wheel steering system (in addition to the well documented increased cornering agility and stability): there was more even tire wear......the rear tires stayed cooler on track, stabilizing at a higher level of performance, resulting in better laptimes.
- They worked closely with Michelin on a bespoke "N0" version of the Pilot Sport Cup 2 for the GT3.
- Why 20" wheels?......1) visual reasons as the 991 had such huge wheelwells, 2) lower profile tires deliver better transient response as long as the suspension is optimized and 3) the 20" wheels actually lighter than the previous 19" wheels from the 997 GT3.
The first article is extremely well written and provides insights and explanations from Andreas Preuninger and others on the development of the 991 GT3 that I have not read from anywhere else. Some highlights for me include:
- One of the development goals for the new engine was to ensure revving to 9000rpm with complete reliability over the life of the engine, which means over 100,000 miles before needing a rebuild. There is lot of detail in the article to list all the features of this engine to reach this goal.
- We all know that the GT3 engine is about 44lbs (20kg) lighter than the Carrrera 9A1 engine, which significantly helps to improve the polar moment of inertia for a rear engine car. But this weight savings is completely offset by the higher weight (44lbs/20kg) of the PDK-S box. However, the gearbox sits very low and is in line with the rear wheels, ahead of the engine, which means that extra weight is transferred forward to result in better weight distribution and handling, even though the engine/gearbox combo is not lighter than before.
- Because the PDK-S gearbox is partnered with a dual-mass flywheel, the extra weight of the unit is definitely felt when the throttle is blipped in neutral (even though the flywheel is already 10% lighter than the Carrera's). There is a comment that because of this, the 991 GT3's engine does not possess the racecar feeling of super light internals and the more aggressive revvng that the previous RS 3.8 and RS 4.0 models had with their single-mass flywheels.
- PDK-S is worth 4.0 seconds per lap on the Ring; Timo Gluck set the benchmark Ring laptime of 7 min 25 sec; the shift speed of the PDK-S was benchmarked against the Carrera Cup cars' sequential gearbox with near instant gearshifts.
- The new electro-hydraulically controlled variable locking differential, which replaces the previous mechanical LSD, is a major reason for the increased cornering speeds. In addition to providing the exact amount of correct locking by each of the driven wheels for any given situation under load, it also runs as an open differential on the over-run and under braking, which aids turn-in. The partial locking of the previous mechanical LSD under braking contributed to some understeer when entering a turn.
- During high speed endurance testing at Nardo, they discovered another advantage of the rear wheel steering system (in addition to the well documented increased cornering agility and stability): there was more even tire wear......the rear tires stayed cooler on track, stabilizing at a higher level of performance, resulting in better laptimes.
- They worked closely with Michelin on a bespoke "N0" version of the Pilot Sport Cup 2 for the GT3.
- Why 20" wheels?......1) visual reasons as the 991 had such huge wheelwells, 2) lower profile tires deliver better transient response as long as the suspension is optimized and 3) the 20" wheels actually lighter than the previous 19" wheels from the 997 GT3.
