Join Date: Aug 2012
Location: Austin, Texas
Car: 2001 VDC/SC One of a Kind
Feedback Score: 2 reviews
More air needs more fuel. I have 410 cc injectors to supply the fuel. I am going to upsize to 650 cc to get even more. When the ECM was remapped for the supercharger, the injector latency was changed in order to get the proper fuel shot for the added air charge, along with the timing and knock retard. The last three logs I ran was on E85 and the latency was changed after each to gain the perfect mix, what I have now.
I also have a larger volume fuel pump. The OE fuel pump will supply the necessary flow needed for E85 everyday driving. I just wanted to be sure it would be capable to provide flow for "racing" where the engines runs from 4-7k rpm.
An NA or forced induction engine can be remapped to perform better and gain in fuel economy. To run E85, the latency is increased to provide a longer period of open since the combustion process needs a higher volume of alcohol to get the same burn as gasoline. Generally, 25% more volume is needed. Given the injectors can operate safely up to 85%, I would think that a NA engine can be reprogrammed to run E85 safely, unless you keep the engine rpm on the high side, then you would need to up the injector size. But, when the fuel map is changed to run E85, when gasoline is put in it will run rich. The car doesn't distinguish between the two fuels. It doesn't have an alcohol monitor or capability to switch its map. That would be up to the operator. Switching programming takes less than 3 minutes. If you do the remap, save the original ROM or an updated one on the laptop. Run the E85 program for E85. Switch to the OE or modified for gasoline.
I can run gasoline in the car with the map I run for E85 and keep the mix at stoichiometric for gas. It just doesn't run as well for power output and I have to watch the AF gauges to make sure I don't go rich by changing my foot position on the accelerator. It's just a matter of throttle control.
For math calculation, 14.7:1 is for gas, 9:1 is prime for alcohol.