Running E85? We built a simple excel spread sheet to calculate Stoich AFR with different amounts of alcohol. The calculator also finds drop in intake temperature, fuel pump requirement, injector requirement, etc. Have fun! We picked up 80 rwhp on a turbocharged car by removing the intercooler and switching from VP113 to pump E85! This is a very simple calculator for finding stoich, fuel consumption, and heat removed from air charge when using some percentage of ethanol. (Including 0% – Pure gasoline) Note, gasoline is a fairly complicated mixture of chemicals. I’ve represented gas with C8H15 For this reason stoich values will not be exact but pretty close darn close. I’ve also represented air as oxygen and nitrogen only which is not correct, but close enough for me.
To find the drop in temp I’m using the specific heat * delta T or heat of vaporization. This isn’t the best way to do this. If anyone has a better way of doing it please let me know. I don’t have any property tables or ethanol or gasoline so I’m not sure how the specific heat changes with temperature nor do I know the where its going to come out of the liquid/vapor line.
Drop in temperature seem extreme? Remember that all fuel must be vaporized before it is burned. If it doesn’t vaporize, it doesn’t burn and passes threw the cycle as a unburnt hydrocarbon which is directly associated with combustion efficiency. To change states (example liquid to vapor) the liquid must soak up energy. This is where the drop in temperature comes from. Ethanol does a better job of this than gasoline. It soaks up about 3 X the energy that gasoline does and you have to use quite a bit more of it than gasoline.
Enjoy!
Excel spreadsheet for burning E85 or some percentage of ethanol and gasoline
