Quote:
Originally Posted by gwyllion
I must confess that the fuel quantity numbers in the press release seem to make sense after all.
We know that the target efficiency is 16.36 MJ/kg for petrol and 18.46 MJ/kg for diesel. And we can assume that the fuel density is 0.754 kg/l for petrol and 0.8338 kg/l for diesel.
This means the following amount of energy is available per lap for the different powertrain options: - petrol, 0M hybrid: 16.36 * 0.7540 * 4.95 + 0 = 61.07 MJ
- petrol, 2M hybrid: 16.36 * 0.7540 * 4.80 + 2 = 61.22 MJ
- petrol, 4M hybrid: 16.36 * 0.7540 * 4.65 + 4 = 61.37 MJ
- petrol, 6M hybrid: 16.36 * 0.7540 * 4.50 + 6 = 61.52 MJ
- petrol, 8M hybrid: 16.36 * 0.7540 * 4.42 + 8 = 62.53 MJ
- diesel, 0M hybrid: 18.46 * 0.8338 * 3.99 + 0 = 61.42 MJ
- diesel, 2M hybrid: 18.46 * 0.8338 * 3.93 + 2 = 62.50 MJ
- diesel, 4M hybrid: 18.46 * 0.8338 * 3.81 + 4 = 62.62 MJ
- diesel, 6M hybrid: 18.46 * 0.8338 * 3.68 + 6 = 62.65 MJ
- diesel, 8M hybrid: 18.46 * 0.8338 * 3.56 + 8 = 62.80 MJ
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I decided to redo my earlier calcuations, with the updated numbers from Appendix B.
- no ERS
- petrol: 148.0 * 0.41375 = 61.2 MJ
- diesel: 140.3 * 0.43634 = 61.2 MJ
- 2 MJ ERS
- petrol: 143.5 * 0.41375 + 2 = 61.4 MJ
- diesel: 138.4 * 0.43634 + 2 = 62.4 MJ
- 4 MJ ERS
- petrol: 139.0 * 0.41375 + 4 = 61.5 MJ
- diesel: 134.0 * 0.43634 + 4 = 62.5 MJ
- 6 MJ ERS
- petrol: 134.5 * 0.41375 + 6 = 61.6 MJ
- diesel: 129.7 * 0.43634 + 6 = 62.6 MJ
- 8 MJ ERS:
- petrol: 132.2 * 0.41375 + 8 = 62.7 MJ
- diesel: 125.4 * 0.43634 + 8 = 62.7 MJ
Note that the more powerful hybrids appear to get slightly more energy per lap. However, if we assume that only
95% of the hybrid energy can converted into mechanical energy, this is no longer the case:
- no ERS
- petrol: 148.0 * 0.41375 = 61.2 MJ
- diesel: 140.3 * 0.43634 = 61.2 MJ
- 2 MJ ERS
- petrol: 143.5 * 0.41375 + 0.95 * 2 = 61.3 MJ
- diesel: 138.4 * 0.43634 + 0.95 * 2 = 62.3 MJ
- 4 MJ ERS
- petrol: 139.0 * 0.41375 + 0.95 * 4 = 61.3 MJ
- diesel: 134.0 * 0.43634 + 0.95 * 4 = 62.3 MJ
- 6 MJ ERS
- petrol: 134.5 * 0.41375 + 0.95 * 6 = 61.3 MJ
- diesel: 129.7 * 0.43634 + 0.95 * 6 = 62.3 MJ
- 8 MJ ERS:
- petrol: 132.2 * 0.41375 + 0.95 * 8 = 62.3 MJ
- diesel: 125.4 * 0.43634 + 0.95 * 8 = 62.3 MJ
Some observations:
- Non-hybrid cars get exactly the same amount of mechanical energy per lap (i.e., 61.2 MJ) independent of the engine type.
- The same holds for the 8 MJ hybrids. These hybrid cars probably get a bit more energy than the non-hybrids because they weigh 20kg more (850 vs 830 kg).
- For the other options there is the strange situation that diesel cars get 1 MJ more mechanical energy than their petrol counterparts. This is the consequence of the mysterious "k technology factor".