all-wheel-drive vs rear wheel drive
01-08-2012, 01:55 PM
#81
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Notch, the axis of rotation is the rear wheels, and the vette actually has more weight in between its wheels than a mid-rear; engine and gearbox within wheelbase, with a mid-rear setup the gearbox (unless its a purpose built race car) extends past the rear axle. AWD wont happen regardless.
01-08-2012, 03:36 PM
#82
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I believe the car will generally rotate around its CG.
I'd like to see the data on that. The weight of the respective engine and transmission is of course important, as is the specific location of each with regard to the center point of the referenced wheels. I believe that the LP570-4 V12 is probably heavier than the Vette's V8, and I believe the Audi R8 5.2 FSI V10 is also heavier than the Vette's engine. These engine weights are offset by the weight of the transmissions, but I don't think the entire transmission is behind the rear wheels (I'd have to look at each of them to see).
I'd like to see the data on that. The weight of the respective engine and transmission is of course important, as is the specific location of each with regard to the center point of the referenced wheels. I believe that the LP570-4 V12 is probably heavier than the Vette's V8, and I believe the Audi R8 5.2 FSI V10 is also heavier than the Vette's engine. These engine weights are offset by the weight of the transmissions, but I don't think the entire transmission is behind the rear wheels (I'd have to look at each of them to see).
01-08-2012, 04:33 PM
#83
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They might. However, I am sure more than a few believe it is a front engined resign, just as some think a Ferrari is a rear engined car. Neither would be correct. Words have meaning, without using them correctly you cannot ensure your statements are clear. You use of traditional mid-engined is fairly recent. Most early autombiles were mid-engined and not mounted behind the driver.
Why would someone just as well think they mean that they want the engine in the middle of the car?
Do you remember when vans had mid-engines behind/between the seats and front weight bias? I do.
They should say what they mean, and they should understand the facts.
Why would someone just as well think they mean that they want the engine in the middle of the car?
Do you remember when vans had mid-engines behind/between the seats and front weight bias? I do.
They should say what they mean, and they should understand the facts.
mid·en·gine
[mid-en-juhn] Show IPA
adjective Automotive .
of or pertaining to a configuration in which the engine is located behind the driver and between the front and rear wheels:
Corvette is an FMR (front mid-engine/rear wheel drive) design.
And while I agree words have meaning, my wife is an English teacher and I am a published author, being blatantly obtuse to try to one up someone in a debate is unworthy.
And still, there have been a lot of forces mentioned that would explain why a Corvette would benefit from a traditional mid-engine (RMR layout) but no actual explanation. Sure, everyone knows it works best on F1 cars, but how does that relate to a street sports car?
And the weight distribution on a Corvette C6 officially is 50/50 on some models and 51/49 on others. I have the spec sheet from GM here somewhere, just not handy at the moment. From different magazine reviews, depending on model, it ranges from 52/48 to 49/51.. With the Z06 usually listed at 50/50 but the ZR1 usually listed at 51/49
01-08-2012, 07:34 PM
#84
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The conventional definition of mid-engine is
mid·en·gine
[mid-en-juhn] Show IPA
adjective Automotive .
of or pertaining to a configuration in which the engine is located behind the driver and between the front and rear wheels:
Corvette is an FMR (front mid-engine/rear wheel drive) design.
And while I agree words have meaning, my wife is an English teacher and I am a published author, being blatantly obtuse to try to one up someone in a debate is unworthy.
And still, there have been a lot of forces mentioned that would explain why a Corvette would benefit from a traditional mid-engine (RMR layout) but no actual explanation. Sure, everyone knows it works best on F1 cars, but how does that relate to a street sports car?
And the weight distribution on a Corvette C6 officially is 50/50 on some models and 51/49 on others. I have the spec sheet from GM here somewhere, just not handy at the moment. From different magazine reviews, depending on model, it ranges from 52/48 to 49/51.. With the Z06 usually listed at 50/50 but the ZR1 usually listed at 51/49
mid·en·gine
[mid-en-juhn] Show IPA
adjective Automotive .
of or pertaining to a configuration in which the engine is located behind the driver and between the front and rear wheels:
Corvette is an FMR (front mid-engine/rear wheel drive) design.
And while I agree words have meaning, my wife is an English teacher and I am a published author, being blatantly obtuse to try to one up someone in a debate is unworthy.
And still, there have been a lot of forces mentioned that would explain why a Corvette would benefit from a traditional mid-engine (RMR layout) but no actual explanation. Sure, everyone knows it works best on F1 cars, but how does that relate to a street sports car?
And the weight distribution on a Corvette C6 officially is 50/50 on some models and 51/49 on others. I have the spec sheet from GM here somewhere, just not handy at the moment. From different magazine reviews, depending on model, it ranges from 52/48 to 49/51.. With the Z06 usually listed at 50/50 but the ZR1 usually listed at 51/49
Many have explained why a mid-rear configuration is better. The difference is less pronounced in most normal driving conditions on the street unlees the weight bias is severe or the conditions are severe. They manfest themselves more when you get abouve 7/10ths driving.
What has not been discussed is disadvantages of that configuaration for normal daily street driving.
01-08-2012, 07:41 PM
#85
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01-08-2012, 07:53 PM
#87
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However, the main disadvantage would be a need to move to something other than leaf spring in the rear.
Losing the weigh of torque tube could be quite devastating as well...If this ever happens, the vette would be in the double digit designation though, maybe C14, C15?
01-08-2012, 10:44 PM
#88
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The mid-rear configuration is less safe in head on collision. This is normally the most deadly, and with the mass behind the passenger compartmentit changes the crash dynamics. A mass in motion tends to stay in motion. Your are now between the massive engine and the immovable object you ran into. you are soft and squishy, the engine is not.
Rear weight bias tends to cause oversteer and sometimes "snap oversteer", these are less contollable by an inexperienced driver. In a high powered car it can be worse. Lift oversteer can be a problem, most people on determining that they are going to fast in a turn lift the throttle, which with the rear weight bias can cause oversteer.
Cooling of the engine can often be a problem, espeically in traffic. Droning and NVH can be a problem depending configuration and construction.
Where is your gas tank? In the front, the most common place for severe deformation in the worst wrecks? In the back next to the engine, a good source of ignition in case of a ruptured tank?
No configuration is ideal for everything in every situation.
Rear weight bias tends to cause oversteer and sometimes "snap oversteer", these are less contollable by an inexperienced driver. In a high powered car it can be worse. Lift oversteer can be a problem, most people on determining that they are going to fast in a turn lift the throttle, which with the rear weight bias can cause oversteer.
Cooling of the engine can often be a problem, espeically in traffic. Droning and NVH can be a problem depending configuration and construction.
Where is your gas tank? In the front, the most common place for severe deformation in the worst wrecks? In the back next to the engine, a good source of ignition in case of a ruptured tank?
No configuration is ideal for everything in every situation.
Last edited by Racer X; 01-08-2012 at 11:12 PM.
01-09-2012, 12:15 AM
#89
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The mid-rear configuration is less safe in head on collision. This is normally the most deadly, and with the mass behind the passenger compartmentit changes the crash dynamics. A mass in motion tends to stay in motion. Your are now between the massive engine and the immovable object you ran into. you are soft and squishy, the engine is not.
Rear weight bias tends to cause oversteer and sometimes "snap oversteer", these are less contollable by an inexperienced driver. In a high powered car it can be worse. Lift oversteer can be a problem, most people on determining that they are going to fast in a turn lift the throttle, which with the rear weight bias can cause oversteer.
Cooling of the engine can often be a problem, espeically in traffic. Droning and NVH can be a problem depending configuration and construction.
Where is your gas tank? In the front, the most common place for severe deformation in the worst wrecks? In the back next to the engine, a good source of ignition in case of a ruptured tank?
No configuration is ideal for everything in every situation.
However, there are some that offer more performance oriented solution than others, including weight savings.
01-09-2012, 10:44 PM
#92
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Are you sure about it? I think you may be way off on this one, due to physics... What you need up front is a CRUMPLE zone, not a rigid object transfer to momentum transfer. I call you out on this one based on the same laws of physics you just quoted.
.............
Again, advances in safety engineering. Seems like the car most commonly associated with this problem, was Ford Pinto, with the tank in the rear, right behind rear bumper. Rear collisions are just as common as front end collisions. Also, cars come with front safety structures and location of the tank tends to be well past initial impact zone. Incidentally, have you ever considered the battery location in Z06 and ZR1? Just as dangerous as gas tank.
Exactly However, there are some that offer more performance oriented solution than others, including weight savings.
.............
Again, advances in safety engineering. Seems like the car most commonly associated with this problem, was Ford Pinto, with the tank in the rear, right behind rear bumper. Rear collisions are just as common as front end collisions. Also, cars come with front safety structures and location of the tank tends to be well past initial impact zone. Incidentally, have you ever considered the battery location in Z06 and ZR1? Just as dangerous as gas tank.
Exactly
However, there are some that offer more performance oriented solution than others, including weight savings.The cooling issue may not be as great as it was but it still exists. There is just more room for a larger radiator in front, and the longer coolant lines are more prone to damage. That is solved in some cars due to coolant running through the frame, but I am not sure I like that idea either.
On the tank issue there are mitigations and solutions. My point is we always talk about the advantages, but there are disadvantages. Nothing is perfect. All work fine in normal low stress street driving. The problems come up in near the edge performance situations, bad conditions, and emergency situations. The ones that come up in emergency situations with normal human responses are the most problematic.
Back on topic, since I am an add lightness minded guy, AWD is not the solution I prefer for any sports car.
01-10-2012, 12:56 AM
#94
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Having had a Lotus Elise with a beautifully designed crash structure, there are some things that can mitigate the risks. However when your feet reach almost to the centerline of the front wheels, and having seenn enough wrecks with the front wheels pushed back I still have concerns. I think the problems are more with head ons due to higher closing speeds and theings like head ons in to poles and walls where the front doesn't have enogh mass to shear the pole or punch through the walls and the engine keeps moving towards the pole. Also I have seen more Ferraris and Lamborghini with the rear end sheared when hitting a pole or such, than I seen Corveete with the front end sheared, and there are a lot more Corvettes. I think it has to due with the dynamics oversteering inherent in a rear weight bias that causes more spins or partial spins. No doubt there are a lot of rear collisions, but they tend to less severe on average.
The cooling issue may not be as great as it was but it still exists. There is just more room for a larger radiator in front, and the longer coolant lines are more prone to damage. That is solved in some cars due to coolant running through the frame, but I am not sure I like that idea either.
On the tank issue there are mitigations and solutions. My point is we always talk about the advantages, but there are disadvantages. Nothing is perfect. All work fine in normal low stress street driving. The problems come up in near the edge performance situations, bad conditions, and emergency situations. The ones that come up in emergency situations with normal human responses are the most problematic.
Back on topic, since I am an add lightness minded guy, AWD is not the solution I prefer for any sports car.
The cooling issue may not be as great as it was but it still exists. There is just more room for a larger radiator in front, and the longer coolant lines are more prone to damage. That is solved in some cars due to coolant running through the frame, but I am not sure I like that idea either.
On the tank issue there are mitigations and solutions. My point is we always talk about the advantages, but there are disadvantages. Nothing is perfect. All work fine in normal low stress street driving. The problems come up in near the edge performance situations, bad conditions, and emergency situations. The ones that come up in emergency situations with normal human responses are the most problematic.
Back on topic, since I am an add lightness minded guy, AWD is not the solution I prefer for any sports car.
And the rest, we are just exchanging ideas and wishful thinking, I have no illusion GM would even consider mid engined vette at this time or ever, if they did, they would have done it back in the 70's. IMO, this is a great shame but this is just my opinion.
