My bottle will heat up to 900, maybe 1000, that's it. How do i adjust the hobbs switch to get the temp up to 1100-1200psi? turn the screw out or inward? Thinking of trying a 1/4 turn at a time..help please

 

your bottle pressure should never go above 900psi otherwise you will start running nitrous rich. which will end up making your motor run lean. nitrous kits are designed to run at 800-900 psi. if your trying to squeeze more juice out of it and are at the top setting make sure you increase your fuel jets if you increase the pressure

 

TY! good info. I have 4lbs left in my 15lb bottle and it's running a little less powerful. Wonder if my bottle was turned a little so its not getting every little drop of n20. I thought 1200 was the psi you wanted? guess not! TY for the info!

 

i dont exactly know why but the bottles when they get low just wont push the amount of n20 anymore but i think it may be because there is less nitrous in the bottle so when the heater brings it up to 900 there isnt enough nitrous to maintain that pressure. if your using it for bracket racing i highly suggest that you get a second bottle or get your own refill station. there is a way you dont even need a pump all you have to do to get the bottle to fill is put it in ice water and decrease the pressure but in the large tank set it in the sun and let the pressure increase but maintain an eye on it so it doesnt go to high. when im at the track and dont have time to use the pump thats what i do just stick the bottle in the cooler and let the pressure drop. just make sure that you have a cap on your fittings so that no water will be sent inside the tank later.

 

As you use the nitrous during a pass, the level in the tank drops. As the level drops, some of the liquid nitrous in the tank has to vaporize to fill the void created by the nitrous that was removed from the bottle. The only way for the liquid to vaporize is for it to absorb heat from the remaining liquid nitrous, reducing the temperature of the nitrous. As the temperture drops, the pressure drops, and the nitrous flow through the system drops. This always happens, on every pass, but the lower the level in the tank, the more noticable the loss is.

With a full tank, the BTU's absorbed via autocooling are taken from a larger mass of nitrous, causing a smaller temperature drop = smaller pressure drop - lets say 50psi for an example with a full tank. Your heater may even be able to replace the BTU's and limit the pressure loss to something even smaller.

As the level in the bottle continues to drop, the amount of liquid nitrous available to provide the required BTU's is reduced, so the remaining nitrous cools off faster as nitrous flows out of the tank during a pass, and the pressure drops faster - lets say 200psi for example on a pass with a low level tank. Your heater probably can't keep up with the demand for BTU's.

The lower pressure at the end of the pass flows less nitrous = less power, since there's less oxygen in the combustion chamber, and the mixture is richening up. You slow down.

There is nothing "limiting" the nitrous pressure to 900psi. Some manufacturers use that as the standard pressure for selecting their jet sizes. Increasing the pressure will increase the nitrous flow by the square root of the pressure ratio, so running 1000psi will flow 5.4% more nitrous than running at 900psi.

While increasing pressure increases flow, following the rule of the square root of the pressure ratio, things don't behave "normally" once you exceed the critical pressure of the nitrous. Above 1,050psi, the fact that the substance can exist as both a liquid and a vapor can cause the amount of flow gained to be less than calculated.

 

I run @ 1200 psi.

 

ive never heard of a kit running that high of pressure. ive had 5 different kits and never had it set above 900.

 

I have always set up customers cars to run 1,000PSI on a full bottle and it has worked well.
1200 will just give ya more hose and as long as the fuel is jetted for it that's fine. That's if your solenoids can cope with that much pressure. Like Fred said it may not be predicable.

When your bottle gets low CHANGE IT. They make scales to weigh the thing.

 

You seem to be locked into "kits" and what they are designed for. There's nothing that says you HAVE to run what came in the kit, or the jets they told you to run, or even run it the way the instructions tell you to. Yes, its a good idea to follow the manufacturer's instructions for the initial install, particularly for people new to nitrous, or if your not familiar with all aspects of the technology. But if you limit yourself to the "kit" approach, you're missing out on all the fun.

Mike has done more with his "kit" than most people will ever try and do. I'm still running components from the NOS 5176 "kit" I bought in 1995..... but they are used in a 300HP dry system. You have to use your imagination.

 

A couple of problems running bottle pressures up to 1200 is that anything over 1050 nitrous is turns to gas and also has a major density drop. Also the higher the pressure you satart out with the faster the bottle presure will drop. This isn't normaly an issue with smaller kits but does become a problem on larger kits.

As a side note to give you an idea of how dramtic the density change is, to get the same 1.66 lb/gal density change you get from going from 950psi to 1050psi you would need to go from 950psi to 300psi for there to be an equvilant rise in density

 

I run mine at 1050. I plan on going with a nitrogen push system next year

 

Just run 2 bottles instead.The nitrogen is carrying the weight of two bottles when one is nothing to burn. Two bottles on NO2 will probably last all night with a bottle warmer.

 

When ya run 300+ shot ya need 2-3 bottles at a time to make it work correctly. Then 1200 is not such a big issue.

 

very interesting thread, to make it clear of my situation.....I have a 15lb bottle. After tons of test n tune, i finally got everything working correctly. I noticed the N20 was not giving me the UPMH it once had. I had 4.5lbs left with my bottle psi at 900. I would like to be able to increase the bottle temp to 1200 when I'm low at 5lbs or less to maximize the full tank of N20. So which way to I turn the allen on the hobbs to increase bottle pressure? Thinking of turning it a 1/4 at a time and watching the pressure???

 

Get another bottle, it's safer.