I got this chart on n2o from this board

deg psi shot

32----------460-------- ?
40--------- 520-------- ?
50----------590 ?
60---------675 ?
70 760 ?
79 850 ?
80 865 ?
83 900 ?
87 950 ?
91 1000 ?
I want to figure out what shot at what psi I would be spraying.

Thanks Wes

 

the shot relies on the jet sizes,that chart was just for relating pressure to temperature.

every manufacturer has a recommended pressure for each system,and thats where the jets come in to specify the horsepower.

there is no real way to see what size "shot" you have with the lower pressures unless you dyno the hell out of the combination.

 

Thanks. I have 125 hp jets. I don't have a bottle heater yet. I was trying to get a rough ideal on how much hp I was getting from my n2o. I know it is running rich because my bottle is mostly around 72 degrees. So i wouldn't be getting the full performance of n20 kit ?


Thanks Wes

 

yes,your car is running very fat if the bottle is only 72 degree's,get a heater,you wont believe the difference.

 

Thanks for the help!!!

 

out of curiosity, what temp will a bottle heater make the bottle, I should say, what temp do you want the bottle at, looks like around 91* to me, but I dont know. And if you are running low on fluid, can you make it hotter to compensate for the loss in pressure?

 

i run 1000-1050 psi,never hit the bottle with the temp gun though. i have a guage mounted in the dash,and use that for pressure.

you can heat it up more for less nitrous in the bottle...but there is a point where there just isnt enough left to do anything.

 

I hate that point

I always go off pressure not temp. I can really tell a diffrence from 900psi and 1,500 where I like to have it. Stop playing around and get a heater that is the most important part of a tuned N20 setup

 

You can approximate the change in nitrous flow due to pressure changes, by taking the square root of the pressure ratio.

Let's say you're spraying 150 HP at 900psi (83degF). The bottle temp drops to 60degF, leaving you at 675psi.

Calculate the "pressure ratio":

675 / 900 = 0.75

Take the square root:

0.75^0.5 = 0.866

Calculate the HP loss: 150HP X 0.866 = 130HP

In other words, dropping the bottle pressure from 900psi to 675 psi reduces your nitrous flow by 13.4%. It will probably reduce power by even more than that, since you will still be spraying enough fuel to handle the 150-shot, but you will only be spraying enough nitrous to support 130HP, and its running richer than the original tune.

Bottle pressure, at the start of a pass depends ONLY on bottle temperature, not on the amount of "fluid" (liquid nitrous) in the bottle. The temperature at the end of the run will be lower if you started with a low bottle level. The liquid nitrous leaving the bottle creates a void. To fill that void, some of the nitrous in the bottle changes from a liquid to a gas. That takes a lot of heat out of the remaining liquid, and the pressure drops. So... start with a bottle less than 1/2 full, and the pressure is going to drop steadily as you go down the track. A good reason not to run the bottle low.