For track: Weight or Power?
Discussion
On a track, what is more important for chasing laptimes? Lightness or Power?
Let's say for example you take a Caterham 620r, VS a Porsche GT3 RS.
Caterham being lighter but the Porsche possessing more power and being heavier.
GT3 RS 359 bhp per ton
Caterham 620R 508 bhp per ton.
Nurburgring time
GT3 RS - 6:65
Caterham 7:14
Surely the Caterham should have faster lap times considering its lightweight and higher power-weight ratio.
Let's say for example you take a Caterham 620r, VS a Porsche GT3 RS.
Caterham being lighter but the Porsche possessing more power and being heavier.
GT3 RS 359 bhp per ton
Caterham 620R 508 bhp per ton.
Nurburgring time
GT3 RS - 6:65
Caterham 7:14
Surely the Caterham should have faster lap times considering its lightweight and higher power-weight ratio.
507bhp said:
Surely the Caterham should have faster lap times considering its lightweight and higher power-weight ratio.
Much less total power though - and thats what you need to overcome drag at higher speeds.simple illustration - small car, 200hp, vs a car twice as heavy with 400hp.
Suppose it takes (aribitrary but round/ high figure) 100hp to push either through the air at 100mph.
Above that speed , the heavier car has 300hp left to accelerate it; the small car only 100 - so now the available power :weight & power: drag is in favour of the more powerful car; and since power to overcome drag goes up with V^3, it only gets worse from there. More total power will be faster on a high-speed track.
Edited by Huff on Thursday 15th July 17:34
(Huff said:
Much less total power though - and thats what you need to overcome drag at higher speeds.
simple illustration - small car, 200hp, vs a car twice as heavy with 400hp.
Suppose it takes (aribitrary but round/ high figure) 100hp to push either through the air at 100mph.
Above that speed , the heavier car has 300hp left to accelerate it; the small car only 100 - so now the available power :weight & power: drag is in favour of the more powerful car; and since power to overcome drag goes up with V^3, it only gets worse from there. More total power will be faster on a high-speed track.
and so the difference between tracks is stark. Cadwell vs 'Ring. one for Caterhams the other for GT3ssimple illustration - small car, 200hp, vs a car twice as heavy with 400hp.
Suppose it takes (aribitrary but round/ high figure) 100hp to push either through the air at 100mph.
Above that speed , the heavier car has 300hp left to accelerate it; the small car only 100 - so now the available power :weight & power: drag is in favour of the more powerful car; and since power to overcome drag goes up with V^3, it only gets worse from there. More total power will be faster on a high-speed track.
Edited by Huff on Thursday 15th July 17:34
Caterhams can make you feel like a god too. Or at least a David taking down a Goliath a peg or two. I am no track star, very far from it , but I still recall overtaking a Porsche GT3 one lap , and a GT2 the next at Croft in a 160bhp Seven. Of course it helped that I know the track very well, and they may have been even more of a plodder than me - but it was still a buzz. Sailing past most cars' braking point is also curiously pleasing .
Interesting question. Lightness for sure. But then again, power can help in some scenarios on track days.
- it can help overtaking slower stuff who are not very co-operative in the straights.
- it can help carrying a bit more weight for either a passenger or simply for a bit more comfort/space/versatility on the way to the track, particularly to the Ring/Spa without having to tow a car.
- it may add a bit of safety in case of impact (by helping to carry more weight, including crumple zones) although the kinetic energy does go up too
- it may mean that you can run one road/track car rather than 2 cars
- it helps traction thanks to the (usually) added mass (that can be a negative).
Apart from that it's all downsides but all cars are compromises on track, including the light ones.
- it can help overtaking slower stuff who are not very co-operative in the straights.
- it can help carrying a bit more weight for either a passenger or simply for a bit more comfort/space/versatility on the way to the track, particularly to the Ring/Spa without having to tow a car.
- it may add a bit of safety in case of impact (by helping to carry more weight, including crumple zones) although the kinetic energy does go up too
- it may mean that you can run one road/track car rather than 2 cars
- it helps traction thanks to the (usually) added mass (that can be a negative).
Apart from that it's all downsides but all cars are compromises on track, including the light ones.
Edited by nickfrog on Friday 16th July 09:06
with an arbitrary target of 300bhp per tonne...
cadwell park, blyton park you probably want 150bhp in a 500kgs car
oulton, castle combe, snetterton you probably want 300bhp in a 1000kgs car
donington, and definitely silverstone you want 450bhp in a 1500kgs car.
for a trackday, i'd err on the side of power rather than lightweight. because you need power to overtake on the straights, which is where you're allowed to. in a race situation where you could sling it up the inside on the brakes, lightness is probably more important.
cadwell park, blyton park you probably want 150bhp in a 500kgs car
oulton, castle combe, snetterton you probably want 300bhp in a 1000kgs car
donington, and definitely silverstone you want 450bhp in a 1500kgs car.
for a trackday, i'd err on the side of power rather than lightweight. because you need power to overtake on the straights, which is where you're allowed to. in a race situation where you could sling it up the inside on the brakes, lightness is probably more important.
brillomaster said:
with an arbitrary target of 300bhp per tonne...
cadwell park, blyton park you probably want 150bhp in a 500kgs car
oulton, castle combe, snetterton you probably want 300bhp in a 1000kgs car
donington, and definitely silverstone you want 450bhp in a 1500kgs car.
for a trackday, i'd err on the side of power rather than lightweight. because you need power to overtake on the straights, which is where you're allowed to. in a race situation where you could sling it up the inside on the brakes, lightness is probably more important.
It would be an interesting comparison cadwell park, blyton park you probably want 150bhp in a 500kgs car
oulton, castle combe, snetterton you probably want 300bhp in a 1000kgs car
donington, and definitely silverstone you want 450bhp in a 1500kgs car.
for a trackday, i'd err on the side of power rather than lightweight. because you need power to overtake on the straights, which is where you're allowed to. in a race situation where you could sling it up the inside on the brakes, lightness is probably more important.
Let's say roughly:
- R300 Caterham
- E30 M3 ex-race car softened up? VX220 turbo? Turbo'd MX5?
- 997 GT3 RS
As said above, at the end of the day many of us are on a restricted budget, and not having to buy new tyres and brakes every two or three track days is a definite benefit that you get from a lighter weight car.
My TVR is 1060 kg, my R888r track tyres are about to do their 8th track day in September, and there is plenty of tread left. I am sure Lotus and Caterham drivers have a similar experiences.
I upgraded the power of my car from 300 to 400 bhp, because I thought I needed loads more power, but in fact I am not really any quicker because track speed is a mix of the cornering abilities of the car and the driver. Instruction at the track will make you faster down every straight because it will help you get out of the corners faster.
My TVR is 1060 kg, my R888r track tyres are about to do their 8th track day in September, and there is plenty of tread left. I am sure Lotus and Caterham drivers have a similar experiences.
I upgraded the power of my car from 300 to 400 bhp, because I thought I needed loads more power, but in fact I am not really any quicker because track speed is a mix of the cornering abilities of the car and the driver. Instruction at the track will make you faster down every straight because it will help you get out of the corners faster.
^^ So much.
My old 3.2 boxster wrote off a set of tyres in 2 trackdays at significant expense. Can't recall what it is, about 265bhp/1250kgs? Brakes didn't last that long either. My 150bhp caterham isn't even close to that, must be about 10? days and I've just put new pads in the front / due some new tyres (which run to less than half of the cost of the boxsters for a set).
I'd guess the caterham is faster round most of the tracks I do, but then I'm a better driver now. It's certainly an easier car to extract the most from. It would however get spanked my the boxster on silverstone gp. But both were/are great fun, so what really..
My old 3.2 boxster wrote off a set of tyres in 2 trackdays at significant expense. Can't recall what it is, about 265bhp/1250kgs? Brakes didn't last that long either. My 150bhp caterham isn't even close to that, must be about 10? days and I've just put new pads in the front / due some new tyres (which run to less than half of the cost of the boxsters for a set).
I'd guess the caterham is faster round most of the tracks I do, but then I'm a better driver now. It's certainly an easier car to extract the most from. It would however get spanked my the boxster on silverstone gp. But both were/are great fun, so what really..
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