what's the faster wagon?

What is fast, top speed or 0-60?

The '01 V70 T5 had 247 HP, and weighed 3368 lb

The '01 XC70 had 197 HP and weighed 3699 lb.

Geared properly, the T5 should definitely be faster.

In message , ~^ beancounter ~^ writes

V70R gas powered afaik.

pw

0-60 speed...and...the year i am considering is 2002 ... awd t5 vs. awd r ... right? those would be the two fastest?....i imagine the r would edge out the t5 by a bit...then it would come down to auto vs. manual tranny?

T5 is a tuned "cooking" engine, R is "Race-tuned". So car for car R must be faster all round than T5. Mind you the T5 fitted in the V50 is very very fast but that is a different model chassis.

Cheers, Peter.

peter...so, the r series is really "built to go" from the chassis up...lots of items different...i may be wiser to do the "r" series...i want a fast, solid performing wagon...that i can drive hard ocassionaly when i want....

and the weather. When the roads are rain-slickened, the AWD will be about twice as fast as the FWD. One thing that entertains me is to floor the throttle in wet weather in my XC70. I have a '01 viscous AWD and it hasn't shown a single flaw. On wet roads I can floor the throttle and not feel a single bit of slip. The Haldex is supposed to be even better.

"The Haldex is supposed to be even better. "

and the haldex starts in 2002 v70's? did it also start in 2002 for the "r" series v70's??

thanx

That is because of the torque limiting factor brought into play when the transmission senses conditions likely to promote wheel slip. It has nothing to do with the FWD wheel spin caused by a lessening of the weight on the driven wheels as the weight transfers rearwards under acceleration.

Cheers, Peter.

It might have something to do with the fact that wheel torque is limited by the traction and not the engine power, hence having maximum torque on all 4 wheels give twice as much acceleration as maximum torque on 2 wheels.

"Peter K L Milnes" wrote:

Where did you learn your physics Stephen? You don't have that much traction, which is limited by the grip of the four little footprints of tyre on the road surface. You want to see four-wheel spin? Switch off the traction control.

Cheers, Peter.

guys...is there such an animal as a 2004 or 2005 v70r...or are the r wagons only in the v60r version (in recent years)?..

thanx...

Speaking of physics, an interesting fact is that the area of the footprints of the tire have no effect on the traction, they tires could be as wide as the car and they would still slip just as easily. It's all in the weight and the frictional coefficient of the material.

I think the limitation of the theory as applied to car tires is the strength of the rubber compound. Under stress the rubber tends to tear away, reducing traction for tires that are below a threshold width (determined by the rubber compound).

Mike

At the Oregon State University and the University of Pennsylvania. I am a physicist.

That is why with twice as many tires being driven, you get twice the acceleration. It is not quite twice, since the weight distribution is not perfectly 50:50. It is more like an 80% increase.

XC70 AWD doesn't have switchable Traction Control so I can't switch it off. Without Traction Control it would only have three-wheel spin. With Traction Control it has 4-wheel spin in glare ice.

I was going to say that, because on dry hard surfaces it is true. In physics class they use blocks on a table top where it is true. But with a wet surface, the thickness of the layer of water changes as the area and hence the pressure on the water changes. The coefficient of friction is dynamic and varies with the thickness of the layer of water and the roughness of the road surface and tire surface. The softness of the rubber is another variable that changes the coefficient of friction with pressure. So in principle, I agree, but there are second order effects.

There are V70R's.... I seem them sitting at the Volvo dealer I goto, waiting to be sold. They look SWEET, I'd love to buy one if I actually had the money they want for one... I'd honestly have one over an S60R.

Even on dry pavement the coefficient of static friction (which is what applies when the tire is rolling) also does not increase linearly with pressure (despite what many secondary and college texts have to say on the matter). A larger contact patch does in fact yield greater friction, otherwise there would be no reason to worry about limiting weight transfer during cornering and braking.

Just another Physicist checking in, Bill

There must be more to it than just a wet surface. Think of a Formula 1 or Cart/Indy race car - they must have those big fat rear tyres for something, and it's certainly not aerodynamics. If it wasn't for the rules limiting tyre width, the designers would have them even wider. Wear rates are improved, but I don't think that is the primary reason.

how much of an effect does tire pressure have?....