will i need a new tune all together when switching to e85?

[tuned2boost]

I had a local guy calibrate and tune my car for 2 bar SD on 91 oct. turbo with 60#
The car runs pretty good and at wot it stays in the 11.0-11.5 afr(which is where i wanted it)
The tune is also unlocked.

I would like to switch to e85 and i was wondering what is needed when switching(tune wise)
I figured calibration of the SD and injectors arent needed but might need a retuned?

or is it as simply as switching the stoich AFR value to 9.83252?
then watching the WB and see double check tune is still lined up?
im not after perfect spot on tune but i want the car to run good ofcourse.


Id hate to pay a few hundred again for a retune if its something i can do. (im still in the process of learning)
tuning WOT is something i can do but calibration i cant. timing I can live with what it has (being conservative is fine as its a street car)

[tommytuner]

changing stoich to reflect your alcohol content is definitely a good place to start, but a large part of the point to running ethanol is to be able to tolerate more spark. you'd be leaving a good amount on the table if you don't alter your spark tables as well. another thing to be aware of-you never mentioned your mods or boost level, but if you're making any decent amount of power now on gas-60 pound injectors are not going to take you far on ethanol....

[tuned2boost]

changing stoich to reflect your alcohol content is definitely a good place to start, but a large part of the point to running ethanol is to be able to tolerate more spark. you'd be leaving a good amount on the table if you don't alter your spark tables as well. another thing to be aware of-you never mentioned your mods or boost level, but if you're making any decent amount of power now on gas-60 pound injectors are not going to take you far on ethanol....

thank you for your response. ill look into tuning the spark more. but will it need an overall tuning or should i focus more on WOT and then work towards fine tuning overall spark?

ill be aiming for 500-550whp.
60# 320lph 70mm turbo
5.3 stock engine
boost wise what ever gets me to my goal or max out my injectors but im thinking 10-15psi. I know its going to be my limiting factor. ill switch later down the line to 80# but thats also when i do a FPR with return. I just want to enjoy the car for now before i tear it down again. besides i have to save up for the funding on those

[shoaf85]

Try to find a flexfuel 5.3 tune to look over. That will give you an idea of the difference in timing when it comes to gas vs ethonal. You will need to advance the timing in the entire table especially in the idle/ low load part throttle area to take full advantage of E85. A complete re tune probably isn't necessary. Just change the stoich, setup the WOT PE/Boost enrichment the way you want and start logging. Once the WOT fueling is on point then start adding a couple degrees of timing advance under boost to see what it likes. BE SURE TO WATCH INJECTOR DC.

[tommytuner]

60's at 55 ish psi fuel pressure might get you about 550 whp, but you'll be really close to 100% DC.