Stoichiometric AFR for Isopropyl Alcohol
- Thread starter slipstick
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Hypothetically, why would it matter? Its not like the motor will be run on 100% Iso. And you still have to contend with figuring how much fuel is displaced.
AFR is a non issue. Hasnt been even for guys running 40-50% fuel replacement. As the tune is looking for greatest power... and that varies from motor to motor.. and amount displaced.
HTH
AFR is a non issue. Hasnt been even for guys running 40-50% fuel replacement. As the tune is looking for greatest power... and that varies from motor to motor.. and amount displaced.
HTH
Thanks for the reply.
The answer to the question I asked (what is stoich for Isopropyl?) would help me analyze Turbolink and LM-1 data I have collected. I am interested in monitoring and understanding the effects of fueling changes as presented by these tools. Of course, increased performance is the ultimate goal; however, collecting and studying data is fun (and sometimes rewarding).
The answer to the question I asked (what is stoich for Isopropyl?) would help me analyze Turbolink and LM-1 data I have collected. I am interested in monitoring and understanding the effects of fueling changes as presented by these tools. Of course, increased performance is the ultimate goal; however, collecting and studying data is fun (and sometimes rewarding).
Monitor in Lambda (voltage) instead of AFR. Lambda is the same for all fuels, and you shoot for the same 0.780-0.800's that you do when using the stock narrowband sensor readings. For example, stoich for denatured alcohol is ~9:1 AFR, that will be 1.0 Lambda, whereas on gasoline the accepted values are 14.7:1 is also 1.0 Lambda. So even if you mix the two, as long as you are looking at lambda values, shooting for that (usual max power) 0.800 range in lambda will make it ok. You don't have to do math in your head while watching the WB, or calculate how much % you are spraying. HTH's -Chuck
DMan
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Uhhh, hold on a second there monte.
Your definition of lambda is correct, but stock 02 sensor readings are NOT equivalent to lambda readings.
If I recall correctly, a stock 02 sensor cascades through stoichiometry at .45v or thereabouts. A 'rich' reading on an 02 sensor is a 'high' voltage. A 'lean' reading is a low voltage. This is contrary to your correct definition of lambda.
It is funny though how the numbers seem to make sense right around 0.8 volts!
But after that, if you want to get richer, thats a lower lambda, but a higher stock o2 voltage reading.
A way to get a lambda reading is to get a wideband o2 sensor and display. They can usually display both AFR and lambda.
And having knowledge of where the effective lambda is for our dual-fuel vehicles would be helpful, but many alky-holics have done quite well without the info. Still it would be useful data, in the name of SCIENCE!
Your definition of lambda is correct, but stock 02 sensor readings are NOT equivalent to lambda readings.
If I recall correctly, a stock 02 sensor cascades through stoichiometry at .45v or thereabouts. A 'rich' reading on an 02 sensor is a 'high' voltage. A 'lean' reading is a low voltage. This is contrary to your correct definition of lambda.
It is funny though how the numbers seem to make sense right around 0.8 volts!
But after that, if you want to get richer, thats a lower lambda, but a higher stock o2 voltage reading.A way to get a lambda reading is to get a wideband o2 sensor and display. They can usually display both AFR and lambda.
And having knowledge of where the effective lambda is for our dual-fuel vehicles would be helpful, but many alky-holics have done quite well without the info. Still it would be useful data, in the name of SCIENCE!
The balanced equation is C3H8O + 9/2 O2 = 6 CO2 + 8 H2O, and the molecular weights are C3H8O = 60 g/mol and O2 = 32 g/mol. So, 1 mol * 60 g/m C3H8O : 9/2 mol * 32 g /mol O2, or 60 : 144 or 1 : 2.4. However, air is only 21 % O2 so to get 2.4 g O2 you need 2.4 / 0.21 = 11.4 g air, so the stoichiometric ratio by weight for isopropanol is 11.4 : 1.
Yeah, yeah, I'm going, I'm going ...
Yeah, yeah, I'm going, I'm going ...
Fuel AFRst FARst Equivalence Lambda
---- ----- ----- Ratio -----
=======================--====================================
Gasoline stoich 14.7 0.068 1 1
Gasoline Max power rich 12.5 0.08 1.176 0.8503
Gasoline Max power lean 13.23 0.0755 1.111 0.900
=======================--====================================
E85 stoich 9.765 0.01235 1 1
E85 Max power rich 6.975 0.1434 1.40 0.7143
E85 Max power lean 8.4687 0.118 1.153 0.8673
=======================--====================================
E100 stoich 9.0 0.111 1 1
E100 Max power rich 6.429 0.155 1.4 0.714
E100 Max power lean 7.8 0.128 1.15 0.870
From HERE was where I got my numbers. I was prolly a little in error, I apologize, memory getting rusty at times. -Chuck
---- ----- ----- Ratio -----
=======================--====================================
Gasoline stoich 14.7 0.068 1 1
Gasoline Max power rich 12.5 0.08 1.176 0.8503
Gasoline Max power lean 13.23 0.0755 1.111 0.900
=======================--====================================
E85 stoich 9.765 0.01235 1 1
E85 Max power rich 6.975 0.1434 1.40 0.7143
E85 Max power lean 8.4687 0.118 1.153 0.8673
=======================--====================================
E100 stoich 9.0 0.111 1 1
E100 Max power rich 6.429 0.155 1.4 0.714
E100 Max power lean 7.8 0.128 1.15 0.870
From HERE was where I got my numbers. I was prolly a little in error, I apologize, memory getting rusty at times. -Chuck
