Gearing graph

On the gearing ratio box, there is a horizontal redline which indicates the engine’s redline, but what about the second red line underneath?
Also the yellow bars show the engine speed when traveling at a particular speed, but what does the bold end of the yellow line mean?

Also how is economy calculated? That is, is there a particular speed at which the car is traveling so I know which speed to match with gearing and engine speed to optimise fuel efficiency?


  1. the bottom redline indicates 80% of the max power if I remember correctly
  2. the bold yellow line indicates the gearing use if the car shifts at the redline every time.
  3. I’m not sure about the economy, it’s quite complicated, but to my experience my guess is that it’s based on fuel consumption when cruising at certain speeds (30-50-70-90-120 kph), or something similar.

Economy i think is measured at 62 mph/100kph try and get either as low a rpm as possable or as close to your engine’s peak efficiency rpm ( that green line in the dyno screen) at that speed for the best fuel economy.

Right, so when my super ultra #&%@ off fast turbo car returns 55l to the 100 kilometres, what that really means is that it’ll make it maybe twice around la Sarthe at full chat before it runs out of fuel… :laughing:

Fuel economy calculations aren’t quite that simple. The car is run at 30, 50, 70, 90 and 120 km/h (if possible) and the gear which gives the lowest consumption is chosen (considering throttle position and engine efficiency at these revs). To each of those figures we add acceleration phases and then all these results are weighted and added up such that a mixed-use figure is calculated.

Well that’s cool, I had not realized how in depth it was.

Allways nice to be shown what goes on “behind the curtain” so to speak. Makes my inner geek very happy. :slight_smile: :geek: :slight_smile: