Heavy vs light cars at speed.
Discussion
Hi There
My reference points are the roads in North Wales around Snowdonia. In Feb - Apr when I am up there it is asy to hack along at speeds up to 100mph on quite twisty and undulating roads.
Performance, ie 0-60 and braking, being equal am I better off in a 950kg ish car or a 1350kg ish car? So for example a Porsche 911 (say a 993, 996 or 997) or something like an Elsie/Exige VX220 type of car. Or indeed a very hot hatch?
From my limited experience the heavier performance cars are much better when you really get the speeds up. At lower speeds the lighter cars feel more dynamic though.
What do the people who really know say?
All the best
Berni
My reference points are the roads in North Wales around Snowdonia. In Feb - Apr when I am up there it is asy to hack along at speeds up to 100mph on quite twisty and undulating roads.
Performance, ie 0-60 and braking, being equal am I better off in a 950kg ish car or a 1350kg ish car? So for example a Porsche 911 (say a 993, 996 or 997) or something like an Elsie/Exige VX220 type of car. Or indeed a very hot hatch?
From my limited experience the heavier performance cars are much better when you really get the speeds up. At lower speeds the lighter cars feel more dynamic though.
What do the people who really know say?
All the best
Berni
It's all to do with inertia.
The heavier the car, the more force is required to make it deviate from the straight, and that applies to being knocked about by winds as well as trying to turn into a corner.
Wind resistance goes up as the square of speed, so if you double your speed, you multiply the wind resistance by 4 times. As your speed increases, then any cross wind component will have more effect.
So the heavier car will be less inclined to be knocked about and less reliant on good aerodynamics. It will be easier to track straight at speed.
The lighter car is more nimble, and without good aero, darty at speed.
This effect an be compounded by geometry set up as well. Newcomers to sports cars sometimes complain about 'twitchy' handling. This may well be due to coming from a diet of saloons which have been trimmed for stability.
The heavier the car, the more force is required to make it deviate from the straight, and that applies to being knocked about by winds as well as trying to turn into a corner.
Wind resistance goes up as the square of speed, so if you double your speed, you multiply the wind resistance by 4 times. As your speed increases, then any cross wind component will have more effect.
So the heavier car will be less inclined to be knocked about and less reliant on good aerodynamics. It will be easier to track straight at speed.
The lighter car is more nimble, and without good aero, darty at speed.
This effect an be compounded by geometry set up as well. Newcomers to sports cars sometimes complain about 'twitchy' handling. This may well be due to coming from a diet of saloons which have been trimmed for stability.
Hi Berw
I have never tried an Elan Sprint but I have had two Elan +2's around those roads and they handle them well. The Sprint would be much better of course. Indeed I crashed one into a slate embankment when I was lost on one moonless night. The headlights were never up to much and I thought I was on a long straight instead of a short sudden corner. I was pleased the car had such a long nose as it took a lot of the force of the impact out.
Although my +2's were reasonably well sorted they did get a bit floaty when pressing on. Great fun on the tighter stuff though. I am wondering if an Elise would feel similar on the faster runs due to the relative lightness.
Hi Paul, I have just seen your post. Some cars have quite small frontal areas but are fairly heavy and I put my 993 in this category. It does change direction well and seems to get better the faster you go.
I could not agree more about lighter cars being more fun at low speeds though. I would much rather dash to the local station in my Mk2 Golf GTI than the 993, although I get the feeling that an Elise would be much more fun still for that type of dash and general pootling about.
Berni
I have never tried an Elan Sprint but I have had two Elan +2's around those roads and they handle them well. The Sprint would be much better of course. Indeed I crashed one into a slate embankment when I was lost on one moonless night. The headlights were never up to much and I thought I was on a long straight instead of a short sudden corner. I was pleased the car had such a long nose as it took a lot of the force of the impact out.
Although my +2's were reasonably well sorted they did get a bit floaty when pressing on. Great fun on the tighter stuff though. I am wondering if an Elise would feel similar on the faster runs due to the relative lightness.
Hi Paul, I have just seen your post. Some cars have quite small frontal areas but are fairly heavy and I put my 993 in this category. It does change direction well and seems to get better the faster you go.
I could not agree more about lighter cars being more fun at low speeds though. I would much rather dash to the local station in my Mk2 Golf GTI than the 993, although I get the feeling that an Elise would be much more fun still for that type of dash and general pootling about.
Berni
Edited by berni29 on Tuesday 24th August 07:45
Top speed is a function of power and drag, weight does not come into it (except in the fact that it presumably increases the drag of the bearings).
So you're better having a powerful car with a small frontal area and efficient aerodynamics.
Lighter cars tend to handle better, although that doesn't have to be the case.
So you're better having a powerful car with a small frontal area and efficient aerodynamics.
Lighter cars tend to handle better, although that doesn't have to be the case.
Edited by kambites on Tuesday 24th August 08:32
I'd say, on those roads and in the dry you'd be hard pressed to beat a 300bhp rear wheel drive <1000kg car in ANY other road car eg. S/C elise with stickies and decent susp set up.
In the wet I'd make a call on either an Evo fq400 or the LP 570-4 Superleggera, both weigh in around the 1300kg mark so maybe a little to heavy??
I dont think the aero will come into it much, as speeds wont go much passed 120 at best.
In the wet I'd make a call on either an Evo fq400 or the LP 570-4 Superleggera, both weigh in around the 1300kg mark so maybe a little to heavy??
I dont think the aero will come into it much, as speeds wont go much passed 120 at best.
Hi Pvapour
Yes, 120 would be the absolute max. These roads are not designed for those speeds so you get the suspension working really hard and the car can compress and unweight quite suddenly. Also you can be mid bend when this happens, and at those sorts of speeds you can generate quite significant lateral forces. The road surfaces tend to be really rough so even in the wet you can really push on. It seems to me also that it is in the wet that the heavier cars are more benign, although intuitively perhaps it should be the other way round as there is less weight trying to take the car off the road.
Berni
Yes, 120 would be the absolute max. These roads are not designed for those speeds so you get the suspension working really hard and the car can compress and unweight quite suddenly. Also you can be mid bend when this happens, and at those sorts of speeds you can generate quite significant lateral forces. The road surfaces tend to be really rough so even in the wet you can really push on. It seems to me also that it is in the wet that the heavier cars are more benign, although intuitively perhaps it should be the other way round as there is less weight trying to take the car off the road.
Berni
I'd have thought that when it comes to weight, more weight is always harder to control than less weight, always. Over Welsh roads Loti, old and new, would be almost unbeatable, due chiefly to their lack of weight.
As someone has said, even a 40 year old Elan can be very fast indeed on those roads.
As someone has said, even a 40 year old Elan can be very fast indeed on those roads.
heebeegeetee said:
I'd have thought that when it comes to weight, more weight is always harder to control than less weight, always. Over Welsh roads Loti, old and new, would be almost unbeatable, due chiefly to their lack of weight.
As someone has said, even a 40 year old Elan can be very fast indeed on those roads.
I'd think an Imprezza P1 could give a Lotus a run for it's money on Welsh roads. When you consider most of the time they are damp. As someone has said, even a 40 year old Elan can be very fast indeed on those roads.
Paul Drawmer said:
It's all to do with inertia.
The heavier the car, the more force is required to make it deviate from the straight, and that applies to being knocked about by winds as well as trying to turn into a corner.
Wind resistance goes up as the square of speed, so if you double your speed, you multiply the wind resistance by 4 times. As your speed increases, then any cross wind component will have more effect.
So the heavier car will be less inclined to be knocked about and less reliant on good aerodynamics. It will be easier to track straight at speed.
The lighter car is more nimble, and without good aero, darty at speed.
This effect an be compounded by geometry set up as well. Newcomers to sports cars sometimes complain about 'twitchy' handling. This may well be due to coming from a diet of saloons which have been trimmed for stability.
You sure? A side wind is acting at 90 degrees to the direction of travel, so what affect does your speed have on it? A stationary car subjected to a 60mph side wind would lean over as much as car travelling at 60mph subjected to the same side wind, non?The heavier the car, the more force is required to make it deviate from the straight, and that applies to being knocked about by winds as well as trying to turn into a corner.
Wind resistance goes up as the square of speed, so if you double your speed, you multiply the wind resistance by 4 times. As your speed increases, then any cross wind component will have more effect.
So the heavier car will be less inclined to be knocked about and less reliant on good aerodynamics. It will be easier to track straight at speed.
The lighter car is more nimble, and without good aero, darty at speed.
This effect an be compounded by geometry set up as well. Newcomers to sports cars sometimes complain about 'twitchy' handling. This may well be due to coming from a diet of saloons which have been trimmed for stability.
busta said:
You sure? A side wind is acting at 90 degrees to the direction of travel, so what affect does your speed have on it? A stationary car subjected to a 60mph side wind would lean over as much as car travelling at 60mph subjected to the same side wind, non?
Yes, but if you get blown slightly off course you'll travel further in that direction before correcting, so requiring a bigger correction than the same angular deviation at a lower speed.
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