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Nitrous Express Stage 1 Proton EFI Nitrous Kit for 1990 Honda Civic

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1990 Honda Civic
Door Config  [Trim Level]
Application / Notes
(Stage 1 Plus) (10 lb Bottle) (Full Single Nozzle Kit)
(Stage 1 Plus) (15 lb Bottle) (Full Single Nozzle Kit)
(Stage 1 Plus) (5 lb Bottle) (Full Single Nozzle Kit)
(Stage 1) (10 lb Bottle) (Full Single Nozzle Kit)
(Stage 1) (15 lb Bottle) (Full Single Nozzle Kit)
(Stage 1) (5 lb Bottle) (Full Single Nozzle Kit)

Fuel Line T-Fitting
Drive by Wire Adapter (if not already included)

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Nitrous Express Stage 1 Proton EFI Nitrous Kit Description

Emissions Warning: This product is not designed for public highway or street use, and is only legal for formally sanctioned race use on a racing vehicle that may never be used on a public highway or street.

The Nitrous Express Proton Stage 1 EFI Nitrous Kit is the best entry level nitrous system on the market for Honda Civics. This is probably the best "bang for your buck" nitrous system out there. Available in horsepower levels from 35 to 150, this system is a complete bolt-on solution for adding big power to your fuel injected Honda Civic.

This system is fully adjustable and requires no engine modifications and will operate with your stock fuel pump.

Standard in Nitrous Express's Proton systems is a wide-open throttle switch and bracket. This switch eliminates unreliable push-button activation and allows the driver to use the system only at full throttle. Thus adding another degree of safety to the system. Customers with Drive by Wire vehicles (such as 2006+ Civics) will need the Drive by Wire adapter for the throttle switch to work.

Key Features:
  • In standard configuration, single nozzle Stage 1 systems add 35, 50, or 75 wheel horsepower (or about 90 horsepower at the flywheel). Stage 1 Plus systems add 35, 50, 75, 100, or 150 wheel horsepower (or about 175 horsepower at the flywheel).
  • Piranha Nozzle with mounting bung. Proton Stage 1 Plus kits include the Patented Shark Nozzle instead.
  • Proton Series integrated solenoid that uses one unit to control the fuel and nitrous delivery. Having a single unit makes installation and wiring easier and less obtrusive.
  • Nozzle Adapter (on Proton Stage 1 Plus kits only).
  • Limited Lifetime Warranty Solenoids.
  • Proton Stage 1 Plus kits feature a Lightning 45 Bottle Valve featuring an integrated gauge port, an integrated push port, a large .325 orifice and an improved flow path with only one 45 degree turn.
  • Wide-open throttle switch (on Proton Stage 1 Plus kits only).
  • Master arming switch.
  • Push button switch (for standard Proton kits).
  • 40 Amp relay and relay harness, 1/4 inch fuel T fitting, and stainless bottle brackets.
  • 24 inch D-3 stainless braided solenoid to nozzle lines, 15 foot D-4 stainless braided nitrous feed line, 18 inch D-4 fuel feed line, and nickel plated fittings.
  • Proton Stage 1 Plus kits include every nut, bolt and electrical connector needed to complete the installation.
OPTIONAL FUEL LINE T-FITTING NOTES: This is a 5/16" Hose Barb to 4AN Male fitting recommended for use with older vehicles where a fuel line will need to be cut to feed fuel into this nitrous system.

Nitrous FAQ

Q: What is the difference between a WET and DRY nitrous system?
A: A WET nitrous system automatically adds the proper amount of fuel with the nitrous, which allows for safer operation and eliminates the need to re-calibrate the factory computer. A DRY system relies on the fuel injectors to supply the extra fuel. Since nitrous is not distributed equally to all cylinders, a DRY system can result in a lean condition, which may cause damage to the engine. All Nitrous Express kits sold here are WET systems (also called "foggers" because of the fine mist of N20 and fuel they shoot out).

Q: Do I need to purchase anything else?
A: You don't have to, but we highly recommend getting the Nitrous Express GenX or GenX-2 accessory kit. They add some important safety and convenience features. If you decide not purchase either of these, we HIGHLY suggest getting a nitrous pressure gauge because using nitrous at the wrong pressure can lead to decreased performance and possibly engine damage. Purchasing the automatic bottle opener is optional.

Q: Why not just use a supercharger or turbocharger?
A: There is no right one to choose, it depends largely on personal preference and budget. Some people just like nitrous better because it is much less expensive and only comes on when you want it to.

Q: Will it cause engine damage?
A: Nitrous, like any other big power modification, is only dangerous if it is installed or used incorrectly. Today, the nitrous systems available to the consumer market are so well designed and fine-tuned that they are literally plug-and-play. Still, Nitrous Express systems include numerous automatic and manual safety features to eliminate any chance of engine damage. Given you follow the basic guidelines presented in this FAQ, the only way you can cause damage to your engine is if you activate the nitrous at a low rpm (2500 or below) in a high gear. This is because the engine will not be able to rev "freely" and may detonate.

Q: How much nitrous should I use and what is a "shot"?
A: A "shot" is simply how much horsepower you will get. Nitrous Express, unlike other manufacturers, measures their systems using "wheel horsepower" (whp), which is usually about 15% less than standard flywheel horsepower (hp). So a NX 50 shot will give you 50 whp and about 59 hp. Keep in mind that your torque will go up much more than your horsepower, and will come in at a lower rpm. This will have the effect of forcing you back in your seat when you activate the nitrous. Nitrous Express is also unique compared to other nitrous companies in that they offer a 35 shot designed specially for new nitrous users. This is a great option to have if you are just beginning and are unsure about using large shots.

Which shot you actually use depends on how much power you want, and how much your engine can handle. Here are some specific guidelines for running each type of shot. If you follow these guidelines, your car will remain free of any abnormal wear and tear. If you have an old car, you should do a compression or leakdown test before using nitrous. This will ensure that you engine is in sound mechanical condition and will prevent any problems down the road. This is true with any big power modification.

35-40 Shot: You shouldn't need to purchase anything but 1 degree colder non-platinum spark plugs (iridium is preferred).

50 Shot: Get a set of 1-2 degree colder non-platinum spark plugs, preferably iridium. If you have an older car with a distributor, you may want to get an aftermarket ignition and spark plug wires, as this can yield more power and also provide an added measure of safety.

60-75 Shot: Same as 50 shot, but you should retard ignition timing by 2-3 degrees to be safe. Definitely get an aftermarket ignition and wires if you have a distributor. You may also find you need a stronger clutch. It would be a good idea to get an air/fuel ratio gauge to see if you are running lean or rich, and then correct it with a fuel pressure regulator or ecu controller.

90-100+ Shot: Mandatory to do everything mentioned in the 60-75 shot plus you should upgrade your engine internals (forged pistons, rods, etc.). A stronger fuel pump will be needed too. Dyno tuning is recommended as well.

Q: How should I mount the bottle?
A: Mount it at about a 15-degree angle with the valve end higher and pointing towards the front of your vehicle.

Q: What should I know about nitrous pressure?
A: Keep it between 900-1050 PSI. A warm bottle will have a higher pressure than a cooler one. On the NX gauge, the needle will be in the green area if it is safe to use. If it is too low, you will not get enough power, too high and it can cause damage. Too heat up the bottle, use a bottle warmer (included in the GenX accessory kits). To cool it down, use a wet towel or chamois.

Q: How long does a bottle of nitrous last?
A: You use about .8 lbs of nitrous for every 10 seconds of use on a 100 shot application. For other shots, divide the above usage by the correct amount (e.g. a 50 shot will use .4 lbs every 10 seconds). Nitrous costs about $2.00 - $3.00 a pound.

Availability and Condition: Unless otherwise noted, this product is in brand new condition and usually in stock at one of our warehouses, or will ship directly from the manufacturer.

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