Showing posts with label Hybrid Electric Corvette. Show all posts
Showing posts with label Hybrid Electric Corvette. Show all posts

Saturday, August 6, 2016

Long Rumored Mid-Engine Corvette Coming In 2019

Rumors of a mid-engine Corvette have been floating around for decades. In theory, putting the mass of the engine near the center of a car improves handling. Why? Because it allows the car to turn and change direction more quickly. Let’s try a little experiment to see if that’s true.
Mid-engine Corvette

Take a 4 feet long stick and attach a one pound weight to the front of it. Hold the stick in the center with one hand and turn it left and right. Your wrist will tell you it takes some effort to get the stick moving. When you try to turn it back the other way, it takes more effort to get it to stop turning one way and start turning the other. You have just discovered what scientists call the polar moment of inertia.
 Congratulations, you have simulated the handling characteristics of a 1954 Buick, the one that featured “Advanced Thrust” because engineers had moved the engine as far forward in the chassis as possible.
Now turn the stick around so the weight is in the back. One again, your wrist will tell you the weight makes it hard to start moving the stick in one direction and hard to get it to stop moving in that direction and turn back the other way. This time you have simulated the handling of early Porsches, which had the engine as far back as possible in the chassis.
Now put the weight in the center of the stick. Suddenly, you can twirl it one way and then the other with ease. The polar moment of inertia has been reduced almost to zero. A car built this way would be perfectly balanced, ready to eat up any curve that comes its way. It would be instantly responsive to the driver’s commands. That’s the theory, anyway.
In reality, things are much more complex. There are heavy items like the chassis, brakes, transmission, windows, doors, people, and luggage that keep any car from being perfectly balanced. But putting the engine — the heaviest component of all — in the middle of the car helps make the finished product as well balanced as possible.
Sources tell the Detroit News, “It’s happening. Mark Reuss wants it,” referring to the automaker’s global product development chief. “It’s the worst kept secret in town.” Bob Lutz, formerly the head honcho at GM, says the car was actually approved back in 2007 but the infamous corporate bankruptcy forced it onto the back burner. He thinks the mid-engine configuration could open up the possibility of adding electric motors to the front wheels of the car for limited all wheel drive capability and an overall fuel economy rating approaching 80 mpg city.
Such an electrified Corvette would be similar to the new Acura NSX and the Ferrari LaFerrari but cost much less. Corvette has always offered supercar performance at a relatively affordable price.
Corvette buyers are getting older. A plug-in hybrid electric car could appeal to younger customers or it could drive away the Corvette faithful. The car has remained basically the same since 1953 — a front engine, rear wheel drive, two seat sports car using a pushrod internal combustion engine. Jeep struck out when it dropped round headlights. Harley Davidson owners gave the cold shoulder to the technically brilliant V-Rod because it didn’t sound right. New Coke was the biggest disaster in marketing history.
Will Corvette buyers accept a mid-engine car? That remains to be seen. The design concept by Car and Driver — with its enormous flying buttresses — is quite unappealing, especially compared to the daringly swoopy seventh generation Corvette in showrooms today. It will be interesting to see what sort of package the designers come up with for the new mid-engine Corvette. Look for it to break cover in 2018, if the rumors are true.

Long Rumored Mid-Engine Corvette Coming In 2019

Rumors of a mid-engine Corvette have been floating around for decades. In theory, putting the mass of the engine near the center of a car improves handling. Why? Because it allows the car to turn and change direction more quickly. Let’s try a little experiment to see if that’s true.
Mid-engine Corvette
Mid-engine Corvette design concept by Car and Driver
Take a 4 feet long stick and attach a one pound weight to the front of it. Hold the stick in the center with one hand and turn it left and right. Your wrist will tell you it takes some effort to get the stick moving. When you try to turn it back the other way, it takes more effort to get it to stop turning one way and start turning the other. You have just discovered what scientists call the polar moment of inertia.
 Congratulations, you have simulated the handling characteristics of a 1954 Buick, the one that featured “Advanced Thrust” because engineers had moved the engine as far forward in the chassis as possible.
Now turn the stick around so the weight is in the back. One again, your wrist will tell you the weight makes it hard to start moving the stick in one direction and hard to get it to stop moving in that direction and turn back the other way. This time you have simulated the handling of early Porsches, which had the engine as far back as possible in the chassis.
Now put the weight in the center of the stick. Suddenly, you can twirl it one way and then the other with ease. The polar moment of inertia has been reduced almost to zero. A car built this way would be perfectly balanced, ready to eat up any curve that comes its way. It would be instantly responsive to the driver’s commands. That’s the theory, anyway.
In reality, things are much more complex. There are heavy items like the chassis, brakes, transmission, windows, doors, people, and luggage that keep any car from being perfectly balanced. But putting the engine — the heaviest component of all — in the middle of the car helps make the finished product as well balanced as possible.
Sources tell the Detroit News, “It’s happening. Mark Reuss wants it,” referring to the automaker’s global product development chief. “It’s the worst kept secret in town.” Bob Lutz, formerly the head honcho at GM, says the car was actually approved back in 2007 but the infamous corporate bankruptcy forced it onto the back burner. He thinks the mid-engine configuration could open up the possibility of adding electric motors to the front wheels of the car for limited all wheel drive capability and an overall fuel economy rating approaching 80 mpg city.
Such an electrified Corvette would be similar to the new Acura NSX and the Ferrari LaFerrari but cost much less. Corvette has always offered supercar performance at a relatively affordable price.
Corvette buyers are getting older. A plug-in hybrid electric car could appeal to younger customers or it could drive away the Corvette faithful. The car has remained basically the same since 1953 — a front engine, rear wheel drive, two seat sports car using a pushrod internal combustion engine. Jeep struck out when it dropped round headlights. Harley Davidson owners gave the cold shoulder to the technically brilliant V-Rod because it didn’t sound right. New Coke was the biggest disaster in marketing history.
Will Corvette buyers accept a mid-engine car? That remains to be seen. The design concept by Car and Driver — with its enormous flying buttresses — is quite unappealing, especially compared to the daringly swoopy seventh generation Corvette in showrooms today. It will be interesting to see what sort of package the designers come up with for the new mid-engine Corvette. Look for it to break cover in 2018, if the rumors are true.

Sunday, April 5, 2015

Hybrid Electric Corvette Design Study

BarraVette
What’s the hottest hybrid sports car: The Porsche 918 Spyder, the BMW i8?….and how much do they cost? In the case of the Porsche don’t even ask. You can’t afford it. The i8 is attainable for those that can afford to spend 100,000+ on a novel sports car.
But what about GM? We all know that the current Corvette offers a maximum bang for the buck in the performance department compared to the exotics. Could GM bring this same design philosophy to an electric hybrid version of the Corvette? If they did, what configuration would it be?

A Look at the Competition

It’s always good to know what you are up against. What are the details of the Porsche 918 Spyder and the BMW i8 power trains?
Slide1
The 918 is an mid engine AWD with an electric front axle. The ICE is a V8 mounted lengthwise ahead of the rear transaxle. Sandwiched between the V8 and the transaxle is an electric motor. The transaxle gearbox is a conventional 7 speed. A battery sits cross wise in the car behind the driver’s seat. The front and rear inverters are separate units instead of integrated ones in the gen 2 Volt.
Slide2
The i8 is also a mid engine AWD with an electric front axle. The 1.5 liter inline 3 is mounted transversely and mated to the tranaxle assembly resulting in a much more compact design than the Porsche. A belt-driven 20 horsepower motor generator is added in the rear to supply regen and to act as a starter motor. The transaxle gearbox is a conventional 6 speed. The battery runs down the tunnel of the car unlike the 918. The front electric axle incorporates a 2 speed gear box.

GM Design

One thing is clear when looking at the competition. They chose a mid engine AWD design. While some may think that the Corvette is traditionally a front engine RWD car, a mid engine design from GM is not without precedence. The father of the Corvette Zora Duntov was a big fan of mid engine AWD. In fact he designed more than 1 prototype. The most noted being the CERV II shown in figure 3.
Slide3
Knowing what the competition is doing, what technology could GM leverage to improve on the i8 and 918 designs.
Slide4
The first and simplest change is to integrate the inverters as GM has done in Gen 2 Volt. The i8 and the 918 use separate inverters.
The second improvement is to use an electric front axle utilizing a co axial gearbox as in the Spark EV. This results in a much more compact design.
The 3rd improvement is in the ICE. BMW is already talking about an M version of the i8 that uses a 4 cylinder instead of a 3 cylinder. GM should therefore just go with a turbo i4 with 2000 cc instead of a 1500 cc turbo 3 boosting power from 228 to 300 horsepower. In addition GM should mount the ICE transversely like the i8 for a more compact transaxle than the Porsche.
The 4th improvement is the biggy. Both i8 and Porsche are using conventional 6 and 7 speed gearboxes. Their transaxles are mostly ICE powered. The main electrical part is the front electric axle. This results in poor performance in EV mode. The i8 0-60 time in EV mode is only around 12 seconds.
GM should leverage Gen 2 Voltec technology in the rear transaxle assembly. This would give the electric corvette superior performance in EV mode over the i8. Existing gen 2 motors could be used. However the mechanicals such as shafts and gears would need to upgraded to handle the higher power output of the ICE.
Slide5
The performance specs of the new AWD electric Corvette are presented in figure 6.
Slide6
What is the first thing we notice in the comparison? The new Vette has a respectable 0-60 time in EV mode where the i8 does not. The Corvette has more AER. The new corvette will be a fundrive in EV mode. 4.9 seconds is just fine for everyday electric driving.
The next thing you notice is that the new Corvette blows the doors off the i8 when the ICE is on. The Corvette gets to 60 in 3.2 seconds compared to 4.5 for the i8. This is primarily a result of the whopping 557 combined horsepower when the ICE is on. In EV mode the Corvette still sports 320 horsepower compared to only 129 horsepower for the i8.
I’m sure Zora Duntov would be proud of this new AWD electric Corvette. It will provide superior performance to the i8 for tens of thousands of dollars less.

Source: GM-Volt