Have searched this site and the web but have not found an answer.

Tuning AFRs with gas, or gas with water injection is straight forward as only the gas is affecting AFRs. Thus to tune from 11.4 to 11 AFR is easy as: 11.4/11 = 1.036.
Add 3.6% more fuel. It normally only takes 1 run to retune and get the AFRs I want.

But when running a water-meth system where the flow rate is fixed causes the ratio to gas to vary by rpm. If I want to change AFR from 11.4 to 11 will not work because I am only changing the flow rate of the gas injected and not the water/meth. Thus it still ends up being leaner than the target but richer than before. It takes many runs to get it corrected.

Is there any formula that can be used to shorten this process.
Maybe something based on the ratio of btus of injected fuels, or ccs of fuel?

 

It would be very difficult and probably not very accurate, gotta just keep testing and tuning. Maybe you could look at the ms view of the fuel map and somehow calculate your gas to meth ratio for each cell and calculate it that way somehow.

 

That is what I have done so far for my first EXCEL work sheet.