I have some reservations about the boss noss system based on my limited nitrous experience. This may ramble on for a while as I have many queries and I may ramble off at a few tangents as I raise queries.
The system looks lean and clean with few components. I'm not sure how long this brand has been up and running, or what results they have come up with in competition.
The idea is not new. The principle is not new. The way the liquid nitrous draws fuel out of an orifice is the same way that a compressed air paint gun works. Most of us on here are familiar with the Bernoulli effect !
Heres the basic principle in a plain diagram:
Its a shame the guy didnt go into more technical detail about how the metering injector can maintain a constant 300psi nitrous outlet pressure regardless of bottle pressure? This has confused me somewhat. Or is he saying that the bottle pressure needs to be 300psi?? We all know that an orifice of any size can only flow a maximum volume of whatever, regardless of inlet pressure. But there is a point lower in the pressure range where flow volume through an orifice will alter dependant on the inlet pressure. And as inlet pressure rises the flow volume will stall at a set amount regardless of inlet pressure.
My guess at this time is that the bottle needs to be higher than 300psi, which it will be at ambient temperatures above 10F. At 85 F the bottle pressure will be approx 950psi. That is a huge pressure differential. ?
But I think this is why the system has been made. He has designed a system that should operate without the need for a bottle heater blanket to maintain a stable bottle temperature. For small shots of gas I can see this being a benefit as the temperature of the liquid nitrous will be low and the charge will be very dense.
And if this jetting is correct you should get a good hit from a small shot of very dense nitrous. And if the fuel metering jet is sized to match you would have a very efficient system. But what happens when you go from a 25-50hp shot up to the 300 shot that I use? This is where my confusion steps in to the equation.
Looking at that piston assembly which has a seemingly fixed pressure return / holding spring. I can see how it works. You open the nitrous line and this nitrous pressure builds in the manifold to push the piston back against the spring. The action of the spring being depressed opens the fuel port. The action of the nitrous flow across the fuel port causes a pressure depression (of 15" of mercury, which equates to 7.3psi of negative pressure over the fuel orifice) and draws an amount of fuel into the nitrous stream for discharge into your inlet manifold. This would be at X nitrous flow. So what if we wanted X times 10 nitrous flow?
I assume we would fit a piston with a bigger hole to allow the extra nitrous flow. Would the extra nitrous flow through the bigger orifice in the piston not reduce the amount of back pressure placed upon the spring and therefore reduce the amount of opening of the piston which in turn would reduce the flow of fuel leading to a lean nitrous mix?? This is all speculation based on the vids I have seen from Boss Noss.
The demo vid shows what happens with all the equipment stable and static on a table. But what happens to the fuel flow from the fuel tank when the vehicle is accelerating hard?
In my own car the fuel cell is at the rear of the vehicle with 10 feet of fuel line to the engine bay. The 7psi of suction + pipework resistance will be hindered by the 0.8 G my car pulls off the line.
I have to say that I am not convinced by this system. I can see a test in a static vehicle working on a dyno with a small shot of gas. But the math is obvious. If you have a certain bottle pressure, that pressure will drop in a linear fashion when you draw a fixed amount of nitrous from it. So if I had this system on my car with the bottle at 950 psi and flowing a 300 shot, the pressure drop in the bottle would still be the same regardless of the smart box thing.
You cannot regulate and control an oultet pressure and flow volume from any device with a fixed orifice unless the fixed orifice has already attained max flow potential at the lowest possible inlet pressure from the source. At this point you can confirm that the outlet pressure and flow will remain stable regardless of inlet pressure.
In order to maintain a fixed outlet pressure the control device must be made in such a way that it can increase the orifice size of the inlet feed to the jet as oultet pressure drops.
My guess would be that this system fitted to my car with my fuel pump removed and spraying a 300 shot off the line would see me having a meltdown about 300 feet out on the 1/4 mile??
I may be doing the Boss Noss guy a great injustice as my comments are based on what I have just seen. Maybe I have missed a valuable point somehwere and I will stand corrected shortly.
What if I wanted this system fitted on my V8 motor? How would I spread that discharge evenly into my inlet manifold?
Sorry to ramble on so much. But I see so many flaws in this simple system.??
Heres my disclaimer before I have legal guys onto me:
My observations are based on my interpretation of the test videos I have seen and in no way are intended to berate the functionality or design of the system in question.
My comments are purely hypothetical and are intended to encourage lively debate and positive feedback.
Having said the above I would not use this system on my own race car because in my own opinion it would not work to suit my needs.
Regards
Perry
