Nitrous / NOS

[Ste]

Nitrous
This is a guide about nitrous, not how to fit a nitrous kit or anything similar. This is purely to help you understand the funny stuff.

First of all let me explain nitrous because most people believe nitrous is flammable and dangerous. They also believe nitrous turn a standard car into a supercar. Well neither are true in our case, the 1.6l engine can’t handle enough nitrous to instantly turn it into a fire breathing monster. But with some simple, expensive, modifications you can easily double the performance from your engine.

What is N20
So what’s this about nitrous not being flammable? It’s not it’s called an Oxidiser. The air we and our engines breathe doesn’t just contain pure oxygen there’s loads of shit in there, in fact the main gas in air is Nitrogen by about 79% and then followed by oxygen at 20%. The other tiny percentage is made up of C02/H20 and argon. However oxygen is what we need to combine with fuel to get out the power, this is why we like colder air because it contains more oxygen. SO we now know the air we breathe usually contains around 20% of oxygen. So how does nitrous help get more oxygen into the air? Nitrous is a gas called N20, this gas oxidises with heat. When it oxidises or breaks down it produces/changes into Nitrogen and Oxygen, producing more Oxygen in our air. So if we are injecting nitrous into the engine we air getting a larger percentage of Oxygen per cylinder full of air, which in short means the air is denser. I will explain how this boost in oxygen helps shortly.

Nitrous also has a second impact to increase power; N20 is stored as a liquid due to the high pressure it’s put under in the tank. When this liquid is injected it expands into a gas and causes a massive drop in temperature where you inject it. So the result of this is the production of oxygen (from the nitrous breaking down with heat) in a much denser combination of air due to the air being so cold. As the colder air is the more dense it is, which is mixed with more fuel as the more oxygen in the air being sucked into the engine there is the more fuel you can mix with it.

So now we have a nice oxygen rich mixture of air, how does all this air make you go faster? It doesn’t it’s the fact that the more oxygen you have in the air the more fuel you can mix with it. So instead of making our engine bigger, say 2.0 litres to get more power, we are using Nitrous to get more oxygen in our cylinder than would normally fit. So with this huge boost in oxygen we need a boost in fuel. This is why nitrous kits come with two solenoids; ill explain what a solenoid is further on.

You need to inject fuel and nitrous together so you get a bigger bang. So now you know what nitrous is and exactly how it helps, now I’ll explain what each bit does and give some advice on fitting. I’m not showing anyone exactly how to fit it as this is just a guide not a manual. You will get a manual with any new nitrous kit. This is just to explain a nitrous system.

You will see different types of nitrous system the main being Wet and Dry. Both do the same thing however, a Dry system basically means you keep the manifold dry. So the nitrous is injected through the fuel injectors or on a separate rail fuel rail fitted with injectors. A Wet kit is the most common on after market systems and is the type of kit being explained. Where the nitrous and fuel are injected separate to the cars fuel system.
 
A basic Nitrous kit usually contains the following;

Nitrous Bottle 5lb – This contains the nitrous, you NEED a bottle with a pressure release valve. This prevents your bottle from exploding if its overfilled or if the pressure increases in a fire by safely releasing gas when it gets above a safe pressure.

Nitrous Solenoid/Pulseoid – This is the device used to spray the nitrous. This is the most important bit of kit. Don’t buy second hand ones unless you plan on getting them serviced by a nitrous dealer. If one of these fails you can either let way too much nitrous in or not enough. A pulseoid is the better option as it is designed specifically with nitrous in mind and will last loads longer than a solenoid.

Fuel Solenoid/Pulseoid – This is the device used to spray the fuel. And as above don’t buy second hand unless getting services. And buy a pulseoid if money permits.

Injector – This is where the nitrous and fuel meet and are sprayed into the intake. If you have a single throttle body you can position this anywhere in front or behind of the throttle body. Just make sure it is positioned before the standard fuel injectors on the car. The engine will suck the mixture in when its sprayed. If you have throttle bodies without a plenum you will need an injector for each throttle body tract. And again they will need mounting before the fuel injectors. So if you have Jenvey style bodies that mount onto a manifold you would put the injector on the trumpet not the manifold.
Fuel T Piece – This is used to provide a place for the fuel solenoid to suck fuel from. You split your fuel pipe that leads to the fuel rail and insert the T piece. The fuel hose then goes from the T piece to the Fuel Solenoid as well as your fuel rail. This T Piece must be placed after the fuel filter & fuel pump, the best place is just before the fuel rail.

Jets – These are another very important part that needs to be specified for your engine setup. Don’t just use what everyone else is using. I’ll explain what jet size produces what power further on in the guide. These fit in the solenoids and restrict the amount of nitrous and fuel that can be injected. You generally fit a fuel jet half the size of the nitrous jet. EG: A nitrous jet size marked at 100 would need a fuel jet size of 50. This gives a safe air to fuel ratio. Also a jet size does not indicate how much power it will produce, at all.
Fittings – You will also get the nylon hose used to connect the nitrous bottle to the nitrous solenoid, the fuel T piece to the fuel solenoid and both solenoids to the injector. These are cut to your required length by you and are held on using an olive and nut style where the nut and olive clamp down on the hose.

Electrics – The parts above are all that is need to plumb in the nitrous kit. All you need now is a method of turning on the system and activating the solenoids. You get two switches, one is to make the system live and means that the solenoids are ready to be used, the other is to activate the solenoids and make them spray fuel/nitrous. The first switch needs mounting somewhere easy to access and where it won’t be knocked. The second needs fitting underneath your accelerator or on the throttle body – so the switch is only pressed on Wide Open Throttle (WOT). This prevents damage from incorrect usage.


Fitting Necessities

The nitrous bottle, as explained earlier, contains nitrous in liquid form so it needs mounting in the correct angle. By default the pipe in the bottle is positioned to suck up the liquid from the bottom so the bottle needs mounting at an angle with the outlet at the top where the pipe connects pointing down. This ensures when accelerating there’s always liquid nitrous available.

Fit a longer nylon tube from the nitrous solenoid to the injector than on the fuel solenoid. This stops nitrous getting to the engine before the fuel and produce a dangerous mixture. 2 inches longer is sufficient, an easy way to do this is to loop the tube.

Fit a grade colder spark plug and go colder for every 50bhp you increase.

Make sure the fuel system is working 100%.


Jetting
Jetting is a crucial step when planning your nitrous kit, fitting the smallest jet isn’t the way and fitting the largest you’ve seen anyone else doing with your setup it isn’t’ the way either. People often talk about nitrous jet sizes in terms of the power they produce. This is bollocks, always will be bollocks and should be taken with a pinch of salt. If a company says their jets make 25bhp then they have tested them themselves and they are not referring to a general size chart, other companies jets may be different sizes so buy a selection of jets at once from the same company. The power depends on many things so many it would take another guide to explain. However here is the info you need to test.

Fit the jet you think is right; now activate the fuel solenoid to see how long it takes your fuel solenoid to fill up a pint glass.

A fuel jet that gives roughly 25bhp increase will be 0.4mm in size and take 260 seconds to fill a pint glass. This jet should be matched with a 0.6mm nitrous jet if your bottle is at 800psi.

A fuel jet that gives roughly 40bhp increase will be 0.5mm in size and take 162 seconds to fill a pint glass. This jet should be matched with a 0.75mm nitrous jet.

A fuel jet that gives roughly 50bhp increase will be 0.55mm and take 130 seconds to fill a pint glass. This should be matched with a 0.85mm nitrous jet.

Any higher than this on a 1.6 litre engine and you need to speak to a nitrous distributor. Chances are you will need a controller. Generally you should start with a 25bhp spec. This will be good enough to start with.
 
Going bigger
If you want nitrous for drag racing you will probably want the most power you can get to the tarmac. However fitting a jet that instantly gives you as much power as a 1.1, in addition to your engines current power can do some serious damage. You can spit conrods through your engine, melt spark plugs, and cause pre-detonation and most likely blow your intake clean off the engine.
So here is where a nitrous controller comes in, you fit a jet capable of delivering say 1000bhp (the fuel jet for this would fill a pint glass in 6 seconds just to give you an idea) to the solenoid. And the controller runs the solenoid at a percentage of its power. E.g. you tell the controller to start at 25% of full power and increase to 100% over 2 seconds or 5 seconds etc. Then when you activate the system the controller kicks in and gently increases the power. This also helps ease strain on the clutch and gives better chances of getting traction.

With a controller you can gently ease the power in and massively reduce the strain on the engine. Personally I would choose to fit a controller from the start. They are very easy to wire up and very easy to program.
It’s also advisable to fit a fuel pressure gauge and nitrous pressure gauge if you’re going for large gains. A fault can result in a blown engine.

Purge System
A purge system is simple, its an extra solenoid that sprays nitrous through the system into the atmosphere to make sure the nitrous has been cleared from the pipes ready for use. This is only needed on cars with multiple cylinders like a V8 where the ammount of nitrous being used is quite large and high performance is a necessity.

Legislation
This seems to be a grey area; it is legal to have a nitrous kit fitted and plumbed in ready to be used. However it is illegal to use on the roads and if you have a full bottle you need to have a sticker visible from the outside of your car stating you have an oxidiser in the vehicle.

So its not something you will be done for having connected and having a full bottle for. But you will get done if you are caught purging etc.

Its also worth noting that you WILL need a specialist insurance company to insure you if you have nitrous fitted. And even through those it will, at best, double your insurance.

I dont want to edit the above, but maddison_VTS has cleared up the above;

as williamsvts said. its legal to have it fitted and to use on the road. what is illegal is to break the speed limit using it, thats it. but thats illegal anyway.

you don't have to have a compressed gas sticker, its advised but is not the law, its simply to inform emergency services you have it.

my insurance went up £90 for having nitrous fitted, not exactly breaking the bank.

i spent a LOT of time looking up the law on nitrous before i installed it all so i'm 99.9% sure what i've put above is correct.

Reasons not to buy Nitrous
Your insurance will rocket.

It can cause torque steer at high speed.

A fuel pump failure or fuel solenoid failure can result in a blown engine.
Refill stations are rare.

Your engine will need servicing a lot sooner.

For any reasonable gains you’ll need a stronger clutch.

You can’t use it that often or for very long.

The bottles are fairly heavy.

It’s expensive to do right.

[Paulp]

Good stuff Ste, should see a few less 'dummy' threads being created on a daily basis now

Also on the insurance point, some insurance companies won't even insure you if you have nos.

[Phils_VTR]

I didn't even think nos was road legal..its not..is it?

[Nij]

it is road legal BUT finding someone to insure you except on a competition car insurance scheme will be hard work and expensive.

[Ste]

Also if anyone disagrees with any info or has any questions about what ive put. Please PM me, im happy to change the details and i wont bite anyone's head off who actually has taken the time to research and understand what their doing.

[DusheR]

Good stuff mate But needs reasons to buy nitrous

[col101]

Originally Posted by Phils_VTR

I didn't even think nos was road legal..its not..is it?

Originally Posted by Nij

it is road legal

I always thought the law was abit vague in this area. Last I heard was it was not illegal to have nitrous installed, but was illegal to actually use it?

[Ste]

It legal to have it there, the bottle full and switched off. However if the bottle is full you need a sticker stating you have an oxidiser on board for emergency services.

It is illegal to use on public roads.

[williamsvts]

ive got a book wrote by the owner of wizards of nos, he says it is not illegal to use on the roads aslong as you have insurance for it. he also says you do not need to have a sticker on the outside of the car, just on the bottle.

[sufc_paul]

Originally Posted by Ste

It legal to have it there, the bottle full and switched off. However if the bottle is full you need a sticker stating you have an oxidiser on board for emergency services.

It is illegal to use on public roads.

ha emergency services munchies is an emergency

[maddison_vts]

Legislation
This seems to be a grey area; it is legal to have a nitrous kit fitted and plumbed in ready to be used. However it is illegal to use on the roads and if you have a full bottle you need to have a sticker visible from the outside of your car stating you have an oxidiser in the vehicle.

So its not something you will be done for having connected and having a full bottle for. But you will get done if you are caught purging etc.

And even through those it will, at best, double your insurance.

thats not right bud.

as williamsvts said. its legal to have it fitted and to use on the road. what is illegal is to break the speed limit using it, thats it. but thats illegal anyway.

you don't have to have a compressed gas sticker, its advised but is not the law, its simply to inform emergency services you have it.

my insurance went up £90 for having nitrous fitted, not exactly breaking the bank.

i spent a LOT of time looking up the law on nitrous before i installed it all so i'm 99.9% sure what i've put above is correct.

i don't want the post to come across like i'm trying to be a ''know it all'', just trying to help!

[mechsman]

Originally Posted by maddison_vts

thats not right bud.

as williamsvts said. its legal to have it fitted and to use on the road. what is illegal is to break the speed limit using it, thats it. but thats illegal anyway.

you don't have to have a compressed gas sticker, its advised but is not the law, its simply to inform emergency services you have it.

my insurance went up £90 for having nitrous fitted, not exactly breaking the bank.

i spent a LOT of time looking up the law on nitrous before i installed it all so i'm 99.9% sure what i've put above is correct.

i don't want the post to come across like i'm trying to be a ''know it all'', just trying to help!

I have to agree with the above. As far as I am aware it IS legal to have nitrous fitted AND use it on the road as long as you stay within the law regarding speed/driving like a tool etc etc.

Can I repectfully suggest this: http://www.nitrous.info/ as highly recommended reading for anyone planning to install a nitrous system. It shows you pretty much everything needed to design and install your own diy nitrous system.

[Kris_VTR]

Originally Posted by Paul

Also on the insurance point, some insurance companies won't even insure you if you have nos.

Thought i read sumwhere Nos was illegal?????

[mechsman]

Originally Posted by Kris_VTR

Thought i read sumwhere Nos was illegal?????

You may have read it, doesn't mean it's correct though!
As posted in the replies above, it's legal as long as you are insured to use it on the road (i.e. declared) and you don't break any laws when you are using it.

[Saaamon]

Not really different to any other tuning mod really to be fair. Not my sort of thing, bit to fast and furious for me, i tend to keep things abit slower lol.. But each to there own.

[mechsman]

^ True. Handy to have an extra 50 bhp if you need it though.