yep, to what you guys said. i agree and have noticed this also, wondered why I could not hold 1150psi, as it would drop fast when just purging, then never come back up it seemed? I may wire in my 85* thermastats and compare to the 95*, dual bottles and dual thermastats, yes I have all I need to test this out and see if things are so?
Robert

 

Boy, I sure hope that I didn’t fall into the “internet brainiac club” category. Some people can’t afford to attend college and I just figured my eight years of schooling would pay off a little for you guys. Hope I didn’t offend.

Ben R, couldn’t have said it better myself concerning pressure measurement! I was trying to hint at it, but I sometimes get longwinded. I would definitely be interested in seeing results on this (PM me when you have anything, if you don’t mind). And I do have to say that I love the racepak units, very slick.

Concerning supercritical phase (state of phase after critical point is reached)…the link posted has a great Temperature Pressure diagram . A more useful tool for thermo is a pressure-temperature-specific volume diagram. Here you can view changes in the supercritical phase and what effects it will have on density. Since we all know that specific volume is the reciprocal of density it’s easy to assess changes. Yes supercritical phase can have liquid like density, HOWEVER it is clear that it is exactly that, liquid like! Check out the ptv diagram and you can see how close the liquid line is to the supercritical phase and based on that curve (hyperbolic function from tp) it’s impossible to achieve densities of liquids. At best a density close to the critical point density can be achieved. No magic tricks here. Plug random numbers into the equation and you’ll see what happens v = 1/rho. As specific volume goes up its obvious that density will be a continuously decreasing function. As specific volume goes down, density will be continuously increasing, but guess what, hit a certain point and you’re right back to liquid phase.

Concerning pressure drop… The key here is consistency! What happens to your N/F ratio once you’re down 1/8mile? What happens to your N/F ratio once you’re down 330ft? 60ft? etc. And pointed out by many of you, is a problem at higher initial bottle pressures. Yes you can compensate with larger bottles and multiple bottles but your density will not be any better than at the critical point. Which I believe N2OGMC was hinting at (wouldn’t mind seeing any data you guys have logged either).

It’s a shame that most of these tech articles turn out like this, haha which is exactly why Matt posts here and not me. Nobody knows everything and it should always be a learning experience for all, which I believe was the point Ricky was trying to make. Again my apologies, to those who were offended, for sharing my knowledge. Regardless of my view of the world, thanks all for the great info and maybe we can all present this for the next Nobel peace prize in physics?? PS PM any questions/hate mail to Matt@HSW, I rarely get a chance to check the boards and that’s probably the quickest way to reach me.

Nick

 

YEs and NO way in hell...

That is what we saw on the bench was a huge pressure drop at the high pressures... You can even see the nitrous plumes look different... Ever fire a nozzle kit or a large kit, you get a surge of nitorus plume, than for a breif moment a hickup and then more nitrous... This hick up I believe is the line emptying and the nitrous in the bottle has not kept up..
Now about that bottle valve problem you mention.. You seen our DF5 bottle valve.. 5/8 syphon tube, with a 1/2" hole straight throu. Think of a ball valve on steroids... we can empty a 10lb bottle in less than 3 seconds..

I think everyones testing has some criss crossing and agreeance on, but we all make our stuff work in our worlds..

Now lets throw this one out there. In the past I have seen liquid nitrous dancing on the table... We emptied a bottle rather quickly and remove the bottle valve, turn the bottle upside down and this liquid fill out and started boiling... you could see it, looked like a drop on water in a very hot pan. Now we all know pressure turns nitrous into a liquid and back to gas..
Now lets make it cold, really cold, ice hanging off the bottle that just got discharged. I believe the bottle was so cold it allowed the nitrous that breif moment to stay as a liquid with no pressure on it.. any thoughts..
Ricky

 

If the above holds true I think the loss of mass flow after suprcritical will not be proprtional to the reduction in density. I think if the pressure continues to climb the flow of the SC nitrous will continue to climb as well after its intital drop off at 1051.


I still think that we need to do the test. lets all pitch in $50 each to someone to pay for the juice to do the tests. We can lay out our predictions and whoever gets closest can take half the pot. The other half goes to pay for juice

 

Ricky,
Ive seen the same thing. We emptied out a 75lb tank to change the valve. Once all the pressure was out we removed the valve and flipped the bottle over, and about a 1/2 gallon poured out on the concrete. It was pretty crazy.
Vinny

 

Above from my first post.

A is a 5 lb bottle @1500psi with a .047 jet
B is a 20 lb bottle @1500psi with a .047 jet
C is a 20 lb bottle @900psi with a .047 jet

What my testing has shown is that A will add approx 150hp for the first 2 seconds of activation and then lose pressure very quickly dropping off to approx 100hp or even a tad bit lower by the end of a 10 second period. Pressure drops off quickest for A

B will add approx 170hp for about 5 seconds and begin to drop off fairly gradually to approx 130 - 140hp after about 10 seconds of activation.
Pressure drops off pretty quick for B, but not as quick as A

C will add approx 100hp from start to finish and hold pressure very steadily.

The above assumes starting with a full bottle and my average tune which may be a little on the aggressive side compared to the average.

Condition A loses so much pressure so fast that my fueling overshoots going into the rich zone and losing power by the end of the run. To compensate I run leaner which is on the edge for the first couple of seconds and then averages out as the pressure drops. Doing this for such a short time and in the lower gears is generally not a danger to the engine unless you're running hot plugs and/or hot coolant temp from the start.

Condition B: Loses pressure fast due to the higher pressure, but not so bad as the smaller bottle.

Condition C: A very large bottle at low pressure and a small jet doesn't lose significant pressure.


Now what if we used a 10 lb bottle for condition B :
You may start out with 170hp for the first couple of seconds, but then quickly fall back to 100hp for the rest of the run.

Compare this to condition C

My testing has shown that this new condition B will still run much faster than condition C
The only difference is the much higher starting pressure.

It's what I was saying in my first post, and is what my in-car testing has shown consistantly.

 

But C is most consistent, correct?

 

White2000s10- Have you got any data on how your above comparison performs in the higher horsepower settings (200+)? I would think that bottle A would perform even worse, bottle B would perform similar to A in the first comparison, and C would perform similar to B in the first comparison. So you would need an even bigger bottle to keep C performing consistent. Have found a "limit" to the amount of power you can make with the nitrous and keep it consistent from start to finish using bottle C? If so, what pressure are you starting at to keep it consistent?

 

I think you're correct in that prediction. I haven't tested 20 lb bottle at 1500psi with jetting for 200hp out of fear... perhaps in the future though.
I have had great consistency in the 800 - 900 psi range for the 20 lb bottle. I'd suspect it would take a lower pressure to equal the consistency with a smaller 10 lb bottle... of course depending on the shot size too.


Macon, yes C is definately most consistent.

My results tell me that the lower the starting pressure is, the more consistent the flow will be because you don't lose as much pressure during the test.

I assumed that one reason is that the bottle is emptying slower at the lower pressure. Posts in this thread conflict with this assumption, so that may be wrong.

I haven't verified that more mass is leaving the bottle at higher pressures, only that there is more power produced. I suppose a lower temperature at the release point could explain that.

 

I really want to see this supercritical satate with my own eyes. I have a small ss pressure tank that I could modify with a 1"thick piece of lexan to give me a 'window' into the bottle. hmmm.....

 

Not a bad idea Vinny, but be very very careful with the lexan. I wonder how high of a pressure it will hold up to? Kinda off topic but it would be great to do something similar to an intake to actually see what happens when spraying a wet system through it.

Sorry, my mind constantly wanders from the path (I think it's called ADD, haha). Back on topic.

 

I believe per our lunch conversation that White2001S10 and I will be conducting a few experiments in line with this discussion soon. We will be using thermocouples and accurate scales and guages to determine with hard facts the effects of ultra high pressure Nitrous usage.

My hunch is that we will see a significant increase in the charge density in a high pressure shot regardless of wether or not the volume of gas increases or decreases.

 

Speedtech made a little video of their Diffuser plate kit in action while on display at the PRI show. It was definately a thing of beauty.

 

wow gone for just a minute and look at what happens.. Viny the bottle with lexan please do not do this.. Bottle handle the pressure becuase of no sharp corners in side the bottle introducing a piece of lexan now gives an edge, and even at 1 inch you are asking for trouble... I hope you were kidding.. Even a small bottle at pressure is a very dangerous toy.
Ricky

 

Yes I have seen it done also when empting a bottle and pure liquid comes out. But thats what you want. Is liquid not gas. The liquid is more dense and doesnt expand until its in the manafold. If we could get liquid n20 in the manafold we would, we are working on it though.

Yes we have valves like that, we have modified for our use. But I was talking about ones we sell to the public.
As stated before in this thread somewhere somebody stated using nitrogen to push the n20 out. NXricky says make the bottle freezing cold and try that. When you use nitrogen to push the bottle has to be freezing with the lowest amount of pressure possible because the nitrogen is going to increase the pressure a whole lot.But im not talking about that anymore.

White-Have you every tried different nozzles for what you are doing. That has a large effect on the way it runs. I know of some companys that recommend high pressure to combat there bad nozzle designs. Try different nozzles and see what you get.Also the area after the sylinoid matters. As in how well it flows on the bench, runs and makes power. Just cause it makes big power doesnt mean it will accelerate at the track.
And wouldnt you want something that is repeatable every pass and stay the correct mixture the whole time.

Yes Ben we did have a plate display at PRI. But it only had a .63 or so jet. ANd I think the pump put out 60 or so psi. Imagine what it looks like with a .120 in it. It also only had mineral spirts in it no N20.

 

If you are seeing more consistency with 900-950 psi, which according to N2O's behaviour makes perfect sense...Why wouldnt you just want to up the jet size on bottle C to make more power, consistently? Are you counting on the benefits of that initial power surge your seeing sometime during the run?

And before trying the lexan bottle window, Id stress test that puppy in something REALLY strong, or in a remote area. By adding a window, you will reduce the strength of the entire bottle by a great amount. Someone has obviously photograped this event before, since N2O was discovered a LONG time ago?

 

Because that was an example.
A lot of the time when I'm testing my own system I don't run a jet, so that would be why running higher pressure.

Every nozzle I own is the NOS hi-flow part. I'm sure there are bigger ones and smaller ones out there, but that's what I own.

Personally I'd rather not see what's in the bottle and would never cut into a bottle... this coming from someone who would run with double burst disks

I'm bringing my test equipment over to Homeslices place this weekend to do a few tests. Hopefully it will show some reliable results.

 

Great, Im anxious to here the results!

 

DAMN , you know if White wouldn't do something then it's got to be dangerous, . Just messin' with ya' White.

I too am really interested to see the results from your upcoming testing. So hurry up, we're all waiting here!

 

My thermocouple will only go down to -50*F so we are scrambling to find a model to go lower. If we can't get one then it will have to wait for a new thermocouple reader to come by mail.