Pretty cool. Kudo's. I cannot wait till spring time to get back on the spray.

 

I dont understand how this works. Nitrous oxide molecules do not split (releasing the 2 oxygen molecules) until they've entered the combustion chamber and reached ~ 570 degrees F . How does the MAF measure them prior to combustion.

I'm not saying it doesnt work I just dont know how it does work.

impressive numbers for a 20shot!

 

Temperature drop. when the nitrous goes from liquid at 1000psi to atmosphere and phase changes, the temp in the maf drops ALOT. The ECU dumps in a bunch of injector pulsewidth to compensate for the temperature change. This won't work so well with stock injectors, you need some "spare duty cycle".

And isn't it 1 oxygen molecule and 2 nitrogen molecules?

 

yea.. your right. I always thought it was 2 Os getting loose but I guess it's just 1. That's interesting that it ends up being the right amount of richness from the temp drop.

 

It's probobly not the correct amount of fuel correction from the maf reading the nitrous. Thankfully it's wrong to the rich side! If it was spot on, the A/F woudn't change at all when the nitrous comes on.

My guess is that any significant amount of nitrous injected into the maf will peg the temp sensor cold, and you could just increase the amount of nitrous as your tuning variable untill the A/F ratio is where you want it. Id bet the amount of fuel the ecu is putting in from the temp sensor is constant no matter if you spray a 20,40,60,100,150,200 shot through the maf. A 20 might run super rich but still make good power. 200 might be super lean. Somewhere in the middle will be the ideal.

 

Hi DS, is a single point wet fogger setup safe if you're gonna run 150 shot of nos? This is of course on a non MAF equipped DSM. Just wanted to know cause am running 100 shot on my car now and am gonna run 50 more in next years drag season. Sorry if I'm off topic here..

 

Sorry, that setup took me back to the 80's, puzzled faces, good times, and a pocket full of cash...

 

Pictures don't load anymore for me

I'm interetested in this, still debating weither or not to do nitrous or meth injection.

Could you send me the pictures of the setup?

 

Correct. I made a typo. Actual name is dinitrogen monoxide= N2O

 

I'm not saying that it reads the actual oxgen molecules packed into the N2O, the same way it doesn't read the specific amount of O2 in the air as it is ingested by the engine. The Karman sensor on the car counts "vortices" of air as they pass by the sensor, then does an equasion to figure the amount of air that is being ingested by the engine. When you spray it in front of the MAF I would assume the number of these "vortices" increase, as well as the much colder air stated by DSMotorsport and the computer adjust for this by increasing duty cycle. Interestingly enough the GM MAF on an LS1 car is also a Karman sensor.

 

so on an evo how do you go about putting it in front of the MAF do u drill a small hole directly behind the air filter? Any pics? Also the bottle in a bag is slick as hell

 

haha thats cool.

 

All you need to do is have the line spraying towards the filter. No holes need to be drilled. If you have an air box this is even easier to do and hide. Im going to make a braket that will hold the end of the line up to the bottom of the filter, so you wont see anything. You want the nitrous to get sucked into the maf, not sprayed into it.

And this is why I think that people get good power out of those intercooler sprayers. I dont think its so much as the cooling affect on the intercooler, but more that most of the gains come from the filter sucking in the nitrous and whalla a small dry shot.

 

My theory is that if not spraying directly INTO the maf's sensing passage, the only way the MAF can add in fuel is from the temp drop. If your not spraying into the sensing passage, there would be no additional vortices generated, as the intake velocity would be the same and teh airflow frequency signal would be the same. The MAF sensor has no way to distiguish oxygen concentration in the incoming air. (be it ~19% o2 for atmosphere or 33% in N2O). Can you datalog intake temp, baro pressure, and airflow HZ signal and see what changes and what the value drops to for AIT? I really want to understand how this works and what the limits are.

After seeing pictures of how this is setup, Im pretty confident that increasing the jet size will have no affect on fuel delivery.The A/F ratio will just lean out a bit more relative to each jet size increase. That's good, simplified tuning up untill you hit the limit of safe A/F ratio.

 

I have no way to datalog the car

And with my experieces if you spray directly into the maf you have the chance of freezing it. And also when you shoot it at the maf it is a very jerky hit as the nitrous comes on. But if you spray away from the maf and let it get sucked through then the power comes on nice and smooth.