NITROUS OXIDE ( nos / n2o ) advice forum

I recently read a few posts on a US forum, where some guys were complaining about the problems they'd had, trying to pulse US kits, while another guy was 'claiming' he'd had good results from pulsing one.

I offered to explain why some guys might 'think' they were getting good results and why other guys were getting bad results but I was accused of trying to advertise my products, even though I hadn't mentioned them, so I've decided to deal with the matter here instead. That way they can't say I'm 'using' their forum to advertise, when all I was trying to do was EDUCATE them, by giving them the benefit of my 30 years of knowledge on the subject.

Now why anyone would pass up the chance to learn some extremely valuable knowledge for FREE is beyond me, especially when my knowledge on pulsing solenoids is UNIQUE.

In the simplest terms, the guy who 'thinks' he's getting a good result, is probably not asking much in the way of progression and certainly has no idea what is going on inside his system/manifold.

The guys who have been unhappy with the results have a better understanding of what's going on and are probably expecting the system to deliver what the controller is set at, when in fact that is IMPOSSIBLE!!!

I'll get back with the technical explanations for why this is the case later but if any of my super smart forum members feel inclined to post what they know on the subject, please feel free to help me out, as my time is at a premium right now.

I guess I am not the smartest crayon in the box,but from the way I see it, pulsing systems is not the answer for US kits that is.
Thats just a band aid fix for someone to try and use, as they are limited, knowlege wise implementing nitrous to an engine.

Tom

It's unfortunate that some people take my efforts to enlighten the world about the limitations of other kits as 'bashing' them.

There is a world of difference between a system 'working' and a system 'working correctly/well' and whilst I accept there are US kits that 'work', they ALL suffer from the same major flaws, so I can't accept that any of them 'work correctly/well'.

Sure Speedtech kits and other US brands are used on world record cars but they still have the same flawed solenoid design, pipe size and jet location, etc. etc. as those that blow engines to bits. The only difference between these groups, is that the successful guys have learned how to apply the numerous band aids that are needed to avoid engine failures happening so often.

The only time the extent of these flaws will be fully appreciated, is if someone ever replaces the flawed components with correctly designed items and runs THE SAME CAR with the improved system. Till then it's WRONG to claim that just because such systems are on record setting cars, that they are designed correctly or work correctly, ALL you can say is that they work adequately to produce the times they run.

If people are ever going to improve their understanding of nitrous, they are going to have to get over the manner I deliver my information in and accept that I'm offering them valuable knowledge, that some people would kill for if they appreciated exactly how valuable it is.

Down to the FACTS and as there are quite a few I'll deal with them in small bits.

1) FACT 1 - Generic solenoids are NOT designed to be pulsed, the fact that they do (albeit very badly in almost all cases), is due more to luck than anything else.

2) FACT 2 - Most US kits run just 2 solenoids (per stage) and as a consequence they have to be large to flow an adequate volume of nitrous.

3) FACT 3 - Think of solenoids as you would engines. If you wanted a fast responsive engine which would you build, an engine with 2 BIG cylinders or an engine with 8 smaller cylinders? - Obviously the answer is, the engine with 8 smaller cylinders, because it would rev far quicker and up to a much higher rpm.
For the same reasons pulsing multiple small solenoids at a higher speed (frequency) is better than pulsing a couple of large solenoids at a lower frequency.

That'll do for now.

FACT 4 - Although most solenoids will respond to pulsing, most of them do NOT respond ACCURATELY or over a wide enough range, at a high enough frequency, to produce good, safe and repeatable results.

FACT 5 - Most solenoids do NOT respond to the signals from the electronic control unit, as companies falsely claim and as most people would like them to.

FACT 6 - Nitrous solenoids and fuel solenoids are under different loads and are made to different specifications, therefore they respond differently to being pulsed.

For example a fuel solenoid finds it much easier to open when pulsed (because it has very little pressure to overcome), while a nitrous solenoid is subject to a MUCH higher pressure and is therefore harder to open. This means a fuel solenoid is likely to open easily to a pulse as low as say 10% but the nitrous solenoid will fail to open at all. This imbalanced situation can exist (on most brands of solenoids), up to 40% and this leads to engines stumbling, due to running too rich till the nitrous solenoid manages to open.
Here is a typical scenario;
You set the progressive to start delivering 10% power, rising to full power over 3 seconds. You activate the system and the fuel solenoid opens immediately but the nitrous solenoid can't open (causing the engine to flood/bog), until it reaches say 30%. By the time the nitrous solenoid reaches the point it can open, you've lost the race but then when it does open, instead of getting a manageable 10% start that you programmed, it kicks in at 30% and when you were least expecting it, but by then it's too late anyway.

Now that's bad enough but at the other end of the scale the problem becomes more of a concern. At high percentages the nitrous solenoid also struggles to 'respond' to the electrical pulses, just as it does at low percentages. However, instead of staying closed it stays open, supplying 100% nitrous flow to the engine, while the fuel solenoid is still able to respond well to the pulsing, resulting in less fuel delivery compared to the nitrous delivery.
To put some numbers to this situation, the nitrous solenoid may fail to respond to the off pulse above 70%, so at 71% the nitrous delivery jumps to 100% whilst the fuel delivery continues to deliver only 71% of the required fuel. Depending on the build time that's been selected, this lean running period could continue for a minimum of a few milliseconds up to 5 seconds or so and we all know what that would lead to.

FACT 7 - Nitrous and fuel are totally different media and are supplied at widely different pressures and therefore the flow rates are different.

Open a pair of nitrous and fuel solenoids that are connected to a 5 foot length of pipe and the nitrous will exit the end of the pipe long before the fuel does.
I call this the differential in nitrous to fuel delivery and this is even a problem on a well designed fixed hit system but the problem is much worse when the system is pulsed, because it occurs up to 300 times more often during a typical run.

Now if we could flow fuel at the same pressure it would not be 'such' a problem but even then it would still be less than ideal, because nitrous is a liquid that has a strong desire to expand, whereas fuel is not.

When solenoids are pulsed the nitrous is repeatedly fed to the engine quicker than the fuel and if it wasn't for the badly designed nitrous kits being SO BAD, they would cause engines to alternate between lean and rich cycles rather than ever being anywhere near correct.

Thankfully for everyone using any brand of nitrous kit other than a correctly designed WON system, the fuel delivery lags so far behind and most kits are so badly designed, that even though the fuel and nitrous 'initial' deliveries are so far out of sync., the mismatch does even out to some degree although this is ENTIRELY due to luck and NOT design.

MORE LATER.

In summary to deal with matters so far;

1) Generic solenoids are not suitable to be pulsed and even when pulsing they operate at a different rate to each other and over a different range.

2) Just dealing with this aspect of the problems, it is common for pulsed generic kits to deliver fuel only at the start of the pulse range, kick in unexpectedly at a higher than desired power level, before running excessively lean.

3) The characteristics of the media that the solenoids control (fuel & nitrous), are so different that it's impossible for them to respond in the same way as each other.

4) Just dealing with this aspect of the problems, it's impossible for the desired amounts of fuel and nitrous to reach the engine at the required time, which throws the mixture ratio out the window and the results are anyones guess.

The following graph is the closest graphical representation I can come up with to explain how the plungers/solenoids work;



The main curve (black) is the effect of the rising Voltage on the magnetic pull on the plunger, when a pulse of 12 Volts is sent from the control unit to the solenoid.

The blue trace is the Nitrous plungers response and the red trace is the fuel plungers response.

You can see that the fuel plunger is lifted sooner than the nitrous plunger, because the required magnetic flux (force) to lift it is lower.

You can also see that the fuel plunger stays open for longer than the nitrous plunger, because the magnetic force takes longer to drop to the lower level required to hold it open, whilst the nitrous plunger releases more quickly.

These are only SIMPLE representations and not actual graphs just to avoid making this overly complex but they are close enough to real results to prove a point.

It should also be noted that ALL these factors are variable as they are dependent on a number of other factors. For example, if you change the brand and/or size of solenoid all the results would be changed, just as would be the case if you changed ANY of the controller settings.

Another analogy you could use is compareing hi-fi speaker drivers, for higher frequencies and more accurate control, you don't use a big 24" speaker, it won't work!. Several slightly smaller speakers is always better than one big one.

Ian.

Right I've covered the deficiencies of the generic solenoids, the inability of the solenoids to respond the same when flowing such different media and the fact that the media themselves don't respond the same as each other.

Now I've repeatedly pointed out my UNIQUE jet location which has been ridiculed by virtually every 'nitrous expert' :lol: and even copied by one or two hypocrites.

Now there are advantages with my jet location even on a fixed hit kit (but we'll not go into those here), however, it really is of major importance when used with pulsed technology.

Here are some representations of the effects of different jet locations fitted to different systems.



In the drawing above you have the solenoid seat to the left and the flare jet at the right, with a braided hose connection between.
The top depiction is without flow
The middle depiction shows the nitrous density during the INTENDED flow period, with pipe work filled with 'relatively' dense nitrous liquid.
The bottom depiction shows the nitrous density just after the solenoid has closed, showing the pipe work 'still' filled with 'relatively' dense nitrous, that will take a good deal of time to flow through the jet, extending the flow period beyond the intended length.

For this example I'll use the following specification (but it is far from the worst possible scenario); a solenoid which is capable of flowing 500 HP and a 250 HP jet and just to keep the maths simple, I'll work on the basis that the volume of the pipe work is exactly the same as the solenoid flow when energised for 20% duration but in reality the pipe volume (including distribution block), will almost certainly be MUCH GREATER than that!!!
I'll also select a launch setting of 50 HP (20% of the jet size) and 'assume' that the 'generic' solenoids will 'actually' open at such a low level, even though it's very unlikely that most will.

Now consider the following;
1) What we want is for the engine to receive JUST 20% of the FULL nitrous flow.
2) The FULL nitrous flow is determined by the jet sizes.
3) The solenoid is sent an electronic pulse that will 'theoretically' open the solenoid for 20% of the full on time.
4) By looking at the magnetic flux graph above, it can be seen that the nitrous plunger doesn't open immediately but for simplifying this example, we'll assume that it does.
5) However in this arrangement what actually happens, is that the solenoid flows 500 hp for 20% of the time and fills up the braided pipe work (which acts as a nitrous reservoir) with 100 HP worth of nitrous.
6) For the duration of the pulse, HALF the nitrous flows out through the jet.
7) To deliver JUST 20% (50 HP) the flow through the jet needs to be stopped at the same time the electronic pulse is stopped.
8) In this example the pipe work still contains roughly the same amount of nitrous AFTER the solenoid has closed, as it has already flowed to make the intended 20% power gain.
9) This means the jet will continue to flow nitrous after the electronic pulse has been switched off and in simple terms will flow DOUBLE the amount of nitrous that was intended and will therefore make 40% more power (100 HP), rather than the desired 50 HP.



In the drawing above, you have the solenoid seat to the left with the metering jet secured in the outlet of the solenoid, connected to an APPROPRIATELY sized NYLON (preferably) or hard pipe, of equivalent length to the first set up, with the end of pipe on the right connected to a nozzle.

The top depiction is without flow
The middle depiction shows the nitrous density during the INTENDED flow period, with pipe work filled with 'relatively' dense nitrous liquid.
The bottom depiction shows the nitrous density just after the solenoid has closed, showing the pipe work filled with EXTREMELY low density nitrous, as the dense nitrous quickly vents through the nozzle, preventing any extension to the flow period beyond the intended length.

Once again we'll use the same scenario as the first example, with a solenoid capable of flowing 500 HP, with a 250 HP jet with an initial launch requirement of 50 HP (20% of the jet size).
In this example the volume of the pipe work is MUCH LESS than the first example and therefore has negligible effect on the pulsed flow.

Now consider the following;
1) In this arrangement the solenoid flows 500 hp for 20% of the time but because there is no pipe work between the solenoid outlet and the metering jet, there is little to no reservoir effect.
2) For the duration of the 20% pulse almost ALL the nitrous that flows through the jet, flows out through the nozzle.
3) In this example when the electronic pulse is shut off, the flow through the jet is also shut off, as there is NO reservoir of nitrous to continue feeding the jet, therefore ONLY 20% (50 HP) of nitrous is delivered to the engine.
4) The ONLY nitrous that forms a reservoir is shown by the dark blue section in the last drawing

Even if overly large bore braided pipe is used in this scenario, the amount of nitrous delivered to the engine will remain the same but the engine performance will not be quite as good, as when using appropriate sized nylon pipe.

It should be kept in mind that NUMEROUS factors influence these results and many vary during a run and from run to run (depending on selected settings), so the effect on the results will vary. Some settings may produce an acceptable result, while others will produce totally unacceptable results.

Even with APPROPRIATELY selected components ONLY a WON system will deliver the most accurate results, for all the reasons given above.

That's nicely put Trev. I still don't understand why people do it any other way. You would never for example use one of the other generic kind of fuel solenoid and separate injector for use witn an ECU/fuel injection system. So it amuses me that people think its ok for N2O.

Ed

Thanks Ed,

I can assure you that it's not all that easy to get such tech stuff across in an easy to understand form, so it's gratifying to know I managed it.


Now to summarise;

For fear of repeating myself I've covered;
1) The deficiencies of the generic solenoids to pulse,
2) The inability of the solenoids to respond the same when flowing such different media
3) The fact that the media themselves don't respond the same as each other.
4) The unsuitable location of the metering jets
5) The combined reservoir effect of the jet location and excessively large pipe volume.

The result being that a large percentage of generic solenoids produce the following results when pulsed;
1) When activated at low percentage start levels the nitrous solenoid fails to open whilst the fuel opens and floods the engine.
2) When the nitrous solenoid eventually opens it's far too late and at a much higher percentage than desired.
3) Not only does the nitrous solenoid start at a higher flow percentage than desired but because of the reservoir effect it's more than possible, that more than DOUBLE the electronic percentage of power is delivered to the engine at that point.
So if you set the start power at 20% and the solenoid doesn't open till 40%, then the actual flow is doubled (or more) by the reservoir effect, what you could end up with is 80 or even 100% of the flow, defeating the whole object of a progressive system.

I've read widely differing reports about US pulsed kits ranging from engine failures to great results, so who is to be believed and which is right?
Obviously after reading all this thread you're ready to believe that it must be the guys reporting problems that are telling the truth but in fact it is possible that they're all telling the truth.
The reason why this is possible is due to the potential range of adjustable settings being extremely wide and although when using most settings the results are nothing like what was desired, it is possible with some settings to achieve something close to what is wanted.
If you were to choose a start setting of 35% or above, most generic solenoids would open when required.
If you use a short ramp up (or build time), in the region of 0.5 secs then the reservoir effect has minimal time to seriously effect the results.

The thing is, if you are ONLY using such a narrow progression then you'll never get the full potential from your vehicle or nitrous, so it's little consolation that you get the results you want when your target is so low.

Ony one more chapter to come.

As far as I'm concerned, fact #6 is enough.

Briefly stated:
Unless the solenoids are specically designed for pulsing,
- Solenoid opening time does not necessary correlate to the pulse width %
- Fluid flow does not necessarily correspond to the solenoid opening time

That about sums it up Bob, ANY one of the flaws I've listed is enough to screw the whole principle up, yet most people still think you can just use any old solenoid and pulse it.

I only have a basic education in Physics but I can still understand all this stuff, so it must be simple, yet I read such garbage from people with degrees in physics, quoting this law and that law to prove I'm wrong on every aspect of nitrous I care to discuss.

I'm just glad I left school at 16 years old and educated myself from then on.
It seems to me that the more educated some people are the less common sense they have.

Here's another graph I've drawn up, in an effort to better demonstrate the reservoir effect;



The green trace is the ideal pulse signal sent out by the electronic control unit (progressive controller) and as in the previous example, represents a 20% 'ON' pulse to an 80% 'OFF' period, which would therefore 'theoretically' deliver 50 HP to the engine (when using 250 HP jets), 'IF' the nitrous system was designed CORRECTLY!!!!.

Allowing for the fact that excessively large flow solenoids are frequently used, along with the fact that the plungers in most generic solenoids DON'T respond to this clean pulse exactly (if at all) as they should, along with the reservoir effect caused by excessively large bore pipes, with metering jets located at the nozzles, the blue trace is a representation of the gas flow/density delivered to the engine.

The area under each trace is representative of the actual power that the engine would make and in this example the area under the blue trace is MUCH more than that under the green trace, so instead of the engine making 50 HP it could be making in excess of 200 HP.
At some point in the sequence of events, the reservoir doesn't have time to empty completely, before it is topped up again by the next pulse and will eventually get to a point where it is always full, which will result in the engine getting 100% of the flow of the jet, despite the solenoid still being pulsed. The start of this unavoidable consequence is shown in solid blue in the graph above.

For the engine to receive the ACTUAL power level that's indicated by a progressive control unit, the solenoid plunger must respond as quickly as possible to the electrical pulses and there must be NO reservoir effect on the nitrous flow.
In other words, the nitrous delivery (blue trace) would have to match exactly to the pulse signal sent by the electronic control unit, as indicated by the green trace.

The blue trace is only an INDICATION of the amount of nitrous that is actually delivered to the engine when using a badly designed pulsed system (which means ALL others except WON), but the ACTUAL amount that arrives at the engine depends on the following variable factors;

1) Solenoid response rate, which itself depends on numerous other factors (design, supply voltage, nitrous pressure, wiring, etc. etc.
2) Solenoid orifice size
3) Metering jet location
4) Metering jet size
5) Volume of reservoir, which itself depends on pipe length and bore, plus distribution block design
6) Settings of the control unit

In the worst case scenario the pulsing of ANY nitrous kit that is not a WON system, could be TOTALLY INEFFECTUAL and in the best case scenario, it will only reduce the full flow marginally and briefly, but IN ALL CASES it will NOT deliver anything like the figures the control unit indicates.

If we look at the previous example but select settings of say 50% (instead of 20%), the following graph shows the potentially HUGE difference, between the amount of nitrous INTENDED to be flowed and the ACTUAL amount that reaches the engine, as a consequence of all the deficiencies in the design of ALL other pulsed kits;



In this example the engine will receive almost 100% of the FULL flow despite being pulsed at ONLY 50%, as the volume of nitrous in the reservoir doesn't have time to drop, for all the reasons given above.

When I first tested the progressive units from other companies I was in hysterics at the range of adjustment they offered, because I knew that changing either the start percentage or the build time by 0.1 (never mind 0.001 as some offer/claim), was absolutely RIDICULOUS and would have ZERO effect on the ACTUAL nitrous being delivered to the engine.

FACTThere is ONLY one system in the world that achieves anything like accurate pulsed results and that's WON Pulsoid systems.

FACT: I think that you don't need to prove to anyone, anymore about WNOS, because anyone with brains would figure it out by themself, by now..

As a new member to this forum, I'll stick my two penny worth in.
The graphs etc above are all well and good. I'm no Einstein, but I do have a reasonably good knowledge of fluid dynamics, and refrigeration systems. Nitrous oxide does behave like a refirigerant from my 3 years experience with it. The design of the generic solenoids is not very good as they basically act as expansion chambers in the gas flow line. You cannot expect a fluid of this type to have an even flow characteristic when the fluid path has differing sizes along its length. You are expecting the fluid to start as a liquid, then expand to maybe a supersaturated vapour, and then compress back to a liquid as it passes into a smaller bore. This is not really possible unless you have a means of subcooling the fluid line after the expansion chamber / generic solenoid. When using a fixed hit system, this type of solenoid may fill due to the stack effect, assuming the primary fluid line before the solenoid is big enough to keep the solenoid full, and there is sufficient restriction after the solenoid to aid the stack effect.

Let me put this another way. I have used a NOS system for 3 years with no problems. I had a single fixed hit system first, then a 2 stage fixed hit system which was great. But, the problem I was having was too much power delivery too quickly. So how was I going to stop snapping half shafts and knacking gearboxes with my 50+100 system?
I know, I'll fit a progressive controller and rejet a single system to a 150hp shot. So I toddle off and buy a progressive controller. Get it fitted and tested all ok and make my way to the Pod.
As I had never used a controller before, I decided to fit 2 brand new solenoids. I had been advised by a well known supplier of Nitrous equipment that pulsing would cause the NOS solenoid seals to wear quickly. I was told that I may need to change the solenoid seals about every 50 operations of the pulsing device. OK, I can live with that if it means I get a good even power delivery and increase my times. But it would mean I would be spending about 40 quid to overhaul the solenoids every few months. I got my car to the track, and got to the start line. Everything was purged and ready for action.

1st stage light...2nd stage light...3 ambers...and GO!

I planted my right foot and guess what happened?

It was like riding a bike with no tyres over a cobbled street. I had several trips to the pits to check stuff over, but I had the same result on the strip.

Rough as **** everytime.

So I went and bought myself a set of used WON Pulsoids and swapped the cheater plate for a WON plate with 4 crossifre jets ( 1 for each barrel on my carb) and guess what?

A smooth run, 0.6 quicker over the 1/4 with an ET of 12.8 @ 110mph for the same shot of gas on a 32 year old 213 ci Rover V8 in my street legal MGB.

That time is now repeatable in my car with the WON system time and time again. With the old system it was a bit hit and miss on ET's and mph even on fixed stages.

Another fact with the old spray bar system I was using is that the cylinders to the rear of the V8 engine alway ran lean on fuel. I was injecting the nos from the front of the cheater plate, which seems to prove that the NOS system was not big enough to flow sufficient liquid to fill the spray bar so I got an even spray pattern across the length of the spray bar.

Now I'm using the crossfires, I get an even plug colour across all 8 pots.

Sorry I can't be more scientific and talk theory, I can only relate to my actual and factual experiences with the two systems.

And for informations sake, I had the car Dyno'd with the WON system running a 50 shot. It produced an extra 77bhp at the wheels with the gas on. I just wished I had had it Dyno'd on the old system for a comparison.

I'm going to take my old MGB back to the Pod this weekend to see how the old 3500 handles a 200 shot via the mini max. This engine is 32 years old, has only had a hot cam and a Weber fitted plus a balance and new rings.
I have a new 4.6 lump to go in soon so I'm going to see just how much gas the old girl can handle before she blows.

Sorry to have rambled on a bit, but I've been watching this forum for a while and decided to join in the fun.

Regards
Perry

Unfortunately not everyone has the kind of brain that can figure that out, otherwise the vast majority (rather than the minority) of racers, would already be using my systems.

Maybe the OBVIOUS advantages of the Revo will solve this problem.