Top speed V8V, V8VR, V8VS
Discussion
Good morning,
I have a small question regarding the Vmax of V8V, V8VR and V8VS. I tried the search but didn't get far, so if it has been discussed before and someone knows where, I would appreciate the link.
My question is on the differences in Vmax that seem not quite logical from a technical/physical point of view.
V8V / V8VR 4.3: 175 mph (280 kmh)
V8V / V8VR 4.7: 180 mph (290 kmh)
V8VS / V8VRS: 190 mph (305 kmh)
The difference 4.3 to 4.7 seems ok - 40 bhp difference should roughly account for the 5 mph.
What I do not get:
1) V8V and V8VR same top speed: how is that possible? The Roadster has for sure a much worse drag coefficient than the Coupe.
2) V8V(R) vs. V8V(R)S 10 mph difference. 10 bhp more give 10 mph more top speed? That might work with 50 bhp and 60 bhp but 420 bhp vs. 430 bhp, that should bring a mile more, if at all. Is this related to the ratio of the final gear? If so, is the final gear of the V8V too "long" or too "short" to reach more than 180 mph?
Thanks in advance,
Max
I have a small question regarding the Vmax of V8V, V8VR and V8VS. I tried the search but didn't get far, so if it has been discussed before and someone knows where, I would appreciate the link.
My question is on the differences in Vmax that seem not quite logical from a technical/physical point of view.
V8V / V8VR 4.3: 175 mph (280 kmh)
V8V / V8VR 4.7: 180 mph (290 kmh)
V8VS / V8VRS: 190 mph (305 kmh)
The difference 4.3 to 4.7 seems ok - 40 bhp difference should roughly account for the 5 mph.
What I do not get:
1) V8V and V8VR same top speed: how is that possible? The Roadster has for sure a much worse drag coefficient than the Coupe.
2) V8V(R) vs. V8V(R)S 10 mph difference. 10 bhp more give 10 mph more top speed? That might work with 50 bhp and 60 bhp but 420 bhp vs. 430 bhp, that should bring a mile more, if at all. Is this related to the ratio of the final gear? If so, is the final gear of the V8V too "long" or too "short" to reach more than 180 mph?
Thanks in advance,
Max
TKP said:
If you say it's marketing you mean it's not correct? I'm not talking 0-60 times, it's top speed and that you can measure quite accurately.
Your assumption would be the V8VS does not go the 190 mph?
Well certainly in my experience, Ive had my 4.3 "flat out" on a few occasions on airfields and autobahns. I see 160 to 165mph on GPS. Your assumption would be the V8VS does not go the 190 mph?
Few people can give you an answer on all these cars other than the manufacturer. Even the car magazines that publish figures dont necessarily do all the models under the same conditions on the same day.
Try achieving the 0-60mph time; unless you are a pro tester and have all day to spend trying to get the best results, thats another marketing figure that all the car manufacturers use.
All these figures are most useful for school boys playing "Top Trumps" in the playground
(a card game in 70s' and 80s)Im not saying there is no difference between models, no doubt someone has tested them, but also someone in marketing will have their say in what figures are quoted and no-one can really argue because all these figures are so variable in the real world.....
Edited by bogie on Thursday 22 September 09:50
I just want to understand it from a technical perspective as it seems not consistent - and if you drive in Germany, the figures are not theoretical, you can definitely drive 180 or 190 mph on German highways; not as often as I would like it, but it's possible, especially very early or very late.
I've commuted for several years about 40 miles (one way) and hit every morning and every evening the 155 mph the Merc was limited to.
I've commuted for several years about 40 miles (one way) and hit every morning and every evening the 155 mph the Merc was limited to.
Yes you are correct, the figures are not consistent, because there is some marketing involved, naturally 
I have driven thousands of miles in Germany. I took my Vantage for a 3000 mile tour a couple of months after buying it in 2007. It did 160mph a few times on the autobahn for a few minutes at a time. The fuel computer showed 6mpg though, so I decided it was faster to get to my destination by cruising about 120mph and save all the fuel stops
There are some members on here that work in the car industry, im sure they will be along to explain the technical differences. Im just an old cynic that doesnt believe manufacturer performance figures, or aftermarket dynos either
Add 0.5 to 1 sec onto the achievable performance figures and knock 10% off the top speeds, then you are somewhere near real world results.
I have driven thousands of miles in Germany. I took my Vantage for a 3000 mile tour a couple of months after buying it in 2007. It did 160mph a few times on the autobahn for a few minutes at a time. The fuel computer showed 6mpg though, so I decided it was faster to get to my destination by cruising about 120mph and save all the fuel stops
There are some members on here that work in the car industry, im sure they will be along to explain the technical differences. Im just an old cynic that doesnt believe manufacturer performance figures, or aftermarket dynos either
Add 0.5 to 1 sec onto the achievable performance figures and knock 10% off the top speeds, then you are somewhere near real world results.
TKP said:
If you say it's marketing you mean it's not correct? I'm not talking 0-60 times, it's top speed and that you can measure quite accurately.
Your assumption would be the V8VS does not go the 190 mph?
The difficulty is that you simply can't measure the top speed of a car accurately then apply that to everyone of it's type. Two cars of the same spec may top out differently depending upon so many factors ranging from wind speed / direction, tyre pressures / spec, fuel type, speedo/gps error, air temperature and even how flat your German Autobahn is. The impact may be small but it would be enough to say that each models published top speed is going to be more theoretical than physically measured. In the real world a good roaster in favourable weather conditions may be faster than the equivalent coupe, especially if the coupe was a little 'tired' mechanically and the conditions were against it.Your assumption would be the V8VS does not go the 190 mph?
Remember, Jaguar launched the E Type on the basis it had a 150 mph top speed, something no production car ever got near! Also, Le Mans race-cars post their fastest lap time in the early hours of the Sunday morning as traditionally that's when the air is cooler which makes the engine stronger. There is more to top-speed than simply a mph number.
Ex Boy Racer said:
So, if it can't do the claimed top speed, can you take it back for a refund?
You could try, but they might want Mr Darren Turner to drive your car first, before agreeing any refund.
That might possibly be embarrassing for you.
This is an interesting and very technical topic.
davek_964 said:
There are far more obvious things that are claimed but never achievable - mpg for one.
I just fill when needed so do not know the mpg, but whatever the fuel consumption is, I thought recent research praised AML.
It was reported on the internet, so must be correct!
Dieselgate: The only car that actually passes new 'real world' fuel consumption tests - an Aston Martin Vantage.
Aston Martin’s gas-guzzling Vantage sports car is the only vehicle to achieve its advertised fuel consumption, according to new research.
A study by testing company Emissions Analytics found the 190mph vehicle managed 21.5 miles per gallon, beating the manufacturer’s claim of 20.5 mpg, according to the official testing regime.
http://www.telegraph.co.uk/business/2016/08/31/die...
Edited by Jon39 on Thursday 22 September 12:22
Jon39 said:
davek_964 said:
There are far more obvious things that are claimed but never achievable - mpg for one.
I just fill when needed so do not know the mpg, but whatever the fuel consumption is, I thought recent research praised AML.
It was reported on the internet, so must be correct!
Aston Martin’s gas-guzzling Vantage sports car is the only vehicle to achieve its advertised fuel consumption, according to new research.
A study by testing company Emissions Analytics found the 190mph vehicle managed 21.5 miles per gallon, beating the manufacturer’s claim of 20.5 mpg, according to the official testing regime.
http://www.telegraph.co.uk/business/2016/08/31/die...
0-60 and mpg and top speed are different things to me.
0-60 is extremely depending on outside conditions, tires, road, clutch, driver etc.
mpg is correct under the same test environment as it is measured. It's far away from reality, but you would get there in the same environment.
But Vmax is - imo - something very different, technically. The engine revs at certain RPM at Vmax. If the V8VS has the same gearbox and diff (and tyre size), it would need to rev about 5% higher if it's 10 mph more top speed. However, why would the normal V8V 4.7 be "stuck" at 300-400 RPM less?
If the answer is truly "AM marketing", ok. But e.g. Porsche go as fast as they claim in top speed, I tried it with a few.
0-60 is extremely depending on outside conditions, tires, road, clutch, driver etc.
mpg is correct under the same test environment as it is measured. It's far away from reality, but you would get there in the same environment.
But Vmax is - imo - something very different, technically. The engine revs at certain RPM at Vmax. If the V8VS has the same gearbox and diff (and tyre size), it would need to rev about 5% higher if it's 10 mph more top speed. However, why would the normal V8V 4.7 be "stuck" at 300-400 RPM less?
If the answer is truly "AM marketing", ok. But e.g. Porsche go as fast as they claim in top speed, I tried it with a few.
TKP said:
0-60 and mpg and top speed are different things to me.
0-60 is extremely depending on outside conditions, tires, road, clutch, driver etc.
mpg is correct under the same test environment as it is measured. It's far away from reality, but you would get there in the same environment.
But Vmax is - imo - something very different, technically. The engine revs at certain RPM at Vmax. If the V8VS has the same gearbox and diff (and tyre size), it would need to rev about 5% higher if it's 10 mph more top speed. However, why would the normal V8V 4.7 be "stuck" at 300-400 RPM less?
If the answer is truly "AM marketing", ok. But e.g. Porsche go as fast as they claim in top speed, I tried it with a few.
I think you're taking a slightly simplistic view. You think 0-60 depends on outside conditions, but top speed doesn't? You don't think gradient / wind / temperature (air density) makes a difference to top speed?0-60 is extremely depending on outside conditions, tires, road, clutch, driver etc.
mpg is correct under the same test environment as it is measured. It's far away from reality, but you would get there in the same environment.
But Vmax is - imo - something very different, technically. The engine revs at certain RPM at Vmax. If the V8VS has the same gearbox and diff (and tyre size), it would need to rev about 5% higher if it's 10 mph more top speed. However, why would the normal V8V 4.7 be "stuck" at 300-400 RPM less?
If the answer is truly "AM marketing", ok. But e.g. Porsche go as fast as they claim in top speed, I tried it with a few.
In any case, unless you are actually playing top trumps - why does it matter whether your car does 175mph or only 170mph? Does anybody really buy a car based purely on it's top speed?
The only people that know "the truth" about the published top speeds of the different models are the guys doing the testing at the factory. How and when these speeds we were achieved, we dont know.
For all we know, some of the models may have posted better top speeds on the day, but someone in marketing marked it down 5mph to save sales of the next model up that didn't do so well on the day it was tested due to say wind conditions.
There is a test day at Bruntingthorpe this Saturday where you can run your car to top speed with timing gear to measure it. Perhaps there will be a few different Aston owners there. Not going myself this time.
I can concur on the fuel economy though, the 4.3 Vantage easily achieves its claimed figures, no bullsh*t there
For all we know, some of the models may have posted better top speeds on the day, but someone in marketing marked it down 5mph to save sales of the next model up that didn't do so well on the day it was tested due to say wind conditions.
There is a test day at Bruntingthorpe this Saturday where you can run your car to top speed with timing gear to measure it. Perhaps there will be a few different Aston owners there. Not going myself this time.
I can concur on the fuel economy though, the 4.3 Vantage easily achieves its claimed figures, no bullsh*t there
davek_964 said:
I think you're taking a slightly simplistic view. You think 0-60 depends on outside conditions, but top speed doesn't? You don't think gradient / wind / temperature (air density) makes a difference to top speed?
In any case, unless you are actually playing top trumps - why does it matter whether your car does 175mph or only 170mph? Does anybody really buy a car based purely on it's top speed?
As I wrote, the conditions for top speed are IMHO much easier to control as for 0-60. Get a flat highway, wait for low/no wind (or drive back and forth and take the average), do it when temperature is roughly ok (meaning in between 10 and 20 dregree Celcius). The deviations are much smaller than when you try to get the to the factory 0-60.In any case, unless you are actually playing top trumps - why does it matter whether your car does 175mph or only 170mph? Does anybody really buy a car based purely on it's top speed?
And no, I guess no one buys a car purely based on top speed (maybe Veyron/Chiron drivers), at least I didn't as I bought the Aston without even testing the top speed.
For me just the differences in between V8V and V8VR as well as V8V and V8VS top speed seem strange when I look at the figures and the technical data and I was wondering if any of the experts here know how a V8VS can go 10 mph more with just 10 bhp more. Might be a gear/diff ratio thing, I don't know. That's why I'm asking and the answer "it doesn't matter" is probably correct but helps little to resolve this.
But maybe that's just me expecting too much precision on the specs of a British car (no offense intended)
Edited by TKP on Thursday 22 September 15:23
TKP said:
But maybe that's just me expecting too much precision on the specs of a British car
I'd say even allowing for some variation on the 'precision' of the cars, there are just too many external variables when it comes to top-speed. There just aren't enough long, private flat roads where manufacturers can top-out their cars, (even Millbrook scrubs off speed on the bowl) and if there was one somewhere would all the manufacturers really take every variant there to produce a profile of maximum figures. The press can do this when doing a road-test but even then it's down to the conditions on the day and which runway they have access to which is why different magazines often publish different top speeds, which are again different to the manufacturers figures. Bugatti use the VW testing grounds in Germany which has a 3 mile straight (from memory of James May on Top Gear) but I can't see them letting Aston Martin use it for example.0-60 is easy and can be done on any disused runway or at Millbrook for example and mpg figures are always done on the rollers in a lab which is why 'real-world' figures are often miles out.
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