As Grover said, relays and fuses serve two very different functions. It's NEVER a good idea to run power directly to a relay without a fuse. When I was installing my kit, I called John Stewart (RIP) @ The Nitrous Warehouse and he gave me some recommended ratings. I don't have them handy, but I remember the solenoid one was 25 or 30 Amps. Another thing is DON'T separate the N20 and fuel solenoids...if one fuse/relay fails, you don't want the other to be able to activate.

 

Is there a max distance the relay should be away from the solenoid? Also, does the purge solenoid need a relay since it is very short duty-cycle?

Also what about my question on using the fuel relay as a switch for the n2o relay? This way both are on relays lessening the total current draw on just one, and yet the juice can't fire without the fuel relay operating. I would still have the FPSS after the fuel relay and before the solenoid as a second fail safe, and the window and WOT switches before EVERYTHING...

 

This is exactly what i did. I have one 40amp relay running both fuel and nitrous selenoids with a 30 amp fuse on the power. Then a 15 amp fuse on another 40 amp relay for the purge. The ignition fo rthe radio is running another 30 amp relay in the car that has a 20 amp fuse on it. this 30 amp relay i run to a 15 amp fuse that goes to 2 gauges, my radar, and from the fuse to my mast arm switch. the master goes to the purge switch and to my switch on my hurst t-handle. and then the purge switch goes straight to the purge relay under the hood. and the t-handle switch goes to the FP safety switch to the fuel/nit relay. confusing, but it seems to work like a charm.

 

the fuses should be as close to the battery as possible. you want to catch the short asap so it doesnt melt down. like what somehow happened to me. I just put two fire extinguishers in my car too. just to be safe. you never know. i saw a g-body burn to the ground last year at the cruise, and it wasnt that bad at first. he had to watch his car burn to a crisp...total lose. there was nothing left at all. maybe the wheels...

 

i wonder why NX doesn't specify for a fuse to be run from the relay then??? Seems like a common sense thing. Well, maybe thats the same reason they don't specify to use a window switch either...........................

 

No there is no max distance that the relay can be away from the solenoids. But asianice25 is correct that the fuse should be as close to the battery as possible.

You could use 2 relays, but it would be simplier wiring wise to just have 1 relay with both the nitrous and fuel solenoids off of that. And use your window and WOT switches to switch the 12V and the FPSS to switch the ground to the relay.

I wan't planning on using a relay for the purge. I was going test the current draw on the purge solenoid and run it off of a fused switch. Looking at the size of that solenoid compared to the others, I don't think it's going to draw much current. I will find out and let you know.

 

You don't absolutely have to, but you SHOULD use a fuse and relay for the purge solenoid as well. My experience is that they can draw up to 3A, and depending on what type of manual switch you use to activate it, that may not be enough. Lots of the Radio Shack type switches are only rated around 2A. In any case, what I've found is that people tend to tap the button quickly and that can cause large current spikes as the coils field collapses. Even better would be to put a diode across the leads like most relays have. I've got a 7A fuse on mine. If I tapped it quickly numerous times it would occassionally blow the 5A that NX originally recommended.

 

I have the pushbutton that comes with the NOS purge kit...

 

I'd hope that it's properly rated then...but couldn't tell ya, don't have an experience with NOS stuff. Even so, over time I wouldn't rely on it without a relay. Relays and fuses are cheap insurance and easy to install for a nice robust installation.

 

Fuses are put into a circuit for the purpose of protecting the WIRING not the device. If the device goes bad a fuse will not help it. The best thing to do is to fuse each solenoid separately(according to how much current it draws)(Keep in mind that it takes a lot more current to pull in a solenoid than it does to keep it pulled in too). And try to set up your system so that if you loose fuel pressure the nitrous relay will not energize. And if the nitrous solenoid takes a dump on you, the car will just run RICH. This will be an indicator that you have a problem on the nitrous side .
Keep it Safe!
Skip

 

Explain something to me please. At 10:54 you said your wiring burned up because the fuses didn't blow. Now you state it works like a charm
Skip

 

well i wired my nitrous 3 different times. I had to take it out once becauyse i had to take it into the dealership. then i put it back in and it worked fine for a year until i took it into this shop by my house for some neons. There, in their own garage it melted down for some odd reason. I think those guys messed with my wiring and fudged it all to hell. and then i just re-wired it like a week ago and it works fine...like acharm. so, im just not going to take my car in anywhere for any type of electrical work. if you want something done right...youve gotta do it yourself.