Hernj65

Tried searching here and didn't see many (if any) modern post about this. I'm wanting to know what afrs people are running with on ethanol. I've heard so many different answers on different platforms from 11.5-12.5 in boost and 14.7 to 16.5 everywhere else. I currently am running a max of 13.5psi and target about 12-12.2 on the top. 12 early on and taper to 12.2 near the end. For idle and cruise I haven't really touched my afr besides running maybe a .1-.2 leaner in certain areas. So 14.7 idle and 15.3 cruise.

themonkeyman

That’s crazy lean for e85, stoich for gas is 14.7, for e85 it’s around 9.7:1. Take a look here

https://ftyracing.com/tech/lambda-afr-table/

Also Lambda is always quoted as the ratio of stoichiometric to 1, so ideal lambda for any fuel is going to be 1.0, but it represents a different AFR for different types of fuel.

Hernj65

@themonkeyman right I understand whay you are saying but in my situation my wideband reads gas and e85 stoichiometric the same lambda like you said. Stoichiometric for gas afr is 14.7 which equals 1 lambda but it also reads e85 the same lambda which is stoichiometric 9.7. So in essence I do not have to change my afr targets to be 9.7 because the way the wideband outputs the afr. A lot if tuners here is the states will just leave the wideband settings the same and not change any targets. What I have heard is that you can get away with running a touch leaner on e85. Say you target 11.7 afr in boost which is roughly .8 lambda. Some people say you can run .82 lambda which is about 12afr or 8afr if your wideband reads e85 stoichiometric. I don't think I'm the best at explaining this maybe others can chime in or if you want to look into it search some of the threads here or on hp academy they explain it as well.

themonkeyman

If the car is tuned well on gas I'd leave the fuel table basically untouched for e85, timing is the big game changer with ethanol. Someone more experienced than me can chime in about running leaner targets in ethanol (it burns cooler so thats maybe a thing) but it seems to me targeting stoich makes the most sense.