L3ETT Posted July 13, 2004 Report Share Posted July 13, 2004 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? Link to comment Share on other sites More sharing options...
Woppum Posted July 13, 2004 Report Share Posted July 13, 2004 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 Link to comment Share on other sites More sharing options...
Riz Posted July 13, 2004 Report Share Posted July 13, 2004 [ 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 mmmm the Z4 must have thought the R32 is $hit.... you should have dropped a gear or two and made use of the torque... between 2800-3200rpms.... Next time woop his a$$ properly Riz Link to comment Share on other sites More sharing options...
L3ETT Posted July 13, 2004 Author Report Share Posted July 13, 2004 If i'd dropped a gear or two i'd have been on the rev limiter!! I think 60 in 5th is about 3500 rpm, and my butt dyno tells me that i get a kick in the back at 4k, so i assumed that was the best rev range to be in... Link to comment Share on other sites More sharing options...
odnet Posted July 13, 2004 Report Share Posted July 13, 2004 naaa, i'm with riz, drop & floor!!! ivan Link to comment Share on other sites More sharing options...
Woppum Posted July 13, 2004 Report Share Posted July 13, 2004 At 60 you can drop it happily to 3rd, very happily Link to comment Share on other sites More sharing options...
Daemon Posted July 14, 2004 Report Share Posted July 14, 2004 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 Link to comment Share on other sites More sharing options...
Viraje Posted July 14, 2004 Report Share Posted July 14, 2004 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. Link to comment Share on other sites More sharing options...
Riz Posted July 14, 2004 Report Share Posted July 14, 2004 5th gear doing 60mph = 2700rpms.... 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 Link to comment Share on other sites More sharing options...
Viraje Posted July 14, 2004 Report Share Posted July 14, 2004 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? Link to comment Share on other sites More sharing options...
fatcat Posted July 14, 2004 Report Share Posted July 14, 2004 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 Link to comment Share on other sites More sharing options...
Riz Posted July 14, 2004 Report Share Posted July 14, 2004 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.... Is it actually any worse or better then just slamming on the throttle pedal? Riz Link to comment Share on other sites More sharing options...
fatcat Posted July 14, 2004 Report Share Posted July 14, 2004 [ 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.... Is it actually any worse or better then just slamming on the throttle pedal? Riz [/ QUOTE ] I think you have answered your own post there me 'ol mucker. Link to comment Share on other sites More sharing options...
Riz Posted July 14, 2004 Report Share Posted July 14, 2004 [ 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.... Is it actually any worse or better then just slamming on the throttle pedal? Riz [/ QUOTE ] I think you have answered your own post there me 'ol mucker. [/ QUOTE ] Ooops duh... 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? Riz Link to comment Share on other sites More sharing options...
Skidmark Posted July 14, 2004 Report Share Posted July 14, 2004 [ 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.... Is it actually any worse or better then just slamming on the throttle pedal? Riz [/ QUOTE ] I got that feeling too thought it was just me much happier now Link to comment Share on other sites More sharing options...
Daemon Posted July 15, 2004 Report Share Posted July 15, 2004 [ 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.... 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 Link to comment Share on other sites More sharing options...
cerbera Posted July 15, 2004 Report Share Posted July 15, 2004 Great post Ian! Enjoyed reading that JT Link to comment Share on other sites More sharing options...
fatuscatus Posted July 15, 2004 Report Share Posted July 15, 2004 Great explanation Daemon, can someone explain this to Wopps - he is your 'foot the floor' type of driver. .......... he won't listion to me Link to comment Share on other sites More sharing options...
bazza_g Posted July 15, 2004 Report Share Posted July 15, 2004 [ 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 ] makes sense, well expained ...so anyone volunteering for this experiment I'd love to but alas, I have no VAG-com Link to comment Share on other sites More sharing options...
Daemon Posted July 15, 2004 Report Share Posted July 15, 2004 [ 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 Link to comment Share on other sites More sharing options...
fatuscatus Posted July 15, 2004 Report Share Posted July 15, 2004 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... Link to comment Share on other sites More sharing options...
BURTON Posted July 15, 2004 Report Share Posted July 15, 2004 Very interesting! And after being to the Pod (1/4 mile) on sunday i can relate to this!! Ahh trackdays here we come! Leda and Mag wheels!! mmmmmm Link to comment Share on other sites More sharing options...
Woppum Posted July 15, 2004 Report Share Posted July 15, 2004 [ 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... [/ 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 Link to comment Share on other sites More sharing options...
fatuscatus Posted July 15, 2004 Report Share Posted July 15, 2004 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 mine, however does go a tad faster............... Link to comment Share on other sites More sharing options...
fatuscatus Posted July 15, 2004 Report Share Posted July 15, 2004 + I don't think I'd want to be a 20 year again - far too drunk the first time around. Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now