Nitrous Jet Selection Calculator

Nitrous jet size from desired HP increase and system type.

Inputs

Desired HP gain

Bottle pressure (PSI)

Bottle size (lbs)

System (0=wet, 1=dry)

Fuel (0=gas, 1=E85)

Tab to move between fields

Results

N2O jet number

Fuel jet number

N2O flow (lb/hr)10

Added fuel flow (lb/hr)52

Bottle duration (sec)3,600

1/4-mile passes360

Timing retard (°)4

Plug steps colder2

Corrected N2o Flow10

Duration Minutes60%

Safety NoteModerate — verify fuel system capacity

How to Use This Calculator

Enter Desired HP gain, Bottle pressure (PSI), and Bottle size (lbs).
Set System (0=wet, 1=dry) and Fuel (0=gas, 1=E85).
Review N2O jet number and Fuel jet number.
Use N2O flow (lb/hr) and Added fuel flow (lb/hr) to inform your decision.

How the result changes with Desired HP gain

Desired HP gain	N2O jet number	Fuel jet number
73	29	30
191	59	53
334	97	81
453	100	90

What each input means

Desired HP gain: Target horsepower increase from the nitrous system.
Bottle pressure (PSI): Nitrous bottle pressure (optimal: 900-950 PSI at 80°F).
Bottle size (lbs): Nitrous bottle capacity in pounds (common: 10 lb, 15 lb).
System (0=wet, 1=dry): Wet system adds fuel at nozzle; dry system relies on ECU enrichment.
Fuel (0=gas, 1=E85): E85 requires ~30% more fuel flow than gasoline.

What each result means

N2O jet number: Recommended nitrous jet size (NOS/ZEX jet numbering scale).
Fuel jet number: Recommended fuel jet size for wet systems (0 for dry systems).
N2O flow (lb/hr): Required nitrous oxide flow rate.
Added fuel flow (lb/hr): Additional fuel flow required to maintain safe AFR.
Bottle duration (sec): How long the bottle lasts at continuous wide-open throttle.
1/4-mile passes: Approximate number of full quarter-mile runs per bottle.
Timing retard (°): Recommended ignition timing retard in crankshaft degrees.
Plug steps colder: Number of heat range steps colder for spark plugs.

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Desired HP gain = 100, Bottle pressure (PSI) = 900, Bottle size (lbs) = 10, System (0=wet, 1=dry) = 0 = 5 input(s) provided
Calculate N2O jet number
N2O jet number = max(16, min(100, n2oJetNumber))
36 = 36
Calculate Fuel jet number
36 = 36
Calculate N2O flow
N2O flow = desiredHpGain / 10
10 = 10
Calculate Added fuel flow
Added fuel flow = desiredHpGain * bsfcOnNitrous
52 = 52

Engine last updated August 5, 2026. Checked against 2 independently-derived tests — how we verify calculators.

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