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Nitrous Oxide Jet Calculator

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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.

If you have a Palm PC running PalmOS 3.5 or later, or want to have a version that runs on your Laptop/Desktop PC, CLICK HERE.

Wanna see the car that I have the Nitrous Oxide installed on? It is my 1991 Geo Storm. Yea, yea. . .you say that now, but I'll still smoke you. Checkout my Storm project and the modifications I have done!

Until next time; "Get in, sit down, shut up, and hang on when I push the fun button!"
-Robie

The Nitrous Jet Calculator will help you calculate Horse Power ratings for jets used in nitrous oxide systems. If you are using a 'wet' setup, you can calculate what the Fuel Jet size is by filling out the nitrous pressure and fuel pressure fields for a given Nitrous Jet.

To see the other downloadable versions of the Nitrous Jet calculator for the Palm and your computer, CLICK HERE

Fuel Pressure (PSI):
(info only needed if you are using a 'Wet' setup)

Nitrous Bottle Pressure:
(info only needed if you are using a 'Wet' setup)

Nitrous Jet Size:Thousandths of an inch.
(Will calculate Horse Power(HP) rating for jet)

Number of Jets/ports:
Single fogger/direct port/etc...




Results

The Fuel jet size should be 0.000" or 0.000mm

A Nitrous jet size of [NJ]" or mm should produce:
0.00 HP with [NP] port(s)

Actual HP to the wheels: 0.00 HP


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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

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

 

 

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