Methods for controlling bottle pressure???

Draco1340

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I think we can all agree that its time to start a new thread.:please:

With all the recent discussion centered on methods of getting N2O into the motor, I wanted to compare and discuss various methods of accurately and simplistically controlling the flow of nitrous via controllable and steady bottle pressure. I have tried all of the following methods, and I don’t care for any of them! They all suck. Advice please??

The propane torch method – Yup, have to admit that in a pinch with only 5 minutes between rounds, I’ve succumb to the “fast-stupid†method. Take your plumbers tourch and heat that bottle up, checking with your on board gauge, and purge down to 1kpsi right before your run. Some tracks point a blind eye to this. Some will kick your ass off the track. Dangerous and stupid, but also cheapest, fastest and lightest.

Heater blanket and pressure relay method- This is the most standard method were a pressure switch switches the blanket on and off between 850 and 1050 psi. On a 50 shot, this can swing you’re A/F ratio +/- 0.5. If you add a purge valve and an accurate gauge, you can always purge down to the 850 psi and tune for that, but you have added about 4 pounds of crap to your ride. Also, expect to have to replace and charge your battery continually. These systems draw big current. They can also turn on during a run, pulling available current away from the coils.

The bottle in the truck method – This is the ultimate “keep it simple methodâ€. If you have 4 bottles, you can just keep them in the truck at a moderate 75F and swap them between rounds. Unfortunately all of us frequently experience the 1 hour oil down right after we roll up to pre-stage. Bottle pressure drops down to 750 psi, and all of a sudden you’re A/F ratio has dropped 1.5. I have personally logged runs as low as 10:1 after having tuned for nominally 12:1 under this scenario.

Land Speed considerations - So far all of these systems work OK for the drag strip (although never reliably enough for me) but none of them work well for land speed were you might be on the spray for 20 seconds or more. I log bottle pressure with my data logger, and was amazed at how bottle pressure drops as a function of time. With a 2# bottle starting at 1100 psi, I initially purge down to 1Kpsi. On solenoid activation with a 50 shot, the bottle immediately drops to 750 psi. The pressure eventually drops to about 700 psi in the first 4 seconds. By 15 seconds, the bottle is down to 400 psi. The phase change “super chills†the bottle, and the pressure drops like a stone. Even if you tune for super lean in the beginning, you can see you’re A/F drop over 2.5 points. To combat this you can see Tiger racing caries 3 x 2# bottles. I also remember seeing a ZX12 with a 5# bottle looking a bit like Wiley Coyote. Bigger volume creates less drop, but its still a crap shoot on a 30 second pass like Maxton.

The Nitrogen Gas “push†method – A buddy of mine and I played with this method for a while. We created a bottom feed nitrous bottle with a second inlet into the top. We attached a regulated supply of nitrogen gas to the surface of the nitrous and pushed the N2O out with this regulated supply. The system was complicated, and took at least 45 minutes between runs. It comprised of a carbon paint ball canister charged to 4kpsi with nitrogen, and a specially engineered adjustable regulator. The system could completely drain a full bottle with no drop in pressure. It also added at least 10 pounds to the rig, and was arguably a bloody time bomb in a crash. One tech inspector just rolled his eyes and walked away...:whistle:

The N2O regulator method – I was initially skeptical of this method, but I started using this method at the end of last year as an experiment with a 30 shot. I have the nitrous regulator set at 750 psi, and I just let the bottle pressure be what it wants as long as its moderately warm to the touch. Low tech, simple, cheap and light. Quick purge in the water box, and that’s it. I don’t have enough experience to know if this is limited to very small shots.

Pictures forthcoming. My daughter lost my USB cable this weekend, but I want other ideas and solutions to this problem.
 
WoW there's other wayz of doing it besides the Propane Torch ??? :laugh: Na, on the real......Good info draco :thumbsup: This ALWAYS seems to be the biggest nightmare for us n2o junkies. Like you mention, with our bottles being so small(2lbs compared to the traditional 10lbs of a car kit)its next to impossible to maintain a good bottle psi. Maybe someone on here has this issue ironed out? :please:
 
I had my bottle pressure being logged on my data logger and the most I ever saw it dropped was 100psi. Mostly it was 50psi.

I think he might be refereeing to LSR?

Draco, could you explain what you meant about using "nitrogen" to help with bottle psi? How does this work, this is my first time hearing of this one ???
 
I had my bottle pressure being logged on my data logger and the most I ever saw it dropped was 100psi. Mostly it was 50psi.

First 4 or 5 seconds I see about the same thing if you start small with a progressive. After that the bottle becomes COLD and the pressure drops HUGE. Big shots ramping quickly will cause bigger drops. I will post plots tonight. Check your bottle pressure immediatly at the end of a run. Its frightening.
 
I think he might be refereeing to LSR?

Draco, could you explain what you meant about using "nitrogen" to help with bottle psi? How does this work, this is my first time hearing of this one ???

I first got this idea from the doorslammers that were running 4 or more BIG bottles in their cars to cut down on the pressure drop they saw during a 6 second run. Think of how a spray paint can works. A pressurized gas sits on top of the liquid and pushes the liquid down and out of a siphon tube. In this case you carefully regulate a 1000 psi source of nitrogen above the surface of the N2O and push the N2O out the siphon tube. This is all requires custom flow valves and such, and is not commercially available, but it works regardles of its complexity. The nitrogen gas never changes pressure because it never goes through phase change and because its going through a regulator. The other little detail is that you have to turn the nitrogen off because you will increase the partial pressure of Nitrogen gas into the liquid N2O. You effectively drop the oxygen content of the liquid nitrous from 33% to something slightly less. Probably more detail than anyone cares about....
 
I first got this idea from the doorslammers that were running 4 or more BIG bottles in their cars to cut down on the pressure drop they saw during a 6 second run. Think of how a spray paint can works. A pressurized gas sits on top of the liquid and pushes the liquid down and out of a siphon tube. In this case you carefully regulate a 1000 psi source of nitrogen above the surface of the N2O and push the N2O out the siphon tube. This is all requires custom flow valves and such, and is not commercially available, but it works regardles of its complexity. The nitrogen gas never changes pressure because it never goes through phase change and because its going through a regulator. The other little detail is that you have to turn the nitrogen off because you will increase the partial pressure of Nitrogen gas into the liquid N2O. You effectively drop the oxygen content of the liquid nitrous from 33% to something slightly less. Probably more detail than anyone cares about....

wow sounds like alot of headaches!
 
How about a combination of bottle heater with controller along with a regulator?
 
hum maybe time for a 2 bottle set up? maybe figuring out a timing method that will switch from one bottle to the other when the peak pressure drops below where you want it to be....? I don't know just an idea, maybe it can be done maybe not, if you figure it out and patent it I want 25% of the proceeds..LOL
:poke:
 
hum maybe time for a 2 bottle set up? maybe figuring out a timing method that will switch from one bottle to the other when the peak pressure drops below where you want it to be....? I don't know just an idea, maybe it can be done maybe not, if you figure it out and patent it I want 25% of the proceeds..LOL
:poke:

2 or 3 bottle setups are fairly common. One in the arm, and one on both sides of the rear subframe. Thats a 12 pound weight penalty, but it does work to reduce the drop. It can make setting the initial pressure even more difficult.
 
Funny this topic came up cause i'm running two bottles. One 2.5lbs and one 1lbs bottle. I just installed the second bottle this year to try and see if I can keep my bottle pressure steady. I'm experimenting to see if the small bottle can just keep the pressure steady without having to add another 2lbs one. What you think?
 
The whole nitrogen idea sounds good, almost like a blatter tank on a oil burner. Its a metal tank that has a rubber blatter on the inside that seperates the hot water from an air pocket. The top ( or bottom ) of the tank has a little air valve on it ( like a tire valve )
and you keep 18-35 lbs of air in it. When the tank is filled with hot water the air pressure in the blater keeps the hot water psi steady. You sound like you can make stuff so mabye try that if you havent already.:idea:
 
Remember, every 10 lbs you add to your bike with gauges and valves, and hoses and extra bottles and purge valves costs you 3 1/2 MPH at the back end of the track.

Thus, I gave up on the nitrogen idea due to complexity, weight, and time between runs. I wouldn't recomend it.

Professor, regarding suggestion on bottle heaters, I "might" consider using one if I had a car battery I could leave at the starting line. Connecting one to the bike battery was a disaster.
 
Professor, regarding suggestion on bottle heaters, I "might" consider using one if I had a car battery I could leave at the starting line. Connecting one to the bike battery was a disaster.

Ohh no doubt... I was thinking more of an external power source in staging. I'm not sure you could build enough heat in a warmer during a 8 second pass to do anygood. Back at the trailer or in the lanes to maintain bottle heat might be a different story.
 
There is another method for controlling Nitrous that I have been working on that has worked extremely well. The system that I designed doesnt use any Nitrous jets. It uses an adjustable regulator to controll the Nitrous. I'm still mapping what pressures give what horsepower setting but so far it has alot of promise. :cheerleader:
 
There is another method for controlling Nitrous that I have been working on that has worked extremely well. The system that I designed doesnt use any Nitrous jets. It uses an adjustable regulator to controll the Nitrous. I'm still mapping what pressures give what horsepower setting but so far it has alot of promise. :cheerleader:
Tell us more Gixx :thumbsup: or are you still in design phase?:beerchug:
 
Data:

These tests were run at 5C ambient temperature with 2# bottle.

N2Obottlepressure.JPG
 
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