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Great Corvette, Cadillac and 24 Hours of LeMans wining driver Andy Pilgrim, explains that the supposed 50-50 weight distribution perfection model, is really not. Thanks to CorvetteOnLIne for this wonderful article. If you have not yet found CorvetteOnLine, it nicely and thankfully appears in my daily email inbox.
Thank you Andy Bolig/CorvetteOnLine for the following excellent article:
https://www.corvetteonline.com/featu...gine-corvette/
Thank you Andy Bolig/CorvetteOnLine for the following excellent article:
https://www.corvetteonline.com/featu...gine-corvette/
Originally posted by corvetteonline
Andy Pilgrim Explains The Benefits Of A Mid-Engine Corvette
By ANDY BOLIG FEBRUARY 21, 2019
https://www.corvetteonline.com/featu...gine-corvette/
The concept of a mid-engine Corvette has been passed around the halls of Chevrolet for decades. Zora Arkus-Duntov was a key proponent in the push to move the engine rearward in America’s beloved two-seater. Ever since the first generation Corvette, Zora was exploring the benefits, using his clout within Chevrolet to build and test vehicles with a mid-mounted engine. Up until the C5 Corvette came on the scene with its near “perfect” 50/50 weight distribution, Chevrolet always seemed to have a test-bed, mid-engine Corvette prototype dangling in front of the public view.
Corvette started out with a very conventional front-engine design, but it wasn’t long before engineers were looking at alternative locations for their engines.
All that seemed to change when Chevrolet was able to better limit the weight on the front wheels by mounting the C5 Corvette’s transmission in the rear of the car, directly in front of the differential. This opened up Corvette to the world as a perfectly-balanced sports car with the highly sought-after 50/50 weight bias. The new design put the engine as far rearward as possible while still being accessible by a front-opening hood.
It seemed that since Corvette was now tipping the scales so evenly, the thought of moving the engine back with the transmission was shelved. There are likely several reasons why Chevrolet could have deemed the move unnecessary. Undoubtedly, the main reason was the enormous cost of re-engineering Corvette to a mid-engine format. Beyond that, improvements to vehicle control systems and Corvette Racing’s dominance on the racetracks around the globe were a testament to the effectiveness of the front engine design.
The C5 Corvette platform was introduced in 1997. The same basic configuration has carried over to both C6 and C7 generations of Corvette. Each generation improved on the basic design and brought about better control, refinement, and performance potential. The increase in performance may be the very reason Corvette needs to be a mid-engine design with the next generation ‘Vette.
We recently had a conversation with Andy Pilgrim. Long-time Corvette enthusiasts will recall Andy was one of the original drivers of the Corvette Racing team on the C5-R Corvette. He is now a valued consultant and team member for the National Corvette Museum and the NCM Motorsports Park in Bowling Green, Kentucky. Andy has extensive experience driving front-, mid-, and rear-engine cars in both competition and on the street. Check out the Racing Sports Cars website for a growing list of cars Andy has wielded around the apexes in competition. Andy is also an excellent instructor in both driving safety and performance driving. We asked Andy to help us understand, given Corvette’s current 50/50 weight ratio, what more could a mid-engine configuration bring to Corvette.
A MORE Perfect 50/50
We’ve grown accustomed to touting Corvette’s “perfect” 50/50 weight ratio, but there’s actually more to it than dividing front and rear parts equally. “It’s all about physics,” Andy says. “You have to look at things like the vehicle’s center of gravity as well as weight distribution. Things like the height of weight distribution/CG [center of gravity] can have a profound effect on a car’s handling. Beyond that, other characteristics such as a car’s polar moment [resistance to change direction] can change the way a car performs. It’s all VERY important.”
In 1964, Chevrolet created the XP-819 concept car that had the engine hanging off the back, much like a Porsche. The Corvette Indy was created in 1986 with a much more mid-engine design.
Andy explains the concept of polar moment so well by using a simple broom as an example. “Grab the handle end of a broom and try to swing it. It doesn’t want to change direction hardly at all. Grab in the middle of the handle and it’s easier, but still quite hard. But if you twist near the brush end, it changes direction much more easily.”
It’s the same when shifting the placement of an engine – you’re moving that polar moment. When you place mass in the middle, instead of the outer points of the car, it is much easier to turn. So much so, that the car’s newfound willingness to change direction can become a stability issue. The car can become super-responsive, to the point of being quite twitchy. Andy explains though, “The engineers can fix all that! That’s what they work on.”
When the C5 (and subsequent C6 and C7) hit the streets, it was touted as having a near-perfect 50/50 weight bias. While distributed evenly among the front and rear wheels, there were still better ways to carry the weight. Photo: GM Archives
Another consideration is how high the car’s center of gravity is from the road surface. Andy explained how a move to mid-engine would solve several issues that have plagued Corvettes. “I’ve learned an incredible amount from engineers, but I’m not an engineer. I’ve learned that with a front-engine configuration, you’ve got a ton of stuff packed around the engine. You need to connect the front wheels with steering, which typically resides under part of the engine. That means you can’t get the engine down low enough. With a mid-engine, you can lower the engine and have a ton of space to do what you want with the suspension/steering.” Our ears perked up as he (without prodding) further explains why this is important: “Now you’ve got the room to put alternate power up front.” We like the sound of that!
Pursuit, Or Result Of Performance?
Corvette engineers have devised some ingenious ways to harness Corvette’s power potential throughout the years, but subtle refinements to a car’s chassis cannot outrun exponential increases to its engine’s horsepower output. Recently, we have seen horsepower numbers soar with the C6, and now C7 ZR1 and Z06 Corvettes. With horsepower numbers nestled snugly amid super-car status, it could be said that Corvette’s chassis configuration was left wanting. A scenario that Andy knows all too well.
Andy Pilgrim was selected for Corvette Racing’s first factory ALMS effort in the 1999 Corvette C5-R. He has since driven various race cars for GM. He resides in Bowling Green, Kentucky and offers driving safety and performance driving instruction at the NCM Motorsports Park. Photo: NCM Motorsports Park
“The current Grand Sport is superb on the racetrack. It’s a well-balanced package and you can utilize ALL of it,” he adds. “I can be extremely aggressive with a Z06 or ZR1; I know what they’ll do. But with the additional power of the Z06 and ZR1, after a hot lap or two, they totally over-drive the tires. Even in a straight line, cars with 250 less horsepower can out-power a ZR1 for loss of traction.”
The move to mid-engine would place the weight of the engine more on the rear tires, which would help with traction in severe acceleration situations. How severe you ask? Andy is confident that a mid-engine Corvette could be quite capable of breaking the 3-second 0-60 barrier! A feat not even possible with a front engine, mass-produced car.
On the downside, moving the engine to the car’s mid-section can also benefit its braking. Andy explains, “Once braking starts, it can unsettle the rear in a front-engine car. With the mass further back, you can be more aggressive on both the front and the rear, as the rear brakes will be able to do more work. It’s all dependent on how the engineers set up the suspension.”
A mid-engine car can also offer more stability in an extreme braking event, both in a straight line and while turning. Having driven everything from the extremely overpowered, front-heavy (57 Front/43 Rear) Hellcat Red Eye to the rear-engine 911 at their limits, Andy shares his thoughts on what he thinks that means for the mid-engine Corvette. “It’s decreased polar moment means it is more resistant to understeer, but also should be a more stable platform, as forces occur equally at both ends of the car. It should feel INCREDIBLY stable!” Andy says.
A mid-engine layout puts the engine directly mounted to the transmission in the rearward part of the car. This aids in traction and lowers the car’s polar moment, or resistance to changes in direction. The result is a more agile, better turning car. Photo: MidEngineCorvetteForum.com A Different Driving Style
We asked Andy what the different driving characteristics of a mid-engine Corvette may mean to the Corvette enthusiast. Would it require a complete change in driving style? He assured us that any learning curve would be full of benefits for both the average Corvette driver or seasoned veteran track star.
He explains, “Whether on-track or on the street, with a front-engine car, the front tires will warm up quickly while the rear tires will take more time. With a rear engine car, there’s obviously more weight on the rear tires, which is essentially safer even when tires are cold. A mid-engine configuration balances between both scenarios.”
He goes on to explain, with the mid-engine car’s lower polar moment, the front will react quicker, meaning the driver will notice that the car is more responsive to turning input of the steering wheel. In a sense, the car will give you more of what you want, the driver simply needs to be aware of the car’s improved responsiveness. Of course, engineers seek to capitalize on the benefits and limit any unwanted characteristics.
Andy confides this is all part of the suspension setup. “It’s not simple” he explains. “It’s quite complicated. But the general consensus is, it will be a better handling vehicle and have much greater potential for a quick racing vehicle.” Other Benefits of the Move
There are other concerns when designing a mid-engine street car. Corvette buyers like a car that has storage space. A mid-engine layout makes that more difficult, and brings new design challenges for engineers. “Today’s Corvette is a street car, and buyers like the utility of the current Corvette,” Andy states. “It will be interesting to see how they have addressed that with a mid-engine Corvette. I’d be stunned if they did not address storage!”
These leaked CAD drawings help show how the engine/trans will be nestled over the rear cradle for the suspension. Swapping storage from the rear to the front allows a lot of area for improved chassis geometry and other items, but doesn't help with where to put the golf clubs. Photos: MidEngineCorvetteForum.com
His experience in driving other mid-engine cars assures him that Corvette owners will soon cozy up to some of the inherent benefits besides performance. “Corvettes have always had that big hood out front, and with this car, that all changes. The windshield will be expansive and you’ll have a panoramic view of the world around you. You won’t have a big hood out in front, which tends to help the driver feel more in control.”
Overall, there should be a safer feeling, as they can drive and see things better. The short hood has a lot of benefits. Along with the amazing view, it helps give a totally different driving experience. I think enthusiasts are going to love it!”
As we ended our conversation, it was clear that Andy is just as enthusiastic as the rest of us to experience the car first-hand. He understands Corvette’s roots and heritage, but also knows what it takes to stay on top of the competition. He sees the move to mid-engine as a natural progression of improving the car’s performance, but also acknowledges that it is a bold step.
“There’s a history there,” he says. “It’s a huge risk, but you’ve got to give a hats-off to any company that takes on this task. There aren’t many sub $100,000 mid-engine sports cars out there, yet it affords much greater potential for a quick racing vehicle. It will be able to run up with the best! It’s gonna be great!”
By ANDY BOLIG FEBRUARY 21, 2019
https://www.corvetteonline.com/featu...gine-corvette/
The concept of a mid-engine Corvette has been passed around the halls of Chevrolet for decades. Zora Arkus-Duntov was a key proponent in the push to move the engine rearward in America’s beloved two-seater. Ever since the first generation Corvette, Zora was exploring the benefits, using his clout within Chevrolet to build and test vehicles with a mid-mounted engine. Up until the C5 Corvette came on the scene with its near “perfect” 50/50 weight distribution, Chevrolet always seemed to have a test-bed, mid-engine Corvette prototype dangling in front of the public view.
Corvette started out with a very conventional front-engine design, but it wasn’t long before engineers were looking at alternative locations for their engines.
All that seemed to change when Chevrolet was able to better limit the weight on the front wheels by mounting the C5 Corvette’s transmission in the rear of the car, directly in front of the differential. This opened up Corvette to the world as a perfectly-balanced sports car with the highly sought-after 50/50 weight bias. The new design put the engine as far rearward as possible while still being accessible by a front-opening hood.
It seemed that since Corvette was now tipping the scales so evenly, the thought of moving the engine back with the transmission was shelved. There are likely several reasons why Chevrolet could have deemed the move unnecessary. Undoubtedly, the main reason was the enormous cost of re-engineering Corvette to a mid-engine format. Beyond that, improvements to vehicle control systems and Corvette Racing’s dominance on the racetracks around the globe were a testament to the effectiveness of the front engine design.
The C5 Corvette platform was introduced in 1997. The same basic configuration has carried over to both C6 and C7 generations of Corvette. Each generation improved on the basic design and brought about better control, refinement, and performance potential. The increase in performance may be the very reason Corvette needs to be a mid-engine design with the next generation ‘Vette.
We recently had a conversation with Andy Pilgrim. Long-time Corvette enthusiasts will recall Andy was one of the original drivers of the Corvette Racing team on the C5-R Corvette. He is now a valued consultant and team member for the National Corvette Museum and the NCM Motorsports Park in Bowling Green, Kentucky. Andy has extensive experience driving front-, mid-, and rear-engine cars in both competition and on the street. Check out the Racing Sports Cars website for a growing list of cars Andy has wielded around the apexes in competition. Andy is also an excellent instructor in both driving safety and performance driving. We asked Andy to help us understand, given Corvette’s current 50/50 weight ratio, what more could a mid-engine configuration bring to Corvette.
A MORE Perfect 50/50
We’ve grown accustomed to touting Corvette’s “perfect” 50/50 weight ratio, but there’s actually more to it than dividing front and rear parts equally. “It’s all about physics,” Andy says. “You have to look at things like the vehicle’s center of gravity as well as weight distribution. Things like the height of weight distribution/CG [center of gravity] can have a profound effect on a car’s handling. Beyond that, other characteristics such as a car’s polar moment [resistance to change direction] can change the way a car performs. It’s all VERY important.”
In 1964, Chevrolet created the XP-819 concept car that had the engine hanging off the back, much like a Porsche. The Corvette Indy was created in 1986 with a much more mid-engine design.
Andy explains the concept of polar moment so well by using a simple broom as an example. “Grab the handle end of a broom and try to swing it. It doesn’t want to change direction hardly at all. Grab in the middle of the handle and it’s easier, but still quite hard. But if you twist near the brush end, it changes direction much more easily.”
It’s the same when shifting the placement of an engine – you’re moving that polar moment. When you place mass in the middle, instead of the outer points of the car, it is much easier to turn. So much so, that the car’s newfound willingness to change direction can become a stability issue. The car can become super-responsive, to the point of being quite twitchy. Andy explains though, “The engineers can fix all that! That’s what they work on.”
When the C5 (and subsequent C6 and C7) hit the streets, it was touted as having a near-perfect 50/50 weight bias. While distributed evenly among the front and rear wheels, there were still better ways to carry the weight. Photo: GM Archives
Another consideration is how high the car’s center of gravity is from the road surface. Andy explained how a move to mid-engine would solve several issues that have plagued Corvettes. “I’ve learned an incredible amount from engineers, but I’m not an engineer. I’ve learned that with a front-engine configuration, you’ve got a ton of stuff packed around the engine. You need to connect the front wheels with steering, which typically resides under part of the engine. That means you can’t get the engine down low enough. With a mid-engine, you can lower the engine and have a ton of space to do what you want with the suspension/steering.” Our ears perked up as he (without prodding) further explains why this is important: “Now you’ve got the room to put alternate power up front.” We like the sound of that!
Pursuit, Or Result Of Performance?
Corvette engineers have devised some ingenious ways to harness Corvette’s power potential throughout the years, but subtle refinements to a car’s chassis cannot outrun exponential increases to its engine’s horsepower output. Recently, we have seen horsepower numbers soar with the C6, and now C7 ZR1 and Z06 Corvettes. With horsepower numbers nestled snugly amid super-car status, it could be said that Corvette’s chassis configuration was left wanting. A scenario that Andy knows all too well.
Andy Pilgrim was selected for Corvette Racing’s first factory ALMS effort in the 1999 Corvette C5-R. He has since driven various race cars for GM. He resides in Bowling Green, Kentucky and offers driving safety and performance driving instruction at the NCM Motorsports Park. Photo: NCM Motorsports Park
“The current Grand Sport is superb on the racetrack. It’s a well-balanced package and you can utilize ALL of it,” he adds. “I can be extremely aggressive with a Z06 or ZR1; I know what they’ll do. But with the additional power of the Z06 and ZR1, after a hot lap or two, they totally over-drive the tires. Even in a straight line, cars with 250 less horsepower can out-power a ZR1 for loss of traction.”
The move to mid-engine would place the weight of the engine more on the rear tires, which would help with traction in severe acceleration situations. How severe you ask? Andy is confident that a mid-engine Corvette could be quite capable of breaking the 3-second 0-60 barrier! A feat not even possible with a front engine, mass-produced car.
On the downside, moving the engine to the car’s mid-section can also benefit its braking. Andy explains, “Once braking starts, it can unsettle the rear in a front-engine car. With the mass further back, you can be more aggressive on both the front and the rear, as the rear brakes will be able to do more work. It’s all dependent on how the engineers set up the suspension.”
A mid-engine car can also offer more stability in an extreme braking event, both in a straight line and while turning. Having driven everything from the extremely overpowered, front-heavy (57 Front/43 Rear) Hellcat Red Eye to the rear-engine 911 at their limits, Andy shares his thoughts on what he thinks that means for the mid-engine Corvette. “It’s decreased polar moment means it is more resistant to understeer, but also should be a more stable platform, as forces occur equally at both ends of the car. It should feel INCREDIBLY stable!” Andy says.
A mid-engine layout puts the engine directly mounted to the transmission in the rearward part of the car. This aids in traction and lowers the car’s polar moment, or resistance to changes in direction. The result is a more agile, better turning car. Photo: MidEngineCorvetteForum.com A Different Driving Style
We asked Andy what the different driving characteristics of a mid-engine Corvette may mean to the Corvette enthusiast. Would it require a complete change in driving style? He assured us that any learning curve would be full of benefits for both the average Corvette driver or seasoned veteran track star.
He explains, “Whether on-track or on the street, with a front-engine car, the front tires will warm up quickly while the rear tires will take more time. With a rear engine car, there’s obviously more weight on the rear tires, which is essentially safer even when tires are cold. A mid-engine configuration balances between both scenarios.”
He goes on to explain, with the mid-engine car’s lower polar moment, the front will react quicker, meaning the driver will notice that the car is more responsive to turning input of the steering wheel. In a sense, the car will give you more of what you want, the driver simply needs to be aware of the car’s improved responsiveness. Of course, engineers seek to capitalize on the benefits and limit any unwanted characteristics.
Andy confides this is all part of the suspension setup. “It’s not simple” he explains. “It’s quite complicated. But the general consensus is, it will be a better handling vehicle and have much greater potential for a quick racing vehicle.” Other Benefits of the Move
There are other concerns when designing a mid-engine street car. Corvette buyers like a car that has storage space. A mid-engine layout makes that more difficult, and brings new design challenges for engineers. “Today’s Corvette is a street car, and buyers like the utility of the current Corvette,” Andy states. “It will be interesting to see how they have addressed that with a mid-engine Corvette. I’d be stunned if they did not address storage!”
These leaked CAD drawings help show how the engine/trans will be nestled over the rear cradle for the suspension. Swapping storage from the rear to the front allows a lot of area for improved chassis geometry and other items, but doesn't help with where to put the golf clubs. Photos: MidEngineCorvetteForum.com
His experience in driving other mid-engine cars assures him that Corvette owners will soon cozy up to some of the inherent benefits besides performance. “Corvettes have always had that big hood out front, and with this car, that all changes. The windshield will be expansive and you’ll have a panoramic view of the world around you. You won’t have a big hood out in front, which tends to help the driver feel more in control.”
Overall, there should be a safer feeling, as they can drive and see things better. The short hood has a lot of benefits. Along with the amazing view, it helps give a totally different driving experience. I think enthusiasts are going to love it!”
As we ended our conversation, it was clear that Andy is just as enthusiastic as the rest of us to experience the car first-hand. He understands Corvette’s roots and heritage, but also knows what it takes to stay on top of the competition. He sees the move to mid-engine as a natural progression of improving the car’s performance, but also acknowledges that it is a bold step.
“There’s a history there,” he says. “It’s a huge risk, but you’ve got to give a hats-off to any company that takes on this task. There aren’t many sub $100,000 mid-engine sports cars out there, yet it affords much greater potential for a quick racing vehicle. It will be able to run up with the best! It’s gonna be great!”
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