Its been cold the past few days so the pressure is low as usual. Tonight I was driving and couldnt tell if it was or not since the pressure was so low(300-400). This is my first time and need to know how to tell.
I took the bottle out and opened it and it still seemed to spray something out quickly(and loud)... but not much "white" to it.
Any quick ways to tell if your bottle is empty?

 

You can probably tell by the low pressure but I think the best way is to disconnect it and weigh it, the proper empty and full weights are on the bottle.

 

The pressure is determined by the temperature of the contents, as long as there is liquid N2O in the bottle. But a 400psi pressure would correspond to about a 25degF bottle temperature. If it wasn't that cold, it means the contents of the bottle were only gaseous N2O, and not liquid. That means it's empty "for all practical purposes" It will continue to flow out of the bottle until you let all the gas phase nitrous out of the bottle.... just like letting the air out of a tire. But you don't want gas phase nitrous flowing into your system.

You don't want to let your bottle get near empty. When you're spraying, as liquid nitrous flows into the main line, some of the liquid nitrous in the bottle has to vaporize, to fill the space left by the liquid that flowed out of the bottle. The vaporization takes "heat" out of the liquid nitrous, and cools it down, dropping the bottle pressure. As bottle pressure drops, flow through the system drops, so you end up with less nitrous flowing, the further you go down the track. You run richer and lose HP. The more "full" your bottle is, the less affect this auto-cooling will have on your performance. With a 300-shot, I'll switch bottles after two passes, to avoid losing pressure during the next pass.

 

i just had my bottle filled for the first time today.my pressure is stuck at 800psi.isnt it suppose to be more.and how do i get it where it needs to be?
i sprayed a 75 shot wet, it worked very well i will step it up to 100 when i get the pressure thing figured out.any info?

 

A bottle heater will warm the bottle and liquid nitrous. It should be on for a while though to ensure uniform temperature, otherwise the pressure will drop dramatically when the system is activated. All systems experience a drop during use. Your tuneup may be able to be adjusted for the lower pressure. Purge valves are used by racers to drop the system pressure to a predetermined pressure level right before a run (they also ensure liquid is at the solinoid, but that only takes a very brief activation). The pressure swing to a nitrous sytem can be very wide on a typical spring day, especially in the middle of the country. Another thing to note is that the typical 1.5" nitrous gauge can be pretty inaccurate. I would try to find someone, such as your refill station that has an accurate gauge to compare yours to. You may want to mark your gauge where theirs is 1000 psi for example. I will post an ambient temp to pressure chart for you in a bit.

Use this link for some info:
http://www.dragstuff.com/techarticle...e-heaters.html

 

so how can i adjust my tune up for lower pressure? oh and i do have a purge to clear all the air out of the line before use my nitrous.

 

I don't know what kind of system you have, if you care to describe it then I may be able to lead you in the right direction. First you need to find out what pressure the system is calibrated for. With cooler weather it will run richer than optimum. For you own fun, or the occasional street scuffle I just wouldn't worry about it because you won't have to worry about changing something when the weather warms up.
Purging the system briefly before a run will help aleviate a stumble that may occur upon activation if the supply line was full of gaseous nitrous. The stumble is caused by an over rich condition where the supplemental fuel is flowing, but the oxygen (nitrous) is not. You don't have to buy a purge valve if you are using a lone button to activate the system. Rev the engine up to 2500 or so and bump the button 2 or 3 times. When it revs cleanly you are good to go. With a wot switch I do not recommend this approach!

 

its all n.o.s brand...
it has a fuel cheater solenoid and super power shot solenoid for the nitrous.
and for some reason the purge that came with it is the same part# as the super power shot 16020.
i also have a 10lb bottle with a highflow valve and guage and a bottle blanket.
the kit came with an assortment nitrous works jets 25-100hp.
pretty much your basic wet kit all braided lines and nice fittings.its all wired up with a n.o.s relay(nice part) made it real easy to wire up.and at the moment i have a arming switch a momentary purge button and a nitrous button.i will go with a w.o.t if i get into running more at the strip.but at the moment i need to get everything working correctly. i was woudering about venting the bottle outside the car too, how do i do this? there is a little valve on the side to vent the bottle how do i hook up to it?i want to be legal to run at the strip.

 

thanks for the great info guys! took it to a local speedshop, there was only a pound left. Got it filled for 27 bucks!

 

How long can you go with the bottle being open?
Also, without a purge is it ok to close the bottle and leave the nitrous in the lines for extended periods of time?
Once again, thanks.
I'm an NX user.
<3 NX

 

27 bucks, lucky. I have to pay like 45 bucks here

 

The SuperPowerShot nitrous solinoid is factory rated to at least 175hp potential, so your kit can grow with you.
Depending on the bottle, if it has a cap with a lanyard attached you can hook a -8 line to that fitting to vent outside of the car. If there is no -8 fitting on the side of your bottle then what you have is a blowoff difuser and it will need to be replaced when the bottle is empty with the safety external blowdown kit. It takes at least 1300 psi to rupture the blowoff disk. This can happen if the bottle is in direct sunlight under glass. I can tell you that if it pops while you happen to be in or near the car you will want to look for a bathroom.

 

The bubble seal on a nitrous solinoid is augmented by pressure. But, if any little piece of rust from the refill station, dirt, grit, hose making fragment, or toothpick gets stuck on the seal then eventually its gonna leak and reward you with a modified intake manifold and hood on startup if the bottle is left on. My rule of thumb is 20 minutes on a street car. On the drag car I turn it on right before we pull into the water and turn it right off when the car gets back into the pits. My feeling is that prolonged pressurization of the nitrous solinoid deforms the seal requiring a more frequent rebuild, which I don't like to have to do. We also purge it down after tuning off the bottle. An open bottle is an accident waiting to happen. You do not ever want to be around a start nitrous explosion, which is another reason I won't use a wot switch on anything.

 

bodydropped - sorry for the muliple posts - I personally prefer to do most tuning on the nitrous side. The fuel jet/pressure determines the horsepower you can make depending on how close you're willing to run on the edge. So if you have a low bottle pressure day (cool weather) then I would step up the nitrous jet. As I mentioned before the kits are calibrated on the rich side. I would tell you that if bottle pressure is down 100 psi, say 800 like you said that you would want to go up one step in nitrous jet on your chart. The fuel side allows you to do the fine tuning with pressure if you have a seperate fuel system, which I'm fairly certain you don't. Its not mandatory at the level you're playing with, and in fact its not at mine either. Nitrous can be very easy and relaible horsepower and if you take your time and think things through you will never hurt any parts. The most important thing I can share with you is pay attention to your engine and don't be aftraid to take a ton of timing out of the engine during activation. Pay attention by looking at your plugs. When you are first sorting out your new kit you want to have fresh plugs to look at. When you eventually have it all dialed in your plugs will look brand new if its running tip top.
A ton of timing is more than the recommended. Manufactuers are afraid to tell you to take a bunch of timing out because people will immediately discount it. Others prey on that feeling and tell you you don't have to take timing out of their kits.
Take the timing out. If you jet to 100 - take out 5-6 degrees. Its not because nitrous makes the engine detonate, its because nitrous changes the flame travel speed and the engine doesn't need as much timing.
By the way, I'm not a guru, I found this out by hooking up a muti-step retard wrong a long time ago. I installed a cheater kit and put the 175 hp jets in. I hooked up my retard and tested the car. It flat thundered and pulled harder in high gear than I could have ever imagined. Turned out I had hooked up the 20 deg start retard instead of the correct retard channel. I tried the 8 deg retard chip and the car slowed down by a significant amount. End of story, good luck.

 

Thanks for all the great info. Is there a fast, cheap way to retard the timing?
Can you explain why, how, and when the "blow down" tube should be used? I see it in my kit but I didnt install it. I didnt even know how or what is was for. I have the bottle in my back seat so I can easily turn it off and on... so I just skipped out on the "blow down" tube.