BannedCR500Riders.com

Nitrous Pressure Vs. Bottle Temperature


Degrees
Fahrenheit Bottle Pressure (PSI)

-30 167
-20 203
-10 240
0 283
10 335
20 387
32 460
40 520
50 590
60 675
70 760
80 865
97 1070
109 1150

Perhaps a cold bottle was to blame for Brit getting spanked?



Effects of temperature on Flow by Holztman Engineering

http://www.holtzmaneng.com/

As mentioned above, nitrous oxide at atmospheric conditions is a gas, having a boiling point of -127F. If you tried to carry it around in its gaseous state, the storage bottle would be much bigger than the snowmobile. That is why it is pressurized, the increased pressure raising its boiling point, causing it to liquefy. One important point to remember; the pressure existing in a bottle of nitrous oxide has essentially nothing to do with how much nitrous oxide is inside. It does not make any difference whether the bottle is full or there is only a tablespoon-full inside, the pressure is the same at any given bottle temperature. Well, this sounds like it would be the ideal situation. If the pressure does not change with the amount of nitrous in the bottle, then for any fixed size nitrous jet, the nitrous flow will be constant. Constant nitrous flow is good. So what is the problem?


Nitrous oxide vapor pressure changes drastically with temperature. Therefore, even though the bottle pressure does not change with bottle fill, the bottle pressure does change with changes in bottle temperature. Some specific examples will help. Nitrous oxide stored in a bottle at 0F has a pressure of 283 PSI. Another way of saying this is that nitrous oxide at 0F has a vapor pressure of 283 PSI, or conversely, the boiling point of nitrous oxide at 283 PSI is 0F. At 50F it has a pressure of 590 PSI. Nitrous oxide flow through a jet is compressible and sonic, and mass flow rate under these conditions varies directly with pressure modified slightly by the absolute temperature. In other words, if you double the pressure, the flow approximately doubles. The chart shows the effect of nitrous temperature on nitrous pressure and its approximate effect on flow (relative to the flow at 0F). Actual tests on a fixed nitrous jet (.029”) showed a delivery rate at 320 PSI (+7F) of 7.6 grams/second, 8.9 grams/second at 520 PSI (40F), 10.8 grams/second at 660 PSI (58F), and 13.1 grams/second at 800 PSI (73F). In other words, the nitrous delivery rate increased 72% from 7F to 73F.


This inconsistency presents a real problem when using nitrous oxide on a snowmobile. On a cold 0F morning, you start out with a 0F bottle having a pressure of 283 PSI. As the day goes on, air temps increase and, coupled with under-hood temperature rise, the bottle temperature can easily increase to 50F, giving a bottle pressure of 590 PSI. In a typical snowmobile application, nitrous oxide mass flow rate can double between a cold bottle temperature and a warmer bottle temperature.


Does this mean that using nitrous oxide on a snowmobile is hopeless? How can you live with a system with this much inconsistency? If the nitrous oxide delivery rate changes significantly, the power will change significantly, and if nothing is done to the supplemental fuel, it can either be too rich or too lean. Several methods are used to get around these problems.


One method is to just let the nitrous pressure and mass flow rate change, but adjust fuel flow accordingly to prevent a rich condition when the bottle pressure is low or a possible burn-down when the pressure is too high. There are several systems out that do this by various methods. I cannot speak to how well they work, but the main drawback is that the supplemental power delivered by the nitrous oxide system will vary with bottle temperature. Going back to our specific example of 0F and 50F bottle temperatures, if the nitrous oxide system is delivering 30 hp at 50F, it will only deliver about 15 hp at 0F.




I have developed a method which uses a patent pending nitrous nozzle to automatically maintain an essentially constant nitrous oxide delivery rate from 283 PSI (0F nitrous temperature) to 865 PSI (80F nitrous temperature). Our 30 hp nozzle is designed to deliver about 10 to 11 grams/second of nitrous oxide. Tests on one of our 30 hp nozzles delivered 10.1 grams/second at 300 PSI, 11 grams/second at 510 PSI, 10.1 grams/second at 740 PSI, and 10.3 grams/second at 840 PSI. We intentionally allow the nitrous to fall off about 20% as the temperature approaches -40 to protect the engine. Now, since nitrous flow rate is constant, supplemental fuel flow just needs to be kept constant (which is relatively easy to do), and supplemental nitrous power is consistent.

That would definatly explain the running rich as hell, now I need a cheepie way to keep the bottle at 80f



The biggest reason I keep getting spanked is I dont wanna die going over the whoops at the bottom

I SMELL PUSSY

Contact Holtzman about their "Flow Control" nozzle.



They have some cool shit, like this dual action solenoid.

1. Simple to mount.

2. NO WAY the fuel solenoidcan stay closed, while the N20 solenoid is open.

hagendog wrote:I SMELL PUSSY

Hell yea and a big fat hairy one at that !!!!

Brit, I stent a while talking to dewayne yesterday, and he made a couple of suggestions about your setup. For one, if you get a proper setup to amke it run better off the bottle, it will be faster ON the bottle! He said that noleen pipe is junk and you'd be better off with a stocker. also said a bigger carb would do you a ton of good.

I just tried calling but they are only open from 9 -noon


Thats my kind of hours!!!!!

dannygraves wrote:Brit, I stent a while talking to dewayne yesterday, and he made a couple of suggestions about your setup. For one, if you get a proper setup to amke it run better off the bottle, it will be faster ON the bottle! He said that noleen pipe is junk and you'd be better off with a stocker. also said a bigger carb would do you a ton of good.

Danny you need to ride this thing man, when its working properly its flat EVIL on the bottle


I cant see how a carb would make ANY different on how it runs on the juice, ask MFDB how well it does with the throttle closed and the nos squirtin and thats the same as having a 1mm carb

dannygraves wrote:if you get a proper setup to amke it run better off the bottle, it will be faster ON the bottle!

Yup....

X2 on that, if she runs good without should be great WITH THE RIGHT JETS. No rejetting required!

[quote="AlisoBob"]Contact Holtzman about their "Flow Control" nozzle.



That thing is nice, I like it. Does that noosle from above screw in that? Also, where are the jets?

If your bike is popping alot when on the juice and bottle pressure is around 900#, lean out your fuel.
I'd run a 25 NOS jet with a 23 fuel jet.

Bob is correct... low bottle pressure will make your bike run like ass.
I use a paint stripper style heat gun on mine before a ride.

On the flip side, I've had too much bottle pressure and stuck the NOS solenoid closed. That much extra fuel with no extra O2 makes it run like super ass!

slomas wrote:If your bike is popping alot when on the juice and bottle pressure is around 900#, lean out your fuel.
I'd run a 25 NOS jet with a 23 fuel jet.

Bob is correct... low bottle pressure will make your bike run like ass.
I use a paint stripper style heat gun on mine before a ride.

On the flip side, I've had too much bottle pressure and stuck the NOS solenoid closed. That much extra fuel with no extra O2 makes it run like super ass!

Thanks to scotts advice I also warmed the bottle to 70 before running the bottle. Havent had any issues yet ?

britincali wrote:

hagendog wrote:I SMELL PUSSY

Hell yea and a big fat hairy one at that !!!!

Now see if you learned how to ride moto it would take care of that problem. In the mean time just lean back a little. To far over the bars and you may swap like a mad man.

your not using a pressure regulator ?

100hp honda wrote:your not using a pressure regulator ?

Nope from what I heard they are $200 and about as reliable as the govt.

i thought you were working side by side with Pstofers on this project but aparently not. better give him a call and see how he does it.

I think I found the problem, I pulled the nos line from the fogger to check the jet and found it clean, I hit the juice and mostly gas came out but nothing froze and it din't seem as stong as normal.

I pulled the bottle and weighed it, I had just under a pound left in it.

I emptied the gas out and re-filled it from my big bottle, re- installed and tried it. Bigtime difference, freezing thick blast of nos coming from the line now.


I think that bottle I borrowed from MFDB to fill the tank is contaminated with something, thinking back I noticed when I filled my bottle at the dunes it din't freeze the fill line when I cracked it. It would also explain why it ran fine earlty on sat (before I re-filled it the first time).

Empty whats left in that bottle justin

should look at the nanno nitrous guys too, they have a sweet system that maintains power by topping the bottle pressure

Has anyhone ran the Boondocker kit on a bike?
Ran tons of them on sleds. They work by pressure (adjustable) sent to the float bowl to supply the fuel needed.

http://www.boondockers.com/nitrous/nitrouskits.htm#

4Z wrote: They work by pressure (adjustable) sent to the float bowl to supply the fuel needed.

Hmmmm....
As I recall Peterson and Whitlock were running Boondocker and did very well with it.
Pretty sure Travis is still running it.
Don't fool yourselves, Boondocker kits make great power.

Robie and Travis can go over on Mopeds... N20 or not.

It is a simple operation, the spray goes through replaceable nozzles (number of holes dictate shot) and hits a arm that feeds the force through the needle used for adjusting inside the manifold and pushes this reflected pressure via a tube to your float bowl vent, forcing fuel up through the main jet if WOT or any of the jets depending upon throttle position.

To tune it, just start off fat and pull back fuel until motor is happy. The cool thing is that you can hit the button at the same time you hit the trottle and it is equal throughout the throttle range. The only thing a sled has over bikes is that once your piston wash and plug readings are baselined, you rip the duct tape off the EGT grage and that is your "number" (probe location counts towards the final reading), then you can tune the 'docker via your baseline number. A little more difficult for a bike unless you go with a Racepack or Digitron, but I plan on running one when I get to that point, just to be different, or maybe I am just used to using this type of tool. Can you imagine a guy running around with a tack/EGT guage on the bars?LOL

I have won tons of hill climbing races on sleds from modified stock motors to the watercraft triples I built for buddies over the years. Imagine a 1200 cc, ported, 48 mm Lectron, triple piped 270 horse motor pluss the 90 Boondocker shot on top right our of the hole!!!