Mark Seymour - Reference and Resources

Login FormClose

Description: Ginetta G40 Power to Weight

The following describes the standard G40 with 1.8 Ford Zetec, 17" wheels, Avon ZZR tyres, Quantum shocks, one Tillett seat and one Cobra seat. The example calculations at the bottom show weight reductions and/or ballast from standard, if racing outside Ginetta-controlled championships.

Standard Weight

  • Factory quoted weight: 840 KG
  • Measured weight (dry, no fuel): 915 KG

Power

  • Factory quoted power: 135 BHP
  • Power measured by Dyno Driven: 140 BHP (5k miles on the clock)

Standard power to weight

  • Including 85 KG driver: 140 BHP / tonne (1000 KG, 140 BHP)
  • Excluding driver: 153 BHP / tonne (915 KG, 140 BHP)

Weight reduction / adjustment

To adjust power to weight, you could remove or change the following items and add ballast to adjust. The ballast plate mountings are in the floor under the passenger seat position.

  • Passenger seat (Cobra) - 12 KG
  • Passenger seat rail mountings, race harnesses and mounting points, inertia reel seatbelt - 5.5 KG
  • Air conditioning pump, belts, condenser and pipes - 5 KG (estimated - note this may also increase BHP slightly)
  • Lighter (carbon) doors are available (as used in Junior)
  • Windscreen could be replaced with a perspex screen from a professional racing supplier
  • Fuel load (fuel weighs approximately 0.77 KG / litre and the capacity of the fuel tank is approx. 42 litres)
  • BHP calculator (launchtech.co.uk)

Example for racing: 750 MC Roadsports Class D

  • Class D = 145 BHP / tonne excluding driver, post 45-min race (42 litres full)
  • Remove passenger seat and belts = 915 - 17.5 KG = 897.5 KG
  • Fuel weight post race from full at start = +7.5 KG (approx. 10 litres remaining)
  • Calculation without ballast = 897.5 + 7.5 KG = 905 KG = 154.7 BHP / tonne (note: Class C is 180 BHP / tonne)
  • Add ballast = 61 KG minimum = 966 KG = 144.9 BHP / tonne

Example for racing: 750 MC Roadsports Class C

  • Class C = 180 BHP / tonne excluding driver, post 45-min race (42 litres full)
  • Remove passenger seat and belts = 915 - 17.5 KG = 897.5 KG
  • Fuel weight post race from full at start = +7.5 KG (approx. 10 litres remaining)
  • Calculation without ballast = 897.5 + 7.5 KG = 905 KG = 154.7 BHP / tonne
  • Further weight to remove (aircon and ?) = -125 KG = 780 KG = 179.5 BHP / tonne

Example for MSV Trackday Championship / Trophy Class D

  • Class D = 125 BHP / tonne including driver, post 45-min race (42 litres full)
  • Remove passenger seat and belts = 915 - 17.5 KG = 897.5 KG
  • Fuel weight post race from full at start = +7.5 KG (approx. 10 litres remaining)
  • Driver weight = 85 KG
  • Calculation without ballast = 897.5 + 7.5 KG + 85 KG = 990 KG = 141.5 BHP / tonne
  • Add ballast = 130 KG minimum = 1120 KG = 125 BHP / tonne

Example for MSV Trackday Championship / Trophy Class C

  • Class C = 150 BHP / tonne including driver, post 45-min race (42 litres full)
  • Remove passenger seat and belts = 915 - 17.5 KG = 897.5 KG
  • Fuel weight post race from full at start = +7.5 KG (approx. 10 litres remaining)
  • Driver weight = 85 KG
  • Calculation without ballast = 897.5 + 7.5 + 85 KG = 990 KG = 141.5 BHP / tonne
  • Further weight to remove (aircon and ?) = -55 KG = 935 KG = 150 BHP / tonne