NITROUS OXIDE ( nos / n2o ) advice forum

I recently read a few posts on another forum where some guys were complaining about the problems they'd had trying to pulse other brands of nitrous kits and then one guy was 'claiming' he'd got good results from pulsing his.

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.

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 this 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.

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

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.

I'll deal with this 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 and safe 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, but a nitrous solenoid finds it very hard.
Therefore a fuel solenoid is likely to open easily when sent a 10% pulse but the nitrous couldn't open at all. This imbalanced situation can (on many types of solenoids) exist up to as high as 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 20% power, rising to full power over 1.5 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 25%. 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 gentle 20% start that you programmed, it kicks in at 25% and when you were least expecting it, but by then it's too late.

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 struggles to act (just as it does at low percentages) but instead of staying closed it stays open, supplying 100% nitrous flow to the engine. Meanwhile the fuel solenoid is still able to respond well to the pulsing, so the fuel delivery is less than 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 set, this lean running period could continue for a minimum of a few milli seconds 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 kits being SO BAD, they would cause engines to alternate between lean and rich cycles rather than ever being anywhere near correct.

Thankfully, 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.

Here's the closest to a quick graphical representation 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 force is achieved sooner due to it requiring a lower level to lift.

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.

how do your solenoids solve this problem?

[/quote]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.[/quote]
same q, i added bold
do you run much longer n2o lines than fuel?

That's all dealt with in my Pulsoid threads, although at present I keep the 'exact' details of how it's done secret.

Once the Revo's are replacing Pulsoids, I'll disclose the secrets of the Pulsoid designs in full.

It doesn't involve long pipes though.

In your dry application it's a different situation altogether.

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' 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 is at the start of the flow period with pipe work filled with 'relatively' dense nitrous liquid.
The bottom depiction is just after the solenoid closes showing the pipe work filled with 'relatively' less dense nitrous, that will flow through the jet extending the flow period.

We'll assume the following specification but it is far from the worst possible scenario. For this example we're using a solenoid which is capable of flowing 500 hp and a 250 hp jet.
To keep the maths simple we'll assume 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) is often MUCH GREATER than that!!!
We'll assume that we want to launch at 50 hp (20% of the jet size) and that the 'generic' solenoids will 'actually' open at such a low level, even though it's very unlikely.

Now consider the following;
1) The solenoid is sent an electronic pulse equivalent in duration to 'theoretically' deliver just 20% of the nitrous that the jet would flow if the solenoid was energised continuously.
2) By looking at the magnetic flux graph above, it can be seen that the nitrous plunger doesn't open immediately but for simplicity we'll assume it does.
3) However in this arrangement what actually happens is that the solenoid flows 500 hp for 20% of the time and fills up the pipe work, acting as a nitrous reservoir.
4) For the duration of the pulse, HALF the nitrous flows out through the jet.
5) To achieve JUST a 20% (50 hp) delivery the flow through the jet needs to be stopped at the same time the electronic pulse is stopped.
6) Unfortunately in this example the pipe work still contains roughly the same amount of nitrous as was flowed to make the 20% power gain that was required.
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 pipe of equivalent length to the first set up.

The end of pipes on the right would be connected to a nozzle.

Once again we'll assume the same scenario with a solenoid capable of flowing 500 hp and a 250 hp jet.
In this example the volume of the pipe work is much less than the first example and has no effect on the pulsed flow.
Again we'll assume that we want to launch at 50 hp (20% of the jet size) and that the 'generic' solenoids will 'actually' open at such a low level, even though it's very unlikely.

Now consider the following;
1) The solenoid is sent an electronic pulse equivalent in duration to 'theoretically' deliver just 20% of the nitrous that the jet would flow if the solenoid was energised continuously.
2) By looking at the magnetic flux graph above, it can be seen that the nitrous plunger doesn't open immediately but for simplicity we'll assume it does.
3) 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.
4) For the duration of the pulse nitrous flows out through the jet.
5) To achieve JUST a 20% (50 hp) delivery the flow through the jet needs to stop at the same time the electronic pulse is stopped.
6) In this example the lack of a reservoir stops the flow through the jet in accordance with the electronic pulse finishing and ONLY a 20% (50 hp) increase is delivered to the engine.

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 blue trace is the ideal signal sent out by the electronic pulse unit (progressive control unit) and in this example represents a 30% on pulse to a 70% off period and would therefore 'theoretically' deliver 30 hp if the system had 100 hp jets fitted.

Allowing for the fact that the solenoid plunger doesn't respond to this clean pulse exactly (if at all) as it should and the reservoir effect of large pipes with metering jets located at the nozzles, the red trace is a representation of the gas flow 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 red trace is more than double that under the blue trace, so instead of the engine making 30 hp it will make in excess of 60 hp.

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.
In other words the gas delivery would have to match exactly the pulse signal sent by the electronic control unit as indicated by the blue trace.

The red 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), but the REAL amount that arrives at the engine depends on the following variable factors;

1) Solenoid response rate
2) Solenoid orifice size
3) Volume of reservoir (which depends on pipe length and bore, plus distribution block design)
4) Metering jet size
5) Percentage settings of the control unit

In the worst case scenario the pulsing could be totally ineffectual and in the best case scenario it will reduce the full flow marginally and briefly, but IN ALL CASES it will NOT deliver anything like the figures the control unit indicates.

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.

In my opinion it is CRIMINAL that so many companies are getting away with making positive claims for pulsed systems, when they OBVIOUSLY have NO IDEA what such systems ACTUALLY DO!!!!

FACTThere is ONLY one system in the world that achieves anything like accurate pulsed results and that's my 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 fook everytime.

So I got the 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 Rover V8 in my MGB.

That time is now repeatable in my car with Trevs system. With the old system it was a bit hit and miss on ET's an mph.

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 cant 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.