Solenoids wired in series

I'm close to finishing up the install of a safe nitrous system (with a load of help from one of our resident N2O gurus).

Heres a question: I want to protect against the future possiblity of a bad fuel solenoid coil. Can I run the fuel and N2O solenoids in series? My thought is that the current would have to flow through both before both would activate; But I haven't thought through what that would do to the voltage and current through each and if they'd operate properly in this arrangement.

If not, I was thinking about running a seperate fuel solenoid relay and triggering the N2O solenoid off the fuel relay (so if the fuel solenoid sees current from a completed circuit, the N2O relay will trigger).

I know, I'm making this more complicated than it needs to be and I should just spray it, but it's easier to do this than pull a motor and spend big bucks on a new engine. (I'm also thinking of plumbing a second nitrous solenoid, but that'll be for later).

 

I installed it the normal way for now (parallel).

The only way I could wire it with the 2 relays like I wanted would have had the current from the fuel solenoid running through the relay trigger (magnetic coils) and I figured the relay wouldn't like that too well. I'm sure there's a way with a resistor or diode, but I don't know enough about electronics to figure that one out....yet.

 

No, if you put two solenoids in series, they will see only see 6 volts each.
They need to be wired in parallel so they each receive 12 volts.

The relay idea isn't foolproof either. A solenoid is basicly a coil, that when energized, will pull open a valve. Here's one failure scenario: A solenoid coil can still energize, but it's possible the valve portion could hang up....and your relay would think all is well and open the NOS solenoid.
I'm not an expert on NOS systems, but I would think some sort of fuel pressure (or flow) activated switch to trigger the NOS solenoid would be the only foolproof way to do what you wish. It must have been done before, hope you find the solution :TU:

 

Thanks Walt. That makes sense.

I have a hobbs switch that is pressure activated to keep or turn the entire system off unless there is enough fuel pressure, but it's on the upstream side of the solenoid. I think if there was a way to sense flow or pressure on the downstream side, that's the way to go. Sounds like a good idea.

 

The nitrous solenoid pulls @9 amps and the fuel only draws 1.2 amps. The fuel solenoid coil would burn up with the current of the nitrous coil pulling thru it. If you could find a relay with a switching coil rated at the same as the fuel coil then you could run a parrallel curcuit using a relay to activate the nitrous coil. The closest coil relay pulling close to the same current as the fuel is a starter relay on 80's model Ford's, that I know of.

I wouldn't be too worried about it, failures on the fuel side are very rare. I have never heard of any.

I wouldn't give a second thought to running a second nitrous solenoid unless it was for a second stage of Nitrous. You are just asking for more pressure drop and having to figure out new jetting due to the added restriction.

 

Yeah, I gave up on the idea (for now). Maybe in the dead of winter I'll be bored and figure something out just for the sake of tinkering.

On the 2nd solenoid, I also figured heck, how would I know if one went bad without checking them both all the time anyway. I might as well check or rebuild the one I have routinely.

Look for a report back soon, prolly around the same time you get your fogger down the track.

(I just realized that what you were spraying with your plate system was almost equal to what I'm making on motor alone!)

 

You can't wire them in series, they have to be in parallel.

As a point of interest, my fuel pressure cutoff switch only shuts off my nitrous solenoid. My fuel solenoid would stay open.

Also, every solenoid has a pressure drop that "warms" the nitrous, so adding an extra solenoid will decrease performance.

-Bob C.

 

Why is yours set up this way? I set mine up in series with the WOT switch so that if i lose fuel pressure the entire system is inoperable