Technical > Spud Miller's Cave

nitro mixture with 02 aensor

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wideopen231:
Spud,

 A question came up cpl days ago in a bench race session. Lot of folks running o2 sensor instead of EGT now days. How does a nitro mixture effect reading and could o2 be used to tune with running nitro?

noslin:
question is what you think the afr would be with the mixture your running.  meaning, in a pro mod their afr is like 3.2 on meth. at 50-60psi (guess) boost and making 2k-3k hp.   problem is getting a sensor AND a controller to read that low.  NTK makes laboratory grade sensors to do it then you have to find the controller.  not all will read that low.  if i recall correctly the standard bosch and ntk sensor will read down to like 4.5-4.7 afr meth. or say .7 lambda as a guess.  id have to dig out my notes to get more accurate.  i messed with this with my last car which was EFI.  i switched from gas to meth and did research, spoke to moran about it too.   

so, need to figure out what the afr on meth adjusted for percentage of nitro is for the HP calc that your looking for and then find a sensor and controller to read that low.  my guess is, if trying to run 200mph which would be about 1400 hp guess on say 450 cube motor which is only 3hp/cube you would be looking at 3.7-4.0 afr meth;  thats just a swag. 

dean   

dreracecar:
Nitro burns/combust as a liquid and is compression sensitive, I don't think that adding more O2 or lessoning it as a big effect as much as what blower boost adds to compressing it to make a bigger bang. My understanding is the only about 45% is used for making power and the rest is used during overlap for cooling. HP is heat/BTUs and its with those thermal indicators is where you will find your tune

noslin:

--- Quote from: dreracecar on January 08, 2020, 05:16:05 PM ---Nitro burns/combust as a liquid and is compression sensitive, I don't think that adding more O2 or lessoning it as a big effect as much as what blower boost adds to compressing it to make a bigger bang. My understanding is the only about 45% is used for making power and the rest is used during overlap for cooling. HP is heat/BTUs and its with those thermal indicators is where you will find your tune

--- End quote ---

this is interesting, i dont know anything about percentages burned.  but, looking at a sensor, they will ruin quickly if say saturated like this. you generally clean them with gasoline, if they are not too gone.   it might be a deal where the environment for the sensor on a mechanical setup is just too wet lets say where it would not even work anyways because of the saturation.

dreracecar:
Notice when a fuel car idles and raw fuel is "misting" out the pipe, that's during the overlap period when both valves are open, you do that to control heat and to make sure there is fuel at the hit. any O2 sensor would be saturated. Effective Stoich for gas is 14 to 1  ALC is  6 to 1   Nitro is 1 to 1 but also carries its own O2 molicules  (CH3N02) .  You can't tune fuel like one tunes for gas, Its like trying to bake an apple pie but use potatoes instead

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