0-60mph launch technique?
Discussion
Bit of a tangent this one. Been playing with a Video VBox on my R500 and looking at acceleration etc.
So on a GPS-accurate Vbox, I accelerated in 1st gear from 38.7mph for 59.6mph in 1.33 seconds. So a gain of 21mph. This is in the meat of the torque, so I think this is about as much acceleration G force possible without slipping the clutch.
If I extrapolate a 0-60mph time from this, I get 3.81 seconds. Caterham quote 2.88 seconds for the car. So this makes me wonder how they launched the car? The must be slipping the clutch until quite high speeds to get the acceleration required for the book 0-60.
So not that I ever have done/will do one, but how do you do the 2.88s 0-60 time?
So on a GPS-accurate Vbox, I accelerated in 1st gear from 38.7mph for 59.6mph in 1.33 seconds. So a gain of 21mph. This is in the meat of the torque, so I think this is about as much acceleration G force possible without slipping the clutch.
If I extrapolate a 0-60mph time from this, I get 3.81 seconds. Caterham quote 2.88 seconds for the car. So this makes me wonder how they launched the car? The must be slipping the clutch until quite high speeds to get the acceleration required for the book 0-60.
So not that I ever have done/will do one, but how do you do the 2.88s 0-60 time?
I don't have an R500, but it feels so much quicker than my 911 even though it's not. I know its not an answer for you but its just the love of the feel for me. A bit of clutch slip, full on power power power and I am so happy. Ah well that's just me. If i get the gear change done quick and smooth, so much the better.
A 2.88 0-60 time is very hard to achieve.
I did literally hundreds of launches in my car (not an R500) to see how low I could get the time, and I can comment that the technique is NOT to slip the clutch at all.
What is critical is the launch RPM and releasing the clutch so that any slip is at the rear tyre contact patch with the road. Get this right, and you will be using warm sticky tyres, a surface with a high grip coefficient (Dunsfold is very good for this) and about 8000rpm.
Mechanically sympathetic, it is not.
I did literally hundreds of launches in my car (not an R500) to see how low I could get the time, and I can comment that the technique is NOT to slip the clutch at all.
What is critical is the launch RPM and releasing the clutch so that any slip is at the rear tyre contact patch with the road. Get this right, and you will be using warm sticky tyres, a surface with a high grip coefficient (Dunsfold is very good for this) and about 8000rpm.
Mechanically sympathetic, it is not.
EFA said:
and about 8000rpm.
Isn't that just going to leave a very impressive set of "11"s down the road and not really get you anywhere 
As said though, mechanical sympathy is not the key, with a 1600 roadsport the technique is to hold the revs at ~2500 revs and sidestep the clutch, the initial bite (while putting massive strain on the drivetrain) is enough to get the car to 10mph the fastest, after that it's easy
The shift should be nothing to do with it... the R500 can reach 60mph in 1st gear with the sequential box, which I assume is part of the reason the 0-60 time is so low. I think when Ariel do their 0-60 times they do it in 2nd, so there is no gear change which adds 0.2s even if you're a real hot foot.
ahhh ok
I was talking generally
having such a long first gear I imagine you would need heaps of revs off the line like arnie suggested ?
watch out for your diff mounts and drop the clutch ( or what remains of it) at somewhere between peak torque and max bhp ? maybe around 7500rpm ? might be worth trying or slipping till you have traction ?
do you have the ability to record the 64ft times ? that would be interesting as a comparison
I think the best I have ever recorded is about 2.07 seconds
I was talking generally
having such a long first gear I imagine you would need heaps of revs off the line like arnie suggested ?
watch out for your diff mounts and drop the clutch ( or what remains of it) at somewhere between peak torque and max bhp ? maybe around 7500rpm ? might be worth trying or slipping till you have traction ?
do you have the ability to record the 64ft times ? that would be interesting as a comparison
I think the best I have ever recorded is about 2.07 seconds
I'm guessing you don't have the launch control?
According to the following linky: http://www.skiddmark.com/2008/06/25/caterham-r500-... the launch control is capable of exceeding 1g to 60, although the guy from Caterham said it was possible to beat the launch control if you really knew what you were doing. So I am presuming they achieved in excess of 1g during the 2.88 run.
As I figured it was more of a gimmick, I haven't spec'd launch control on the R500 I have coming next March, and have no idea what revs it finally settles on when it asks you to dump the clutch.
Anyone with a launch control equipped car able to comment on the revs at launch?
According to the following linky: http://www.skiddmark.com/2008/06/25/caterham-r500-... the launch control is capable of exceeding 1g to 60, although the guy from Caterham said it was possible to beat the launch control if you really knew what you were doing. So I am presuming they achieved in excess of 1g during the 2.88 run.
As I figured it was more of a gimmick, I haven't spec'd launch control on the R500 I have coming next March, and have no idea what revs it finally settles on when it asks you to dump the clutch.
Anyone with a launch control equipped car able to comment on the revs at launch?
Edited by mattmurdock on Wednesday 3rd November 11:11
Nope, no launch control.
If you pull 1.04g from 0-40mph (slipping the clutch) and then 0.76g from 40-60 (what my VBox measured) then you get a 0-60 time of 2.97s. Assuming you could maintain 1.04g, you would need to be slipping the clutch until 45mph to get the 2.88s 0-60 time.
I wish I had someone else's car to have a play with getting these times, don't think I could do it to mine in good conscience!
If you pull 1.04g from 0-40mph (slipping the clutch) and then 0.76g from 40-60 (what my VBox measured) then you get a 0-60 time of 2.97s. Assuming you could maintain 1.04g, you would need to be slipping the clutch until 45mph to get the 2.88s 0-60 time.
I wish I had someone else's car to have a play with getting these times, don't think I could do it to mine in good conscience!
Murray993 said:
I don't have an R500, but it feels so much quicker than my 911 even though it's not.
Hey Murray... (Just for the record), Yes it is.Having owned a Porsche 996 Turbo S and and two R500s, and driven both on track many times, the Caterham is MUCH quicker than any Porsche. And I mean several seconds a lap, not tenths of seconds.
The R500 was quicker than the Bugatti and Zonda round the Top Gear track, which were both a country mile ahead of any Porsche.
Not knocking Porsche mind... great cars, and 4x4 astonishing in the wet
Edited by GetCarter on Wednesday 3rd November 17:11
GetCarter said:
Murray993 said:
I don't have an R500, but it feels so much quicker than my 911 even though it's not.
Hey Murray... (Just for the record), Yes it is.Having owned a Porsche 996 Turbo S and and two R500s, and driven both on track many times, the Caterham is MUCH quicker than any Porsche. And I mean several seconds a lap, not tenths of seconds.
The R500 was quicker than the Bugatti and Zonda round the Top Gear track, which were both a country mile ahead of any Porsche.
Not knocking Porsche mind... great cars, and 4x4 astonishing in the wet
Anyway, for comparison my GT-R had a G-force gauge on the funky LCD screen. It would accelerate at 0.7g up to ~45mph (e.g. in first) and the Caterham can do 0.76g up to ~60mph (again in first.) A like for like comparison would be both cars in 2nd gear, as they will both go up to about 75-80mph in 2nd gear. The GT-R would show significantly less G-force acceleration than the Caterham in 2nd. When my GT-R was remapped to ~550bhp it would do about 0.8g in 1st, and I would estimate it would be comparable in 2nd gear.
So straight line speed I would say 550bhp GT-R roughly equivalent to R500. And what Porsche is equivalent to a 550bhp GT-R? Maybe a GT2? No idea really. I've never been out-accelerated by Porsche on the track in the R500, and it monsters them under braking/corners.
mattmurdock said:
Anyone with a launch control equipped car able to comment on the revs at launch?
It depends what sector you select, it has 8 of them, varying from 1 for a wet slippery surface to 8 for dry i.e most agressive. Rather than bore everybody (but mostly me) here's the two extremes:Edited by mattmurdock on Wednesday 3rd November 11:11
Sector 1 - 2,000rpm for 1 s, 3,000rpm for 1 s, 3,700rpm to max 3s.
Sector 8 - 4,500rpm to max 3 s.
I can't comment on launching an R500, but I know the best repeatable technique for launching the porker is to balance wheel slip with the clutch rather than the throttle, and aim to keep a constant (high) rpm.
The difficulty then is judging the speed of the initial clutch pickup to get sufficient weight transfer. Getting it as close to perfect as I can I've achieved a sub 3.7s 0-100km/h launch, which was pretty good.
Having said that, the best Porsche launch I've ever seen was Nick Tandy's at Monza, where the second the lights went out the back end instantly banged down hard, and it took off cleanly like a scalded cat and pulled a good few car lengths on everyone else by the first corner. That can't have been clutch slip.
The difficulty then is judging the speed of the initial clutch pickup to get sufficient weight transfer. Getting it as close to perfect as I can I've achieved a sub 3.7s 0-100km/h launch, which was pretty good.
Having said that, the best Porsche launch I've ever seen was Nick Tandy's at Monza, where the second the lights went out the back end instantly banged down hard, and it took off cleanly like a scalded cat and pulled a good few car lengths on everyone else by the first corner. That can't have been clutch slip.
The Wookie said:
I can't comment on launching an R500, but I know the best repeatable technique for launching the porker is to balance wheel slip with the clutch rather than the throttle, and aim to keep a constant (high) rpm.
The difficulty then is judging the speed of the initial clutch pickup to get sufficient weight transfer. Getting it as close to perfect as I can I've achieved a sub 3.7s 0-100km/h launch, which was pretty good.
Having said that, the best Porsche launch I've ever seen was Nick Tandy's at Monza, where the second the lights went out the back end instantly banged down hard, and it took off cleanly like a scalded cat and pulled a good few car lengths on everyone else by the first corner. That can't have been clutch slip.
'The difficulty then is judging the speed of the initial clutch pickup to get sufficient weight transfer. Getting it as close to perfect as I can I've achieved a sub 3.7s 0-100km/h launch, which was pretty good.
Having said that, the best Porsche launch I've ever seen was Nick Tandy's at Monza, where the second the lights went out the back end instantly banged down hard, and it took off cleanly like a scalded cat and pulled a good few car lengths on everyone else by the first corner. That can't have been clutch slip.
Never driven a Porche, but had plenty of practice in the R400. As you say, weight transfer is the key to a good launch and 'less' is often 'more' for the first few milliseconds.
I've been told the figures Caterham quote are obtained by putting in full fuel with a pax, and then using very high(max?)RPM and then controlling wheel spin with the clutch. The theory is that extra traction out ways the the extra weight and that the stored kinetic energy in the engine can be used to full advantage. Maybe a myth but is was form a 'insider' who didn't recommend doing it as it breaks things very quickly - but at least they get their times!
Best times require short gearing. I used to run around 6.1mph/1000rpm - any taller and the 60ft time would be much higher. 60ft time is critical as can be seen on one of my better 1/4 mile slips.
Leaving rubber up the track is a non issue - look at F1.
You need to be sure your tyres are in the sweet spot between ruthless wheelspin and 0% slip. About halfway seems about right - lets you keep the engine near peak torque, which prevents any bogging down.
A low inertia engine (whihc the Duratec will never be) helps, as does a small clutch with a high torque rating (i.e the 5.5" clutch I ran had a 450ft/lb capacity) to provide an off/on fucntion rather than a slip. Any clutch with a sprung centre plate will cause bogging down issues.
Leaving rubber up the track is a non issue - look at F1.
You need to be sure your tyres are in the sweet spot between ruthless wheelspin and 0% slip. About halfway seems about right - lets you keep the engine near peak torque, which prevents any bogging down.
A low inertia engine (whihc the Duratec will never be) helps, as does a small clutch with a high torque rating (i.e the 5.5" clutch I ran had a 450ft/lb capacity) to provide an off/on fucntion rather than a slip. Any clutch with a sprung centre plate will cause bogging down issues.
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