RE: Light cars are not the answer: Tell Me I'm Wrong
Discussion
With respect to the comment about strength being important, it's perhaps worth pointing out that what matters is torsiopnal rigidity to weight ratio, not absolute torsional rigidity because the twisting forces being applied to the chassis vary in direct proportion to weight.
In other words you can make a car flex less by removing (non-structural) weight.
In other words you can make a car flex less by removing (non-structural) weight.
Hmm, I understand/accept some of the points made but it goes against everything I've always believed in! Surely light weight is preferable as it is simply more efficient. I.e. the McLaren F1 only needed 627 BHP to achieve 0-200 MPH in 28 seconds and the Veyron needed another 50% more horsepower to knock a couple of seconds off of that time! Less weight also allows more relaxed damping with softer springs to keep the mass in check which is beneficial to road driving. Look at the WET Weather times achieved in various magazines by the super-stiff Nissan GTR, they are pretty poor really compared with, say a bog standard 911 Carrera or a Golf R or something. Also, whilst I know the GT-R can do a single lap in record time, how long does it last on a track day before wearing out its pads and tyres? No where near as long as Caterham 7 I bet!
GreenArrow said:
Hmm, I understand/accept some of the points made but it goes against everything I've always believed in! Surely light weight is preferable as it is simply more efficient. I.e. the McLaren F1 only needed 627 BHP to achieve 0-200 MPH in 28 seconds and the Veyron needed another 50% more horsepower to knock a couple of seconds off of that time!
The Veyron didn't 'need' 50% more power to knock a few seconds of the 0-200 time. It needed 50% more power to reach it's target Vmax (recall that to go 2x faster you need 6x the power). You could shorten the gearing a lot and use less bhp to beat the F1's time. The difference in 0-200 times will be a function of power and weight, yes, but also traction (Veyron 4WD, McLaren RWD), gearing and tyres - tyre technology has moved on a lot since the days of the McLaren F1. I agree that low weight aids efficiency, but your example is weak and potentially misleading.kambites said:
An F1 car has to be going pretty damned fast to generate a tonne of downforce. I can't see a vehicle running at a ride height suitable for use on the road managing it.
Brabham style fan car with sideskirts I suppose as by it's very nature you can't generate a lot of downforce at low speeds.... and god help you if you hit a bump hard that unsettles the ground effects and you lose that downforce....As far as the article is concerned, could not disagree more where sports cars are concerned I'm afraid. Lighter is definitely better all things being equal.
NelsonP said:
T0MMY said:
My understanding is that the extra grip from having more weight is exactly balanced in cornering by the extra inertia you're fighting against
Don't think it is a linear relationship, but someone smarter than me can probably clarify.Also more weight = slower acceleration and deceleration, regardless of cornering.
The other misunderstood bit is about roll. The weight transfer and therefore the centrifugal forces applied are the same irrespective of the amount of roll. So you really want light irrespective of the roll's dynamic range. It's the dampers that control the lateral weight transfers, the less weight, the better they work.
Problem is, apart from being a bad solution from a consumable cost POV, enlarging the tyres (and increasing power) to compensate doesn't event help as the relationship is not linear even for the best compounds...
There is literately no substitute for lightness. Having just moved from a 1450kg car to a 1200kg car, the benefits are pretty dramatic although other factors come into play and there also some downsides, traction management and refinement being the obvious ones.
Edited by nickfrog on Thursday 8th January 19:21
RenesisEvo said:
The Veyron didn't 'need' 50% more power to knock a few seconds of the 0-200 time. It needed 50% more power to reach it's target Vmax (recall that to go 2x faster you need 6x the power). You could shorten the gearing a lot and use less bhp to beat the F1's time. The difference in 0-200 times will be a function of power and weight, yes, but also traction (Veyron 4WD, McLaren RWD), gearing and tyres - tyre technology has moved on a lot since the days of the McLaren F1. I agree that low weight aids efficiency, but your example is weak and potentially misleading.
Plus when talking about 0-200mph the weight is far less of an issue than in 0-100mph. When the speeds get that high, power:drag is far more important than power:weight, as any Caterham owner will know!nickfrog said:
NelsonP said:
T0MMY said:
My understanding is that the extra grip from having more weight is exactly balanced in cornering by the extra inertia you're fighting against
Don't think it is a linear relationship, but someone smarter than me can probably clarify.Also more weight = slower acceleration and deceleration, regardless of cornering.
...
T0MMY said:
nickfrog said:
NelsonP said:
T0MMY said:
My understanding is that the extra grip from having more weight is exactly balanced in cornering by the extra inertia you're fighting against
Don't think it is a linear relationship, but someone smarter than me can probably clarify.Also more weight = slower acceleration and deceleration, regardless of cornering.
...
It does increase traction of course.
Witness the GTR being around 1g which is what a GT86 will achieve on non-eco tyres. In other words a GTR is no quicker than a GT86 at the apex (but is quicker everywhere else of course). http://www.caranddriver.com/reviews/2014-nissan-gt...
" the only other measurable improvements over the last base 2013 GT-R we tested were in braking (145 versus 161 feet) and lateral grip (1.02 versus 0.97 g)."
Edited by nickfrog on Thursday 8th January 19:23
T0MMY said:
nickfrog said:
NelsonP said:
T0MMY said:
My understanding is that the extra grip from having more weight is exactly balanced in cornering by the extra inertia you're fighting against
Don't think it is a linear relationship, but someone smarter than me can probably clarify.Also more weight = slower acceleration and deceleration, regardless of cornering.
...
Another thing to consider is that grip is the sum total of the grip of all four tyres. Because of the non-linear load/grip curve you can see that the maximum potential grip is when all four tyres are equally loaded, but when you actually generate grip when cornering you also have to consider weight transfer. The two more loaded outer tyres will move up the curve and the more lightly loaded tyres move down the curve, but the sum total is now less than when all four were equally loaded. The more weight transfer you have the more grip potential you lose. The heavier the car the more weight transfer when cornering, and the greater the reduction in grip potential, all other things being equal.
My biggest gripe with heavy sportscars is the cost of running them'. Accelerating, cornering and braking 1.5 - 2 tonnes is heavy on fuel, tyres, brakes, suspension etc. etc. Witness a trackday at Brands, a guy had a 700bhp Audi RS6 and by the end of the day two tyres had delaminated their tread and the other two were bald. He went home on a flat bed after spending a couple of hundred quid on fuel, he looked like he have a great day out. Not my idea of fun in a country with a 70mph speed limit. In contrast, by bike engined road car weighs 450kg wet and doesn't use anything really except petrol, I change the brake pads as they get contaminated before they are half worn. But it is refined as a motorbike too, so there has to be a happy medium.....
For me, a happy medium for a sportscar is about 1,000kg , maybe 1,100, and about 3-400bhp. Something akin to a Noble? Refined *just* enough and heavy enough with aero to be stable at high speed, but very little driving aids or over assistance to mask the experience.
GT and touring type cars ( Bentley etc. ) are not really my thing, but then I don't need one for my lifestyle so I have not had a lot of dealing with them and know little of their dynamics. Except I would probably not use it much if I had one. Even driving my wife's fully loaded Boxster S felt to me like shagging a fat bird, she was no delicate Elise in my hands. If I want to be cosseted in complete luxury I can always stay home on my sofa with a glass of Barolo, for driving I want something a bit more involving and pure.
Saying that I did have a passenger ride in Jeremy Clarkeson's old Ford GT at 160mph, I woul gladly give my left b
k for that on my drive.
For me, a happy medium for a sportscar is about 1,000kg , maybe 1,100, and about 3-400bhp. Something akin to a Noble? Refined *just* enough and heavy enough with aero to be stable at high speed, but very little driving aids or over assistance to mask the experience.
GT and touring type cars ( Bentley etc. ) are not really my thing, but then I don't need one for my lifestyle so I have not had a lot of dealing with them and know little of their dynamics. Except I would probably not use it much if I had one. Even driving my wife's fully loaded Boxster S felt to me like shagging a fat bird, she was no delicate Elise in my hands. If I want to be cosseted in complete luxury I can always stay home on my sofa with a glass of Barolo, for driving I want something a bit more involving and pure.
Saying that I did have a passenger ride in Jeremy Clarkeson's old Ford GT at 160mph, I woul gladly give my left b
k for that on my drive. [quote=JDMDrifter]I think the extremes are being focused on here. A better way to look at it is for Instance a 1800kg car won't be as good to drive as a 1400kg car.
yes this is true ..
every car I've had that is close or under 1000 kg is fun . Anything over 1400 feels numb to me ...dosnt matter how fast it is ,
and if you get a car under the 1000 say 700 to 900 ...it will be fun ... even 80 hp in these ..if not fast ..fun in the balance it gives
yes this is true ..
every car I've had that is close or under 1000 kg is fun . Anything over 1400 feels numb to me ...dosnt matter how fast it is ,
and if you get a car under the 1000 say 700 to 900 ...it will be fun ... even 80 hp in these ..if not fast ..fun in the balance it gives
Tyres.
A 1000kg car with 19" wheels and a smattering of rubber painted around the rim is never going to ride well. Put 15" wheels and a taller tyre on and it'll ride very well with very little detriment to the handling. It might even make it a bit more predictable when it does break away too.
Of course, that's not fashionable so it'll never happen these days.
A 1000kg car with 19" wheels and a smattering of rubber painted around the rim is never going to ride well. Put 15" wheels and a taller tyre on and it'll ride very well with very little detriment to the handling. It might even make it a bit more predictable when it does break away too.
Of course, that's not fashionable so it'll never happen these days.
Gassing Station | General Gassing | Top of Page | What's New | My Stuff