Early Notice of Proposed Efficiency Rule Change for Formula SAE 2024
We have proposed a change to the Efficiency event scoring for the Formula SAE Rules 2024. This article provides some background information and further discussion of the basis and reasons why this is proposed.
Please review the draft Formula SAE Rules 2024 and provide any feedback or comments. This is your opportunity to provide comments and feedback prior to publication.
Submit any comments or feedback:
https://sae.qualtrics.com/jfe/form/SV_elgU45vHTBOGjY2
Efficiency
Fuel or Energy Efficiency has been measured the same way at Formula SAE since 2012. However, there are some observations based on the historical results:
Minimal points difference between the top few places
Lowest Score for Combustion is about 30 points out of 100 (with occasional exceptions)
Lowest Score for Electric Vehicles is at least 85 points out of 100
Most EV teams receive more than 90 points out of 100
These observations show that:
Efficiency is actually worth much less than 100 points...
Which makes the Efficiency Event less significant to the overall results
And gives teams little incentive to encourage or prioritize Efficiency
So we want to make a change that would:
Spread scores through the full score range, say from ~15-20 points up to 100 points
Make the relation between energy use, lap speeds, and Efficiency more apparent
Create incentive for teams to improve Efficiency
Proposed Change
Make the Efficiency score equation linear.
What would this change look like for the Formula SAE June 2022 Combustion Efficiency?
Scores are now distributed between 16 and 100 instead of 36 to 100.
For the Electric Vehicles, this is an improvement, however...
Scores only went to about 50 points for the lower finishing positions
Why is this the case?
Review Energy Limit:
Fuel Limit based on 26 ltr/100 km
Conversion Factors from Rules:
Gas 2.31 kg CO2 / ltr
E85 1.65 kg CO2 / ltr (value differs from gas by 1.4, this corrects for the fuel difference)
Electric 0.65 kg CO2 / kWh
Energy Limit – Combustion
5.72 ltr for 22 km Endurance distance (22 * 26/100)
Converts to 5.72 ltr * 2.31 kg CO2 / ltr = 13.213 kg CO2
Energy Limit – Electric
Convert the total CO2 allowed from Combustion to Energy using the Rules conversion factor:
13.213 kg CO2 / 0.65 kg CO2 / kWh = 20.328 kWh
This max energy limit will never be exceeded by an Electric team during Endurance
And the high limit affects the distribution of Efficiency scores
There is no need to use same Energy limit for Combustion and Electric when they are standalone events.
Review of online data and published studies shows that the efficiency of Electric Vehicles, and from that the amount of energy use, could be from 20-40% of the Combustion vehicle limit.
So we will set the energy limit for Electric Vehicles to 33% of the Combustion vehicle limit.
What would these two changes look like together for the Formula SAE June 2022 Electric Vehicle Efficiency?
Scores are now distributed between 22 and 100 instead of 86 to 100
Summary of the Proposed Efficiency Scoring Change
Change the Efficiency score equation to be Linear
Would apply to both Combustion and Electric
For Electric, reduce the max energy limit for Efficiency scoring
What is NOT changing:
Eligibility for Efficiency Points
There is still no maximum capacity for the Fuel Tank or Accumulator. Sizing the Fuel Tank or Accumulator is still a design choice of the team. Remember that there are other considerations besides the capacity.
Please review these proposed rules for Formula SAE 2024. Please give us any input, comments, or thoughts you have.
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