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Z4 3.0i - How Quick?


L3ETT
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Interesting test for the R on the way home tonight on the motorway. Mr BMW decides he wants to ride 2in from my bumper, so I floor it in 5th at around 60mph expecting to see him drop back. But nooo he stays stuck to my bumper well past the ton.

So exactly how quick are the z4's - anyone driven one or own one?

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A friend rented one about a year ago. I got a ride in the car and yes it is fast, but i dont think there would be anything in it between it an a stock 32. Me and him had blast, and it seemed a little faster to about 60 but as soon as thrid gear got going, there was no differance.

BMW claims 5.9 to 60. To 100 its about the same as the 30 i.e 15 something beerchug.gif

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[ QUOTE ]

Interesting test for the R on the way home tonight on the motorway. Mr BMW decides he wants to ride 2in from my bumper, so I floor it in 5th at around 60mph expecting to see him drop back. But nooo he stays stuck to my bumper well past the ton.

So exactly how quick are the z4's - anyone driven one or own one?

[/ QUOTE ] Ermmmm 5th at around 60mph surely not confused.gif mmmm the Z4 must have thought the R32 is $hit.... FIREdevil.gif you should have dropped a gear or two and made use of the torque... between 2800-3200rpms.... jump.gif

Next time woop his a$$ properly wink.gif

Riz beerchug.gif

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3rd gear will take you to 80mph, 4th to 100 something.. 5th

to over 130mph.

Shoulda dropped down to 3rd for sure. Yes you get a kick

in the pants around 3000 rpms, but you're ignoring

the superior effect of gear multiplication. In most gears

you will put more torque to the *ground* (which

is 100% directly proportional to accelleration) even close

to redline where it feels like the power is falling off, than you

will in the next higher gear at *any* rpm, because

of torque multiplication due to gearing. That's what

gears are for.

There's a physiological reason that the car feels

like it's slowing down when the torque curve

starts to fall off, which I'm not going to get into

right now, but suffice it to say, ignore what your

butt dyno is telling you, and go with the math.

This is even more important when you're sprinting

through 1st, 2nd, 3rd.. (take em all to redline)

Only in 4th and 5th might it make sense to upshift

a little before redline.

ian

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Surely you want to be changing up when the effective torque at the wheels in the next gear is higher than in the current gear? This isn't necessarily at the red line is it? (esp. for turbo/diesels with all the torque at the bottom). Same goes for changing down. Revving the nads off an engine doesn't always mean faster accelaration.

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5th gear doing 60mph = 2700rpms.... shocked.gif

Well torque is good but bhp has also a major part to speed..... since the maxium bhp is towards the the redline surely this is why using all gears to the full potential is the way to go?

Riz confused.gif

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Power is just TORQUE x RPM, ie how much work the engine is doing. Doesn't really have a bearing on accelaration, (well apart from being a function of torque).

The reason you change up a gear at higher rpm than peak torque is because until you get to the point where the next gear up is offering you more push than the one you're in, you're better off in the lower gear. The extra torque you're gonna get from the higher gear, (from hitting a sweeter part of the rev range), will be offset by the longer ratio. The crossover point will be up near max power, but not necessarily at the same point.

I hope that all makes some sense?

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A very useful and informed thread, I agree revving the bollox out of thing don't actually mean you go faster, the correct use of the gears and accelerator gives max speed.

Two theories of how to go faster, the floor and flog it brigade and the technial driver - good comment viraje 169144-ok.gif

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Ok another question which has been on my mind....

When i do progressive acceleration (i.e. gently put foot down on pedel until it gets to end) the car seems to react really well and smoothly gets to the limiter....

It feels better then just flooring it.... confused.gif

Is it actually any worse or better then just slamming on the throttle pedal?

Riz beerchug.gif

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[ QUOTE ]

Ok another question which has been on my mind....

When i do progressive acceleration (i.e. gently put foot down on pedel until it gets to end) the car seems to react really well and smoothly gets to the limiter....

It feels better then just flooring it.... confused.gif

Is it actually any worse or better then just slamming on the throttle pedal?

Riz beerchug.gif

[/ QUOTE ]

I think you have answered your own post there me 'ol mucker. beerchug.gif

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[ QUOTE ]

[ QUOTE ]

Ok another question which has been on my mind....

When i do progressive acceleration (i.e. gently put foot down on pedel until it gets to end) the car seems to react really well and smoothly gets to the limiter....

It feels better then just flooring it.... confused.gif

Is it actually any worse or better then just slamming on the throttle pedal?

Riz beerchug.gif

[/ QUOTE ]

I think you have answered your own post there me 'ol mucker. beerchug.gif

[/ QUOTE ] Ooops duh... smirk.gif What i should have asked was how other R32 drivers feel about my post..... could this be the hesistation issue but on a greater scale? shocked.gif

Riz pengy.gif

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[ QUOTE ]

Ok another question which has been on my mind....

When i do progressive acceleration (i.e. gently put foot down on pedel until it gets to end) the car seems to react really well and smoothly gets to the limiter....

It feels better then just flooring it.... confused.gif

Is it actually any worse or better then just slamming on the throttle pedal?

Riz beerchug.gif

[/ QUOTE ]

I got that feeling too blush.gif

thought it was just me confused.gif

much happier now grin.gif

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[ QUOTE ]

Ok another question which has been on my mind....

When i do progressive acceleration (i.e. gently put foot down on pedel until it gets to end) the car seems to react really well and smoothly gets to the limiter....

It feels better then just flooring it.... confused.gif

Is it actually any worse or better then just slamming on the throttle pedal?

[/ QUOTE ]

Worse. Remember when I said I wouldn't get into the physiology?

Ok, here I'm going to get to get into it. Our bodies are

more sensitive to changes in the rate of accelleration than to

raw constant accelleration itself. The reason for this is

twofold.

1. We live in a 1G environment all the time. Notice that

the *feel* of gravity is almost completely filtered out

whether we're standing, sitting, lying down,.. basically any

orientation. Our bodies take a constant rate of accelleration

and just block it out, and we do it very quickly.

2. We are balancing animals. We live on 2 legs, and if we start

to tip over the rate of accelleration increases rapidly, so

our bodies are very sensitive to it, and use it to maintain balance.

How's this relate to the question? Follow the torque curve.

The instantaneous rate of accelleration is *directly* proportional

to torque at the ground, and torque at the ground is just

torque at the crank times gear multiplication minus drivetrain loss.

If the torque curve is flat, then our bodies quickly filter

out the constant rate of accelleration and it actually feels

neutral. If the torque curve is rising steadily then

the rate of accelleration is increasing and we continue to

feel that, and in fact mistakenly interpret it as

constant accelleration. What's worse is that if a flat torque

curve starts to fall off, we actually misinterpret it as

"slowing down". Your brain knows that's wrong, but your body

is convinced. It's why a falling torque curve in a low

gear feels slower than a rising torque curve in a higher gear

and is why people persist in short shifting inappropriately..

Back to the original question again. The R32's stock torque

curve peaks by 3000 rpms, and then falls slowly, all the way

to redline. When you just mash on the gas it instantly rises to

its peak and from then on out, it *feels* like it's slowing down.

It isn't, it just isn't accellerating as fast as it was.

If you slowly work into the throttle then you create that

rising torque curve for yourself, and it feels faster.

It isn't.. because you wasted the real meat of the curve.

It's the same reason that a turbo car often feels faster.

The turbo takes time to spool so the torque curve rises

more slowly, so you get the feel that it's accellerating

longer.

And while yes, you should shift when the curve for the torque

at the ground in the low gear crosses that of the torque

at the ground in the high gear, I can guarantee you that

most of the time that they cross much higher in the revs than

you think due to the effect described above.

In 1st, 2nd gears definitely take it all the way to redline..

probably 3rd gear too, but certainly no less than 250 rpms off

redline. 4th and 5th.. maybe 500 rpms lower, each gear.

If you have VAG-COM, you can log the rpms and speed over time

making runs in each gear, and then plug it into a spreadsheet

to calculate accelleration over speed to actually calculate

the optimal shiftpoints.

Oh.. and one other thing.. Horsepower tells you how far

into the rpm band you can make useable torque. The higher

the rpm you can make torque, the better you're able to take

advantage of that with *gearing*. Horsepower is only useful

if you use gears to multiple the available torque. A car

with a lot of horsepower and little torque needs to be shifted

all the time. A car with a lot of torque and little horsepower

will be stuck accellerating in short spurts before being forced

to shift, and with each shift putting less and less torque to

the ground. Assuming the gearing is there to take advantage

of it, horsepower always wins the straightline race.

ian

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[ QUOTE ]

In 1st, 2nd take it all the way to redline.. probably 3rd gear

too, but certainly no less than 250 rpms off redline.

4th and 5th.. maybe 500 rpms lower, each gear.

If you have VAG-COM, you can log the rpms and speed over time

making runs in each gear, and then plug it into a spreadsheet

to calculate accelleration over speed to actually calculate

the optimal shiftpoints.

[/ QUOTE ]

grin.gif makes sense, well expained znaika.gif

...so anyone volunteering for this experiment 169144-ok.gif I'd love to but alas, I have no VAG-com frown.gif

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[ QUOTE ]

Great explanation Daemon, can someone explain this to Wopps - he is your 'foot the floor' type of driver.

[/ QUOTE ]

If by "foot to the floor" you mean that he doesn't downshift

to make best accelleration in a highway pull, then yes that's

no good, as I've already explained above.

If "foot to the floor" means he takes every gear to redline,

then that's not all that bad. It only hurts you at triple

digit speeds in the high gears. Most people shift way

too early "to get back to the meat of the torque", which

will destroy your 0-60 and 1/4 mile times.

ian

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[ QUOTE ]

I think wopps is more interested in your typical 0-60 times (or 0-30) as it suits his type of driving ie 'foot to the floor', his post on driving an Evo at 100mph in a 30 is proof of that.

Who needs a track day when you can drive like that on the public roads... NONO3.GIF

[/ QUOTE ]

You really are a sad old man. I hate to think that I am constantly plaguing your mind with hate of woppum thoughts. You take any available opportunity. Is it because I have the same car as you, while I am so young? I think you need to get over whatever your problem is because your obsession is starting to get a bit weird.

Ian, I do like my burst of acceleration, and through the first four gears I tend to love take it all the way to the red line, of course as long as roads are clear

beerchug.gif

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I don't hate yer wopps, I want to bond with you, I see fear & despondancy in everything you write, I'm here to help wopps!

Technically we have the same car as each other, I have the budget version and you have the all singing, all dancing one 169144-ok.gif

mine, however does go a tad faster...............

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