How NOS Works: Complete Guide to Nitrous Oxide Systems
Nitrous oxide systems, commonly known as NOS after the brand name, work on a remarkably elegant chemical principle. When N₂O is injected into the intake manifold, it decomposes at high temperatures into nitrogen and oxygen. This released oxygen allows the engine to burn additional fuel, creating more power.
The Basic Principle
Nitrous oxide contains approximately 36% oxygen by weight, compared to air’s 21%. This oxygen-rich compound, when injected at high pressure into a hot intake manifold, rapidly decomposes at around 570°F (300°C), releasing its oxygen atoms for combustion.
Wet vs. Dry Systems
Wet nitrous systems inject both nitrous oxide and additional fuel simultaneously through a plate or nozzle positioned before the throttle body. Dry systems inject nitrous only, relying on the fuel injectors to compensate for the increased airflow demand.
Power Levels
Entry-level “shot” sizes start at 25-50 horsepower for street applications. Racing builds can run 200hp, 400hp, or even higher shots with proper engine preparation. The world’s fastest drag cars run multiple stages of nitrous simultaneously.
Component Breakdown
- N₂O bottle (typically 10-15 lbs capacity)
- High-pressure lines and fittings
- Nitrous solenoid valve
- Fuel solenoid valve (wet systems)
- Nozzle or plate injection point
- Activation switch/throttle switch
- Safety blow-off valve
Nitrous oxide doesn’t actually burn — it releases oxygen that enables more fuel to burn. This distinction matters enormously when calibrating fuel enrichment.
Modern NOS systems include progressive controllers that ramp up the nitrous delivery gradually, preventing wheel spin and engine shock. This technology has made nitrous practical even for street cars with moderate power levels.
