S1 vs S2 on limit behaviour differences

[dom180]

Scuffers said:

dom180 said:

S2 has wider front/rear track too - 20mm at the front and 50mm at the rear and lower CoG - Gavin Kershaw is quoted as saying, "The biggest improvements came from the fundemental design changes - lower and wider stance - plus Bridgestone delivering a bespoke tyre."

Different damper mounting points. Camber changes in the rear suspension to improve unloaded rear wheel contact. Different wishbones....

Yup, they are somewhat wider, but at the same time, the COG and overall weight went up rather cancelling out the track advantage.

chris7676 said:

Different wishbones then? Hmmm...

Yes and no, S2's have slightly longer front wishbones, rears are the same length (although yota ones are braced more and the top rear is a different offset)

CoG went lower with the S2 k-series.

[Scuffers]

dom180 said:

Scuffers said:

dom180 said:

S2 has wider front/rear track too - 20mm at the front and 50mm at the rear and lower CoG - Gavin Kershaw is quoted as saying, "The biggest improvements came from the fundemental design changes - lower and wider stance - plus Bridgestone delivering a bespoke tyre."

Different damper mounting points. Camber changes in the rear suspension to improve unloaded rear wheel contact. Different wishbones....

Yup, they are somewhat wider, but at the same time, the COG and overall weight went up rather cancelling out the track advantage.

chris7676 said:

Different wishbones then? Hmmm...

Yes and no, S2's have slightly longer front wishbones, rears are the same length (although yota ones are braced more and the top rear is a different offset)

CoG went lower with the S2 k-series.

with respect, that's rubbish.

[RobM77]

Scuffers said:

dom180 said:

Scuffers said:

dom180 said:

S2 has wider front/rear track too - 20mm at the front and 50mm at the rear and lower CoG - Gavin Kershaw is quoted as saying, "The biggest improvements came from the fundemental design changes - lower and wider stance - plus Bridgestone delivering a bespoke tyre."

Different damper mounting points. Camber changes in the rear suspension to improve unloaded rear wheel contact. Different wishbones....

Yup, they are somewhat wider, but at the same time, the COG and overall weight went up rather cancelling out the track advantage.

chris7676 said:

Different wishbones then? Hmmm...

Yes and no, S2's have slightly longer front wishbones, rears are the same length (although yota ones are braced more and the top rear is a different offset)

CoG went lower with the S2 k-series.

with respect, that's rubbish.

Do either of you have the figures to prove it? In the absence of them, I'd have to guess the CofG was lower on the S2 purely because the car sits significantly lower and the engine, at least on mine, is the same. That's just a guess though; I'll have to assume that until someone can actually come up with an actual figure from a referenced source.

Scuffers - you don't have a good track record on this thread for making unsubstantiated claims You claimed on the previous page that the downforce differences that I quoted (from a proper referenced source) amounted to no more than a few tubes of lipstick in a handbag, but didn't actually prove it in any way!

[Scuffers]

RobM77 said:

Scuffers said:

dom180 said:

Scuffers said:

dom180 said:

S2 has wider front/rear track too - 20mm at the front and 50mm at the rear and lower CoG - Gavin Kershaw is quoted as saying, "The biggest improvements came from the fundemental design changes - lower and wider stance - plus Bridgestone delivering a bespoke tyre."

Different damper mounting points. Camber changes in the rear suspension to improve unloaded rear wheel contact. Different wishbones....

Yup, they are somewhat wider, but at the same time, the COG and overall weight went up rather cancelling out the track advantage.

chris7676 said:

Different wishbones then? Hmmm...

Yes and no, S2's have slightly longer front wishbones, rears are the same length (although yota ones are braced more and the top rear is a different offset)

CoG went lower with the S2 k-series.

with respect, that's rubbish.

Do either of you have the figures to prove it? In the absence of them, I'd have to guess the CofG was lower on the S2 purely because the car sits significantly lower and the engine, at least on mine, is the same. That's just a guess though; I'll have to assume that until someone can actually come up with an actual figure from a referenced source.

Scuffers - you don't have a good track record on this thread for making unsubstantiated claims You claimed on the previous page that the downforce differences that I quoted (from a proper referenced source) amounted to no more than a few tubes of lipstick in a handbag, but didn't actually prove it in any way!

look,

if you don't have the ability to work the aero figures though yourself, don't expect me to hold your hand...

as for COG, it's also easy enough to calculate, and yes, I have thanks.

I don't really care if you want to believe me or not, makes no odds to me what you want to believe....

[RobM77]

Scuffers said:

RobM77 said:

Scuffers said:

dom180 said:

Scuffers said:

dom180 said:

S2 has wider front/rear track too - 20mm at the front and 50mm at the rear and lower CoG - Gavin Kershaw is quoted as saying, "The biggest improvements came from the fundemental design changes - lower and wider stance - plus Bridgestone delivering a bespoke tyre."

Different damper mounting points. Camber changes in the rear suspension to improve unloaded rear wheel contact. Different wishbones....

Yup, they are somewhat wider, but at the same time, the COG and overall weight went up rather cancelling out the track advantage.

chris7676 said:

Different wishbones then? Hmmm...

Yes and no, S2's have slightly longer front wishbones, rears are the same length (although yota ones are braced more and the top rear is a different offset)

CoG went lower with the S2 k-series.

with respect, that's rubbish.

Do either of you have the figures to prove it? In the absence of them, I'd have to guess the CofG was lower on the S2 purely because the car sits significantly lower and the engine, at least on mine, is the same. That's just a guess though; I'll have to assume that until someone can actually come up with an actual figure from a referenced source.

Scuffers - you don't have a good track record on this thread for making unsubstantiated claims You claimed on the previous page that the downforce differences that I quoted (from a proper referenced source) amounted to no more than a few tubes of lipstick in a handbag, but didn't actually prove it in any way!

look,

if you don't have the ability to work the aero figures though yourself, don't expect me to hold your hand...

as for COG, it's also easy enough to calculate, and yes, I have thanks.

I don't really care if you want to believe me or not, makes no odds to me what you want to believe....

Great - you've done the maths. Can you give us the answers? As in the actual figures you came up with?

I don't particularly "want to believe" anything really, I'm just interested in the figures. I drove the S2 and S1 back to back and preferred the S2, which is an entirely qualitative decision not influenced by numbers. As a huge Lotus fan though I'm fairly interested in what those downforce figures actually equate to in real terms, and of course how the CofGs compare. If you've done the maths I'd love to see the answers - you're quite right of course, quoting coefficients doesn't give the whole picture for downforce - it's a number in Newtons at a given speed that is the real answer. Likewise, saying one CofG is higher than the other doesn't really tell us anything - there could be a millimetre in it or a centimetre! Thus my question.

Edited by RobM77 on Friday 16th October 20:53

[Scuffers]

F = 0.5*((P*V²*S)*C)

F - Force (N)
P - Air dencity (assume 1.225)
V - Velocity (in M/S)
S - Frontal Area (in M²)
C - Lift Coefficent

S1 Elise at std ride heights (160)

Clr +0.053
1.6M2 frontal area

this equates to rear lift of:

100Kmh - 4Kg's
100Mph - 10Kg's
125Mph - 16Kg's
150Mph - 23Kg's

ie. sod all.

COG I don't have to hand.

Edited by Scuffers on Friday 16th October 21:11

[bogie]

so I guess what you are saying Scuffers, is that taking a dump before driving, and emptying ones pockets, would make more noticable difference to us mere mortal amateurs?

[RobM77]

Thanks. Why did that take do long?

As I said earlier, the majority of the improvements for the S2 were in bespoke tyres, increased track and lower stiffer suspension. This aero stuff is news to me (and I read all the info at the time), although those figures don't seem too insignificant actually - I'm sure Lotus must have had a reason for changing it. 10kg of lift at the rear plus a few kgs of downforce at the front is surely noticeable compared with the S2's downforce at both ends? The S1's lift at the back is equivalent to the force you put into lifting a hefty dumbbell (~13kg) placed at the very rear of the car.

Now how about that CofG? Have you worked that one out? My best guess would be 20mm lower on the S2, same as the ride height difference, but I haven't worked it out properly.

Edited by RobM77 on Friday 16th October 21:59

[Scuffers]

bogie said:

so I guess what you are saying Scuffers, is that taking a dump before driving, and emptying ones pockets, would make more noticable difference to us mere mortal amateurs?

lol!

yes,

other bit to consider is nobody runs them at 160 ride hight, and (to a point) lowering them with some rake reduces this somewhat...

[RobM77]

Scuffers said:

other bit to consider is nobody runs them at 160 ride hight, and (to a point) lowering them with some rake reduces this somewhat...

With some modifications one could in effect turn an S1 into an S2. Lower, stiffer and wider are all perfectly doable. Slap a wing on the back and a splitter on the front and the aero would change too.

[TIPPER]

RobM77 said:

Scuffers said:

other bit to consider is nobody runs them at 160 ride hight, and (to a point) lowering them with some rake reduces this somewhat...

With some modifications one could in effect turn an S1 into an S2. Lower, stiffer and wider are all perfectly doable. Slap a wing on the back and a splitter on the front and the aero would change too.

My S1 is lower (100/110), stiffer (400/475) and wider tracked (only just though due to 195/225 tyres). Don't know how it handles compared to a 'stock' S2 though as I've never driven one on track. I can tell you that my car is very pointy but also very stable (if I can catch it - most of the time - then it must be!).

[RobM77]

TIPPER said:

RobM77 said:

Scuffers said:

other bit to consider is nobody runs them at 160 ride hight, and (to a point) lowering them with some rake reduces this somewhat...

With some modifications one could in effect turn an S1 into an S2. Lower, stiffer and wider are all perfectly doable. Slap a wing on the back and a splitter on the front and the aero would change too.

My S1 is lower (100/110), stiffer (400/475) and wider tracked (only just though due to 195/225 tyres). Don't know how it handles compared to a 'stock' S2 though as I've never driven one on track. I can tell you that my car is very pointy but also very stable (if I can catch it - most of the time - then it must be!).

I expect it'd be quite different to an S2 because the S2 is road tuned by the factory. Being a 100% (ok, 90%!) road user, I went for the standard S2 because I wanted a road car expertly tuned by Lotus. It's a different matter if you track your car of course; mind you, I never really found the standard suspension lacking on track either. All I can really comment on is standard S1 vs standard S2, for which I prefer the S2.

[Herman Toothrot]

Thorney said:

we love the shape of the VX220, aerodynamically its a bit of a screw up. The very bluff front end is very successful in generating good downforce (19kg's at 100mph) but the upswept rear clam does an excellent job of generating almost 40kg's of lift at 100mph - not good.

So does that mean the VX220 is more likely to handle like an S1 than an S2 even thought is an S2 Chassis?

Only driven the VX220 once on track where it was alternating between hot and sunny and then pouring with rain, it was also only 3 weeks after getting it, I thought it remarkably stable at speed. My only gripe was that the ABS went mental on the front passenger side baically everytime I touched the brakes so I never really threw it hard coming off the brakes into a corner. I've gone to 195/16 up front and on road its certainly allowed heavier braking, I also went +10mm wider track up front at the same time. Also replaced the rear undertray section with a TAT diffuser, thought it couldn't hurt reading about the amount of lift generated as stock.

Edited by Herman Toothrot on Saturday 17th October 00:07

[Scuffers]

not got the figures for the VX, but I would suggest they are somewhat better than the Elise (slab sides, less complex curves etc).

other bit to remember is that even if they did have some lift at the rear, in terms of their static weight it's really not significant.

[S2john]

You can have the best set up car in the world, it's down to the drivers ability to make it work

[LotusEater666]

S2 ride height is 10mm lower, so CoG is of course going to be lower.

[TIPPER]

RobM77 said:

TIPPER said:

RobM77 said:

Scuffers said:

other bit to consider is nobody runs them at 160 ride hight, and (to a point) lowering them with some rake reduces this somewhat...

With some modifications one could in effect turn an S1 into an S2. Lower, stiffer and wider are all perfectly doable. Slap a wing on the back and a splitter on the front and the aero would change too.

My S1 is lower (100/110), stiffer (400/475) and wider tracked (only just though due to 195/225 tyres). Don't know how it handles compared to a 'stock' S2 though as I've never driven one on track. I can tell you that my car is very pointy but also very stable (if I can catch it - most of the time - then it must be!).

I expect it'd be quite different to an S2 because the S2 is road tuned by the factory. Being a 100% (ok, 90%!) road user, I went for the standard S2 because I wanted a road car expertly tuned by Lotus. It's a different matter if you track your car of course; mind you, I never really found the standard suspension lacking on track either. All I can really comment on is standard S1 vs standard S2, for which I prefer the S2.

For sure, but I wonder how many (enthusiast owned) cars run on factory settings?
When I first got my S12 it was a fun thing but readily did the under/oversteer thing (or spin on track). Some driver mods followed by suspension work seems to have led to a car that doesn't do understeer and seems nicely neutral (a better driver might disagree though - suits me for now!).

[Yuxi]

Early S1's have extruded aluminium uprights on all corners, S2's have all cast steel uprights. The steering arms have got heavier and heavier (to stop them breaking) through the years, what differences has this made?

[TIPPER]

Yuxi said:

Early S1's have extruded aluminium uprights on all corners, S2's have all cast steel uprights. The steering arms have got heavier and heavier (to stop them breaking) through the years, what differences has this made?

My 99 S1 has Ali uprights: if they were replaced with the later steel ones without me knowing I doubt I would know the difference. Probably the same for most drivers of average ability.

[Yuxi]

TIPPER said:

Yuxi said:

Early S1's have extruded aluminium uprights on all corners, S2's have all cast steel uprights. The steering arms have got heavier and heavier (to stop them breaking) through the years, what differences has this made?

My 99 S1 has Ali uprights: if they were replaced with the later steel ones without me knowing I doubt I would know the difference. Probably the same for most drivers of average ability.

I think later S1's had steel rears, then from S2 it was steel all round. Loads less parts with the steel uprights, the taper is machined as part of the upright, rather tahn a seperate steel forging bolted to the aluminium upright with 4 nuts and bolts.