GT3 R Hybrid article/vids
10-04-2010, 09:26 AM
#1
Rennlist Member
Thread Starter
Join Date: Feb 2006
Location: Wishing I Was At The Track
Posts: 13,605
Received 1,839 Likes
on
954 Posts
GT3 R Hybrid article/vids
A couple of (I believe) new videos here:
http://vimeo.com/15347381
http://vimeo.com/15364329
http://vimeo.com/15364002
http://auto-racing.speedtv.com/artic...t3-r-hybrid/P1
ALMS: Inside The Porsche 911 GT3 R Hybrid
It doesn’t use a battery. It draws technology from F1. It handles like an AWD car. And with an extra 160hp on tap, it simply flies. Meet Porsche’s racing hybrid.
Marshall Pruett | Posted September 29, 2010
History, the Hybrid Concept and Execution
Sportscar racing has been the source of dozens of innovations over the past century, but in the last 10 years, the majority of the ground-breaking developments have centered on lowering emissions, pioneering the use of new fuels and exploring hybrid technologies.
The American Le Mans Series has been a regular test bed for factories and privateers to try their hand at finding an advantage that delivers faster lap times while going farther on a tank of fuel, or, in a perfect world, going farther on less fuel while leaving a smaller carbon footprint.
From Panoz introducing their Q9 hybrid-electric sports racer in 1998 to the Nasamax team entering a Reynard-Cosworth powered by bio-ethanol in 2003 to Taurus Sport fielding the first diesel-powered prototype at Le Mans in 2004, many teams have dreamt while climbing a proverbial mountain of obstacles along the way.
As so often happens, the foundation of a good idea is usually taken and perfected by the second or third party to embrace an unproven concept. After the modest efforts by Nasamax and Taurus Sport, diesel-powered prototypes have dominated the LMP1 category in the ALMS and at Le Mans since 2006, and nearly one-third of the field for this Saturday’s 13th annual Petit Le Mans will compete using Cellulosic E85 Ethanol.
Rather than fill the car with batteries, Porsche opted for a unique solution within GT racing by partnering with the Williams F1 team to bring their KERS flywheel unit to the 911 GT3 R Hybrid. (Porsche)
The one main area of development that has been lacking is in the use of hybrid drive systems, and despite valiant efforts by the Panoz Q9 and the underfunded efforts of the Corsa Motorsports team and their battery-based Zytek hybrid prototype, the concept needed the budget and commitment from a major manufacturer to extract its potential.
All of that changed with Porsche’s announcement that they would use their competition department to explore and advance hybrid technology through sportscar racing, but rather than go the familiar route with a sports prototype, they elected to build from their familiar GT racing heritage by using a brand-new GT3 R chassis to push their boundaries of knowledge and innovation. From there, the Porsche 911 GT3 R Hybrid project was born.
Hybrid technology is nothing new in the automotive world, with cars like the Toyota Prius and Honda Element making use of combustion engines and battery-based electric-assisted engines, but getting away from battery dependence is still in its early phases. Porsche also offers a battery-based hybrid with its Cayenne S model, yet rather than locking it away in a private laboratory, they chose to start down the path of a battery-less hybrid in the world of endurance racing.
The rigors and demands of sportscar racing, along with the aspirational qualities of marrying a flywheel-based hybrid to a proven GT car was a challenge the company could not overlook, according to Dr. Daniel Armbruster, Porsche’s Manager of Motorsport Development Systems.
“Why did we decide to do this car? To develop high-power hybrid systems. We have to design for the future. We also have to look at how to reduce CO2 production. Most [battery-powered hybrid] systems today have only 60 kilowatts of power (approximately 80 horsepower). Our goal was to develop a hybrid system that had more performance, and had to give people great emotions about what we are trying to do. When we looked at the Porsche 911, we [thought] this would be the perfect car to use to make a better hybrid system that is truly about performance, not just to use what is common elsewhere. We build the race version of this to learn at a very fast rate.”
To create this mobile testing environment, Porsche chose their 911-based GT3 R racing chassis -- a bigger version of the popular GT3 S Cup car – that started its life on the Porsche production line. The company’s familiar practice of transforming their street cars into purebred GT racing cars continued with the Hybrid, yet a major re-think of how to combine their FIA GT3-spec chassis and a non-traditional hybrid into a functional racing car would first have to take place.
The Formula One series allowed the use of Kinetic Energy Recovery Systems (KERS) in 2009 to mixed results, with battery-based units proving to be the most popular solution. The Williams F1 team, however, went in a different direction by designing a flywheel-based KERS system that stores and releases energy without the use of a battery.
While the various mechanical and electrical systems that operate the Porsche/Williams system are highly complex, how the unit receives energy, turns it into electrical power and delivers it right back to the front wheels at the push of a button is rather simple.
Located between the front wheels is the power generation and delivery unit -- essentially two electric motors that sit in a common housing with reduction gears -- that was designed by Porsche. Halfshafts, made by GKN, connects the left motor to the left wheel, and the right motor to the right wheel. When the wheels rotate the halfshafts spin the electric motor, creating an electric charge under braking.
To prevent hybrid race cars from delivering a continual power boost, the electric motors are only permitted to generate electricity and send it to the flywheel under braking. Drivers have anywhere from 6-8 seconds of boost on tap until the system is recharged once again under braking.
The Porsche Hybrid system follows a system of electric-to-kinetic-to-electric, where electricity is generated at the front wheels, is then sent to the Williams unit where it powers up the flywheel to spin up to 40,000 rpms and becomes kinetic energy. With the flywheel continuing to spin -- acting as a power generator that waits in anticipation of delivering power back to the two front electric motors -- the push of a button on the steering wheel converts the kinetic energy back into electricity and returns it to the front wheels, providing a combined 160 horsepower from the two motors.
The cycle of braking --> boosting --> braking works in a continual loop in the same manner that the electric motors build an electrical charge --> send it to the flywheel for storage --> and receive it back to drive the front wheels. The combination of hybrid power feeding the front wheels while Porsche's 4.0 liter, 480 horsepower flat six-cylinder engine delivers its grunt to the rear wheels provides prodigious amounts of forward momentum.
With all of the new technology and power at play, the Hybrid will race by itself in the ‘Grand Touring Hybrid’ (GTH) class this weekend during Petit Le Mans. While the Hybrid weighs considerably more than the cars in GT2, it also provides a lot more power – about 140 horsepower with the combustion engine and electric motors combined – making it impossible to fit the car into a normal class structure.
Piloted by the trio that won the 2010 24 Hours of Le Mans overall for Audi – Timo Bernhard, Romain Dumas and Mike Rockenfeller – Porsche Motorsport has an amazing line-up to showcase the car during Saturday’s 10-hour/1000-kilometer race.
Just how it will fare against the more developed GT cars is unknown, but it’s safe to say the Hybrid has brought an element of excitement and unpredictability that was otherwise lacking from the race to develop hybrid technologies in sportscar competition.
With a 480 horsepower combustion engine in the back and twin 80 horsepower electric motors up front, the Hybrid puts down 640 angry ponies when called upon. (Marshall Pruett)
The ALMS will be conducting its season finale Saturday while the IZOD IndyCar Series holds its finale on the Homestead-Miami oval. If you want to appreciate the difference in technology between the two series, know that while the IndyCar drivers will have their own ‘Push to Pass’ button that delivers a set limit of 20 uses of less than 20 horsepower – a barely noticeable difference, the Porsche Hybrid drivers will have full use of their ‘Push to Pass’ button throughout the 10-hour race with the kick of an extra 160 horsepower pushing them deeper into the seat. Those 160 horses also come without sending any additional emissions into the atmosphere.
When it comes to putting the most ponies to the ground at the push of a button, that war is being won at Petit Le Mans. If you’re looking for more displays of extreme engineering and technology this Saturday, tune into SPEED at 11 a.m. ET to watch the Hybrid and the rest of the 45-car field battle with every type of engine, fuel and electrical system imaginable.
Inside the Hybrid
Digging deeper into the car and its systems, the Porsche 911 GT3 R Hybrid is a techno geek’s dream:
• The Williams flywheel unit itself is a marvel of engineering. Constructed from Magnetically Loaded Composite (MLC), Williams has done away with the use of a metal flywheel – something that would be easy to magnetically charge – and have fabricated a lighter flywheel out of carbon fiber that is infused with a magnetic powder. The carbon flywheel has proven to be a significant improvement over its metal predecessors, offering better resistance to heat and to electrical charge losses.
• Williams produces their ‘Williams Hybrid Power’ units for custom applications to a variety of customers – this isn’t an off-the-shelf item. The Hybrid unit was designed to a specification provided by Porsche Motorsport.
• Special air intakes are mounted on the body in front of the rear wheels which feed oil coolers that circulate oil to and from the flywheel. Dr. Armbruster says the flywheel unit is kept at 50 degrees C (120 degrees F).
• A large shroud encompasses the flywheel unit when the car is on the track. Dr. Armbruster mentioned that the system uses dry ice situated in a container on top of the unit to aid cooling, and up to three three-inch hoses feed air to the cooling and containment box.
• Having a flywheel the diameter of a Frisbee spinning at 40,000 rpms while mounted to the car would seem like something that wanted to act like a gyroscope, bur Dr. Armbruster mentioned that although the data acquisition sees small traces of the flywheel’s rotational movement on the G sensors, the forces are negligible but due damping within the flywheel housing.
• With so many extra cooling systems and so much space taken by the hybrid componentry, the ACO has given Porsche a special dispensation to race the car without the mandated air conditioning unit.
• The power converter unit – another Porsche design – sits under the front bonnet of the Hybrid. It acts as the go-between from the electric motors to the flywheel. It takes the AC charge from the motors, converts it to DC and sends it to the flywheel. From the flywheel, the DC is then converted back to AC before it is sent to the electric motors to give the 160 horsepower boost.
• The converters generate a massive amount of heat on their own, so Porsche incorporated a cooling system into the unit. A large central radiator is used specifically for the converters. The flat-six engine uses separate water radiators.
• The one downside of the Hybrid system – at least in traditional racing terms – is the extra weight it adds to the car. With all of the systems extra motors, the various electronic control units, the flywheel unit itself, the driveshafts and the wiring, Dr. Armbruster estimates an additional 150 kilos (330 pounds) are on board, if not more. That’s the size of your average NFL defensive lineman.
• The software that controls the Hybrid system was designed in-house by Porsche.
• The traditional data acquisition system is provided by Motec – standard issue on Porsche’s customer racing cars. Motec also provides the Power Control Module (PCM) and telemetry system.
• The wiring for the Hybrid is based on the RS Spyder LMP2 loom. Dr. Armbruster was unable to quantify how much extra wiring the Hybrid carries over an ALMS GT2-spec Porsche, but it appears to be somewhere in the range of 50 percent by visual comparison.
• Like a differential in a transmission, Porsche has designed their software and electronics to receive wheel speed input, throttle input, lateral Gs and steering input to calculate how much power to send to each wheel while the car is cornering. This is all processed with their “Hybrid Control Unit” (HCU). Based on conditions, cornering forces or throttle application, the system will vary how much of the 80 horsepower each of the front wheels receives. Under full straight line acceleration, unless extreme wheelspin is seen by the computer (if it was raining, for example) the drivers would get maximum boost.
• With the ability to send power on demand to each of the front wheels as they can handle it, all of the drivers likened the Hybrid to having all-wheel-drive. Everyone I spoke to on the team is praying for a torrential downpour in the race.
• Brake pad wear is greatly reduced on the Hybrid, allowing the team to use more aggressive ‘sprint race’ pads rather than the usual endurance pads because the electric motors help to slow the car under braking while they receive their charge. The braking assist aspect of the electric motors was not something they expected to have such a big influence in brake pad life.
• With the rather sizable electric motor housing taking up space where the fuel cell normally lives, Porsche was forced to develop a dual cell arrangement. Dr. Armbruster reports that the normal cell was reduced to 80 liters, while a smaller, 40-liter box-like cell was produced Premier Fuel Systems that sits in the passenger foot well.
• Determining the optimum electromechanical output of the electrical motors was done externally by a German university, according to Dr. Armbruster.
• The roof is made of magnesium, rather than carbon fiber. “It is actually lighter,” said Armbruster. “It also has better wear characteristics. It does not need repairs like carbon fiber requires.”
• Mastering the braking characteristics of the car provided the biggest headache in the beginning. Tuning the electric motors to smoothly generate power under braking – without upsetting the car’s balance – was a lengthy process, but it was an expected problem they would have to solve.
• From a handling and use standpoint, the hybrid system has helped to fix the tail heavy traits associated with Porsche’s rear-engined 911s. While Dr. Armbruster would not reveal the exact weight distribution, he did confirm that with the weight of the electric motors up front, the power converter on the left front of the car, and the extra fuel cell and flywheel in the passenger side, drivers reported the 911 GT3 R Hybrid to have a very favorable balance. “The overall behavior of the car is much better than before,” said Armbruster.
• The Hybrid has a splitter and large dive planes that were designed specifically for the car. The rear wing is a standard GT3 R unit.
• Reducing the overall weight of the Hybrid system is the next phase of the car’s development. “The additional weight of this first system does not bother us,” said Armbruster. “We learn from this and have many spare items on the car now. For the future we will look to make the system lighter and with less individual components.”
• With the Hybrid system and mild aerodynamic changes taken out of the equation, the rest of the car is a standard GT3 R. 11x18 RAYS wheels are used up front, with 13x18’s at the rear. Michelin 27/65-18 fronts and 31/71-18 rears are fitted.
• The standard GT3 R weighs 2640 pounds. The car tips the scales at almost 3000 pounds with the hybrid systems in place.
• While softer pads are used, the rest of the brake package is the same, with six-piston calipers and 380mm discs up front, and four-piston calipers and 355mm discs at the rear. ABS is used.
• The car uses Porsche’s familiar six-speed sequential transmission.
• Traction control is used.
• The combustion engine is powered by E10 Ethanol.
• The combination of the Williams flywheel and the fuel cell filling the passenger side of a racing car takes some getting used to. The flywheel housing looks like a mix of “Back to the Future” and the kind of device Jack Bauer would spend a season trying to find and defuse on “24.”
Driving the Hybrid
From the cockpit, Patrick Long -- America’s lone Porsche factory pilot – says the Hybrid is a shot in the arm to GT racing and to Porsche’s DNA:
“What I didn’t expect was how intuitive the car was. The ABS knows what I want as a driver. Next, I expected the boosting to be a gradual thing. I thought it would be like switching to an overtake map where you get some extra power, but not a lot. The first time I used it, it was WAY more than that. It gives you a BIG shot of power. The car is already quick, and when you add the power boost, it’s just amazing.
“The next part of my first impression was that using the system is very strategic. The system isn’t always charged when you want it, depending on when you were on the brakes, so I found myself driving and thinking of how to best use the extra power – to be wise with how you use it. On each lap I was looking at what speeds it might work best, what kind of grip you have available on the track in certain corners, and so on. It isn’t just a magic button that makes the car do whatever you want. If you have some understeer on the exit of a corner and call for the boost, it’s going to make the car push even worse, so you definitely have to be very present when you are driving and look to find the sections of the track or the situation with other cars where it can help you. It’s there to help, but you have to think about when you use it, so I like that. It doesn’t take the skill of driving out of your hands; you’re engaged and working with the hybrid power the entire time.
“Compared to my 911 GT3 RSR, you can feel the extra weight when the Hybrid’s not boosting. But it’s more technical to drive and I like that. You have to be very precise and smooth. You have big tires and you can’t abuse them in the Hybrid, but with the system acting like four-wheel-drive, you get better tire wear too. I’m not a fan of a tiny lightweight car with big power that you can throw around whenever you want – a car where the bravest guy wins. I like a car that you have to methodically drive and manage it through a corner, and that’s what the Hybrid wants. It’s a very harmonious car to drive. It has this incredible hybrid system in it, but it doesn’t take away the feel of the car or dumb things down. Driving a racing car should never be easy and the Hybrid maintains that challenge.”
The Future
The educational aspects of 911 GT3 R Hybrid project serve as the primary motivation for Porsche. While most manufacturers race for glory – to promote their cars through competition – Porsche considers the Hybrid to be a first step in an ongoing development process. As they look to incorporate more hybrid technology into their road cars, Dr. Armbruster says to keep an eye on their GT racing exploits. Every other model they choose to go racing with is used to drive sales, but how they fare with the Hybrid is less about spraying champagne and celebrating victories, and more about pioneering new technology that will find its way onto the showroom floor.
“If you see the new Porsche 918 Spyder, it also has a hybrid system but it is a battery car so it can be plugged in. My team at Porsche Motorsport is working very close with the 918 team. We have been requested, for example, to carry out torque vectoring testing for them with our 911 Hybrid. The battery and flywheel systems are different in so many ways, but there are also many similarities in how the performance is given to the driver. These areas we can develop in conjunction with each other immediately. I think in the future, you will see many [hybrid] systems that are developed first in Porsche Motorsport for our customer cars. Porsche's history is always to create new innovations, and this is why we do this with the 911 Hybrid today.”
Marshall Pruett is SPEED.com’s Auto Racing Editor, and also covers IndyCar and sportscar racing for the site. Pruett grew up at ‘Pruett's Olde English Garage,’ his father's shelter for abused foreign cars, and spent his childhood being dragged across the West Coast to help with his dad's amateur racing exploits.
Pruett spent 20 years working in the IRL, CART, IMSA, and most of the known open-wheel feeder series before retiring from active duty in 2001. And in case you were wondering, he isn’t related to Scott Pruett.
Marshall lives in Northern California with his wife Shabral, and can be emailed HERE. He can also be harassed on Twitter .
http://vimeo.com/15347381
http://vimeo.com/15364329
http://vimeo.com/15364002
http://auto-racing.speedtv.com/artic...t3-r-hybrid/P1
ALMS: Inside The Porsche 911 GT3 R Hybrid
It doesn’t use a battery. It draws technology from F1. It handles like an AWD car. And with an extra 160hp on tap, it simply flies. Meet Porsche’s racing hybrid.
Marshall Pruett | Posted September 29, 2010
History, the Hybrid Concept and Execution
Sportscar racing has been the source of dozens of innovations over the past century, but in the last 10 years, the majority of the ground-breaking developments have centered on lowering emissions, pioneering the use of new fuels and exploring hybrid technologies.
The American Le Mans Series has been a regular test bed for factories and privateers to try their hand at finding an advantage that delivers faster lap times while going farther on a tank of fuel, or, in a perfect world, going farther on less fuel while leaving a smaller carbon footprint.
From Panoz introducing their Q9 hybrid-electric sports racer in 1998 to the Nasamax team entering a Reynard-Cosworth powered by bio-ethanol in 2003 to Taurus Sport fielding the first diesel-powered prototype at Le Mans in 2004, many teams have dreamt while climbing a proverbial mountain of obstacles along the way.
As so often happens, the foundation of a good idea is usually taken and perfected by the second or third party to embrace an unproven concept. After the modest efforts by Nasamax and Taurus Sport, diesel-powered prototypes have dominated the LMP1 category in the ALMS and at Le Mans since 2006, and nearly one-third of the field for this Saturday’s 13th annual Petit Le Mans will compete using Cellulosic E85 Ethanol.
Rather than fill the car with batteries, Porsche opted for a unique solution within GT racing by partnering with the Williams F1 team to bring their KERS flywheel unit to the 911 GT3 R Hybrid. (Porsche)
The one main area of development that has been lacking is in the use of hybrid drive systems, and despite valiant efforts by the Panoz Q9 and the underfunded efforts of the Corsa Motorsports team and their battery-based Zytek hybrid prototype, the concept needed the budget and commitment from a major manufacturer to extract its potential.
All of that changed with Porsche’s announcement that they would use their competition department to explore and advance hybrid technology through sportscar racing, but rather than go the familiar route with a sports prototype, they elected to build from their familiar GT racing heritage by using a brand-new GT3 R chassis to push their boundaries of knowledge and innovation. From there, the Porsche 911 GT3 R Hybrid project was born.
Hybrid technology is nothing new in the automotive world, with cars like the Toyota Prius and Honda Element making use of combustion engines and battery-based electric-assisted engines, but getting away from battery dependence is still in its early phases. Porsche also offers a battery-based hybrid with its Cayenne S model, yet rather than locking it away in a private laboratory, they chose to start down the path of a battery-less hybrid in the world of endurance racing.
The rigors and demands of sportscar racing, along with the aspirational qualities of marrying a flywheel-based hybrid to a proven GT car was a challenge the company could not overlook, according to Dr. Daniel Armbruster, Porsche’s Manager of Motorsport Development Systems.
“Why did we decide to do this car? To develop high-power hybrid systems. We have to design for the future. We also have to look at how to reduce CO2 production. Most [battery-powered hybrid] systems today have only 60 kilowatts of power (approximately 80 horsepower). Our goal was to develop a hybrid system that had more performance, and had to give people great emotions about what we are trying to do. When we looked at the Porsche 911, we [thought] this would be the perfect car to use to make a better hybrid system that is truly about performance, not just to use what is common elsewhere. We build the race version of this to learn at a very fast rate.”
To create this mobile testing environment, Porsche chose their 911-based GT3 R racing chassis -- a bigger version of the popular GT3 S Cup car – that started its life on the Porsche production line. The company’s familiar practice of transforming their street cars into purebred GT racing cars continued with the Hybrid, yet a major re-think of how to combine their FIA GT3-spec chassis and a non-traditional hybrid into a functional racing car would first have to take place.
The Formula One series allowed the use of Kinetic Energy Recovery Systems (KERS) in 2009 to mixed results, with battery-based units proving to be the most popular solution. The Williams F1 team, however, went in a different direction by designing a flywheel-based KERS system that stores and releases energy without the use of a battery.
While the various mechanical and electrical systems that operate the Porsche/Williams system are highly complex, how the unit receives energy, turns it into electrical power and delivers it right back to the front wheels at the push of a button is rather simple.
Located between the front wheels is the power generation and delivery unit -- essentially two electric motors that sit in a common housing with reduction gears -- that was designed by Porsche. Halfshafts, made by GKN, connects the left motor to the left wheel, and the right motor to the right wheel. When the wheels rotate the halfshafts spin the electric motor, creating an electric charge under braking.
To prevent hybrid race cars from delivering a continual power boost, the electric motors are only permitted to generate electricity and send it to the flywheel under braking. Drivers have anywhere from 6-8 seconds of boost on tap until the system is recharged once again under braking.
The Porsche Hybrid system follows a system of electric-to-kinetic-to-electric, where electricity is generated at the front wheels, is then sent to the Williams unit where it powers up the flywheel to spin up to 40,000 rpms and becomes kinetic energy. With the flywheel continuing to spin -- acting as a power generator that waits in anticipation of delivering power back to the two front electric motors -- the push of a button on the steering wheel converts the kinetic energy back into electricity and returns it to the front wheels, providing a combined 160 horsepower from the two motors.
The cycle of braking --> boosting --> braking works in a continual loop in the same manner that the electric motors build an electrical charge --> send it to the flywheel for storage --> and receive it back to drive the front wheels. The combination of hybrid power feeding the front wheels while Porsche's 4.0 liter, 480 horsepower flat six-cylinder engine delivers its grunt to the rear wheels provides prodigious amounts of forward momentum.
With all of the new technology and power at play, the Hybrid will race by itself in the ‘Grand Touring Hybrid’ (GTH) class this weekend during Petit Le Mans. While the Hybrid weighs considerably more than the cars in GT2, it also provides a lot more power – about 140 horsepower with the combustion engine and electric motors combined – making it impossible to fit the car into a normal class structure.
Piloted by the trio that won the 2010 24 Hours of Le Mans overall for Audi – Timo Bernhard, Romain Dumas and Mike Rockenfeller – Porsche Motorsport has an amazing line-up to showcase the car during Saturday’s 10-hour/1000-kilometer race.
Just how it will fare against the more developed GT cars is unknown, but it’s safe to say the Hybrid has brought an element of excitement and unpredictability that was otherwise lacking from the race to develop hybrid technologies in sportscar competition.
With a 480 horsepower combustion engine in the back and twin 80 horsepower electric motors up front, the Hybrid puts down 640 angry ponies when called upon. (Marshall Pruett)
The ALMS will be conducting its season finale Saturday while the IZOD IndyCar Series holds its finale on the Homestead-Miami oval. If you want to appreciate the difference in technology between the two series, know that while the IndyCar drivers will have their own ‘Push to Pass’ button that delivers a set limit of 20 uses of less than 20 horsepower – a barely noticeable difference, the Porsche Hybrid drivers will have full use of their ‘Push to Pass’ button throughout the 10-hour race with the kick of an extra 160 horsepower pushing them deeper into the seat. Those 160 horses also come without sending any additional emissions into the atmosphere.
When it comes to putting the most ponies to the ground at the push of a button, that war is being won at Petit Le Mans. If you’re looking for more displays of extreme engineering and technology this Saturday, tune into SPEED at 11 a.m. ET to watch the Hybrid and the rest of the 45-car field battle with every type of engine, fuel and electrical system imaginable.
Inside the Hybrid
Digging deeper into the car and its systems, the Porsche 911 GT3 R Hybrid is a techno geek’s dream:
• The Williams flywheel unit itself is a marvel of engineering. Constructed from Magnetically Loaded Composite (MLC), Williams has done away with the use of a metal flywheel – something that would be easy to magnetically charge – and have fabricated a lighter flywheel out of carbon fiber that is infused with a magnetic powder. The carbon flywheel has proven to be a significant improvement over its metal predecessors, offering better resistance to heat and to electrical charge losses.
• Williams produces their ‘Williams Hybrid Power’ units for custom applications to a variety of customers – this isn’t an off-the-shelf item. The Hybrid unit was designed to a specification provided by Porsche Motorsport.
• Special air intakes are mounted on the body in front of the rear wheels which feed oil coolers that circulate oil to and from the flywheel. Dr. Armbruster says the flywheel unit is kept at 50 degrees C (120 degrees F).
• A large shroud encompasses the flywheel unit when the car is on the track. Dr. Armbruster mentioned that the system uses dry ice situated in a container on top of the unit to aid cooling, and up to three three-inch hoses feed air to the cooling and containment box.
• Having a flywheel the diameter of a Frisbee spinning at 40,000 rpms while mounted to the car would seem like something that wanted to act like a gyroscope, bur Dr. Armbruster mentioned that although the data acquisition sees small traces of the flywheel’s rotational movement on the G sensors, the forces are negligible but due damping within the flywheel housing.
• With so many extra cooling systems and so much space taken by the hybrid componentry, the ACO has given Porsche a special dispensation to race the car without the mandated air conditioning unit.
• The power converter unit – another Porsche design – sits under the front bonnet of the Hybrid. It acts as the go-between from the electric motors to the flywheel. It takes the AC charge from the motors, converts it to DC and sends it to the flywheel. From the flywheel, the DC is then converted back to AC before it is sent to the electric motors to give the 160 horsepower boost.
• The converters generate a massive amount of heat on their own, so Porsche incorporated a cooling system into the unit. A large central radiator is used specifically for the converters. The flat-six engine uses separate water radiators.
• The one downside of the Hybrid system – at least in traditional racing terms – is the extra weight it adds to the car. With all of the systems extra motors, the various electronic control units, the flywheel unit itself, the driveshafts and the wiring, Dr. Armbruster estimates an additional 150 kilos (330 pounds) are on board, if not more. That’s the size of your average NFL defensive lineman.
• The software that controls the Hybrid system was designed in-house by Porsche.
• The traditional data acquisition system is provided by Motec – standard issue on Porsche’s customer racing cars. Motec also provides the Power Control Module (PCM) and telemetry system.
• The wiring for the Hybrid is based on the RS Spyder LMP2 loom. Dr. Armbruster was unable to quantify how much extra wiring the Hybrid carries over an ALMS GT2-spec Porsche, but it appears to be somewhere in the range of 50 percent by visual comparison.
• Like a differential in a transmission, Porsche has designed their software and electronics to receive wheel speed input, throttle input, lateral Gs and steering input to calculate how much power to send to each wheel while the car is cornering. This is all processed with their “Hybrid Control Unit” (HCU). Based on conditions, cornering forces or throttle application, the system will vary how much of the 80 horsepower each of the front wheels receives. Under full straight line acceleration, unless extreme wheelspin is seen by the computer (if it was raining, for example) the drivers would get maximum boost.
• With the ability to send power on demand to each of the front wheels as they can handle it, all of the drivers likened the Hybrid to having all-wheel-drive. Everyone I spoke to on the team is praying for a torrential downpour in the race.
• Brake pad wear is greatly reduced on the Hybrid, allowing the team to use more aggressive ‘sprint race’ pads rather than the usual endurance pads because the electric motors help to slow the car under braking while they receive their charge. The braking assist aspect of the electric motors was not something they expected to have such a big influence in brake pad life.
• With the rather sizable electric motor housing taking up space where the fuel cell normally lives, Porsche was forced to develop a dual cell arrangement. Dr. Armbruster reports that the normal cell was reduced to 80 liters, while a smaller, 40-liter box-like cell was produced Premier Fuel Systems that sits in the passenger foot well.
• Determining the optimum electromechanical output of the electrical motors was done externally by a German university, according to Dr. Armbruster.
• The roof is made of magnesium, rather than carbon fiber. “It is actually lighter,” said Armbruster. “It also has better wear characteristics. It does not need repairs like carbon fiber requires.”
• Mastering the braking characteristics of the car provided the biggest headache in the beginning. Tuning the electric motors to smoothly generate power under braking – without upsetting the car’s balance – was a lengthy process, but it was an expected problem they would have to solve.
• From a handling and use standpoint, the hybrid system has helped to fix the tail heavy traits associated with Porsche’s rear-engined 911s. While Dr. Armbruster would not reveal the exact weight distribution, he did confirm that with the weight of the electric motors up front, the power converter on the left front of the car, and the extra fuel cell and flywheel in the passenger side, drivers reported the 911 GT3 R Hybrid to have a very favorable balance. “The overall behavior of the car is much better than before,” said Armbruster.
• The Hybrid has a splitter and large dive planes that were designed specifically for the car. The rear wing is a standard GT3 R unit.
• Reducing the overall weight of the Hybrid system is the next phase of the car’s development. “The additional weight of this first system does not bother us,” said Armbruster. “We learn from this and have many spare items on the car now. For the future we will look to make the system lighter and with less individual components.”
• With the Hybrid system and mild aerodynamic changes taken out of the equation, the rest of the car is a standard GT3 R. 11x18 RAYS wheels are used up front, with 13x18’s at the rear. Michelin 27/65-18 fronts and 31/71-18 rears are fitted.
• The standard GT3 R weighs 2640 pounds. The car tips the scales at almost 3000 pounds with the hybrid systems in place.
• While softer pads are used, the rest of the brake package is the same, with six-piston calipers and 380mm discs up front, and four-piston calipers and 355mm discs at the rear. ABS is used.
• The car uses Porsche’s familiar six-speed sequential transmission.
• Traction control is used.
• The combustion engine is powered by E10 Ethanol.
• The combination of the Williams flywheel and the fuel cell filling the passenger side of a racing car takes some getting used to. The flywheel housing looks like a mix of “Back to the Future” and the kind of device Jack Bauer would spend a season trying to find and defuse on “24.”
Driving the Hybrid
From the cockpit, Patrick Long -- America’s lone Porsche factory pilot – says the Hybrid is a shot in the arm to GT racing and to Porsche’s DNA:
“What I didn’t expect was how intuitive the car was. The ABS knows what I want as a driver. Next, I expected the boosting to be a gradual thing. I thought it would be like switching to an overtake map where you get some extra power, but not a lot. The first time I used it, it was WAY more than that. It gives you a BIG shot of power. The car is already quick, and when you add the power boost, it’s just amazing.
“The next part of my first impression was that using the system is very strategic. The system isn’t always charged when you want it, depending on when you were on the brakes, so I found myself driving and thinking of how to best use the extra power – to be wise with how you use it. On each lap I was looking at what speeds it might work best, what kind of grip you have available on the track in certain corners, and so on. It isn’t just a magic button that makes the car do whatever you want. If you have some understeer on the exit of a corner and call for the boost, it’s going to make the car push even worse, so you definitely have to be very present when you are driving and look to find the sections of the track or the situation with other cars where it can help you. It’s there to help, but you have to think about when you use it, so I like that. It doesn’t take the skill of driving out of your hands; you’re engaged and working with the hybrid power the entire time.
“Compared to my 911 GT3 RSR, you can feel the extra weight when the Hybrid’s not boosting. But it’s more technical to drive and I like that. You have to be very precise and smooth. You have big tires and you can’t abuse them in the Hybrid, but with the system acting like four-wheel-drive, you get better tire wear too. I’m not a fan of a tiny lightweight car with big power that you can throw around whenever you want – a car where the bravest guy wins. I like a car that you have to methodically drive and manage it through a corner, and that’s what the Hybrid wants. It’s a very harmonious car to drive. It has this incredible hybrid system in it, but it doesn’t take away the feel of the car or dumb things down. Driving a racing car should never be easy and the Hybrid maintains that challenge.”
The Future
The educational aspects of 911 GT3 R Hybrid project serve as the primary motivation for Porsche. While most manufacturers race for glory – to promote their cars through competition – Porsche considers the Hybrid to be a first step in an ongoing development process. As they look to incorporate more hybrid technology into their road cars, Dr. Armbruster says to keep an eye on their GT racing exploits. Every other model they choose to go racing with is used to drive sales, but how they fare with the Hybrid is less about spraying champagne and celebrating victories, and more about pioneering new technology that will find its way onto the showroom floor.
“If you see the new Porsche 918 Spyder, it also has a hybrid system but it is a battery car so it can be plugged in. My team at Porsche Motorsport is working very close with the 918 team. We have been requested, for example, to carry out torque vectoring testing for them with our 911 Hybrid. The battery and flywheel systems are different in so many ways, but there are also many similarities in how the performance is given to the driver. These areas we can develop in conjunction with each other immediately. I think in the future, you will see many [hybrid] systems that are developed first in Porsche Motorsport for our customer cars. Porsche's history is always to create new innovations, and this is why we do this with the 911 Hybrid today.”
Marshall Pruett is SPEED.com’s Auto Racing Editor, and also covers IndyCar and sportscar racing for the site. Pruett grew up at ‘Pruett's Olde English Garage,’ his father's shelter for abused foreign cars, and spent his childhood being dragged across the West Coast to help with his dad's amateur racing exploits.
Pruett spent 20 years working in the IRL, CART, IMSA, and most of the known open-wheel feeder series before retiring from active duty in 2001. And in case you were wondering, he isn’t related to Scott Pruett.
Marshall lives in Northern California with his wife Shabral, and can be emailed HERE. He can also be harassed on Twitter .
07-02-2011, 05:25 AM
#2
Burning Brakes
