Funny observations about vehicles weights

[kambites]

doogz said:

And from my point of view, it burns/melts much better than steel, which is an issue.

In a racing car, perhaps. I can't say I've ever considered it as an issue in a road car (although magnesium wheels make me slightly nervous ).

[otolith]

12v3pot said:

I'm no engineer, so cannot answer the second question. But it's the same weight as the W201 190E 16V, which is a very sturdy steel 4dr saloon. The NSX's all-alu construction is a gift that keeps taking - for any poor soul who accidentally bends one.

(FWIW, I'm not slagging off the NSX. Really.)

It would be interesting to know how stiff and how robust the two chassis are - the cues that people use to decide that a car is sturdy are not particularly reliable.

[300bhp/ton]

WeirdNeville said:

I don't find it "that" amazing, to be honest. When you look at a car that is truly light, like an elise, you begin to appreciate what has to go to get a car down to ~700Kg.
It has:
An engine
An aluminium monocoque.

It does not have:
ABS
Air conditioning
Electric... anything
carpets
any storage space
interior trim
A proper roof

Plus the fact it's incredibly small to start with.

It's only when cars start to approach 2 tonnes that I start to consider them heavyweights.

I weighed my E36 touring on a weighbridge, and it was 1500Kg wet. same as an M3, and i think a bit lighter than a Cabrio!

All true, although I wasn't really trying to define "lightweight" cars or what would even be considered as "lightweight". Hence why in the op I used the phrase "not heavy" rather than light.

It was more about perceptions, that you can't have a single thread about the 370z without someone bemoaning it's too heavy. Yet the equally heavy/heavier BMW M3 is almost never exposed to these claims.

[kambites]

doogz said:

kambites said:

In a racing car, perhaps. I can't say I've ever considered it as an issue in a road car (although magnesium wheels make me slightly nervous ).

When I said my point of view, I was talking about my work. Shipbuilding.

Ah, I thought you meant your point of view in cars.

Yes, I can understand that you wont really want your multi-billion dollar container ship to be made out of something flammable.

[kambites]

Or them.

[otolith]

300bhp/ton said:

It was more about perceptions, that you can't have a single thread about the 370z without someone bemoaning it's too heavy. Yet the equally heavy/heavier BMW M3 is almost never exposed to these claims.

Personally, the wife's 350Z is too heavy for my tastes. So is an M3.

[12v3pot]

otolith said:

12v3pot said:

I'm no engineer, so cannot answer the second question. But it's the same weight as the W201 190E 16V, which is a very sturdy steel 4dr saloon. The NSX's all-alu construction is a gift that keeps taking - for any poor soul who accidentally bends one.

(FWIW, I'm not slagging off the NSX. Really.)

It would be interesting to know how stiff and how robust the two chassis are - the cues that people use to decide that a car is sturdy are not particularly reliable.

Well, I've had both and both are fairly successful track racers, so I presume that the chassis stiffness is high for both. The longevity of the W201s that survice is a different aspect of its sturdiness.

[GC8]

T.K said:

Excellent post OP!

Indeed! Thats two excellent posts now. 28,139 ste ones to balance out though...

[ImpossiblyDaft]

Devil2575 said:

My mother in law holds the view that BMWs have very expensive tyres. This is obviously from a time when they had metric tyres and so not at all relevant now.

Well, I'd say that's a valid opinion - its all massive low-profile runflats now, which are pretty expensive (albeit most premium manufacturers are doing the same).

[kambites]

doogz said:

Also, if the chassis is lighter, it doesn't need to be as stiff.

But surely it does need to be as stiff around the engine mountings. If you want the engine mounts to do a decent job of isolating the chassis and passengers from NVH, the chassis 'seats' have to be significantly stiffer than the engine mounts dynamic stiffness. Especially if you consider fatigue. Your "I" value needs to be the same, and the significantly smaller "E" value of aluminium needs to be taken into account.

True but again, the lighter the engine the less stiff the engine mounts need to be for a given level of damping and hence the less force will be transmitted to the chassis.

The Elise has the engine mounted in a tubular steel subframe anyway, possibly for the reason you describe.

[kambites]

doogz said:

Is the engine in an Elise lighter than the engine in my steel chassis'd MR2?

The original Elise engine, yes - the Rover K-series seems to be about two thirds the weight of the Toyota engine.

I thought you were talking about engine vibration which is obviously roughly proportional to the weight of the moving parts (assuming similar balancing).

[kambites]

doogz said:

Stop editing things after I've replied!

Sorry. Keep thinking of things to clarify.

[Devil2575]

ImpossiblyDaft said:

Devil2575 said:

My mother in law holds the view that BMWs have very expensive tyres. This is obviously from a time when they had metric tyres and so not at all relevant now.

Well, I'd say that's a valid opinion - its all massive low-profile runflats now, which are pretty expensive (albeit most premium manufacturers are doing the same).

It wasn't when she made it, before runflats came in.

[the-photographer]

Here is the PH random weight table.

Audi TTRS 1450 + 75 = 1525 / 335bhp (manual)

Cayman S 1425 kg / 295bhp (manual)

370z 1496 + 75 = 1571 kg / 323bhp (manual)

BMW 135i 1530 kg / 302bhp (manual)

BMW Z4 sDrive35is 1600 kg / 340bhp (7-speed DSG)

BWM 335i M Sport 1600kg / 306bhp (manual)

M3 Coupe 1655kg / 420bhp (manual)

Ariel Atom 456 + 75 = 531 kg / 245-300 bhp (manual)

Audi S3 1515 + 75 = 1590 / 261bhp (auto)

Caparo T1 689kg / 575bhp (manual)

Lotus Exige S 935 + 75 = 1010kg / 220bhp (manual & ac marked as an option)

Mercedes Benz SLK 350 1505kg / 305hp (auto 7 tronic

Mercedes Benz SLK 55AMG 1575kg / 360hp (auto 7 tronic)

BMW 1 Series M Coupe 1570kg / 340hp(manual)

Car	Weight KG (inc driver & 90% fuel)
Atom	531
Caparo T1	689
Alfa 4c	895 DRY
Lotus Elise	876+75=951
Lotus Elise CR	852+75=927
Lotus Elise S	924+75=999
Lotus Exige 6 cylinder	1176+75=1251
Cayman S	1425
SLK 350	1505
Audi TTRS	1525
BMW 135i	1530
BMW 1 Series M Coupe	1570
370z	1571
SLK 55AMG	1575
S3	1590
BMW Z4 sDrive35is	1600
BMW 335i M Sport	1600
BMW M3 Coupe	1655

[Herman Toothrot]

Would be interesting to see what weight you could get a mk3 MR2 down to with GRP panels, light weight exhaust, suspension components, aluminium belled discs, forged wheels, GRP seats etc. I bet it'd be almost the same as a late Toyota Elise. Yet a much more user friendly daily driver, when looked at like that it makes the Elise aluminium chassis a bit disappointing / pointless.

[Devil2575]

Herman Toothrot said:

Would be interesting to see what weight you could get a mk3 MR2 down to with GRP panels, light weight exhaust, suspension components, aluminium belled discs, forged wheels, GRP seats etc. I bet it'd be almost the same as a late Toyota Elise. Yet a much more user friendly daily driver, when looked at like that it makes the Elise aluminium chassis a bit disappointing / pointless.

Does it?

How much do you think it would cost to do all that to a Mk3 MR2?
Also, you don't actually know how much it would weigh, so a little bit premature to describe the Elise in such a way.

[blank]

I was very surprised at the weight of my TT when I checked the other day.

1,475 kg for a largely aluminium 2 sweater roadster!!

[GC8]

Whereas my 'massively bloated' 944 Turbo only actually weighed 1,420 kilos with half a tank and some luggage...

[otolith]

Herman Toothrot said:

Would be interesting to see what weight you could get a mk3 MR2 down to with GRP panels, light weight exhaust, suspension components, aluminium belled discs, forged wheels, GRP seats etc. I bet it'd be almost the same as a late Toyota Elise. Yet a much more user friendly daily driver, when looked at like that it makes the Elise aluminium chassis a bit disappointing / pointless.

But a MK3 MR2 is a steel monocoque with stressed panels - so if you replaced them with GRP, you'd end up with something as floppy as a crisp packet and lethal to crash. At least in an Elise you've got those big aluminium sills between you and a side impact.

[s m]

WeirdNeville said:

I weighed my E36 touring on a weighbridge, and it was 1500Kg wet. same as an M3, and i think a bit lighter than a Cabrio!

That's quite a weight Neville, what was the spec of your car or were you sat in it?
My 98 SE saloon with sunroof, heated skin and wind and folding rears on 16s was 1420kg ( +/- 25kg ) with half a tank ( same as an E46 CSL with aircon ).





My old E46 330i saloon was over 100kg more