Fuel Requirements Based On Horsepower Enter the flow rate of each injector in cc/min: Enter the hp you wish to achieve: A minus figure indicates you have enough fuel.A plus figure indicates the amount of extra fuel needed. cc/min
The basic formula for calculating fuel requirements is (no. of cylinders x injector flow rate) / 6.75, this equals to about a 90% duty cycle. For example a car with 4 cylinders and 430 cc/min injectors, would have enough fuel for (4 x 430) / 6.75 = 255 hp.
Another useful formula is for calculating
the percentage increase of fuel flow through the injectors if the fuel
pressure is raised. The formula for this is the square root of (new pressure
/ stock pressure). So for example let's say you increase your fuel pressure
from 38 psi to 48 psi, you percentage increase of fuel would be (48 / 38
= 1.26315). The square root of 1.26315 = 1.12, so you have now increased
fuel flow by 12%. So if your injectors are 430 cc/min, you would now have
(430 x 12% = 51.6) + 430 = 481.6 cc/min injectors.