What is going on?

spikyone

spikyone wrote: »

As for engine position, this is clearly nonsense - all high performance cars, regardless of engine position, drive through the rear wheels (or all four wheels)

I should also point out that even in high-performance 4WD cars - e.g. Nissan GT-R, Ferrari FF - power is sent mainly to the rear wheels. Both have their engines in front of the driver (although the FF is technically mid-engined as it sits between the car's axles, but that's another discussion...)

Strider590

spikyone wrote: »

...and mine is formed from a knowledge of physics, and a masters degree in automotive engineering.

Mine is formed from owning and/or driving high performance and/or race prepared cars without the luxury of ANY fancy electronic driver assistance.

Forgive me if I don't take your word on things, but my unqualified mate runs an IT department in a school. They employed a young lady straight from uni with a masters degree in computers/IT and later found that she doesn't even know how to reinstall Windows or change out a failed power supply. Some use that is.....

So anyway...

When the front end of a FWD car loses grip, it's gone and your heading into the nearest ditch. The best you can do is back off and hit the brakes. But..... because the front end has no grip, the brakes aren't going to be much help. You "can" give the handbrake a quick pull to unbalance the rear end enough to regain some grip at the front (causes centre of gravity to shift forward, creating front end grip), it takes some quick thinking and I wouldn't recommended it on a normal road car handbrake (tends to lock).

When you lose grip the front end of a RWD car, you can back off and immediately regain traction, without the thing turning into an oversteering monster.

Lose the rear end grip in a FWD car and you need to hoof it, the front has tonnes of grip hence why it's not sliding, therefore you use that to pull the back end into line.

Lose the rear end grip of a RWD car and you have to back off (opposite to FWD).

The reason road cars are setup to understeer is because the untrained driver will naturally back off if the car starts to oversteer, doing this in a tail happy FWD will see you facing the opposite direction in the blink of an eye.
Try driving an original 306 GTI-6 for an example of a road going tail happy FWD car, head into a corner and come right off the throttle (best do it somewhere with lots of run off, because you'll need it).

FWD racing cars are setup to favour oversteer (oops), which gives the driver the ability to use the front end grip to it's full advantage..... (Basically dragging a dead weight around, instead of trying to push it).

spikyone

Strider590 wrote: »

Forgive me if I don't take your word on things, but my unqualified mate runs an IT department in a school. They employed a young lady straight from uni with a masters degree in computers/IT and later found that she doesn't even know how to reinstall Windows or change out a failed power supply. Some use that is.....

Fair point, but whatever my credentials (and I can assure you I'm neither "straight from uni" nor terrible at my job) I'm at least trying to use physics and facts rather than opinion to prove my point, whereas the young lady to whom you refer possibly wouldn't be able to!

Strider590 wrote: »

Lose the rear end grip in a FWD car and you need to hoof it, the front has tonnes of grip hence why it's not sliding, therefore you use that to pull the back end into line.

In this situation the front end has no more grip than it would in a RWD car - the difference is that with a FWD you can use the front wheels to pull the car out of the slide but with a RWD you can't. It doesn't make the FWD faster because tail-sliding is slow. They only drive like that in the movies because it looks faster.

Ultimately none of what you say on recovering an out-of-control car relates to whether FWD or RWD is faster, because an out-of-control car is not a fast car. Any car can be set up to understeer or oversteer, but a FWD will always work its tyres unequally, and will always be closer to losing front end grip than a RWD car. The FWD will also exit a corner slower (assuming the same apex speed and that both cars are at a steady speed on the apex) as it has to sacrifice either lateral or longitudinal grip, which a RWD doesn't as its front tyres are only providing lateral grip.
I'd genuinely suggest you read and try to understand circles of forces and how they apply to vehicle tyres (this is the most relevant piece of physics here).

Strider590 wrote: »

FWD racing cars are setup to favour understeer, which gives the driver the ability to use the front end grip to it's full advantage..... (Basically dragging a dead weight around, instead of trying to push it)

Absolutely not! FWD race cars are generally set up to oversteer at the start of the race. They wear their front tyres more than their rear tyres during the race and as the race goes on, the front tyres lose grip until they have similar levels to the rear tyres, and the handling becomes neutral/mild understeer at the end. How can a driver possibly "use the front end grip" if the front is sliding? This is the meaning of understeer - the front end losing grip.
Understeer in a FWD leads to more understeer, because understeer means the tyre is scrubbing sideways across the circuit, and physically wearing away. If you set a FWD car up to understeer, it will eat its tyres and the driver will be in the barriers before he knows it.

Strider590

Edit - FWD racing cars are setup to favour oversteer

But of course the FWD will be faster out of a corner than a RWD if both were sliding, you've said it yourself....

In this situation the front end has no more grip than it would in a RWD car - the difference is that with a FWD you can use the front wheels to pull the car out of the slide but with a RWD you can't.

The difference is how much grip the rears have (almost none during oversteer), while the front has more grip than the rears (obviously because it's not understeering).
It should be obvious that the FWD can accelerate out of that corner using that front end grip, whilst the RWD has to wait those extra milliseconds until it regains enough rear end grip to do so. It only takes a few lost milliseconds to lose a race.

Then on the straight im sure you realise that RWD get a slight advantage, with the weight shifting right back onto those rear wheels giving greatly enhanced grip.... But unfortunately in the BTCC there aren't many circuits where that can be used to maximum advantage.

skiddlydiddly

All this fwd, rwd is faster talk is more applicable to us mortals as we aren't anywhere near the skill levels of race drivers.Stick a race driver in a rwd car weighing the same and having the same power as a fwd car and he will be faster in the rwd.They don't barrel into corners and start sliding about, they control the car and steer on the throttle.A rwd car is just more balanced as they usually run the engine longitudely which gets more weight behind the front axle and the rear diff helps distribution even more.

To sum it up,if fwd was better then F1 cars would be fwd

spikyone

Strider590 wrote: »

But of course the FWD will be faster out of a corner than a RWD if both were sliding, you've said it yourself....

If both are sliding then neither is going as fast as they could be! The fastest way is to not slide, which is the normal approach for a racing driver, and in this case the RWD is faster. If the two cars are not sliding, the RWD will be able to get its power down earlier and harder, because its "driving" tyres aren't trying to steer it at the same time.
(EDIT - in fact I never said the FWD will be faster if it's sliding - just that the FWD can be pulled out of a slide by the driving wheels)

Strider590 wrote: »

The difference is how much grip the rears have (almost none during oversteer), while the front has more grip than the rears (obviously because it's not understeering).
It should be obvious that the FWD can accelerate out of that corner using that front end grip, whilst the RWD has to wait those extra milliseconds until it regains enough rear end grip to do so. It only takes a few lost milliseconds to lose a race.

As I've said before, if a car is oversteering it is not going as fast as it could, so this is not relevant. If the driver's sliding his car, he's losing speed because the tyre's slip angle is too high and is creating an additional drag force.

You really do need to read up on the circle of forces and how it applies to tyres. I know I sound like a broken record, but it explains the reason why a RWD can accelerate out of a corner faster than a FWD. Try this website, but avoid wikipedia as it doesn't explain it very well!
In layman's terms, the front tyres of a FWD are trying to do 2 things at once - accelerate it and steer it. If someone tries to do two things at once, they can't do either of them as well as they could if they were doing only one thing. It's the same for tyres. In a RWD tyre, the front tyres are steering, the rears are accelerating. So the tyres at each end of the car are doing one thing only. Essentially a tyre can provide 100% longitudinal grip, or 100% lateral grip, or somewhere in between, but somewhere in between will compromise both longitudinal and lateral grip. This is what FWD cars do when they accelerate out of a corner - they compromise one or the other - and what RWDs do to a much lesser extent (because clearly the rear tyres provide some lateral grip, but far less than the steering tyres).

Strider590 wrote: »

Then on the straight im sure you realise that RWD get a slight advantage, with the weight shifting right back onto those rear wheels giving greatly enhanced grip.... But unfortunately in the BTCC there aren't many circuits where that can be used to maximum advantage.

That's true where the straight-line acceleration is tyre-limited (i.e. exiting slow corners). On straights following medium and high speed corners, the acceleration and therefore the weight transfer are far less significant, and the acceleration tends to be low enough not to overwhelm the tyres anyway. Which is why it's hard to get wheelspin in 3rd gear - in anything other than a supercar - regardless of FWD/RWD.

skiddlydiddly wrote: »

To sum it up,if fwd was better then F1 cars would be fwd

Dammit - he's summed it up far better than me! Additionally, going back to my earlier point - in series' where FWD and RWD cars race together, RWD always has a higher base weight. As I said, I've been following BTCC since the Super Touring era of the 90s (and going back to Andy Rouse in his RS500!), and it's been that way for as long as I can remember. The reason is simple - RWD are inherently faster.

almillar

RWD is the original way cars were designed. FWD was invented (by Citroen? In mass production cars anyway) to save costs and space - everything is under the bonnet, no big drive shaft or differential down the middle to the back of the car.
RWD is better. It's faster in racing conditions. Irrelevant of what happens when sliding (you've sortof lost control by this point anyway), it's better for the car to be pushed by the rear wheels and steered by the front, rather that the fronts trying to steer and pull you along, with the rears just following.
Of course in the snow trying to get up a hill is a different thing, as is being in a race in a RWD car when most others are in FWD, and all that's required to spin you is a tap to the back-side in a corner, whereas everyone else can get away with it!

stampede

skiddlydiddly wrote: »

All this fwd, rwd is faster talk is more applicable to us mortals as we aren't anywhere near the skill levels of race drivers.Stick a race driver in a rwd car weighing the same and having the same power as a fwd car and he will be faster in the rwd.They don't barrel into corners and start sliding about, they control the car and steer on the throttle.A rwd car is just more balanced as they usually run the engine longitudely which gets more weight behind the front axle and the rear diff helps distribution even more.

To sum it up,if fwd was better then F1 cars would be fwd

There is only so much power you can put through the front tyres too, anywhere near 200bhp or more & you are plagued with torque steer, which means you can't get the grip down in the way you want anyway. RWD in skilled hands is always much better than FWD.
Someone that is a less experienced driver will be better in a FWD car than a RWD car due to the fact RWD is less forgiving.

Shoshannah

Bring back the RS Cosworths. :rotfl:

Is RWD going to disappear from BTCC completely? Lost a few BMWs this season compared to last.

almillar

Shoshannah - it's not that they're BMWs, it's not that they're RWD, it's that they're built to older regulations, and they're simply not as fast as the turbo cars are allowed to be. If one of the Beemer teams could afford to build a new car to the 'Next Generation Touring Car' spec, I'm sure they would, but they can't just take an engine out of the current car and stick in the turbo one. The BMWs that are there now WILL disappear at some point, and all of the BTCC cars will be NGTC cars in a few years.