Originally posted by mobiuslogic@Dec 13 2003, 11:53 PM
Well, with the FFV engine and PCM, they are actually 24# injectors (it's like 23.7). However, injectors do not have a "half on" position. They are either fully on or fully closed. 24# injectors and needed in the FFV because ethanol does not have as much energy per volume as gasoline (however it can be burned far more efficiently given proper engine design) so more fuel must be shot depending on what percentage of the gasoline is ethanol, which the computer of course figures out for you, which is why larger injectors are needed for when the car is running a full tank of E85 (85% ethanol, 15% gasoline).
In terms of efficiency though, pure ethanol has an octane rating of 113, and E85 has an octane of 105. What that means is that ethanol (pure) can withstand a compression ratio of close to 14:1, compared to 9.5:1 for the vulcan and 10:1 in the duratec. Because of the higher compression ratio possible, more energy can be extracted from the fuel. And the compression ratio can be increased either with new pistons and rods, or as I want, BOOST. But boost that is coupled to the ethanol meter such that depending on the ethanol content in my tank, it will automatically adjust the boost for optimum firing and energy production.
Also, when you upgrade injectors, no, you do not need to get a calibrated MAF. However you do need a chip or a reflashed PCM that takes into account the increased fuel capacity of the injectors. Without doing that, the PCM will be pulsing the injectors LONGER than needed if you leave the programing at 14# but swap up to 24#. Result is wasted gas, running rich, LESS performance, and the possibility of burning up your catalitic converters. With higher capacity injectors, the PCM must fire them for LESS time than the 14# injectors because they flow at a higher rate.
Does that answer your question.....?