jl123

John F,

What characteristics should a road car possess when conditions turn very difficult? That is when the road is greasy, unreadable/blind curves, obstacles suddenly appear etc. I assume under such conditions one would want a car to have favorable lift-off characteristics, where upon lift the car slightly understeers but remains going in the right direction? I say this because oversteer requires quite some room to correct-more than a public road can offer, as one would on a track? So maybe cars like quattro's, evo's and Impreza's with slightly high front weight bias might be just the thing in these reguards.

Last I assume the 911 T is so good because its traction/grip is so darn good that its rear weight distribution rarly has to enter into the equation- its rarly breached on a public road, plus its rear-engine bias allows one to brake later into curves.

Thanks

[Edited by jl123 - 7/4/2003 1:38:58 AM]

jl123

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[Edited by jl123 - 7/4/2003 1:35:18 AM]

jl123

John,

Thanks for the great write up. Good to feel like I'm actually learning something on scoobynet again!

Yes, that section of the ring should be used by magazines for on limit testing. I'm sure the German magazines use it, but I can only read English. I think a comparison test conducted by yourself and Simon of a few 4WD cars including different systems (turned on and off) such as PSM, anti-yaw, DCCD, and Prodrive's ATD to see just what these do in really demanding senario's like the ring would be a super informative True Grip article. I have to think that some systems would not work very well at the limit on this portion of the ring as they might need more room/road to sort things out than exists.

When you say, "one that is neutrally balanced under a steady throttle" which car (I assume your main experience is with Impreza's) have you found is so neutrally balanced?

Have you compared different (Audi?, Mitsubishi?) 4Wd's or electronic systems on that section of the ring?

Thanks again.

[Edited by jl123 - 7/4/2003 6:34:37 AM]

jl123

I'm surprised this has not been keenly debated already here, but here goes...

What do you all think of the fact that Autocar claim the 911 Turbo is untouchable over almost any road?

I find this claim to be BS, because if you look at their own corner speed results the 911 T rarly cornered any faster than the other cars assembled. It was just down to speed, in fact the article said the UK is just a "power circuit". While I think that statment might be true for most roads, I think that they completly missed the plot forgetting about far more difficult conditions. Therefore if the Mitsubishi or for that matter probably an Impreza, had been equiped with a monster motor of over 400hp they too would have demolished that road.

I have a hard time believing that they really pitched those cars into the most demanding roads/situations, such as blind, wet downhill corners etc. For if they did I think the 911 would have bitten back with its PSM off, or with its PSM control on it would have reined the car in and made it slow compared to the front engine cars. Certainly front-engine has got to be the safest way to travel fast on the public road?

MarkCSC

Very bad article, not only was it illegal (you are not allowed to time a car over a set distance on a public road) but real poorly written. It gave no indication why one car was faster than another just that they were. Made really dull reading

I wouldn't worry about it too much if I were you.

shunty

that's why the new RS6 beat it round some track with a certain tv prog test then
mind you depends which car the girl is driving on these side-by-side tests really doesn't it

shunty

jl123

I agree I think the Autocar write was very limited indeed. But the 911 question remains and no auto mag seems to have bothered to address it, which is a safer means of traveling fast 4 wheel drive with he engine in front or back? I know evo mag should be the one to address this, but as of late they seem to be going rather autocar like- statments without real written examples to expain how or why.

I think that someone on scoobynet such as Simon or John F should arrange a test for true grip mag where a Modded Impreza with big power goes up against a 911 T on road and track. Think it would be a great article.

TurboBoost

Yes but the goal of the Autocar test wasn't to find "which highly modified car can be driven safely by IT contracting nerds at ludicrous speeds without crashing".
It was to find the best point to point standard production car.

I agree the detail of the test was up to Autocars normal standards for being the McDonalds of automotive journalism.

si325i

"Certainly front-engine has got to be the safest way to travel fast on the public road?"

Why?

Simon

jl123

Simon,

I don't pretend to be an expert on chassis dynamics. But stating that front engine cars have the most benign handling qualities is something that just about every auto writer I have ever read- from Fast Lane, to Performance car, to Car to Autocar's big article on handling dynamics, where they stated that the Impreza was a more neutral handling car than the 996- has stated this idea. I'm just going by what the experts have found. Maybe indeed this is wrong. I'd just like to see someone do some sort of well thought out comparison test- like autocar did, to prove it.

iguana

Personally I prefer my porkers a little 'rawer' (and love RS's) but the 996T is devastating cross country esp in the wet, & ive been in one at 193mph (on a laser gun & on GPS) & it did over 190 is approx 8 times with no problems then the brakes begain to complain a bit as it then had approx 500m to stop not many cars can cope with this puishment & only keep the standard service intervals.

I have more experience of- and prefer the older 993 turbo, which I've driven up to 500bhp RUF versions, but yes cross country they are IMHO the daddy.

However the Noble is one bloody sweet beasty, not convinced reliabilty wise yet, but if I was in that budget range It would be a tough call over putting that or a 993RS in my garage


Edited coz I am a halfwit & it made no sence

[Edited by iguana - 7/3/2003 10:30:12 PM]

midget1500

really? well at least the police can to catch speeders!

FERRARINUTTER

Family Friend has a 996 Turbo, and until you've been in the Turbo and driven away from your own Scoob (whilst you and your mate have swapped cars), the 996 is indeed a fast, safe, great car to drive.

Of course there are pro's and cons, price, 4 adults seated comfortably, golf clubs in the boot and so on.

I could go on about the Porkers qualities but I really do prefer Ferrari's.......................

carl

Why do they have 'measured miles' on public roads then?
[PS: I've finally left BT ]

johnfelstead

The easiest to drive and most stable platform for a car is to have the weight balanced just in front of the driver, around where the steering wheel is. In other words have the polar moment just in front of your ****. The GroupS vauxhall Astra was just about spot on, sadly it never got to run in WRC but it was very succesful on a tight budget when run in Rally Cross.

Mid engined or rear engined cars are much harder to drive, the Porsche programme has come on in a masive way and they have addressed a lot of the handling issues inherant in this setup but its still far from ideal.

Personally i would say the ultimate setup would be along the lines of what the WRC cars are trying to achieve, a front engine with a centrally mounted gearbox, so the weight is centred around the front windscreen to steering wheel area.

Supercar wise, something like a lister storm has a lot going for it in the inherant weight distribution design. There is a lot more to a great car than the weight distribution though, which is why the Porshe is now so fabulous.

johnfelstead

a good indication of how cars handle the unexpected has to be the series of corners on the Nurburgring called wiperman. This is probably the most technically challenging section for a cars chassis to cope with as its a series of snaking narrow corners that flow into each other getting tighter and tighter, its also downhill off camber and remains slippy longer than most parts of the track due to trees being overhead.

Every trip to the nurburgring i have done has resulted in at least one 911 being buried into the barriers backwards at the bottom of that section.



Once you get a rear weight biased car out of shape it's hard work to get it back. The transition from grip to spinning is small. The latest Porsche's are much much better, cars like the GT3 in particular, but they are still more prone to crashing in tricky conditions with less than great drivers behind the wheel than a front engined car.

The easiset car to get out of a mess has to be one that is neutrally balanced under a steady throttle, that should react to more power or liftoff well. An AWD car is the easiest to drag back from the brink as long as the driver has the ***** to nail the throttle when the back end starts to spin out when your instinct is to brake.

I think its dangerous to try and give driving advice on a web forum though, the best thing is to go to a driving coach or find a big open space and play with your car and put yourself through the situations you may find, learning from that what works and what doesnt.

image doctor

That is my favorite section of 'ring.

Well actually from Carousel onwards.....the most flowing section of track anywhere on the planet!....ah I need to get back!

I can't comment on this thread but which car would you rather drive round here? Surely if you had the keys to both, which would you take?

MarkCSC

Carl

Taken from Road Traffic Act 1988 (c. 52)
Somehow I don't think Autocar got permisson to do their timetrials.

Yes the police can time cars on public roads but we can't.

Mark

PS thank god you're out of there. BT rots the brain

ex-webby

Hi All

Apologies (to the person who requested I add some thoughts in here) for the delay.

I don't have a lot to add really, I'm afraid, except to say...

Be aware that the term "neutral handling" is rarely understood. A truly nuetral handling car is almost impossilble to drive well. Certainly a car that has "neutral balance under steady throttle" (asuming by "steady" you would mean "neutral throttle") would be an absolute cow to hang on tounder almost any circumstances.

What "neutral handling" seems to mean to many people is the hugely understeer prone passivce characteristics of almost all cars (including race cars). The problem with this is that there is no such thing as a "neutral amount of understeer"... how much understeer afinity does one person think of as "neutral"?

In addition. It is always important to remember, that one person's easy, might be another person's impossible... and vice versa.

You may have someone who is the world champion at checkers, and absolutely useless at backgammon? and another person who is the world champion at backgammon and useless at checkers. You can't draw any conclusions from this as to how difficult each game is.

So it's also important not to draw too many conclusions from magazine articles as to what cars are "easier" to drive.

All the best

Simon

Mungo

The point about the cars being tested being standard is very valid - they could have put in a 600bhp Porsche if you want to go down that route.
No doubt what was done was illegal, but it would be impossible to prove the length of the route that was driven in the given times. I also don't doubt that the route has no side roads, and that Autocar had spotters at each end to call the test driver if an innocent party drove onto the test route, so they could abort.
I'm surprised that the test results came as that much of a shock to people. The Porsche obviosuly handles "okay" - well enough so as to corner at similar speeds to the other main contenders, but it then also has 4WD grip and huge grunt to get it down the straights in between corners, and great brakes to slow it down when it gets there.
Don't forget you're comparing cornering speeds of some great cars - if there was some lesser machinery on test, the corner speed differentials would be much more obvious.
Also, cast you mind back to another Autocar handling test at Mireval, where I beleive the Lotus 340R had massive cornering speeds, but still couldn't match more powerful cars who ate it for breakfast on the straights.
There's only so much grip lateral available to cars without downforce, and the current crop of top road cars must be getting to that limit.

ex-webby

Mungo

Interesting comments and well put.

Although the "limit" of lateral grip available will continue to increase indefinitely as better tyres and suspension are produced and as weight reduction continues.

If you reduce the weight of a car and set it up again to suit you will undoubtedly have increased it's cornering speed potential.

That then goes on to say how important weight distribution is ... article here for anyone who's interested ... as you can then affect the unltimate lateral grip percentages shared front and rear, then trim it further with bars and springs, etc.

Cheers

Simon

Gav

i have A friend who has a 911 turbo, and a gt3 before that. went out in both and believe me they are both truly stunning cars. would wipe the floor with any scoob, and most other road cars. the gt3 in particular was a dream, it basically is a race car for the road, full roll cage, race harnesses etc etc. been in a lot of fast cars but nothing compared to it.

the reason he changed to the turbo is because its more user friendly, a car you can drive everyday. the gt3 hated being driven slowly you could feel it wanting to go all the time.

the porche turbo is the best all round road car money can buy.


gav..

ex-webby

scoobygav

I have to say I wouldn't go quite that far on the porka turbo, but there is absolutely no question, it's a beast of a car.

I find them a challenge to drive on the limit, although strangely the turbo less so that then non-turbo.

The GT3 however is IMHO one of the finest road cars of all time from a performace point of view. I would certainly think that a GT3 driven to the limit would wipe the floor with almost any subaru on almost any dry race circuit.

But of course, you really do need to be able to drive it to the limit.

Cheers

Simon

Mungo

Simon

I read your article and comments - interesting stuff. Certainly I can agree with your comments about tyres, but would be interested to know what you think makes suspension "better". Sure independent wishbones are "better" than a live-axle, but where do we go from there? F1 cars are still running wishbones, so nobody seems to have come up with a major leap forward for some time. I can see how suspension components, springs, dampers etc may be improved, but the actual concept?
Weight is obviously an important factor, particularly w.r.t. distribution, but cars seem to become inexorably heavier these days (Golf Gti?), and only the likes of Lotus and Caterham are prepared to combat this, but are they producing cars which can be driven on rainy days?

ex-webby

great post Mungo

What I meant by better was subtle improvements in damper valving / electronics, etc if you can get the suspension to react quicker and more accurately then you'll effectively have more grip.

It was a bit of a sweeping statement, but the idea is that progress will relentlessly continue.

In terms of road cars increasing in weight. I would suggest that this is mostly down to the increase in safety requirements of the consumers / legalities, etc. Progress will allow us to produce cars even safer with less weight, and the cycle will begin again, etc.

The other thing to consider is this.

The ride quality of a car has a lot to do with the ratio between the sprung and unsprung weight. If you make a big old heavy car, the ride quality is easier to produce as the weight / unsprung weight ratio is so much bigger. Now, this obviously isn't a reason for making a car heavy, but the weight issue isn't as much of a concern to the average consumer.

In addition, there is a strange but commercially necessary procedure in the development of a road car, in that the development of the car happens on test mules, etc.. then the marketing department get hold of it!

I have worked on a number of projects where we've concluded proposals for the final car, and the most common thing that the marketing departments do is put bigger wheels on it which is often not the most performant. But they'll sell a whole load more than if they leave the suggested wheels on.

All the best

Simon

jl123

Simon,

As you and John both seem to indicate, if you really were to push it on the road or have a random obstacle come your way, the 911 might be tricky to control. So how would you want a cars handling to be during such public road manuvering where there is no run off as on a track and stablity is important?

Thanks

ex-webby

Hi J

Well, I was actually hoping I wasn't saying that exactly.

What I'm trying to get across is that everyone will want something different.

For instance. If I came round a corner on a main road and found an obsticle in the way, I would actually prefer a car that was a little UNstable, rather than an overly stable one as it would allow me to change the direction of the car quickly and nimbly.

But another person might want the car to be as stable as possible so they can just hit the anchors and it slow down as much as possible before hitting the obsticle.

Cheers

Simon

Mungo

Horses for courses, exactly.

If you were looking for a strictly performance set-up for the road (and let's face it, the cars Autocar tested weren't mostly too bothered about ride comfort), is there an opening for active suspension, or does that really only come into its own on cars with high downforce? Or are we likely to see a new wave of performance road cars producing proper downforce, rather than just limiting lift as they do today? Or is this irrelevant at B-road cornering speeds?

Re big wheels - so are 16's the best for a Scoob after all? Or just for best ride/handling mix? And I guess it'll be magnesium wheels all round if budgets allow!

Roojai

webmaster,

perhaps you will enjoy (and add to) this thread about mass and cornering speed. I believe a lighter car can corner faster but this thread had me thinking!!!

http://www.gtr.co.uk/forum/upload/showthread.php?s=&threadid=11888

ex-webby

Hi Chaps

Apologies to Mungo, I'll get some time to answer your question later..

I've just looked at the other thread and got a little bored half way through, but the basic deal is..

Mycroft is answering a different question to that being asked.. but is (in the very specific and impossible situation he is quoting) correct. Whether that be relevant or not.

However... the question on the post was on the subject of a lighter car having better braking and cornering performance than a heavier car.

The answer is, the lighter car will out perform the heavier car in almost all conceivable circumstances, unless you go out of your way to devise a specific situation or circumstance that creates the oposite.

The reasons are exactly as pavlo stated in that tyres do not increase their available grip at the same rate as load is applied to them.

So...

If you double the weight of a car, you are doubling the load on the tyres, but not doubling the amount of grip you have.

All the best

Simon