lmao

[quasi-modo]

You don't understand.

I don't?

OF COURSE AWD helps when steering on ANY road.  There   is more power to the ground & more traction w/4 wheels working.

Lets not use the term power liberally, power is energy per unit of time. Then end result of awd would be less power because more energy is lost due to friction before we talk about the kinetic energy of the wheels.

A slick road, gravel, regular clean pavement, it ALWAYS helps you when turning.  As Grok said, the only time RWD helps is in a straight away, which NEVER happens in real life

It may pull you though a turn, but that does not make it better. You cut down your acceleration and top speed with awd so it is not beneficial on your normal roads. Also I am not sliding around turns every day, If I drove awd I would see no difierence in my performance on my trip to work and school. If I raced I would still rather have a rwd car because if you take turns really fast in AWD you are basically going to be in the position of everyone else, having to slow down and accelerate towards the end of the turn. I would not have the losses of an awd car and be able to get up to speed faster when I am coming out of that turn.

[Grok]

You're taking physics too literally.  Try practically.  The differential required to put 300 HP through to a single axle is going to be larger and less efficient than two differentials with lesser requirements.  The less efficient single differential will need to be more dense, stronger, have higher heat dissipation capacity, and all around suffer greater energy losses as a percentage of the source energy provided as input.

For a practical vision, consider a light bulb.  A single light bulb consuming 100 watts does not produce as many lumens as two 50 watt light bulbs.

[quasi-modo]

You're taking physics too literally.  Try practically.  The differential required to put 300 HP through to a single axle is going to be larger and less efficient than two differentials with lesser requirements.  The less efficient single differential will need to be more dense, stronger, have higher heat dissipation capacity, and all around suffer greater energy losses as a percentage of the source energy provided as input.

But there remains the fact that a AWD car does have 2 differentials. It has one in the rear and then power is given to each front wheel individually and there is a tranfer case. Because the front wheels have to able to rotate from side to side means you are having to put the power through a greater number of gears. Then there is the whole transfer case. All of that 300hp is still going through your transfer case (tranfer gearbox) on your awd car. So either way all of the power goes through one gear box. One rwd it is the dif, on awd it is the transfer case. But on the awd you still have the dif and the front wheels.

[CrAz3D]

Why did you totally disregard Grok's info about the heat & density that is needed for the rear differential?  Also, many newer cars have independent? suspension all the way around and don't have a rear axle anymore

[quasi-modo]

Why did you totally disregard Grok's info about the heat & density that is needed for the rear differential?  Also, many newer cars have independent? suspension all the way around and don't have a rear axle anymore

I did not disreguard it and I am not disagreeing with him that there is heat. But he is saying that is because all 300 has to go through the dif. Yes on a rwd car it does, but on an awd car all of that 300 has to go through a transfer case. So, as I have been saying, you loose power in the transfer case. All awd / rwd vehicles have a transfer case. One shaft in and two shafts out. One to the front, one to the wheel. The driver may or may not have control over what it is doing depending on what he drives (a sports car is not going to allow you to turn awd off generally, but a truck is). So his argument is against all vehicles w/ 300 hp it seems, because that 300 is going to go through a gear box other after the trans no matter what kind of drive it has.

[Grok]

I am raising the possibility that the energy transformations (to heat, sound, or deformation) in a RWD exceed those energy transformations in an AWD car due to the efficiency ratings of the components involved.  Show me some measurements so we both stop guessing?

[Adron]

I don't have chains and they don't sound like a good idea to me. I thought you were only allowed to drive real slow with chains?

I don't know about real slow, but slow I'd bet.  No highway speed.  But on icy surfaces, why WOULD you be driving 80 mph's...COULD be fun, til you have to stop

Well, over here, they typically keep the highways clean, so I can go about 40 km at 130km/h. Then the last few km are on smaller roads and icy surfaces, and there I go about 30-50 km/h. Would I have to go out and put the chains on when I turned off the highway?

[CrAz3D]

I don't know.  It'd make sense to drive with chains, to me, on icy roads.

[quasi-modo]

I am raising the possibility that the energy transformations (to heat, sound, or deformation) in a RWD exceed those energy transformations in an AWD car due to the efficiency ratings of the components involved.  Show me some measurements so we both stop guessing?

Let's do this logically (I do not feel like looking on google for 45 minutes to find exactly what we would be looking for)

300hp car:
on rwd the power leaves the tranny and goes into a dif and out to the wheels.
on awd the power leaves the tranny and goes into a transfer case, then it goes into two shafts, the rear shaft takes it to a dif, the front shaft breaks off and takes power to each front wheel.

On the rwd all power must go through the dif, which means that dif is going to get pretty hot, but on an awd car all of the power goes through a trnafer case which means the case is going to get pretty hot. Either war all 300hp goes through something after the trans. My issue with awd is that after it goes through that something on awd you have power going through still more stuff. More energy is lost in the end.

[Grok]

Let's do this practically (I am one to entertain guesses, but eventually like to see reinforcement).

Find me some measurements taken on dyno at the transmission and to the wheels, comparing AWD and RWD.  That's all I ask.  Your assertion may be right.  It may be wrong.  Right now it's just a guess.

[Adron]

And I'll remind you of the logic I tried before just for kicks...

If your car doesn't go fast enough, you can give the engine more power. This can be done as long as you like, but eventually the tires will be unable to transfer more power to the ground. At that point, you have to improve that transfer, and that is best done by adding 4wd with individual control of power transfer for each wheel.

Typically you want to get a certain amount of power into the ground, to accelerate your car. You don't care as much about whether your engine is 100% efficient or not. Especially since this applies at low speeds - at higher speeds, aerodynamic losses will totally overshadow transmission losses.



Also, personally I much prefer a fwd car over a rwd for being able to drive safely under our current weather conditions. By having the driving wheels directly underneath the heavy engine I get more friction. In addition, I don't risk rear wheel spin, loss of grip and ugly skidding if I push the gas a bit too hard in a curve.

[Adron]

I don't know.  It'd make sense to drive with chains, to me, on icy roads.

I use studded tires, works fine for me

[quasi-modo]

Let's do this practically (I am one to entertain guesses, but eventually like to see reinforcement).

Find me some measurements taken on dyno at the transmission and to the wheels, comparing AWD and RWD.  That's all I ask.  Your assertion may be right.  It may be wrong.  Right now it's just a guess.

Okay, let me just find dyno results for a lancer with awd and one with rwd.... My previous post was a bit more then a guess.

[Grok]

Let's do this practically (I am one to entertain guesses, but eventually like to see reinforcement).

Find me some measurements taken on dyno at the transmission and to the wheels, comparing AWD and RWD.  That's all I ask.  Your assertion may be right.  It may be wrong.  Right now it's just a guess.

Okay, let me just find dyno results for a lancer with awd and one with rwd.... My previous post was a bit more then a guess.

You seem to think I am saying you are wrong.  That is not correct.  I am proposing an alternative viewpoint for discussion.  Our arguments about which are correct are not based on engineering, but on common sense and physics, and those typically do not take into consideration the real world.  Engineers have to do things practically, and our cars are engineered.  To test, we can guess (use predictive formulae) all day long, or we can try to create a valid situation where the only difference is RWD vs AWD, and measure the power at the engine and at the wheels of the same car.  This should give us the losses due to the drive linkages to the wheel.  Then we can go back to our formulae and assign constants to use for future guesses on other cars.

By the way, a sample size of 1 is not statistically significant, but I am sure you will concede that and we can have fun talking about efficiencies instead of confidence.

[CrAz3D]

I don't know.  It'd make sense to drive with chains, to me, on icy roads.

I use studded tires, works fine for me

Very cool, just so long as you don't end up like those people in the video posted here a week or so ago that were sliding down the road jumping out of their cars to stop it. 

I like FWD too.  It just feels better coming around corners & such, probably because I'm not totally loosing traction & fish tailing.  Also, I don't tend to spin my tires AS much since there is more weight on the powered tires.

The Pontiac GrandPrix GT I'm renting while my truck is being fixed is way fun to drive.  It has FWD.  It goes fast.  CrAz3D likes going fast.  CrAz3D accelerates to speed limit then is sad because speed limit isn't higher.

Grok, if you dyno'd the @ the wheels on both AWD & RWD wouldn't it be a little hard to compare & get a comprehendable result, since possibly ½ power is going to each set of wheel?  Would you just add the HP from both sets of wheels (on an AWD car) & compare that to a RWD.