Friday 15 May 2015

What does a 'Superlight' R500 Duratec weigh?

Now onto a new 'sore topic'... The car's weight...
I recently had the car flat floored by Rob at Rat Race Motorsport, and during the process the car was weighed to enable each corner of the car to be setup correctly. The weight figure for the car with 16.1kg of fuel and fluids is a shocking 575kg! Which is 69kg heavier than the quoted 506kg weight...
Caterham R500 'Superlight' Duratec going onto the scales - eventually weighing in at 575kg
Caterham R500 'Superlight' Duratec going onto the scales - eventually weighing in at 575kg
There were the following fluids in the vehicle at time of weighing (all approximate figures)...
  • 22 litres of fuel (the weight of the fuel would be 16.1kg)
  • six litres of oil
  • a litre of diff oil
  • a litre of gearbox oil
  • five litres coolant
  • brake and clutch fluids
Using an internet archiving system I've found the R500 'Superlight' Duratec page, and will quote what Caterham advertised the car as weighing at the time I placed my order:-
"Weight savings are achieved through a philanthropic application of carbon-fibre goodies, bringing the total weight of the car in at just 506kgs."
...they go on to say:-
"Mathematicians amongst you will have already calculated that anyone committed enough to strap themselves into the Kevlar race seats will be deploying a mighty 520 bhp-per-tonne with their right foot, capable of firing the car from 0-60 mph in just 2.88 seconds."

There's no suggestion or disclaimer mentioning that the 506kg is a dry weight, so I'm not sure how anyone would be able to 'deploy' 520 bhp-per-tonne with their right foot if the car doesn't have any fluids - as it won't run... which to me - is clearly advertising the car as ready to run in a 520 bhp-per-tonne state.  Using the following online calculator the only way of achieving 520 bhp-per-tonne is by the car weighing 506kg, not the 575kg mine does - providing the engine is actually outputting the quoted 263bhp too!
Caterham R500 advertised weight and bhp-per-tonne
Caterham R500 advertised weight and bhp-per-tonne
So I wondered what else could be adding weight, and have listed the options that would be heavier than standard spec:-
  • Heater (probably a kilo)
  • FIA roll bar (five kg extra max?)
  • Carpets (max two kg)
  • Hoodsticks still fitted underneath boot cover (max one kg)
  • Lowered floors (extra couple of kg max?)
With all of the above accessories fitted (approx 11 kg (maximum)), an allowance also needs to be made for the 10kg I've shaved off by way of lighter shocks, battery, headlights and other bits I've fitted (or removed), so I'd be extremely interested to see what specification Caterham ran when they managed to get a 'Superlight' R500 Duratec to weigh in at 506kg and run...

Let's put it this way - if you add the car (in a useable state with fluids as specified above), then add a driver - (I'm 83kg clothed with crash helmet) you're looking at a total weight of 658kg!  Checking that in the power to weight calculator that gives exactly 400 bhp-per-tonne... hmmm...  That's a very long way off the 528 bhp-per-tonne quoted...

I'm also certain that my car isn't any heavier than any other 'Superlight' R500 Duratecs, so I'd like to see what Caterhams stance on this is... I feel a letter to Caterham HQ coming on!!! :-)


  1. Your seats are heavier than than the standard R500 Tillets
    Liberal coating of paint
    Heater means increased coolant capacity
    ZZR tyres weigh more than CR500

    There's at least 30kg there

    1. I don't think it's as much as that.
      The 620R seats are 2kg heavier each than the standard R500 carbon kevlar tillets.
      The paint would be 7kg
      Heater with additional coolant is maximum 2kg
      and the ZZR tyres are probably 1kg heavier a corner than the CR500's...

      So in total for those items it'd be 17kg.

      I have also shaved off 10kg from the OEM weight which needs to be taken into account.

  2. The Caterham figures are a dry weight i.e. without fluids. Plus if you have weather gear, it also means you'll have a wiper motor and mechanism plus washer bottle with screenwash etc...

    Few more kilos there.

    1. Thanks for your comment - I will say that if Caterhams' weight is a dry weight then their marketing spiel is incorrect. They state that "by strapping yourself in the carbon Kevlar seats you can deploy a mighty 520 bhp-per-tonne with your right foot" which simply isn't the case.

      I will be on a 'weight saving' exercise over the coming weeks, so keep an eye on the blog for everything I take away from my car! And there's me thinking blogging was about adding bits not taking them away!


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