nitro mixture with 02 aensor

[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]

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

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

[wideopen231]

Not disagreeing with most above statements.Matter of fact most where some of my points in discussion of this.  First thing I did not mention and should have. We where talking small mixtures maybe 30%,so would be close to alky numbers or closer. To My understanding. Nitro is 1:1 with full load and goes up with percentage drop(simple reasoning here too). I did not think about sensor saturation deal.  Wonder if reading would be linear to percentage? Just numbers here. Alky 5.5:1 and 100% load 1.2 or so. And 50% load 3.35? Just thinking out loud.Opinion welcomed and don't worry have been told Way off base before and not that nicely too.LMAO

  Also worth noting I was not on pro O2 sensor side of discussion. Always used egt's and no problem since I know no perfect number for every car, all dependent upon other factors.

[dreracecar]

No idea is new, just refined or dismissed, The 02 in CH3NO2  and the air we breath are both the same AND very different. If by using an 02 sensor would help in the tune of any fuel rated percentage, the set up and program would already be available for one to purchase, LOTS of real smart people out there before us.
 The other food for thought is that 02 is gathered by a collective exhaust system (4 into 1 lets say) , so then what would the affect be in a single 02 sensor in a individual exhaust outlet with a system that has 8 and with a tendency for all 8 to run different, which one do you gather info from or do you sample all 8?

[wideopen231]

Do like one member and run 8?  Agree with zoomies its a coin toss as to which one to use,ok lots of coin toss's. Also what is this collector you speak of? I thought all race cars where long skinny and had zoomies.LOL

[noslin]

so lets take some things into consideration.  i think first need a rough idea of horsepower to calc out fuel needed.  then assuming its not making 5300hp like some pro mods you could calc out lambda to see if possible.  reason why i say a pro mod, as mentioned at one time i talked to moran when i purchased some injectors from him for my car (which were too big - my fault)  he told me his ride was 2.9-3.2 afr meth.  now really need to work in lambda for calculations because it doesn't matter what fuel it is, the lambda value is the same regardless of fuel.  if lambda for the mixture is greater then the 2.9 afr meth then i would say yes its possible in an EFI situation because efi has precise control throughout the range.  also, i think most pro mods all run 8 egts as its giving quicker readings then the egts.  some run both.  8egts with controller is big bucks, especially to read that low.

for DISCUSSION purposes only, safe on meth is 4.0 or .63 lambda and lets say (idk... ) safe for nitro is 1.0 afr nitro scale or .59 lambda.

for 30% nitro   70% (.7) meth, 30%(.3) nitro
(.7 x .63 safe meth) + ( .3 x .59 safe nitro) = .68 or 3.97 afr meth.

assuming a sensor can read that low, then its possible at that hp level.    we could create a scale for meth using max meth afr of 3.0 for 5k hp and use .63 for 1300 hp.  then lets say do the same for nitro based on 10k hp and afr ratio to say same 1300 hp and what afr ration nitro it is.  then just put those into lambda, do calcs, then convert back to meth scale if need be. 

the ntk sensor for meth will read down to 2.66 meth which is .42 lambda.  its just a matter of finding a controller that will read that low.  moran wants 600 bucks for one sensor.  assuming .68 is ok, thats 10.0 on gas and you cant run a standard bosch sensor (for long). so you need a ntk sensor.  if you  did all 8 thats 5k plus the controllers.. prob looking at 8-10k min.

as a swag, will it work or read id say yes to about 4k hp lets say if staying with 30% nitro.  but as Bruce alluded too in his post.. it would be so saturated it would be killed in no time. can it read, yes, is it possible i doubt it as the sensor would get killed.  as mentioned on EFI setup they can control precise fuel throughout and prob not kill the sensor. on meth, isnt the tuning window about 2k hp range?  if so, then super fat from idle to the target rpm tuning range window.

dean

[Curly1]

I run 8 O2 sensors and sometimes run up to 8% Nitro and I use the gas scale. Can not tell any difference on O2 when using some Nitro. Now those are small percentages in fact usually 2% or less.

I think the O2 sensor is measuring burnt Oxygen  or lack of so perfect mixture burns all of the Oxygen no matter what fuel. Those sensors read the same and sends SAME signal to the controller where it uses what scale you want but the O2 in the pipe is the same no matter what scale you use.

I think if you are running a carb then 2 O2's one on each side is enough. But if you are running mechanical fuel injection where you put the fuel into each cylinder then you need to measure each cylinder. Every race day it tells me something that could save a burnt piston or worse. I have an 8 cylinder motor and each nozzle is different size to match the needs of that cylinder. Then use main jet for weather changes. Hundreds of people have ran injection for years with no problems but then once in a while people burn pistons and do not understand why or how it happened.

With a carb if it is getting air it is probably getting close to right amount of fuel. With injection your air and fuel are separate. With a carb it works by having some vacuum to draw the fuel out with venturi effect. With injection it does not have that so it allows motor to draw in a little more air giving it the "Potential" to make more power if it gets right fuel mixture.

[dreracecar]

3 stages of burning alc, you can be sooo lean  that you are not making heat and the plugs look new and the engine still runs, so you fatten it up a touch to get color, well , all you have done is made more heat and its still lean, that's when you burn pistons. Better to go way fat on your tune and trim back from there and use the plug threads as your heat indicater.  Never had anything more than the weather station, timeslip, plugs, and for my car water temp to tune with. Noslin has a working relationship with injection/laptop systems, but as old school as I am reading his post was like me trying to read Chinese

[wideopen231]

Thanks guys. Made for good read. As for carbs.Those thing are bad for you .LOL If god wanted man to run that junk he would not have made fuel injection.

  Some good arguing point for next bench race ,bs shooting, beer drinking session.