Nitrous Oxide Jet Calculator - RobieTheRobot.com

I decided to write this app because I couldn't find anything web based at the time that would do this. Most of the info out on the internet required you to have a calculator or do the calculations in an Excel doc.

Fuel Pressure (PSI) (info only needed if you are using a 'Wet' setup)	Nitrous Bottle Pressure (PSI) (info only needed if you are using a 'Wet' setup)
Nitrous Jet Size Thousandths of an inch. (Will calculate Horse Power rating for jet)	Number of Jets/ports Single fogger/direct port/etc...

Nitrous Jet Calculator II
Calculate Jet size from desired HP

Input Values
Nitrous Horsepower Target
Nitrous Pressure (PSI)
Fuel Pressure (PSI)
Nitrous/Fuel Ratio (5.5 - 8.0)
Number of Nozzles


Calculated Values
Nitrous Jet Size
Fuel Jet Size

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Air/Fuel Ratio

What constitutes correct A/F ratio?
Most recommend running slightly rich (generally, between 11.5-12.5:1), but agreement on this point is by no means universal, and some sources recommend going even richer under some circumstances.
At 250 hp and under, you can run the same as the engine's air/fuel ratio. But at 450-500 hp run 11.5:1 as a safety factor.
Try adjusting the exact air/fuel ratio according to engine displacement. A 400hp kit delivers about the same 400hp boost on a 400ci engine as it does on a 600ci engine, but because the larger engine has much more total cylinder volume, the mass fraction of nitrous inducted into that engine as a proportion of that volume is less, so it is more easily absorbed.
The big engine may be happy with an 11.5:1 A/F ratio, but you may have to go as rich as 10:1 on the smaller motor. Finding the exact A/F ratio to run can be somewhat tricky because nitrous carries its own oxygen. The ratio in effect becomes a variable of how much nitrous you put into the engine.

The following equation to work well as a starting point:
Target A/F Ratio = [(engine hp / total hp) x 13] + [(nitrous hp / total hp) x 7]

Actual A/F ratio tuning is accomplished with either a wideband O2 sensor, or by reading the spark plugs. Usually a light tan porcelain color on the plug is an indicator of the right timing. You need to read all of the plugs. If tuning with a wideband O2, the higher the ratio of nitrous power to engine power, the less accurate the O2 sensor will be. That's why most hard-core guys look at the plugs and exhaust-gas temperatures. The plugs won't lie to you.

Bottle Temp to Bottle Pressure ratio

Raising nitrous-bottle pressure makes the system hit harder off the line at the expense of inconsistent taper-off on top. To avoid problems, most experts advocate sticking to the system manufacturer's recommended bottle operating pressures. Although this can vary slightly among different manufacturers, it's usually 900-1,000 psi. "The higher the bottle pressure, the greater the drop-off." If you start out at 950 psi, you'll finish at 750; if you start out at 1,100, you'll finish at 600. The larger the bottle, the less the drop-off." Whatever pressure you run, it should always be consistent, because it affects the rest of the tune-up. There is a direct correlation between bottle temperature and the bottle's internal pressure, so keeping the bottle at a specified temperature will also maintain the desired pressure. For example, if you maintain the bottle at 90-92 degrees F, there will be about 950 psi at the start of the run. The pressure will drop during the run, but you should still have 880-900 out the back. Depending on local climate conditions, this may require a bottle blanket and electric heating device for warming the bottle, or a cold towel and ice to cool it.

Bottle Temp �F	Bottle Pressure (psi)
-30	167
-20	203
-10	240
0	283
10	335
20	387
32	460
40	520
50	590
60	675
70	760
80	865
85	950
97	1069

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N.O.S. Starting Line Jet Map These values are DIRECTLY from NOS Nitrous and are extremely safe, even at the cost of a bit of performance. Pro-Shot and Pro-Race Fogger
HP Level	Nitrous	Fuel@ 6psi	Test Jet	Holley Equivalent
100	.018	.018	.051	51/52
125	.020	.020	.057	58
150	.022	.022	.062	63
175	.024	.024	.068	67
250	.028	.028	.079	72
300	.032	.032	.091	79
350	.036	.036	.102	86/87
400	.040	.040	.113	94/95
500	.042	.042	.119	96
Super Powershot
HP Level	Nitrous	Fuel@ 5.5psi	Test Jet	Holley Equivalent
100	.047	.053	.053	54
125	.055	.061	.061	62
150	.063	.073	.073	70
180	.073	.082	.082	75
Cheater & Dual Shot Cheater
HP Level	Nitrous	Fuel@ 5.5psi	Test Jet	Holley Equivalent
100	.047	.053	.053	54
125	.055	.061	.061	62
150	.063	.071	.071	69
180	.073	.082	.082	75
210	.082	.091	.091	79
250	.093	.102	.102	86/87
Multi-Carb Cheater
HP Level	Nitrous	Fuel@ 5.5psi	Test Jet	Holley Equivalent
100	.033	.037	.052	53
125	.038	.043	.061	62
150	.052	.059	.083	75/76
175	.059	.065	.092	79/80
200	.065	.073	.103	87
250	.073	.078	.110	94
Big Shot including 2 stage
HP Level	Nitrous	Fuel@ 5.5psi	Test Jet	Holley Equivalent
100	.047	.053	.053	54
125	.055	.061	.061	62
150	.063	.071	.071	69
175	.073	.082	.082	75
225	.082	.091	.091	79
275	.093	.102	.102	86/87
325	.102	.110	.110	94
350	.120	.116	.116	95
Multi-Carb Big Shot
HP Level	Nitrous	Fuel@ 5.5psi	Test Jet	Holley Equivalent
150	.052	.058	.082	75
225	.059	.065	.092	79/80
275	.065	.073	.103	87
325	.073	.078	.110	94
350	.085	.082	.116	95
EFI Single Fogger Nozzle Wet
HP Level	Nitrous	Fuel @ 42+psi
70	.042	.026
100	.047	.030
125	.055	.039
EFI Dry w/ 19 lb/hr injectors
HP Level	Nitrous	Tee-Jet
75	.042	.059
100	.047	.053
125	.055	.059
EFI Dry w/ 24 lb/hr injectors
HP Level	Nitrous	Tee-Jet
75	.042	.063
100	.047	.057
125	.055	.051
EFI Dry w/ 36 lb/hr injectors
HP Level	Nitrous	Tee-Jet
75	.042	.067
100	.047	.063
125	.055	.061

MOTORCYCLE WET NITROUS JETTING CHART

The following is intended as a safe baseline for fogger systems. There are two fuel jet columns listed below. One column for fuel jet size with the fuel pump that comes in the kits and the other column for hi-output pumps – like the Holley Blue with 5-7 psi flowing pressure. The nitrous jet chart is based on bottle pressure of 900-950 psi. Ignition timing should as a baseline be retarded to 1/5 to 2 degrees for every 50 h.p. worth of nitrous hp used. Ignition timing should be retarded from the best timing on motor only. (The point at which best MPH or Torque was achieved.)

NitrousJet:	FUEL JET NOS Pump:	FUEL JET Hi-output Pump:	HP Gain/ Per cyl.:	HP Gain/ 2 cyl.:	HP Gain/ 4 cyl.:
14	16	14	6hp	12hp	24hp
16	18	16	9hp	18hp	36hp
18	22	18	12hp	24hp	48hp
20	24	20	15hp	30hp	60hp
22	26	22	17hp	34hp	68hp
24	28	24	20hp	40hp	80hp
26	30	26	25hp	50hp	100hp
28	32	28	30hp	60hp	120hp
30	34	30	34hp	68hp	136hp
32	36	32	38hp	76hp	152hp
34	38	34	40hp	80hp	160hp
36	40	36	45hp	90hp	180hp
40	44	40	50hp	100hp	200hp
42	46	42	60hp	120hp	240hp

This is just a guideline, there are many variables such as – nozzle type and distribution block type that will change
your particular set-up. Consult your engine builder for fine tuning tips.

NITROUS OXIDE HORSEPOWER CHART PER JET

Nitrous Jet	.014	.016	.018	.020	.022	.024	.026	.028	.030	.032	.034	.036	.038	.040	.042	.044	.046	.048
HP Gain per Jet	6hp	9hp	12hp	15hp	17hp	20hp	25hp	30hp	34hp	38hp	40hp	45hp	50hp	57hp	67hp	75hp	82hp	89hp

Nitrous Jet	.050	.052	.054	.056	.058	.060	.062	.064	.066	.068	.070	.072	.074	.076	.078	.080	.090	.100
HP Gain per Jet	96hp	104hp	112hp	121hp	130hp	140hp	150hp	160hp	170hp	180hp	191hp	202hp	215hp	230hp	245hp	260hp	325hp	400hp

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Air/Fuel Ratio

Bottle Temp to Bottle Pressure ratio

N.O.S. Starting Line Jet Map

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