4 wheel drive vs. Elise cornering

dezzy · Post by **dezzy** » Sun Dec 10, 2006 11:41 am

One of my friends just got an Audi TT with four-wheel drive. Another friend seems to think that the TT could corner faster than my Elise, just because it has four wheel drive.

Given equal driver abilities, surely this isn't true? I know it would grip the road better in the wet with the four wheel drive, but surely there's a lot more to it like suspension set up, geo, etc. and I thought the Elise would have been much better in that department?

Please give me some ammunition so I can put an end to this argument (with me being in the right!).

Rory · Post by **Rory** » Sun Dec 10, 2006 12:25 pm

I'd have thought weight is by far the most influential factor in cornering superiority between two cars. And no prizes for guessing which is the lighter of the two....

Dominic · Post by **Dominic** » Sun Dec 10, 2006 12:37 pm

First off, the elise will be a better balanced car. The TT will be nose heavy, and engineered to handle 'safely', i.e. understeer, (as most modern cars). For the skilled driver IMHO oversteer is prefferable

The elise will also handle better in the corners, especially while being subject to gentle of full acceleration, as the weight will transfer to the rear wheels, giving them excellent traction to propel the car, leaving the front wheels to control the the direction. In a 4x4, the front tyres are having to cope with acceleration & steering requirements, therefore, asking more of the tyres will cause them to loose traction sooner... leading most likely to understeer

The key to it all, is to get the liz nose heavy under braking, then, just after you come off the brakes, while the weight is still over the front, get the front end turned into the corner, as the weight transfers to the rear, you can get on the power, and 'drift' the car, beautifully balanced around the corner. Too much power and the rear will start coming round, so you can adjust that with the throttle, & / or steering. 4X4 will be much less able in that circumstance. It will tend to understeer, where more power will push it wider, off line.

The elise's greatest trump card over the TT is it's lack of wieght. A TT at 1260 - 1520kg (dependant on model) has much more weight to haul around a corner than the Liz(860kg). The laws of physics take over! Momentum will carry the already understeery TT off line, while the light nimble Liz, with it's lightweight, super stiff chasis, will grip, and go round the bend.

The only advantage the TT would have, is when you are sliding, it has all four wheels to pull you along... if you can get all four pointing where you want to go! It will have more traction in the wet at the traffic lights grand prix.

Ultimatly, the Liz would be quicker across any country road, and would by my choice. IMHO

TTs of old were not highly regarded as driver's cars. Too heavy & slighly numb.

douglasgdmw · Post by **douglasgdmw** » Sun Dec 10, 2006 12:50 pm

Simple way to prove your friend is wrong :

1) choose a reasonably large roundabout (ideally with 2 lanes)
2) Take TT round until it reaches max grip to cause it to run wide onto next lane
3) Take Elise round until it reaches max grip to cause it to run wide onto next lane
4) COmpare speeds of each car (or time it take to go around the roundabout)
5) Make you mate eat humble pie and let you know you are far superior in a) knowledge of cars & b) choice of cars

Cheers
DMW

johncam · Post by **johncam** » Sun Dec 10, 2006 12:54 pm

Hi Dezzy,
I also have a friend who has the 225bhp 4WD Audi TT. When I got my Elise, I took out another friend for a passenger ride and he 'followed' me in the TT over the back road between Howwood and Lugton (via the Curling Rink). I floored it in 2nd on entering the National Speed limit leaving Howwood and disappeared up the road. I slowed going through the small holdings at the Bowfield Country Club which let him catch up, once clear of the buildings I planted it again, he was wise to it this time and have to say he just about kept up on the straight bit approaching the first series of bends. He attempted the first serious bend at the same speed I did and got round it in one piece (although my passenger said he was bit untidy) but I didn't let up for the long series of bends approaching the reservoir. After that it was all over. Never once did I go above the National Speed limit though I suspect he did as he attempted to catch up on the straightish bits before the Curling Rink. By the time we reached the cross roads at the farm before Lugton I had a good 30-40 second wait for him to catch up...that stretch of road can't be any more than 3 miles if that. He came over to the my car in a bit of a distressed state. Apparently on the first serious bend, his dashboard had lit up like a Christmas Tree as all the electronics attempted to keep his TT on the road. All he could say was that Lotus was 'stuck to the road' and he had never seen anything like it. He was truly astonished how easily I had driven away from him despite the obvious power deficit I had. I didn't have the heart to tell him that I hadn't gone over 4000 revs as my car was cold to begin with and the rev limiter had stopped me.

My point is, as you know I'm far from being the worlds best at the wheel of the Elise, but on a twisty road like that one, pretty much nothing â€˜ordinaryâ€™ is going to stay with you... never mind a VW Golf with a body kit! Its just not designed for that sort of driving.

Cheers,

John

Rich H · Post by **Rich H** » Sun Dec 10, 2006 12:58 pm

The only issue that could be a problem is poor road surface or conditions, obviously the 4x4 has 2x the amount of avaiable rubber for putting the power down but no more to get it round the corners...

mckeann · Post by **mckeann** » Sun Dec 10, 2006 1:03 pm

pretty much to repeat what Rich just said, but 4wd gives better traction, it doesnt give the tyres any more grip. Grip is what gets you round a corner.

Also weight is the enemy. The elise is very good if you are able to manage weight transfer. The audi is ok because it has lots of technology on its side.

I would imagine that an Audi could be faster for the less experienced driver though, but a decent driver will be better off in the elise.

TBH, a decent driver will probably make the difference over what the car does though

Post by **pete** » Sun Dec 10, 2006 1:15 pm

You will get a way better answer than this soon but here's my two penneth.

The amount of g you can generate in a turn must be, very basically a function of the mass of the car vs the amount of grip you are generating.

So a light car needs to generate less grip. Wide, soft tyres have more grip. More grip and less mass gives a higher cornering speed. Thus your Elise can corner faster than a TT, mainly because it is lighter.

As for which wheels are going around. Well if you have a front wheel drive car then the front wheels are being asked to not only turn the car, thus increasing the amount of work they are doing over the back wheels, but also to pull the car along. As the act of cornering will slow the car down, you will have to increase the power to compensate. So the tyres will provide less cornering grip than the back tyres as they are also woking to provide traction and turning force.
A RWD car is better, as the front tyres can work to provide turing force and the rear wheels can provide traction (power).
With clever diffs (which the TT does not have) a 4WD is as good (or better) than a RWD, better when the car is sliding (see optimal slip angles) as you can feed in more power to compensate. But sliding on tarmac is not the quickest way of progressing, it is on the rough stuff though which is why rally cars have 4WD.
The down side of 4WD is that it adds a lot of weight, which you have to increase pwer to compensate, which increases weight and reduces cornering speed. So you need bigger tyres, which increses weight...

So at Knockhill the Elises are quicker than the Imprezas/Evos in the corners until it rains, when the rally barges find it easier to put the power down and can find more traction. A standard Elise laps faster than a WRX (120bhp vs 215) and a 111S faster than an STi (150 vs 275ish). Until it rains. A TT isn't really a sports car but a car for people who like to cut hair, too softly sprung (causing body roll and reducing the effectiveness of the tyres) and too heavy to bother about.

And finally the 4WD stuff understeers more (depending on setup) which although slower than oversteer is easier to drive so mere mortals like me can go quicker in a car set up to understeer slightly. Which is one of the reasons S2 Elises have those skinny front tyres, makes them understeer slightly and keeps the insurers happy after so many S1s crashed (normally just after the driver ran out of talent).

My 50 penneth.

Pete

dezzy · Post by **dezzy** » Sun Dec 10, 2006 3:30 pm

Thanks guys!

I think I'm going to copy and paste this thread into an email and send it to my friend!

I should point out by the way, it's not the (female) friend who owns the car that thinks it corners faster. She bought it because she likes the looks and hasn't even attempted to compare it to the Elise. It's one of our male friends who made these claims. I knew he was wrong . . . I just didn't have the tech-speak to prove him wrong! He's one of these people whose first question about your car is "what engine size is it?", as if he thinks engine size is all that matters and doesn't comment on power/weight/suspension/etc/etc.

Cheers!
D

mckeann · Post by **mckeann** » Sun Dec 10, 2006 3:42 pm

tell him he can come for a pax lap in mine if he still doesnt believe you

r10crw · Post by **r10crw** » Sun Dec 10, 2006 3:49 pm

There was a really good article on this a few years ago, and although it did explain that certain setups will oversteer or understeer more than others it did give a simple explanation. If you take any corner there will be a perfect line to go round it with only thing was that this line varied depending on the car setup (ie engine layout power delivery etc). To keep it simple you had three possible lines front wheel drive, rear and four. The rear wheel drive line through the corner is the shortest hence in any given corner an elise will have less distance to travel. The position of the engine only amplifies or attenuates the effect. Its quite hard to visualise without drawings but hope this helps.

Brian J · Post by **Brian J** » Sun Dec 10, 2006 4:26 pm

Remember driving an early TT (the later ones may be better?) and accelerating through a roundabout - the turbo came in so suddenly that it certainly needed 4 wheel drive to keep it on the road

roadboy · Post by **roadboy** » Sun Dec 10, 2006 4:48 pm

I can't believe nonone's mentioned centre of gravity yet.

But to answer the original point, 4WD makes absolutely no difference to maximum cornering speed.

Dan@JPS

Post by **pete** » Sun Dec 10, 2006 5:21 pm

The early TTs had a big recall to have those ducktail spoilers and traction control fitted after a few well publicised "lift off oversteer into terrain incidents" were feature in the press.

Which should help Dezzy's case even more, none of the driver aids in the TT are there to make you faster, they are there to make you safer. And slower.

Pete

(My overlong explanation was written whilst Mr Humble was writing his more succinct version. He seems to have said in a sentence what I was trying to write in a paragraph or two.)

slg · Post by **slg** » Sun Dec 10, 2006 9:47 pm

Having recently sold my TT (225) I'll give you my tuppence worth aswell. I had mine at a trackday with you guys earlier on this year, a nice sunny evening at Knockhill.

While being able to keep up on the straight I found that the Lotus was carrying more speed through the corners than I could manage (this could be down to the pilot as it was my first track day in the car) but I didn't think I was hanging about & the car was "moving" about in the corners. The Lotus was able to brake much later into the corners & was much more stable going through the chicane part of the circuit. I only passed 3 cars that evening, 2 lotus & a subaru but was passed by a few Lotus who just disappeared into the distance.

For day to day driving on unknown roads in the weather we're having just now, I'd take the TT (but turn the esp off!) and having never driven a Lotus I would imagine that would be much more fun in the dry.

Wouldn't have expected the hairdresser comments on here, as far as I know there aren't any in the TTOC!