Methanol AFR tuning descusion

[wesam]

I need a scientific discussion about the correct AFR for boosted cars when using methanol
Let's say we have a 1000 whp car that using a dual methanol nozzle that spray 30% of car fueling and 70% gasoline
so if we want to know the blend AFR knowing that stoic for methanol is 6.45 and 14.68 for gasoline also for FI cars we know the best lambda should be around 0.78 so we could use the formula
Blend AFR = (0.3x6.45x0.78) +(0.7x14.68x0.78) = 9.52 AFR

but as a lot of us tried before if we reach this AFR (anything less than 10.8) the power will decrease a lot and the car will start bucking badly from this rich mixture so what's wrong with this formula? Do i missed anything ?

[5FDP]

Stick with the same AFR you were running or close to it but included the added meth into the fuel curve if that makes sense.

No need to run it way richer, just reduce the amount of gasoline going in. That is what I'd do anyway.

[mJolnir]

I need a scientific discussion about the correct AFR for boosted cars when using methanol
Let's say we have a 1000 whp car that using a dual methanol nozzle that spray 30% of car fueling and 70% gasoline
so if we want to know the blend AFR knowing that stoic for methanol is 6.45 and 14.68 for gasoline also for FI cars we know the best lambda should be around 0.78 so we could use the formula
Blend AFR = (0.3x6.45x0.78) +(0.7x14.68x0.78) = 9.52 AFR

but as a lot of us tried before if we reach this AFR (anything less than 10.8) the power will decrease a lot and the car will start bucking badly from this rich mixture so what's wrong with this formula? Do i missed anything ?

your wideband measures in lambda an then calculates for the afr scale, leave it on the same scale all the time, if youre using gasoline afr scale (14.7 stoich) then you shoot for 11.4 afr

[steelmesh]

I agree with mJolnir comment, Lambda does not care what fuel you're using. Off the shelf WB02 gasoline gauges are calibrated to output 14.7 when it is reading Lambda 1.0. So if you want to run 0.78 lambda, you need to target 11.47 AFR out of your gasoline scaled WB02 gauge. It does not care what fuel type you're running (Gas, E10, E85, Meth, Alcohol, or any combination mixture). It is measuring Oxygen levels, so it doesn't care what fuel you're burning. Tune your fueling off your WBO2 and knock, there are too many variables to get it right by calculations and theories, just start conservative and then start leaning it out. A dyno is also required to maximize power wit confidence (optimizing timing and AFR for your particular engine/setup and "what it likes").