Carb Question

[Rick Doane]

Have any of you carb guys ever calculated the air/fuel ratios required based on the percent mixtures of our fuel?

 

[Andy Brown]

Would not be hard to do. Just extrapolate. Nitro is about 1.7/1 and Methanol is about 6.5/1.

Only account for the nitro and meth in the fuel, not the oil.

Therefore a fuel mix of 60% nitro, 25% methanol , 15% oil. would produce a 71% nitro and 29% Meth. mixture. If I did the math correctly, this would require an A/F of 2.8/1.

Not a big difference from 100% nitro.

25% nitro, 60% meth, 15% oil. would work out to be 5.0/1

 

[Rick Doane]

Good to hear from you Andy! Thanks for the numbers. When I did the stoichiometric calculations for each component, I got slightly different numbers that I believe is due to the way I did the weighted mean of each component. Anyway, I got around 5.47:1 when weighted for 55% nitro. I may need to go back and rethink. My nitro came out to 1.04:1 pure but when multiplied by the mass-percent of air, (O2), gave a number of 4.48:1.

Thanks again Andy.

 

[Ray Sametz]

Have any of you carb guys ever calculated the air/fuel ratios required based on the percent mixtures of our fuel?

Would not be hard to do. Just extrapolate. Nitro is about 1.7/1 and Methanol is about 6.5/1.

Only account for the nitro and meth in the fuel, not the oil.

Therefore a fuel mix of 60% nitro, 25% methanol , 15% oil. would produce a 71% nitro and 29% Meth. mixture. If I did the math correctly, this would require an A/F of 2.8/1.

Not a big difference from 100% nitro.

25% nitro, 60% meth, 15% oil. would work out to be 5.0/1

Good to hear from you Andy! Thanks for the numbers. When I did the stoichiometric calculations for each component, I got slightly different numbers that I believe is due to the way I did the weighted mean of each component. Anyway, I got around 5.47:1 when weighted for 55% nitro. I may need to go back and rethink. My nitro came out to 1.04:1 pure but when multiplied by the mass-percent of air, (O2), gave a number of 4.48:1.

Thanks again Andy.

Yea I new that, just wanted to see what you guys came up with !!

 

[Tom Foley]

Have any of you carb guys ever calculated the air/fuel ratios required based on the percent mixtures of our fuel?

Would not be hard to do. Just extrapolate. Nitro is about 1.7/1 and Methanol is about 6.5/1.

Only account for the nitro and meth in the fuel, not the oil.

Therefore a fuel mix of 60% nitro, 25% methanol , 15% oil. would produce a 71% nitro and 29% Meth. mixture. If I did the math correctly, this would require an A/F of 2.8/1.

Not a big difference from 100% nitro.

25% nitro, 60% meth, 15% oil. would work out to be 5.0/1

Good to hear from you Andy! Thanks for the numbers. When I did the stoichiometric calculations for each component, I got slightly different numbers that I believe is due to the way I did the weighted mean of each component. Anyway, I got around 5.47:1 when weighted for 55% nitro. I may need to go back and rethink. My nitro came out to 1.04:1 pure but when multiplied by the mass-percent of air, (O2), gave a number of 4.48:1.

Thanks again Andy.

Yea I new that, just wanted to see what you guys came up with !!

Same here Ray !!!!

 

[Charles Perdue]

Just more food for thought.

Take these air/fuel ratios, compress them to 9:1 to 10:1 compression ratios and then tell me why they are not near liquid form or slush, at ignition.

Maybe this is why the glow plug wire gets bent or why we need a larger combustion chamber at higher nitro percentages??????????

Charles

 

[Rick Doane]

Good Morning Charles! Glad to hear from you again. I sure miss these conversations lately. In response to your "appetizer", I believe larger volume chambers are necessary not only for the increased nitro but the increased water vapor.

Where's Ray's popcorn icon when I need it!

 

[dwilfong]

MSV and chamber shape

The volume of the port runners and the shape

Expansion of the mix after the carb

You can atomize it all you want but all this will still turn it to poop.