RE: Light IS Right: PH Blog

[Derek Chevalier]

yonex said:

kambites said:

I think we were using Caymans and Boxster in the context of "not light but probably capable of being made light".

I think the Cayman and Boxster are pretty much entirely average weight as modern two-seater sports cars go. The 911 is pretty light for a big 2+2.

Edited by kambites on Friday 29th April 18:31

What is the GT4, 1450kgs, isn't that similar to an NSX/355? And the above is my point, the odd 100kg might transform the car but the modern 'sports car' is just a bit of a bloater.

Isn't NSX closer to 1350?

[kambites]

yonex said:

You could drive the NSX cross continent and not worry.

I didn't claim otherwise, but I'd be quite happy driving lots of modern lightweight cars across continents.

[kambites]

Ozzie Osmond said:

kambites said:

... engineering integrity ...

"Spock, analysis please."

My point being that the words are easy to use, but what do they actually mean?

It's a statement about the internal culture of a company and/or nation (obviously, a physical object can't have integrity in that sense). Honda had (and to some extent still have but I think they're losing it in the pursuit of competitiveness) an attitude of "there's no such thing as 'good enough'". From a mainstream engineering perspective it's a very rare attitude because, quite frankly, it's stupid - it generally results in over-priced products which are no better for the end-user than anything else and are out of date before they're released. It does however produce the occasional gem.

The Germans tend to be more pragmatic; willing to produce what the market is demanding and no more.


Obviously that's a generalisation but it's one which is borne out time and time again working with engineers from the two countries. I prefer working with Germans, the Japanese are impossible.

Edited by kambites on Saturday 30th April 08:17

[suffolk009]

Sway said:

How good would a £50k, 800kg Mclaren be, with a small and simple fibreglass or better cheap composite chassis and a transverse n/a 4 pot based on one bank of the v8. It'd blow the boxster into the weeds...

It would be brilliant.

[suffolk009]

I've got a tatty old MG midget. The 1500 rubber-bumper model.

I took off the bumpers, the windscreen, the roof, the roll bar, the wipers, the side windows and winders, the door cards, the carpets, the heater, the seat runners, the radio, the spare wheel and jack. Everything possible that could come out, did. All I added where gaffer tape over the holes, two little aero screens and a can of tyre weld.

It needed a significant lowering kit, but it still stands a bit high.

Now it's really great fun.

[kambites]

What does it weigh?

One of my lodgers had a Midget racing car for a while and we had to add quite a lot of ballast to get that up to the weight limit. Unballasted I think it was under 600kg despite having a windscreen, side windows and a hard-top plus obvious a full roll-cage, plumbed in fire extinguisher, etc. Despite being well under 100bhp, I suspect it would have completely flattened my Elise around almost any track.

Without a screen or any sort of roof, I'd have thought 550kg should be easily possible.

Edited by kambites on Saturday 30th April 08:48

[peter450]

suffolk009 said:

Sway said:

How good would a £50k, 800kg Mclaren be, with a small and simple fibreglass or better cheap composite chassis and a transverse n/a 4 pot based on one bank of the v8. It'd blow the boxster into the weeds...

It would be brilliant.

Lotus have been making this car for ages

[DPSFleet]

Force equals mass x acceleration. Simple laws of physics, less mass more fun in my view.

[Sway]

peter450 said:

suffolk009 said:

Sway said:

How good would a £50k, 800kg Mclaren be, with a small and simple fibreglass or better cheap composite chassis and a transverse n/a 4 pot based on one bank of the v8. It'd blow the boxster into the weeds...

It would be brilliant.

Lotus have been making this car for ages

With respect, they haven't.

Focusing only on the chassis, and comparing my GTM to an Elise (bearing in mind the GTM was made in an even smaller shed, and released before the Elise s1), we find the GTM is 50% stiffer torsionally - which someone like Lotus or Mclaren could really take advantage of when designing the suspension.

Yet despite this extra stiffness and comparable weight (again, bear in mind the GTM did not take advantage of the advanced production techniques available today, which could strip 20% of the weight), the GTM has much slimmer sills, making ingress/egress easier. Lots more cabin space, as there aren't chunky extruded box sections needed to achieve the lower stiffness the Elise manages. Quieter. Etc.

All the benefits of a carbon tub over extruded aluminium or spaceframe steel, but much lower price than a carbon tub a la the current Macca range.

It staggers me that two blokes in a shed made a composite tubbed car twenty years ago that in many ways equals or beats the Elise (acknowledging that the Elise steers and handles a tad better), yet no one with proper resources has taken the principle on except at the very high end of the market...

[andy_s]

Sway said:

peter450 said:

suffolk009 said:

Sway said:

How good would a £50k, 800kg Mclaren be, with a small and simple fibreglass or better cheap composite chassis and a transverse n/a 4 pot based on one bank of the v8. It'd blow the boxster into the weeds...

It would be brilliant.

Lotus have been making this car for ages

With respect, they haven't.

Focusing only on the chassis, and comparing my GTM to an Elise (bearing in mind the GTM was made in an even smaller shed, and released before the Elise s1), we find the GTM is 50% stiffer torsionally - which someone like Lotus or Mclaren could really take advantage of when designing the suspension.

Yet despite this extra stiffness and comparable weight (again, bear in mind the GTM did not take advantage of the advanced production techniques available today, which could strip 20% of the weight), the GTM has much slimmer sills, making ingress/egress easier. Lots more cabin space, as there aren't chunky extruded box sections needed to achieve the lower stiffness the Elise manages. Quieter. Etc.

All the benefits of a carbon tub over extruded aluminium or spaceframe steel, but much lower price than a carbon tub a la the current Macca range.

It staggers me that two blokes in a shed made a composite tubbed car twenty years ago that in many ways equals or beats the Elise (acknowledging that the Elise steers and handles a tad better), yet no one with proper resources has taken the principle on except at the very high end of the market...

Er....they have - the S1 was exactly that; whether the GTM had a better/lighter/stiffer chassis is nothing to do with what was said above.

But - you're absolutely right about the principle; there is the skittish Alfa of course - when I saw this I immediately thought it's time for Lotus to get a CF tub, they were quite advanced with the aluminium chassis at the time (except for smaller shedded people) and I thought they should maybe look at CF tubs to update their concept (shed [sic] weight/increase stiffness).

I think McLaren used a technique which increased production speed and made it cheap(er) than the normal process; this should/could have been Lotus turf if it hadn't been for the period of financial/ownership uncertainty. Now of course they are developing what they can with what they've got, perhaps in a few years the next '21st C S1' will be a CF tub with hybrid power weighing next to nothing and costing not much more than the current range... let's see. One of the most frustrating things about Lotus seems the abundance of ideas and technology but without the implementation in their current cars due to money constraints...at the moment anyway. However despite that, they still churn out some of the best sports cars going imo.

[Vee12V]

peter450 said:

suffolk009 said:

Sway said:

How good would a £50k, 800kg Mclaren be, with a small and simple fibreglass or better cheap composite chassis and a transverse n/a 4 pot based on one bank of the v8. It'd blow the boxster into the weeds...

It would be brilliant.

Lotus have been making this car for ages

Exactly. Mine's even 700kg!

[Sway]

andy_s said:

Er....they have - the S1 was exactly that; whether the GTM had a better/lighter/stiffer chassis is nothing to do with what was said above.

But - you're absolutely right about the principle; there is the skittish Alfa of course - when I saw this I immediately thought it's time for Lotus to get a CF tub, they were quite advanced with the aluminium chassis at the time (except for smaller shedded people) and I thought they should maybe look at CF tubs to update their concept (shed [sic] weight/increase stiffness).

I think McLaren used a technique which increased production speed and made it cheap(er) than the normal process; this should/could have been Lotus turf if it hadn't been for the period of financial/ownership uncertainty. Now of course they are developing what they can with what they've got, perhaps in a few years the next '21st C S1' will be a CF tub with hybrid power weighing next to nothing and costing not much more than the current range... let's see. One of the most frustrating things about Lotus seems the abundance of ideas and technology but without the implementation in their current cars due to money constraints...at the moment anyway. However despite that, they still churn out some of the best sports cars going imo.

But why carbon? Material and process costs far higher, for a very small benefit. Why not use those techniques with a cheaper composite fibre, whether fibreglass, flax, bamboo or anything!

My point is that yes, Lotus design and make some of the best sports cars going - how much better could they be with a better chassis, from a performance and usability perspective?

[Sway]

Vee12V said:

peter450 said:

suffolk009 said:

Sway said:

How good would a £50k, 800kg Mclaren be, with a small and simple fibreglass or better cheap composite chassis and a transverse n/a 4 pot based on one bank of the v8. It'd blow the boxster into the weeds...

It would be brilliant.

Lotus have been making this car for ages

Exactly. Mine's even 700kg!

My GTM is 740kg, with bloody heavy 17" wheels, plus spare. Also loads of heavy bits from various MGFs and Metros... None of the fancy machined aluminium pedal porn, etc. Imagine how light the Lotus could be with a proper tub!

[andy_s]

Sway said:

But why carbon? Material and process costs far higher, for a very small benefit. Why not use those techniques with a cheaper composite fibre, whether fibreglass, flax, bamboo or anything!

My point is that yes, Lotus design and make some of the best sports cars going - how much better could they be with a better chassis, from a performance and usability perspective?

Because Carbon Fibre will sell and bamboo won't?

Yes - substitute 'CF' with any material that does the job better and move the platform on a notch - and complies with modern crash test regulations...

[Sway]

That's advertising, and spin.

A full technical pack, showing the strength/stiffness/lightweight/etc., tours for journos around the facility showing carbon and 'fibreglass' running side by side, etc.

If it drives as it should, journos would love it. Lots of people aren't tainted by the 70s beach buggies!

[andy_s]

Sway said:

That's advertising, and spin.

A full technical pack, showing the strength/stiffness/lightweight/etc., tours for journos around the facility showing carbon and 'fibreglass' running side by side, etc.

If it drives as it should, journos would love it. Lots of people aren't tainted by the 70s beach buggies!

Nor the Marcos GTs...!

[kambites]

Sway said:

My GTM is 740kg, with bloody heavy 17" wheels, plus spare. Also loads of heavy bits from various MGFs and Metros... None of the fancy machined aluminium pedal porn, etc. Imagine how light the Lotus could be with a proper tub!

It's not going to save more than 70kg because the Elise tub only weighs 70kg. Realistically at best you're going to shave about 20kg off the total weight of an Elise by swapping the tub for something else; I suspect there are easier targets to save 20kg.

I'd love to see a breakdown how where the extra weight of a current Elise compared to an S1 comes from.


Of course comparing the Elise to the Libra is a little unfair in that the Elise is type approved, the Libra is not.

Edited by kambites on Saturday 30th April 10:37

[Sway]

kambites said:

It's not going to save more than 70kg because the Elise tub only weighs 70kg. Realistically at best you're going to shave about 20kg off the total weight of an Elise by swapping the tub for something else; I suspect there are easier targets to save 20kg.

But would those other weight saving options give such benefits to chassis stiffness/practicality? I'm sure you'd agree thinner sills and more interior room would be welcomed in an Elise.

[kambites]

Sway said:

But would those other weight saving options give such benefits to chassis stiffness/practicality? I'm sure you'd agree thinner sills and more interior room would be welcomed in an Elise.

I'm not sure the Elise needs more stiffness, especially if you get it back to S1 weight. I've certainly never driven mine and though "what this really needs, is a stiffer chassis".

Lower, thinner sills would indeed be a big plus but I don't think you could do it without spending a LOT of money or seriously compromising side-impact protection. As it is, the Elise's doors are bloody heavy to give adequate side-impact protection; I dread to think what they'd be like if you didn't have such strength in the sill above the driver's waist line.

[suffolk009]

kambites said:

What does it weigh?

One of my lodgers had a Midget racing car for a while and we had to add quite a lot of ballast to get that up to the weight limit. Unballasted I think it was under 600kg despite having a windscreen, side windows and a hard-top plus obvious a full roll-cage, plumbed in fire extinguisher, etc. Despite being well under 100bhp, I suspect it would have completely flattened my Elise around almost any track.

Without a screen or any sort of roof, I'd have thought 550kg should be easily possible.

Edited by kambites on Saturday 30th April 08:48

I don't know, never had the opportunity to weigh it.

I had hoped to cut even more out with glassfibre body panels, and then maybe do a K series engine swap. But the price of all that was getting more than a s/h Caterham or early Elise. I just enjoy it for it is at the moment.