Bahnstorming Speeds
Discussion
herebebeasties said:
Panamax said:
Bear in mind that of you're tanking up the 2-lane autobahn at 250 kph (155 mph) and someone moves out from the inside lane at normal motorway speed it's the equivalent of encountering a parked car in the outside lane of the M1.
No, it's not equivalent at all, it's actually three times worse than that.The relative speed differential may be the same, but your kinetic energy isn't proportional to speed, it's proportional to your speed squared.
So the energy your brakes need to dissipate to decelerate from 140mph to 70mph is three times what you need to decelerate from 70mph to zero. (OK you'll also benefit from a bit more air resistance slowing you down from higher speed, but it's not significant compared to maximum braking effort.)
Kawasicki said:
herebebeasties said:
Panamax said:
Bear in mind that of you're tanking up the 2-lane autobahn at 250 kph (155 mph) and someone moves out from the inside lane at normal motorway speed it's the equivalent of encountering a parked car in the outside lane of the M1.
No, it's not equivalent at all, it's actually three times worse than that.The relative speed differential may be the same, but your kinetic energy isn't proportional to speed, it's proportional to your speed squared.
So the energy your brakes need to dissipate to decelerate from 140mph to 70mph is three times what you need to decelerate from 70mph to zero. (OK you'll also benefit from a bit more air resistance slowing you down from higher speed, but it's not significant compared to maximum braking effort.)
Combination of competency and well maintained car (suitable to the task) is needed.
Kawasicki said:
A good autobahn car will be engineered to cope with such braking. It’s also unwise to find out that you are driving a car that can’t cope. Personal responsibility.
When I had to come down hard on the brakes from 120 in the F82 M4...they did cope well with it in fairness. But it also made me think back to the brakes in the E92 M3 though, and if I'd been in the same situation in that...it would've ended in tears in comparison for definite, because the brakes in that were lousy in comparison. Plus arguably the E92 M3 is actually the better autobahn car as well, because all the performance is at the top of the revs, and it actually pulls a fair bit harder than the M4 does at a 100 plus I reckon too, even though the M4 is the faster car on paper though. The M4 definitely feels weaker on its top end for me, but obviously it feels much more punchy everywhere else though.
cerb4.5lee said:
Kawasicki said:
A good autobahn car will be engineered to cope with such braking. It’s also unwise to find out that you are driving a car that can’t cope. Personal responsibility.
When I had to come down hard on the brakes from 120 in the F82 M4...they did cope well with it in fairness. But it also made me think back to the brakes in the E92 M3 though, and if I'd been in the same situation in that...it would've ended in tears in comparison for definite, because the brakes in that were lousy in comparison. Plus arguably the E92 M3 is actually the better autobahn car as well, because all the performance is at the top of the revs, and it actually pulls a fair bit harder than the M4 does at a 100 plus I reckon too, even though the M4 is the faster car on paper though. The M4 definitely feels weaker on its top end for me, but obviously it feels much more punchy everywhere else though.
E90_M3Ross said:
The overall stopping performance from the E92 M3 brakes are really not far off the F82 M4. Where they aren't so good is doing it over and over again. I've got Ferodo DS2500 pads on mine, with uprated fluid (Motul RBF 660) and it's made a big difference.
I always remember having to abort an overtake once in the E92 M3, because a car was coming the other way that I'd not spotted. So I had to stamp on the brakes...and they failed miserably on me! So I've always been a bit harsh on it brakes wise after that experience that is all. I don't remember being especially disappointed with them generally in any other situation though in fairness. cerb4.5lee said:
993rsr said:
I'd love to own a car capable of 200mph for sure.
I've done over 150 indicated on the autobahn dropping down from Cologne, just because, but didn't like it because of other drivers, and the fuel gauge
Occasional squirts to the rev limiter in third, but thats very licence limiting.Steady 85mph/130kmh works well most of the time.
cerb4.5lee said:
E90_M3Ross said:
The overall stopping performance from the E92 M3 brakes are really not far off the F82 M4. Where they aren't so good is doing it over and over again. I've got Ferodo DS2500 pads on mine, with uprated fluid (Motul RBF 660) and it's made a big difference.
I always remember having to abort an overtake once in the E92 M3, because a car was coming the other way that I'd not spotted. So I had to stamp on the brakes...and they failed miserably on me! So I've always been a bit harsh on it brakes wise after that experience that is all. I don't remember being especially disappointed with them generally in any other situation though in fairness. 
E90_M3Ross said:
Stamp on the brakes and mine definitely slows down
I used to love the standard AP Racing brakes on the Cerbera for that too, and because it was relatively light, it used to scrub off the speed really well at high speeds. It did have a tendency to lock a wheel up at slower speeds if you were too hard on them though, because of the lack of ABS.
cerb4.5lee said:
E90_M3Ross said:
Stamp on the brakes and mine definitely slows down
I used to love the standard AP Racing brakes on the Cerbera for that too, and because it was relatively light, it used to scrub off the speed really well at high speeds. It did have a tendency to lock a wheel up at slower speeds if you were too hard on them though, because of the lack of ABS.
RMA 3 days 'Ring trip over 15 yrs ago. Three of us. Friends in 964RS and a 1987 911 CS, me in my Exige.
We left and hit the Autobahn on the way back to Rotterdam for the ferry and hit the 7km autobahn straight with a very slight downward slope (A1, can't remember). We all set off, the Porsches pulled away above 80/90mph but I gradually caught first the CS, then the RS.
I had a standalone GPS sat nav which also read the speed. It got to 172mph. I had visions of taking a photo of the speedo, but the fact was that well before the top speed, the concentration and tightening grip on the steering wheel meant I could do nothing other than feel my eyes on stalks (with ad odd glance at the windscreen mounted GPS) and HR well into the 100s as my arse clenched the seat. It was terrifying and I couldn't wait to slow down.
Years later I did something similar in Italy between Milan and Como in my Alfa Giulia QF. Bumped into a ABT RS6 and a 911 S as I left the toll booth (they drove tho the fastpass lane and waited). We all nailed it, the RS6 pulled away, I was pegged with the 911 until he slowed. Wife asleep, daughter on her iPad in the rear, dog next to her, we gunned it towards Como. I'd set my speedo to KPH and got to 275 before lifting, the RS6 kept going. Similar speed to the experience in the Exige but this time rock solid and felt no different to doing 120 - none of the other passengers even woke/noticed.
We left and hit the Autobahn on the way back to Rotterdam for the ferry and hit the 7km autobahn straight with a very slight downward slope (A1, can't remember). We all set off, the Porsches pulled away above 80/90mph but I gradually caught first the CS, then the RS.
I had a standalone GPS sat nav which also read the speed. It got to 172mph. I had visions of taking a photo of the speedo, but the fact was that well before the top speed, the concentration and tightening grip on the steering wheel meant I could do nothing other than feel my eyes on stalks (with ad odd glance at the windscreen mounted GPS) and HR well into the 100s as my arse clenched the seat. It was terrifying and I couldn't wait to slow down.
Years later I did something similar in Italy between Milan and Como in my Alfa Giulia QF. Bumped into a ABT RS6 and a 911 S as I left the toll booth (they drove tho the fastpass lane and waited). We all nailed it, the RS6 pulled away, I was pegged with the 911 until he slowed. Wife asleep, daughter on her iPad in the rear, dog next to her, we gunned it towards Como. I'd set my speedo to KPH and got to 275 before lifting, the RS6 kept going. Similar speed to the experience in the Exige but this time rock solid and felt no different to doing 120 - none of the other passengers even woke/noticed.
I’ve driven a number of cars on the Autobahn in recent years.
The hariest was the 928 (predictably). A bit floaty even with newish dampers and springs.
The most planted was the 992 S. The engineering shines through even more at these speeds. Quick to accelerate and brake, even in my modest spec.
The most effortless was the older B5 Touring, serene at any speed. You can easily tell where this was tested! Haven’t tried the GT over there yet.
And the V90 CC diesel hit its top speed! Limited to 112mph, obvs.
Overall, I’ve never hit 200, 180-something was enough for me. And as others say, normal cruising is around 80 to 100, with many more limits for noise and pollution nowadays.
The hariest was the 928 (predictably). A bit floaty even with newish dampers and springs.
The most planted was the 992 S. The engineering shines through even more at these speeds. Quick to accelerate and brake, even in my modest spec.
The most effortless was the older B5 Touring, serene at any speed. You can easily tell where this was tested! Haven’t tried the GT over there yet.
And the V90 CC diesel hit its top speed! Limited to 112mph, obvs.
Overall, I’ve never hit 200, 180-something was enough for me. And as others say, normal cruising is around 80 to 100, with many more limits for noise and pollution nowadays.
EmailAddress said:
Panamax said:
Bear in mind that of you're tanking up the 2-lane autobahn at 250 kph (155 mph) and someone moves out from the inside lane at normal motorway speed it's the equivalent of encountering a parked car in the outside lane of the M1.
Not dissimilar to passing a cyclist on a dual carriageway.I've held 205 indicated in my 430 but that car is a real handful above 180, which is about its reasonable comfortable operating ceiling on road; the engine lid open light was flickering thanks to the volume of airflow into the engine bay, lifting the lid high enough to trigger the switch. Needed a lot of concentration as not enough downforce, but very exciting for a short period.
The regular production stuff on the other hand, like M3s, and V8 AMGs - I'll sit at 155 all day in those as the only thing you need to worry about is oncoming hazards. Totally benign.
I'm really comfortable at high speed and I can, and do, maintain it for extended periods. Don't think I'll ever tire of it but I'm sure the ol' brain processesing speed and eyesight will eventually call time on it!
The regular production stuff on the other hand, like M3s, and V8 AMGs - I'll sit at 155 all day in those as the only thing you need to worry about is oncoming hazards. Totally benign.
I'm really comfortable at high speed and I can, and do, maintain it for extended periods. Don't think I'll ever tire of it but I'm sure the ol' brain processesing speed and eyesight will eventually call time on it!
Took an M8 Competition out to Germany the week before last, limited to 155mph but got their quickly on several occasions
Took my V12 V there last year and got about 170mph and have done 175 in a 456 years ago
Fewer de-restricted bits now, though the bit last week from north Luxembourg down to Stuttgart was good - 40-50 miles of easy clear unrestricted motorway. Best I've seen driving wise is the stretch from Chemnitz/Dresden to the PL border
Took my V12 V there last year and got about 170mph and have done 175 in a 456 years ago
Fewer de-restricted bits now, though the bit last week from north Luxembourg down to Stuttgart was good - 40-50 miles of easy clear unrestricted motorway. Best I've seen driving wise is the stretch from Chemnitz/Dresden to the PL border
When I had a C6 RS6 it was quite happy and unperturbed at its software-limited 175mph on the derestricted Autobahn. The scenery goes past quickly in ideal comfort, much like being on a TGV.
It's probably less stressful and hazardous than doing 90mph in the UK because you're not distracted by second-guessing other cars, looking into their cabins to see if they're undercover rozzers. Instead, you can simply focus on anticipating, adjusting and tracking the dynamic behaviour of whatever is ahead.
It's probably less stressful and hazardous than doing 90mph in the UK because you're not distracted by second-guessing other cars, looking into their cabins to see if they're undercover rozzers. Instead, you can simply focus on anticipating, adjusting and tracking the dynamic behaviour of whatever is ahead.
Edited by Jacobyte on Thursday 20th June 13:13
herebebeasties said:
Panamax said:
Bear in mind that of you're tanking up the 2-lane autobahn at 250 kph (155 mph) and someone moves out from the inside lane at normal motorway speed it's the equivalent of encountering a parked car in the outside lane of the M1.
No, it's not equivalent at all, it's actually three times worse than that.The relative speed differential may be the same, but your kinetic energy isn't proportional to speed, it's proportional to your speed squared.
So the energy your brakes need to dissipate to decelerate from 140mph to 70mph is three times what you need to decelerate from 70mph to zero. (OK you'll also benefit from a bit more air resistance slowing you down from higher speed, but it's not significant compared to maximum braking effort.)
You absolutely do NOT need anything like three times the braking effort to get from 140-70 as 70 to 0, the graph for road cars will actually be close to linear. You can even see that in the last 200kph of the Bloodhound graph below.
Edited by Aphrabehn on Thursday 20th June 13:22
Edited by Aphrabehn on Thursday 20th June 13:23
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