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e85fuel [2009/02/16 08:25] twdorris |
e85fuel [2009/02/16 08:31] twdorris |
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The 14.64 figure above comes from the chemically correct stoichiometric ratio of gasoline. A lot more data can be found on the [[http://en.wikipedia.org/wiki/E85_in_standard_engines|wikipedia E85 page]]. | The 14.64 figure above comes from the chemically correct stoichiometric ratio of gasoline. A lot more data can be found on the [[http://en.wikipedia.org/wiki/E85_in_standard_engines|wikipedia E85 page]]. | ||
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For example, if you're running 100% E85 with 850 cc/min injectors, your injectors are flowing the equivalent of 570 cc/min injectors on gasoline: | For example, if you're running 100% E85 with 850 cc/min injectors, your injectors are flowing the equivalent of 570 cc/min injectors on gasoline: | ||
- | 850 * 0.670 = 570 | + | 850 * 0.670 = 570 |
The 0.670 figure comes from the gas ratio column of the table above. | The 0.670 figure comes from the gas ratio column of the table above. | ||
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So now you can calculate your new global fuel using the standard formulas and 570 cc/min injector size instead of 850. | So now you can calculate your new global fuel using the standard formulas and 570 cc/min injector size instead of 850. | ||
- | 450 / 570 - 1 = -21% | + | 450 / 570 - 1 = -21% |
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===== Running custom mixes ===== | ===== Running custom mixes ===== | ||
- | If you're running a mix (say 50% E85 and 50% gasoline), then you have to do a little more work. As an example, let's assume you're running 75% E85 and 25% gasoline. The new gas ratio in this case would be: | + | If you're running a mix (say 75% E85 and 25% gasoline), then you have to do a little more work. As an example, let's assume you're running 75% E85 and 25% gasoline. The new gas ratio in this case would be: |
- | 0.75 * 0.670 + 0.25 * 1 = 0.7525 | + | 0.75 * 0.670 + 0.25 * 1 = 0.7525 |
- | With that new ratio calculated, you can calculate your effective injector flow rate the same as above. | + | With that new ratio calculated, you can calculate your effective injector flow rate the same as above (assuming 850 cc/min injectors again). |
- | 850 * 0.7525 = 640 | + | 850 * 0.7525 = 640 |
So instead of 570 cc/min that results from 100% E85, your injectors will actually flow like 640 cc/min injectors with a 75% E85/25% gas mix. You can then calculate the global fuel same as always. | So instead of 570 cc/min that results from 100% E85, your injectors will actually flow like 640 cc/min injectors with a 75% E85/25% gas mix. You can then calculate the global fuel same as always. | ||
- | 450 / 640 - 1 = -30% | + | 450 / 640 - 1 = -30% |