E85 Tuning

[matturbo]

Hey was wondering if any one could tell me if iam able to use my micro tech afr meter to tune e85 and if I switch it to the alcohol setting

and what afr ratio should I target

and will my nitrous fuel jetting need changing as I am running a direct port kit and a single fogger kit and do not want to hit the gas and it to be lean

[JonnoHR31]

aslong as your afr meter is hooked up to a proper wideband and not one of those useless gauges that uses the stock o2 sensor. if your not sure about target afr's and lambda the least confusing way is to leave the wideband set to petrol and tune to petrol afr's

[SECURITY]

from my own research and tuning experience ive seen the following work on e85 cars using gas widebands...

idle = 13.9-14.2 afr

accelerating in vacuum = 14.7-15 afr

light load (0-5psi) = 12.5-13 afr

moderate load (6-20psi) = 11.5afr

full load/WOT (20psi+) = 10.5-11afr

whether or not that is conservative or aggressive is your job to figure out but in my opinion e85 can run those gas afr's comfortably.

i'm currently in the same boat as you - im tuning e85 with a gas wideband till i do my research on buying a lambda wideband.

[JonnoHR31]

thats pretty rich for e85. you can farely safely go a bit leaner than you can with petrol (by leaner i mean higher afr number/lambda, still more physical fuel than petrol).

but whats best power wise is debateable, richer can take more timing but takes longer to reach peak pressure, resulting is peak pressure at pretty much the same time as a leaner mix with less timing.

[KiwiRS4T]

from my own research and tuning experience ive seen the following work on e85 cars using gas widebands...

idle = 13.9-14.2 afr

accelerating in vacuum = 14.7-15 afr

light load (0-5psi) = 12.5-13 afr

moderate load (6-20psi) = 11.5afr

full load/WOT (20psi+) = 10.5-11afr

whether or not that is conservative or aggressive is your job to figure out but in my opinion e85 can run those gas afr's comfortably.

i'm currently in the same boat as you - im tuning e85 with a gas wideband till i do my research on buying a lambda wideband.

What's a gas wideband? Wideband meters measure presence of oxygen not afrs and express the result as an afr so there is no need to adjust for E85 you can just use the same "afr" targets.

[SECURITY]

if you're talking lambda then yes, you could use the same gauge (but not the same lambda values). a gas calibrated afr gauge will always show the afr's for gas, its not showing the true values for e85.

for example;

gas stoich = 1 lambda (14.7 afr)

gas moderate boost = 0.85 lambda (12.5afr)

e85 stoich = 1 lambda (9.76afr)

e85 moderate boost = 0.71 lambda (6.92afr)

what your afr gauge does is multiply the lambda values by its target fuel's stoich which is how we get our target afr's.

so on a gas afr gauge you arent seeing the 9.76 stoich of e85, you're seeing the 14.7 of gas (e85 stoich will always be 14.7afr on a gas wideband as you are still multiplying by 1, but that is where the similarity stops).

therefore, on a gas calibrated afr gauge you will multiply e85's lambda values by 14.7.

e85 moderate boost = 0.71 x 14.7 = 10.43afr on a gas calibrated wideband.

[scotty nm35]

All highly confusing but correct. I had the same issues when converting mine to e85, I decided, as I was planning to swap back to petrol occasionally, that I would leave the wideband in petrol AFR's and tune it to much the same values as Security. Its been running fine now for nearly a year so the tune must be fairly safe, EGT's never go above 650c.