Topgear track test of Z4m Roadster

[Leadfoot]

Just watched Topgear tonight and it was interesting what they said about the Z4M Roadster. I was surprised that with a 60+hp more than a Boxster S, in a acceleration test it looked like it only beat the Boxster over a 1/4 mile by a length or so, which puts into light what the RS4 did against the M3 with an extra 75hp. And in the hands of the Hamster it was a handful, where the Boxster was pure poetry.

But and this is a big but, in the hands of the Stig it produced a 1:26 lap. That puts it 5.9 seconds ahead of an M3 and 3+ seconds ahead of the Boxster S, hell it even beat the Cayman. To sum it up, in the right hands it's quicker than the sum of it's parts, but for the rest of us, it's as Mr Clarkson said wooden and boring on the road and by the look of Hamster's efforts on the track a bit of an aminal that WILL bite your head off, unless you grab it by the neck and show it who's boss.

Mind you Hamster's powerslide did look the business.

This looks good for the Z4 M Coupe's lap time at the ring, it might get close to the magically 8 minutes.

[frikktion]

you forgot to mention that the koenigsegg was back with a brand new rear spoiler. i wont tell the time but i can tell you that it was fast! :mech: :bye2:

[Erik]

Originally posted by frikktion
i wont tell the time but i can tell you that it was fast!

1:17.6 :hahahehe:

Top 20:
1.17.6 Koenigsegg CCX (With spoiler)
1.18.4 Pagani Zonda F
1.18.9 Maserati MC12
1.19.0 Ferrari F60 Enzo
1.19.5 Ariel Atom
1.19.8 Porsche Carerra GT
1.20.4 Koenigsegg CCX
1.20.7 Ascari KZ1
1.20.9 Mercedes McLaren SLR
1.21.9 Ford GT
1.22.3 Ferrari 360 CS
1.22.3 Porsche GT3 RS
1.22.4 Corvette Z06
1.23.7 Murcielago
1.23.8 Zonda
1.23.9 Koenigsegg
1.25.0 Noble
1.25.1 Lotus Exige S
1.25.8 Gallardo
1.26.2 Porsche Cayman

[ercan]

were is the video of that? (ccx)

[clam]

Horsepower is a calculation based on a strange test they did with a horse. They did it b/c they figured people would have no idea what Watts or NewtonMeters were.
I guess they were right, b/c horsepower is the most popular number.

What really moves a car is Torque. Hp is a calculation with rpm and Torque. At a certain point this formula results in a maximum number. And that number supposedly tells us how many horses it would take to equal the power of this engine.
This calucation favours rpm, b/c expressed in minutes, rpm has a bigger number. So high reving engines, like motorcycle engine, will be able to generate a great number. Although their Torque isn't all that much, so in reality they don't have that much force. And you wouldn't wanna put them in a car.

With a max HP figure you can only guess what the performance is. It may be a big diesel that produces a lot of torque but at slow speeds. It may be a bike engine, that needs little force, but has a very wide powerband.

The real performance number is the Torque curve. That's what will actually move the car. Max HP only gives you a vague idea of what the Torque curve could look like. An engine with a big number is probably developing a lot of torque at high rpms. But for all you know, there's a big torque gap before the engine generates that number.

The Porsche may be shy on maximum numbers, but it produces a big fat torque curve.
The inherit weakness of the straight 6 means BMW has to limits its torque. The block is long and narrow. To make it stronger, they had to make it heavier. But it's already way too heavy, and still limited in the amount of Torque it can handle. That's why BMW are switching to a V8 for the next M3. A V8 is short and stubby, so inheritly strong. Though it is not naturally balanced like an I6.
To get around the torque, the I6 is over-square, tuned for engine speed. Then through short gearing, they compensate for the torque.

VW got around it by creating a slight offset in the cilinders. That allows them to make the block shorter, thus stronger, lighter and more compact. The VR6 is fundamentally a straight 6, in the way it works. So the W engines are in fact V engines. The stubbyness of the VR blocks allows them to put out big Torque number, but be relatively light.

But I digress. The max Torque difference is only 45Nm between the Boxster and the Z4 M. The boxster is also more that 100kg lighter, and the weight of the BMWs straight six played a big part in that. The extra Torque is just enough to compensate for the weight. So that's 45Nm practically wasted.

Now you understand why BMW is switching to a V8. It may not be as romantic as the naturally balanced straight six, but it doesn't waste any torque on dragging around its own weight.

[Leadfoot]

Clam,

I agree vee engine will aways produce more torque and a better curve. Yes they are lighter and the fact they're shorter means more of the weight is moved farther back. I would say the real reason for changing to a v8 is crash safety. The engine is shorter and this allows more space between the front bumper and the engine, plain and simple and the vee makes it seat lower, more space between it and the bonnet. Safety is a big thing now and all manufacturers are trying to stay ahead of the new safety rules.

By the way, Clam. You are wasted on us dumbies, the way you explain thing with such depth I love, I don't all ways understand it, but I love it all the same. Keep it all.:bow:

Why no RS4 on the list, when it was on end of last season, Clarkson said it did the track in 1:25 something, what's the work on that?

[Erik]

Here's the list. http://www.bbc.co.uk/topgear/powerlaps.shtml

What time did the RS4 get? :vhmmm:

[clam]

It's never my intention when I start writing. And I know few people are motivated to read it. I always like to connect all the dots, and reveal the big picture. I think they call it a holistic approach.

Good point about the crash safety. Makes development a lot cheaper. Probably also one of the things that is motivating Audi to change their platform filosophy,... but I digress.

[steve]

Originally posted by clam
Horsepower is a calculation based on a strange test they did with a horse. They did it b/c they figured people would have no idea what Watts or NewtonMeters were.
I guess they were right, b/c horsepower is the most popular number.

What really moves a car is Torque. Hp is a calculation with rpm and Torque. At a certain point this formula results in a maximum number. And that number supposedly tells us how many horses it would take to equal the power of this engine.
This calucation favours rpm, b/c expressed in minutes, rpm has a bigger number. So high reving engines, like motorcycle engine, will be able to generate a great number. Although their Torque isn't all that much, so in reality they don't have that much force. And you wouldn't wanna put them in a car.

With a max HP figure you can only guess what the performance is. It may be a big diesel that produces a lot of torque but at slow speeds. It may be a bike engine, that needs little force, but has a very wide powerband.

The real performance number is the Torque curve. That's what will actually move the car. Max HP only gives you a vague idea of what the Torque curve could look like. An engine with a big number is probably developing a lot of torque at high rpms. But for all you know, there's a big torque gap before the engine generates that number.

The Porsche may be shy on maximum numbers, but it produces a big fat torque curve.
The inherit weakness of the straight 6 means BMW has to limits its torque. The block is long and narrow. To make it stronger, they had to make it heavier. But it's already way too heavy, and still limited in the amount of Torque it can handle. That's why BMW are switching to a V8 for the next M3. A V8 is short and stubby, so inheritly strong. Though it is not naturally balanced like an I6.
To get around the torque, the I6 is over-square, tuned for engine speed. Then through short gearing, they compensate for the torque.

VW got around it by creating a slight offset in the cilinders. That allows them to make the block shorter, thus stronger, lighter and more compact. The VR6 is fundamentally a straight 6, in the way it works. So the W engines are in fact V engines. The stubbyness of the VR blocks allows them to put out big Torque number, but be relatively light.

But I digress. The max Torque difference is only 45Nm between the Boxster and the Z4 M. The boxster is also more that 100kg lighter, and the weight of the BMWs straight six played a big part in that. The extra Torque is just enough to compensate for the weight. So that's 45Nm practically wasted.

Now you understand why BMW is switching to a V8. It may not be as romantic as the naturally balanced straight six, but it doesn't waste any torque on dragging around its own weight.

Indeed, horsepower 'doesn't exist'.

(Nm*RPM*2*PI)/60 is your Watt amount. divided by a thousand (kW) and multiplied with 1.36 gives you that magical HORSEPOWAA!:p

[Leadfoot]

Originally posted by clam
Good point about the crash safety. Makes development a lot cheaper. Probably also one of the things that is motivating Audi to change their platform filosophy,... but I digress.

You might disagree that this is motivating Audi, but very soon it won't be a choice, it will be 'do it or don't sell your car here mate'.

I too like to connect all the dots, and then colour in the picture.:D

[jonas_dg]

he said something silly on the Z4 too though, that it is better looking than the Boxster S...? I don't think I can come up with an uglier car than a Z4 besides the other new BMW models :D