Diesel Control Nitrous

About Nitrous Oxide

Nitrous oxide is a colourless, odourless gas that has many uses. It is used in the food industry and in surgery and dentistry for its anaesthetic effects but, most importantly (for us), it is also used in motor sports, mainly drag racing. Contrary to what many people think, nitrous is not flammable. It is used in motor sports to assist the combustion of a flammable fuel, a process that is sometimes referred to as ‘liquid supercharging’.

Trevor Langfield (Wizards of NOS) with a Nitrous Oxide Jag on BBC’s Top Gear

Nitrous and Motor Sport

Nitrous is stored on-board the vehicle in a cylinder type bottle in liquid form at a pressure of about 600 bar (approximately 9000psi) and, when released into the engine’s intake manifold, quickly turns into a gas. The sudden pressure drop causes this change of state, during which time the ambient temperature liquid NOS turns into a freezing cold gas, which has a massive cooling effect on the surrounding air. Normal air that we breathe has an oxygen content of about 21%. Nitrous oxide has an oxygen content of about 35%, and it’s this additional oxygen that allows more (introduced) fuel to be burned by the engine, therefore creating more power.

NOS Bottle Installed

NOS Bottle Installed

As well as the engine’s usual fuel supply, additional fuel, along with the Nitrous, has to be introduced. This is normally carried out using 2 separate, high power solenoids, one for NOS, and the other for petrol. Jets of carefully chosen sizes to control the air-fuel ratio (AFR) are used to either inject the fuel/air mixture into the throttle body or fogger nozzles are used to distribute the mix to each cylinder.

This additional air/fuel mixture, if not controlled carefully, can cause engine damage, so for high-power applications it is advisable to use an electronic controller instead of a simple throttle mounted on/off micro-switch. These controllers can be programmed to increase the amount of horsepower gain in relation to engine speed and load, eg 30 BHP increase @ 3000rpm to 60BHP increase @ 6000rpm by controlling the solenoids on-time (duty cycle) in accordance with engine speed. Power gains using nitrous on standard road cars is normally limited to about 60 BHP. Anything over this normally requires re-mapping of the ignition system to retard the timing.

Diesel Applications

Select-A-Map NOS System

Select-A-Map NOS System

Nitrous oxide works very well with diesel engines, though to achieve the best results, there are some technical challenges to overcome.

Instead of increasing the fuelling, some people inject propane (LPG) into the intake but this can cause detonation, even though it’s octane rating is much higher than diesel.

The best method is to increase the amount of diesel injected by remapping the ECU but a remap generally does not provide a means to instantly revert back to standard or reduced fuelling the moment the NOS is switched off, resulting in over-fuelling and excessive exhaust smoke.

Diesel tuning boxes can be used but most of these cannot be quickly switched back to a lesser fuelling map when the nitrous is turned off. Nitrous would also be wasted at higher engine speeds since the diesel engine’s maximum fuelling occurs at peak-boost and is reduced from there onwards as engine speed increases. The only method available that addresses all of these issues, to control both diesel and nitrous delivery, is a unique product known as The Select-A-Map . Developed in-house for CRD Technology, this controller enables the correct quantity of diesel and nitrous to be introduced under all conditions.

Click here to read more about Select-A-Map and Nitrous control at CRD Technology .

Nitrous Refilling

Nitrous Refilling Station

Nitrous Refilling Station

CRD Performance, Bolton, has invested in a custom built refilling station that is able not only to fill empty bottles but part filled ones too. All bottles must be delivered to us in person and be of a recognised brand type with clearly visible markings and tare weight.

Michelle on the job - sucking not blowing If you appear at all ‘spaced out’ as if you’ve been inhaling the stuff you will first need to convince us otherwise, possibly by bringing your car with you or answering any type of system related kit questions. When recently Michelle Keegan (Coronation St.) was featured in a Sunday paper sniffing nitrous balloons in a Manchester night club, our entire stock sold out in less than a day (a day!), leaving none for the drag racers.

Nitrous kit Installs

We are able to supply and fit Nitrous oxide systems to most petrol and diesel vehicles. We can either supply our own kits that we’ve sourced from the States, or we are happy to fit customer’s own kits if suitable and complete. Set up is carried out either by using our rolling road or by using an AFR meter on the road; this is to ensure mixtures are set slightly on the rich side to help avoid damage.

The quality of our installs is probably the best you are likely to see as the majority of our business involves dealing with cylinders and pipe work, see our LPG photo gallery.

Click here for our LPG conversions photo gallery


Price Guide

Nitrous refills

Per 1lb of NOS (450g)           £6.00 + VAT

Petrol NOS system (from) *   £700.00 + VAT
*excluding controller.

Diesel NOS system (from) ** £550.00 + VAT
**excluding Select-A-Map.

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