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I have a 2007 AWD Chrysler 300C Hemi. Never again will I have a car that is not AWD. It has saved me countless times in bad weather, with a much more solid handling feel and the ability to plow through snow.
Unless you have some kind of special application, a FWD car with good snow tires is all you would need most places in Massachusetts. AWD is kind of useless on black ice and just gives you a false sense of security. Any standard size sedan with Nokian Hakka R2's or Blizzak's is going to perform better than an AWD car with stock tires. If you tow, then 4wd and body-on-frame is very useful on the boat ramp. If you deal with dirt roads and parking lots during mud month, some ground clearance helps but that's not a 300C.
What Porsche has done is combine the automatic wizadry of a sophisticated AWD system with the rugged toughness of a locking 4x4 system, and still refer to it as AWD.
It's not just Porsche. Range Rover, Acura, BMW xDrive, Jeep Quadra systems and their latest Select Trac (I think that's the most current?) all have AWD systems that have some form of torque vectoring... which no 4x4 can do. They also have the added ability to function as a 4x4 for offroad. However, at their heart, they are all considered AWD systems by the manufacturers.
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Originally Posted by dpm1
If you dont use the presence a locking center diff as the defining part of a 4x4 what exactly do you use?
Having the ability to lock the center diff is a benefit of some modern AWD systems. That function alone does not define what type of drivetrain it is. If it was, then every system using a locking diff would be called 4x4 and not AWD. Yet no manufacturer does this, because they know their systems are more advanced than that.
It's not just Porsche. Range Rover, Acura, BMW xDrive, Jeep Quadra systems and their latest Select Trac (I think that's the most current?) all have AWD systems that have some form of torque vectoring... which no 4x4 can do. They also have the added ability to function as a 4x4 for offroad. However, at their heart, they are all considered AWD systems by the manufacturers.
Having the ability to lock the center diff is a benefit of some modern AWD systems. That function alone does not define what type of drivetrain it is. If it was, then every system using a locking diff would be called 4x4 and not AWD. Yet no manufacturer does this, because they know their systems are more advanced than that.
So how do you define 4x4? A locking center diff is the only difference between AWD and 4wd.
Yes, simulating lockers improves AWD. This is why 4x4s used for heavy off roading pretty much always have lockers. The vectoring is hardly unique to AWD tho. Limted slip differentials, brake driven systems,clutch driven systems are in use on 4x4s as well as AWD and FWD/RWD vehicles.
It's not just Porsche. Range Rover, Acura, BMW xDrive, Jeep Quadra systems and their latest Select Trac (I think that's the most current?) all have AWD systems that have some form of torque vectoring... which no 4x4 can do. They also have the added ability to function as a 4x4 for offroad. However, at their heart, they are all considered AWD systems by the manufacturers.
Exactly. I was not implying that Porsche was the only one, it was just the vehicle used in the discussion. However these vehicles tend to be more expensive, and again - we are talking about someone who may only occasionally venture offroad. The irony of it all is that most of these big expensive SUVs with these very sophisticated All/4WD systems NEVER GO OFFROAD.
Their manufacturers can "consider" them whatever their marketing department tells them will be pleasing to the ears of most of their buyers. AWD sounds smarter, especially when you tack a word like "Symmetrical" or "intelligent" or "Super Handling" in front of it. 4WD sounds like cheap redneck pickup truck. We have to convince these owners that they are justified for buying these types of vehicles which will most likely never leave the pavement after all.
Quote:
Having the ability to lock the center diff is a benefit of some modern AWD systems. That function alone does not define what type of drivetrain it is. If it was, then every system using a locking diff would be called 4x4 and not AWD. Yet no manufacturer does this, because they know their systems are more advanced than that.
Again, they can call it whatever they want. I'm pretty sure in some other countires even the most simplest, cheapest lowliest form of AWD is referred to uniformly as 4WD. Marketing works differently in this country.
There are a few different kinds of AWD systems and we are on different pages. I was referring to a more symmetrical AWD system, while you were going more selective.
Our thinking is effectively the same: in bad conditions all four wheels should be engaged. This can be done by the driver (4x4) or automatically by the car in a selective/variable mode (the AWD you described). With 4x4 though, a low range is included.
What I was saying I didn't like was driving a symmetrical AWD vehicle in dry conditions. With a variable system like you described, the computer would not engage the front axle so it would effectively be 2WD as well.
With Supercars and AWD: When you have a crazy amount of hp, you NEED AWD just to be able to actually get that power down on the road. All 2wd would do is smoke the back tires.
then why on a specific hurrican model with 100 oe so more hp than standard, they converted it to rwd "because of power output?" new dodge viper, 800hp, rwd.
You are ignoring the fact that there is no locking center diff in AWD. You have a slipping wheel all power goes to the slipping wheel and HOPEFULLY your traction control is sufficient for the job if not good luck getting out. This is why full time 4x4s have the option of a locked center diff in 4 high. And AWD system with a center diff than can be locked is a 4x4.
4x4 locks the center diff ensuring each axle receives equal power so if on axle is slipping the other can pull. 4x4 does not (often) have locking axle diffs without locking axle diffs if one wheel on each axle is spinning good luck getting anywhere. 4x4 is superior to AWD. When torque and traction is required any artificial wheel lock tends to fail.
Ultimately all the OP needs to do is watch where they drive and keep on keeping on in the FWD vehicle. AWD/4x4 offers little benefit in a standard car on pavement.
Uhhhh.... depends on the awd system. Sure a viscous coupling doesn't lock, but a car with a torsen center diff can have that option. An awd with lockable center diff is not a 4x4, unlike that, awd is usually always active, and even with a controller to control degree of operation, is not deactivatable(word?) which is the point of awd- it's always there, at least when needed, in reference to part time systems. some 4x4s may not have lockers, but some have f/r lsd's- which is something blthe better awds have, if not, usually the t/c and abs controls the power direction, versus purely mechanical systems.
If you dont use the presence a locking center diff as the defining part of a 4x4 what exactly do you use? AWD MUST have an open diff if it is to be operating 24/7 or it would grenade itself in a week.
No, they need a limited slip center diff- which all symetrical systems, or systems like them have. see; an awd system is variable, so even with a locking center diff, as long as the front wheels can turn at different speeds. which is why most awd systems can also...run staggered wheel sizes.
Unless you have some kind of special application, a FWD car with good snow tires is all you would need most places in Massachusetts. AWD is kind of useless on black ice and just gives you a false sense of security. Any standard size sedan with Nokian Hakka R2's or Blizzak's is going to perform better than an AWD car with stock tires. If you tow, then 4wd and body-on-frame is very useful on the boat ramp. If you deal with dirt roads and parking lots during mud month, some ground clearance helps but that's not a 300C.
until one puts snowtires on an awd car, any drive system is crap on black ice, so that's a moot point, unless...maybe..you have a halftrack. Those cars are on a mercedes chassis, therefore have 4Matic, which is a good awd system. saw one last winter slip a rear wheel, and the front wheel enguaged, and dragged itself until the rear wheels gripped.
No, they need a limited slip center diff- which all symetrical systems, or systems like them have. see; an awd system is variable, so even with a locking center diff, as long as the front wheels can turn at different speeds. which is why most awd systems can also...run staggered wheel sizes.
SOME (most these days) AWD systems have a manner in which to lock the diff, it is not however a requirement to be AWD. An completely open diff AWD would act like this. https://www.youtube.com/watch?v=68lEFjjG798
(yes there is osmething wrong with that car, just the first example I could find. 3 open diffs + one loose wheel = stuck )
Subaru has a much more effective capacity to sort of lock the center diff than most AWD vehicles.
The downfall of AWD is when torque is needed. When that happens most AWD systems cannot send enough torque to the axle that needs it. Locking the center diff (4x4) makes it happen.
Note how the cars with an open center diff lose traction when the front wheels are removed from the ground. And that the cars with limted slip or other torque vectoring systems do not get stuck when only one axle have spinning wheels. . The beemer at 6 minutes is AWD but dows not have any torque vectoring in the center diff.
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