Interview
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Drifting
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From: Sebring FL
Interview
I apologize for the length of this interview but it has some good info in it.
Talking With Tadge Juechter, Assistant Chief Engineer
The following is an edited transcript of a recent interview with Tadge Juechter, assistant chief engineer for the Corvette.
CL: Do you think you've exceeded customer expectations in regard to the performance package and the engine of the 2005 Corvette?
TJ: I think people are going to be stunned -- not only in the absolute level of performance, but the way the car goes about it. The car has an ease to it -- a real elasticity to the powertrain where it feels like the car’s a lot lighter than it is. The engine is very "torquey," and goes about its business in a very unstressed way. The engine feels very refined, very sophisticated and it slingshots the car with very little prompting from the driver.
CL: What is behind the improved performance numbers for Corvette 2005?
TJ: The challenge we faced was to bring the Z06 level of performance to the base Coupe and Convertible. That’s what customers had been asking for since we brought out the Z06. They love the 400-horsepower engine, but they wish they could get it in an open roof configuration, either with the removable hardtop or the convertible. There’s a reason no other manufacturer has a 400- horsepower car that’s not considered a gas guzzler by the U.S. government. That's because it's very difficult to achieve that kind of performance level and not consume a lot of fuel. We brought out the first non-gas-guzzler 400-horsepower car in 2002 with the Z06 -- a car with only a manual transmission and limited option content. One of the things we wanted to do right from the start was to determine how we could get that kind of performance -- 400 horsepower -- in a car that had all the options that people expect plus some new ones, put it in both the Coupe and the Convertible body styles and offer it with an automatic transmission. Again, we brought out the Z06 in 2002 with 400 horsepower and to this day nobody can match that power output and not be considered a gas guzzler. We’re now bringing out the 2005 -- both the Coupe and the Convertible -- with any option combinations you want with no gas-guzzler tax and no stigma from the government about driving a guzzler.
CL: Can you please elaborate on the term "energy balance" and its relation to Corvette?
TJ: Energy balance means taking the vehicle attributes that contribute to fuel economy and performance and balancing them in such a way that you get the performance you want as well as the fuel efficiency you want. There are a great number of factors that affect fuel economy and performance. Obviously, the engine output is a substantial one. But the engine efficiency also contributes greatly to the fuel economy. Then the rest of the car -- the aerodynamic drag of the car, the frontal area of the car, chassis losses, which means rolling resistance both in the driveline and the tires -- all contribute very importantly to the fuel economy. Things like tires, which you normally wouldn’t think of as a big deal, are important. We had discussions with Goodyear very early to make sure they understood what we had to do in the next generation EMT tire and that it had to meet very specific rolling resistance requirements in order to enable the whole car to meet its objectives.
CL: What has been done to improve Noise, Vibration and Harshness (NVH) on the 2005 Corvette?
TJ: There are two broad categories of noise and vibration. The first one is powertrain noise and vibration. The biggest thing we did there was move to a four-point powertrain mounting system. This was initiated by the work done for the Cadillac XLR because the Cadillac needed more powertrain isolation. We elected to share that engine mounting system on the Corvette because we wanted to move the Corvette to a more premium status in terms of isolating the driver from the bad side of powertrain vibration. You want to hear the powerful performance sounds, but you don’t necessarily want to feel the engine working or feel the vibration translating through the car.
In addition to that, we wanted to reduce the noise coming from the road. If you ask a driver of a fifth-generation Corvette how you could improve the car, they’ll tell you that it's a little noisy on coarse roads. That noise makes it difficult to hear the radio without turning it up louder than people would like and conversation in the car is a little strained. So we really wanted to bring down the level of road noise substantially, which in turn also makes the car less fatiguing on a long drive. It makes the stereo sound quite a bit better when that background noise is dropped, and we focused on vocal speech frequencies around 800 hertz to make sure that the conversation within the car would occur a lot more easily. We really looked at a sm, a portion of the frequency spectrum, and tried to drive down the noise in that area.
CL: Speaking of passenger comfort, magnetic ride control seems to be a new and very impressive technology. Can you explain the technology and benefits of magnetic ride control and can you finish by explaining the two selections -- tour and sport?
TJ: Magnetic ride control was introduced with the anniversary edition two years ago. Basically, it's a computer that looks at what’s happening at all four corners of the car a thousand times per second and adjusts the damping -- in other words the applied pressure that the shock absorbers are putting on that suspension corner -- every thousandth of a second. That enables the car to understand what kind of road surface it's traveling on and to tailor the responses differently at all four corners to optimize ride quality.
As you said, there are two positions on the switch -- tour and sport. Set the switch to tour when you want to isolate yourself from the road, maximizing ride comfort. Think of it as the computer trying to keep road imperfections from the ride experience. It's almost like a magic carpet ride where you float over the road -- we call it sky hook -- where it feels as though the car is tied to the sky and not to the ground. When you throw the switch to sport, that implies that the driver wants to be more tied into the road -- he or she wants to feel what the road is doing and wants the car to follow the terrain more precisely. Sport mode also takes out some of the road imperfections to give you a decent ride quality, but it provides a sporty feel to the driving experience.
CL: How does active handling work, and what will customers notice on a vehicle with active handling?
TJ: Active handling is what we call our yaw stability system. It was introduced in 1998 and became standard in 2001. It’s been praised by the press as being the leading system of its type. It's really liked by automotive enthusiasts because it retains a very good safety net around the car while not unnecessarily intervening. We continued to refine the system during the fifth- generation time frame, and now for the 2005 Corvette we’ve retuned it entirely based on the 2005 Corvette chassis characteristic. The new tires, the new magnetic ride system and the additional suspension travel we have in this car enable us to do things we couldn’t previously do with the active handling system. Active handling senses what the driver’s asking the car to do based on steering inputs and the way that the car is actually moving. If the car starts to slide -- in other words, the driver’s asking for the car to go in a direction different than what it's actually going -- the system intervenes. It can apply brakes to any one of four corners to try to bring the car around through the braking forces to put it in the direction that the driver's really asking it to go.
CL: Talk a little about the new Z51 package.
TJ: The Z51 has been offered on Corvette for many years, going all the way back to the fourth generation. What’s new for this year is that it’s a substantially upgraded package in terms of overall performance. Traditionally, Z51 meant you got stiffer springs, bigger stabilizer bars and unique shock tuning along with some other minor coolers. It was designed to give people a sportier ride, and made the car feel a little more comfortable on the track. One thing it did not do was make the car significantly faster on the racetrack. That’s no longer true. For the 2005 Corvette, the Z51 package is a substantial upgrade. In addition to all those things I talked about on the previous package, this generation Z51 gets specific tires, and these tires combine what we learned on the Z06 supercar tire, which is not a run-flat tire. It combines that technology with the third generation of run-flat technology to create a supercar run flat. This tire has tremendously increased capability on the track. It’s a very specific tire for people who want to spend time maximizing the vehicle's performance on the track.
In addition to the tires, there is a substantial improvement in the brakes. The rotors are quite a bit larger in diameter, they're heavier and they’re cross-drilled for a performance look. They also have competition pads.
The last element of the Z51 package that’s unique for the 2005 Corvette is the manual transmission. We took the more aggressive transmission gear ratios out of the Z06 with the exception of fifth gear. We optimized fifth gear for top speed. We tooled new gear set specifically for this application that optimizes top speed at the power peak of the engine.
CL: Can you please explain performance algorithm shifting (PAS)?
TJ: Many manufacturers are applying technologies to their automatic transmissions that make them more fun to drive. One of the things we wanted to do was have the vehicle sense when the driver was driving in a sporty way and then have the transmission adjust its shift schedules to match that. The 2005 Corvette will sense if you’re on a racetrack or if you’re driving in an aggressive manor on the street. It does that by looking at steering inputs, hard braking, high cornering loads and rate of throttle application. What the transmission does then is stay in lower gears so that as you exit a corner you’re already in the low gear and you can step on it and get a nice smooth ramp-up. With regular shift patterns, as you go through a corner at less than full throttle, the car will upshift. Then when you want to go wide open as you exit a corner, it’ll have to down shift. That will put a shock into the chassis and may upset the car just as you’re exiting a corner wanting to go into a straightaway.
CL: How does the 2005 Corvette benefit from the shorter exterior dimensions?
TJ: The fifth-generation Corvette is perhaps the largest sports car in the class. Overall length it certainly is and it's nearly the widest as well. We felt that to make the car more accessible to most customers -- ease of parking, ease of placing the car in your lane, even when driving aggressively -- we had to try to compact the overall dimensions of the outside of the car while keeping everything good about the size of the inside of the car. So, the overall length was reduced by five inches in spite of the wheelbase increasing an inch and a quarter. We kept our class-leading occupant space -- we recognize that Americans like their room -- we didn’t want to sacrifice one millimeter of that.
The fifth generation also had class-leading luggage room. In fact, it's better than most midsized sedans, and our customers got used to that. A lot of Corvette buyers like to take the cars on long cross-country trips and take all their luggage with them. We kind of spoiled them by having by far the most luggage room in the class. We knew we wanted to keep that. So, we really spent a lot of time very early on optimizing the structure. For example, taking the hydro-formed rails and instead of attaching them to the back side of the front bumper beam, we actually extend them through the bumper beam to the front face, which effectively increases the crush length and also brings the bumper beam rearward relative to the driver. That’s one enabler that shortened the front overhang of the car. It’s also designed to make the car more international. We really want to be a global player.
One thing making the car shorter does not do is enable the aerodynamic performance. What that meant was we had to try harder in other areas to take the drag away from the car.
CL: What's new with the targa top this year?
TJ: One of the other attributes we really wanted to make better on the car was the open air experience with the targa top and removable roof coupe. We did that by taking the roof bow -- the pillar behind the driver's head -- and leaning that back. That made the roof opening three inches bigger. We also knew we didn’t want to make the roof itself any harder to handle. So, we concentrated really hard with our suppliers to optimize the magnesium frame that supports that roof to try to take weight out of it. As a result, even though the roof is three inches longer, it’s actually lighter than the roof it replaces. Storing the roof was also something we wanted to improve. In the fifth-generation Corvette, the roof stores down on the floor between the rear wheel wells. We wanted to store it up high and horizontal in the rear compartment, enabling all the luggage room below. We mounted the attachment provisions for the top up on top of the wheel wells and then enabled it to store horizontally underneath the hatch. This means when you’re on vacation with all that luggage you can now take the roof off, lay it on top of the luggage and have it securely stowed and safely drive the car.
Talking With Tadge Juechter, Assistant Chief Engineer
The following is an edited transcript of a recent interview with Tadge Juechter, assistant chief engineer for the Corvette.
CL: Do you think you've exceeded customer expectations in regard to the performance package and the engine of the 2005 Corvette?
TJ: I think people are going to be stunned -- not only in the absolute level of performance, but the way the car goes about it. The car has an ease to it -- a real elasticity to the powertrain where it feels like the car’s a lot lighter than it is. The engine is very "torquey," and goes about its business in a very unstressed way. The engine feels very refined, very sophisticated and it slingshots the car with very little prompting from the driver.
CL: What is behind the improved performance numbers for Corvette 2005?
TJ: The challenge we faced was to bring the Z06 level of performance to the base Coupe and Convertible. That’s what customers had been asking for since we brought out the Z06. They love the 400-horsepower engine, but they wish they could get it in an open roof configuration, either with the removable hardtop or the convertible. There’s a reason no other manufacturer has a 400- horsepower car that’s not considered a gas guzzler by the U.S. government. That's because it's very difficult to achieve that kind of performance level and not consume a lot of fuel. We brought out the first non-gas-guzzler 400-horsepower car in 2002 with the Z06 -- a car with only a manual transmission and limited option content. One of the things we wanted to do right from the start was to determine how we could get that kind of performance -- 400 horsepower -- in a car that had all the options that people expect plus some new ones, put it in both the Coupe and the Convertible body styles and offer it with an automatic transmission. Again, we brought out the Z06 in 2002 with 400 horsepower and to this day nobody can match that power output and not be considered a gas guzzler. We’re now bringing out the 2005 -- both the Coupe and the Convertible -- with any option combinations you want with no gas-guzzler tax and no stigma from the government about driving a guzzler.
CL: Can you please elaborate on the term "energy balance" and its relation to Corvette?
TJ: Energy balance means taking the vehicle attributes that contribute to fuel economy and performance and balancing them in such a way that you get the performance you want as well as the fuel efficiency you want. There are a great number of factors that affect fuel economy and performance. Obviously, the engine output is a substantial one. But the engine efficiency also contributes greatly to the fuel economy. Then the rest of the car -- the aerodynamic drag of the car, the frontal area of the car, chassis losses, which means rolling resistance both in the driveline and the tires -- all contribute very importantly to the fuel economy. Things like tires, which you normally wouldn’t think of as a big deal, are important. We had discussions with Goodyear very early to make sure they understood what we had to do in the next generation EMT tire and that it had to meet very specific rolling resistance requirements in order to enable the whole car to meet its objectives.
CL: What has been done to improve Noise, Vibration and Harshness (NVH) on the 2005 Corvette?
TJ: There are two broad categories of noise and vibration. The first one is powertrain noise and vibration. The biggest thing we did there was move to a four-point powertrain mounting system. This was initiated by the work done for the Cadillac XLR because the Cadillac needed more powertrain isolation. We elected to share that engine mounting system on the Corvette because we wanted to move the Corvette to a more premium status in terms of isolating the driver from the bad side of powertrain vibration. You want to hear the powerful performance sounds, but you don’t necessarily want to feel the engine working or feel the vibration translating through the car.
In addition to that, we wanted to reduce the noise coming from the road. If you ask a driver of a fifth-generation Corvette how you could improve the car, they’ll tell you that it's a little noisy on coarse roads. That noise makes it difficult to hear the radio without turning it up louder than people would like and conversation in the car is a little strained. So we really wanted to bring down the level of road noise substantially, which in turn also makes the car less fatiguing on a long drive. It makes the stereo sound quite a bit better when that background noise is dropped, and we focused on vocal speech frequencies around 800 hertz to make sure that the conversation within the car would occur a lot more easily. We really looked at a sm, a portion of the frequency spectrum, and tried to drive down the noise in that area.
CL: Speaking of passenger comfort, magnetic ride control seems to be a new and very impressive technology. Can you explain the technology and benefits of magnetic ride control and can you finish by explaining the two selections -- tour and sport?
TJ: Magnetic ride control was introduced with the anniversary edition two years ago. Basically, it's a computer that looks at what’s happening at all four corners of the car a thousand times per second and adjusts the damping -- in other words the applied pressure that the shock absorbers are putting on that suspension corner -- every thousandth of a second. That enables the car to understand what kind of road surface it's traveling on and to tailor the responses differently at all four corners to optimize ride quality.
As you said, there are two positions on the switch -- tour and sport. Set the switch to tour when you want to isolate yourself from the road, maximizing ride comfort. Think of it as the computer trying to keep road imperfections from the ride experience. It's almost like a magic carpet ride where you float over the road -- we call it sky hook -- where it feels as though the car is tied to the sky and not to the ground. When you throw the switch to sport, that implies that the driver wants to be more tied into the road -- he or she wants to feel what the road is doing and wants the car to follow the terrain more precisely. Sport mode also takes out some of the road imperfections to give you a decent ride quality, but it provides a sporty feel to the driving experience.
CL: How does active handling work, and what will customers notice on a vehicle with active handling?
TJ: Active handling is what we call our yaw stability system. It was introduced in 1998 and became standard in 2001. It’s been praised by the press as being the leading system of its type. It's really liked by automotive enthusiasts because it retains a very good safety net around the car while not unnecessarily intervening. We continued to refine the system during the fifth- generation time frame, and now for the 2005 Corvette we’ve retuned it entirely based on the 2005 Corvette chassis characteristic. The new tires, the new magnetic ride system and the additional suspension travel we have in this car enable us to do things we couldn’t previously do with the active handling system. Active handling senses what the driver’s asking the car to do based on steering inputs and the way that the car is actually moving. If the car starts to slide -- in other words, the driver’s asking for the car to go in a direction different than what it's actually going -- the system intervenes. It can apply brakes to any one of four corners to try to bring the car around through the braking forces to put it in the direction that the driver's really asking it to go.
CL: Talk a little about the new Z51 package.
TJ: The Z51 has been offered on Corvette for many years, going all the way back to the fourth generation. What’s new for this year is that it’s a substantially upgraded package in terms of overall performance. Traditionally, Z51 meant you got stiffer springs, bigger stabilizer bars and unique shock tuning along with some other minor coolers. It was designed to give people a sportier ride, and made the car feel a little more comfortable on the track. One thing it did not do was make the car significantly faster on the racetrack. That’s no longer true. For the 2005 Corvette, the Z51 package is a substantial upgrade. In addition to all those things I talked about on the previous package, this generation Z51 gets specific tires, and these tires combine what we learned on the Z06 supercar tire, which is not a run-flat tire. It combines that technology with the third generation of run-flat technology to create a supercar run flat. This tire has tremendously increased capability on the track. It’s a very specific tire for people who want to spend time maximizing the vehicle's performance on the track.
In addition to the tires, there is a substantial improvement in the brakes. The rotors are quite a bit larger in diameter, they're heavier and they’re cross-drilled for a performance look. They also have competition pads.
The last element of the Z51 package that’s unique for the 2005 Corvette is the manual transmission. We took the more aggressive transmission gear ratios out of the Z06 with the exception of fifth gear. We optimized fifth gear for top speed. We tooled new gear set specifically for this application that optimizes top speed at the power peak of the engine.
CL: Can you please explain performance algorithm shifting (PAS)?
TJ: Many manufacturers are applying technologies to their automatic transmissions that make them more fun to drive. One of the things we wanted to do was have the vehicle sense when the driver was driving in a sporty way and then have the transmission adjust its shift schedules to match that. The 2005 Corvette will sense if you’re on a racetrack or if you’re driving in an aggressive manor on the street. It does that by looking at steering inputs, hard braking, high cornering loads and rate of throttle application. What the transmission does then is stay in lower gears so that as you exit a corner you’re already in the low gear and you can step on it and get a nice smooth ramp-up. With regular shift patterns, as you go through a corner at less than full throttle, the car will upshift. Then when you want to go wide open as you exit a corner, it’ll have to down shift. That will put a shock into the chassis and may upset the car just as you’re exiting a corner wanting to go into a straightaway.
CL: How does the 2005 Corvette benefit from the shorter exterior dimensions?
TJ: The fifth-generation Corvette is perhaps the largest sports car in the class. Overall length it certainly is and it's nearly the widest as well. We felt that to make the car more accessible to most customers -- ease of parking, ease of placing the car in your lane, even when driving aggressively -- we had to try to compact the overall dimensions of the outside of the car while keeping everything good about the size of the inside of the car. So, the overall length was reduced by five inches in spite of the wheelbase increasing an inch and a quarter. We kept our class-leading occupant space -- we recognize that Americans like their room -- we didn’t want to sacrifice one millimeter of that.
The fifth generation also had class-leading luggage room. In fact, it's better than most midsized sedans, and our customers got used to that. A lot of Corvette buyers like to take the cars on long cross-country trips and take all their luggage with them. We kind of spoiled them by having by far the most luggage room in the class. We knew we wanted to keep that. So, we really spent a lot of time very early on optimizing the structure. For example, taking the hydro-formed rails and instead of attaching them to the back side of the front bumper beam, we actually extend them through the bumper beam to the front face, which effectively increases the crush length and also brings the bumper beam rearward relative to the driver. That’s one enabler that shortened the front overhang of the car. It’s also designed to make the car more international. We really want to be a global player.
One thing making the car shorter does not do is enable the aerodynamic performance. What that meant was we had to try harder in other areas to take the drag away from the car.
CL: What's new with the targa top this year?
TJ: One of the other attributes we really wanted to make better on the car was the open air experience with the targa top and removable roof coupe. We did that by taking the roof bow -- the pillar behind the driver's head -- and leaning that back. That made the roof opening three inches bigger. We also knew we didn’t want to make the roof itself any harder to handle. So, we concentrated really hard with our suppliers to optimize the magnesium frame that supports that roof to try to take weight out of it. As a result, even though the roof is three inches longer, it’s actually lighter than the roof it replaces. Storing the roof was also something we wanted to improve. In the fifth-generation Corvette, the roof stores down on the floor between the rear wheel wells. We wanted to store it up high and horizontal in the rear compartment, enabling all the luggage room below. We mounted the attachment provisions for the top up on top of the wheel wells and then enabled it to store horizontally underneath the hatch. This means when you’re on vacation with all that luggage you can now take the roof off, lay it on top of the luggage and have it securely stowed and safely drive the car.
