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[Hayabusa]

The Most Common Questions about Nitrous and the SRT4. Read this Before Posting any Questions.


Here are some of the most common questions that have come up in this section. If you don't find an answer here or in one of the other stickys please ask. This will be updated as needed.

1. You can safely run a 75 shot of nitrous on almost any SRT4 regardless of power levels if you follow all the advice in this and other stickys. If you have a 600hp SRT4 you wouldn't be asking this question so you don't apply here.

2. You MUST use a wet kit, or a direct port system with the SRT4. The SRT4 does not have a mass airflow system so it can not see the extra air coming into the engine so will not adjust the air/fuel ratio accordingly.

3. You will adjust the air/fuel ratios by changing the fuel jet. This is why you have a wet kit. A wet kit injects both nitrous and fuel into the engine. It is best to start with a jet two sizes larger than recommended and work your way down from there. You do not need larger injectors, the FPR mod, or any other mod to run nitrous or adjust the air/fuel ratio.

4. You may or may not need a new fuel pump. For most cars you won't need one with less than 350hp. A new fuel pump is cheap and easy insurance regardless of whether or not you need it.

5. What kit you get is a personal choice. There are lots of great companies that sell kits. Zex, DynoTune, NOS or Nitrous Oxide Systems, Cold Fusion, NX, and Edelbrock are just a few that you can choose from. Just because I have not mentioned one here does not mean I wouldn't get there kit. You can buy a kit new or used. Just make sure you get a kit with all the basic parts. You can buy the safety devices separate. Although I do not recommend a name brand of kit I will state that Modern Performance carries kits, and safety devices. I have used Modern Performance for almost everything I have on my car. They have great customer service, great prices, and will help you with any problems you have. Just shop around and find a kit that suits you, your price range, and your goals. You can spend a little or a lot, but in the end the power is all the same. On that note Zex rates there jets different than most companies and there parts are not interchangeable with kits from other companies. This is not to say you shouldn't get a Zex kit, it is just something to keep in mind when shopping.

6. You will need to find a way to tap into your cars fuel system. If you have an 03 SRT4 it will have a Schrader valve and you are lucky. You can tap into the fuel rail using the Schrader valve. If you don't have an 03 I would recommend you get a new fuel rail. You can either find a used 03 fuel rail (Mopar does not sell the fuel rail with the Schrader valve even if you order an 03 fuel rail,) or you can get an aftermarket fuel rail. Perrin and Boomba, to name just two, have great fuel rails. The Boomba fuel rail has more ports than you will ever use and is a great looking piece. It however is far from stock looking. You can tap into the fuel system by other means but I do not recommend it. If you want to look into this check out the sticky "Nitrous Install Made Easy." If you scroll through all the posts in that sticky it will give you alternatives to getting a new fuel rail. Do not ask me for advice on this as I will not give it. I recommend you just get a new fuel rail.

7. As a minimum for safety I would recommend that you get a window switch, and either a WOT switch (wide open throttle), or a TPS switch (throttle position sensor.) A wideband is also one of the things I would highly recommend. You can get by without it if you can read spark plugs very well, or you tune your system on a dyno. If you do not have a wideband I would first tune the system on a dyno where you can check your air/fuel ratios. After you have tuned it on a dyno you can just check your plugs after you use the nitrous. You will need to check the plugs often, and check all the plugs. If you do not take my advice and get a wideband, or tune it on a dyno then at least start with the smallest shot you have and slowly work your way up. At the higher levels if you make a mistake and run to lean you can cause severe damage to your pistons, even melt holes in them. If you have a wideband I would start small and work your way up. If you are tuning it on a dyno then you obviously will have to start with the size shot you are going to use unless they don't charge you for more than a few runs.

8. On an SRT4 using nitrous as an intercooler sprayer is not only a waste of money, it is useless. If you are going to use nitrous use it in the engine. If you are worried about your engine either don't use nitrous and go to the water/methanol section, or put it in your engine and use a smaller shot.

9. You can use nitrous with stage 1, 2, or 3 but it is not needed. If you have stage 2 or 3 with toys do not use nitrous in HOM. The advanced timing will cause much greater pressure inside the cylinder and could cause damage to the internals, detonation, or worse.

10. You can run a nitrous system with just a basic kit without any safety devices, but neither I nor anyone on this board would recommend it. No matter how good of a driver you are, or how much experience you have with nitrous will protect you or your engine should you make a mistake without it. Even professional drivers use as many safety devices as they are allowed by there sanctioning bodies.

11. Besides the basic upgrades you will make when installing your system there are other things you should install. At a minimum motor mount inserts and transmission mounts are recommended.

12. You do not have to upgrade your clutch or axles when using nitrous. However as with all methods of increasing power these parts will be more susceptible to wear and tear from the additional power. Eventually they will wear out, and possibly break. This is something you will just have to accept no matter where you get your power from.

13. You can use nitrous in any gear you want. If you have the traction to use it you can use nitrous in first gear as long as you do not have it activate before 3000rpms. Using nitrous in first gear, while launching, is how Das was able to cut 1.7 60ft times with basically a stock car and slicks running a 120 shot from a direct port system. This is also how he ran sub 12 second quarter mile times with the stock turbo etc.

14. You can expect to easily run 12.XX second quarter mile times running nitrous and slicks on the stock turbo. It is possible to break into the 12's on stock tires if you are a really good driver. If you are lucky you will be able to get into the 11's running nitrous with very few other upgrades, but you will have to be a great driver.

15. You will need a nitrous pressure gauge, it can be bottle mounted. You will also need a bottle warmer unless you live in an area where the bottle will stay at 85 degrees or higher. The reason for this is that the bottle pressure has to be at least 900psi to achieve the power you expect from your jets. If you are using jets rated at 75hp and the bottle pressure is lower than 900psi you will not get 75hp. The lower the bottle pressure gets, and it drops fast when it cools off, the less power you get. If you have only 600psi you would be lucky to get any power at all. All you would be doing is adding extra fuel and very little nitrous, you may even lose power due to the rich mixture. Zex claims that there kits prevent this. They do prevent you from running rich, but they are not able to keep the power that is rated by the jets. At less than ideal bottle pressures even the Zex kits lose power exactly like any other kit, they just dont add the same amount of fuel.

16. You need to run a colder plug than stock. A good plug is the NGK4306 gapped to .035

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