Solenoids and current/amperage draw???
04-17-2007, 11:51 AM
#1
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Solenoids and current/amperage draw??? I recently posted a wiring diagram for a NOS EFI dry kit and received some very helpful feedback. Thank you. I have a couple of follow-up questions.
Some of the feedback I received revolved around how to wire the nitrous solenoids. Specifically it was suggested I NOT use the fuel pressure safety switch to directly gorund the nitrous solenoid. I have heard this from other sources as well. This is confusing me since it seems counter to what NOS themselves recommend. If the fuel pressure safety switch cannot directly safely/sufficiently ground the nitrous solenoid then why does NOS show that way on their installation diagram that way? http://www.holley.com/data/Products/...A5177-SNOS.pdf (scroll down once the instructions open to see diagram). This kit has been around for years. I would assume if people were having a problem frying the FPSS from this NOS would have changed their installation instructions?
I find this along with one other related aspect - the size of the solenoid wire leads - confusing. If the solenoids do draw as much current why is it that the manufacturer wired with them with tiny, skinny, little 20 or 22 gauge (or whatever) wire leads? If they draw that much amperage wouldn't they use something much more substantial. Doesn't that seem strange to you?
Thanks,
Matt
Some of the feedback I received revolved around how to wire the nitrous solenoids. Specifically it was suggested I NOT use the fuel pressure safety switch to directly gorund the nitrous solenoid. I have heard this from other sources as well. This is confusing me since it seems counter to what NOS themselves recommend. If the fuel pressure safety switch cannot directly safely/sufficiently ground the nitrous solenoid then why does NOS show that way on their installation diagram that way? http://www.holley.com/data/Products/...A5177-SNOS.pdf (scroll down once the instructions open to see diagram). This kit has been around for years. I would assume if people were having a problem frying the FPSS from this NOS would have changed their installation instructions?
I find this along with one other related aspect - the size of the solenoid wire leads - confusing. If the solenoids do draw as much current why is it that the manufacturer wired with them with tiny, skinny, little 20 or 22 gauge (or whatever) wire leads? If they draw that much amperage wouldn't they use something much more substantial. Doesn't that seem strange to you?
Thanks,
Matt
04-17-2007, 12:23 PM
#2
No. next question please. 
j/k. The reason for both is that different noids draw different amounts of current. The little ones with 20 ga. wire probably aren't drawing more than 3-5 amps. Which may be fine if everything inside the noid is clean and the pressure is perfect. A little too much pressure or a little dirt in the system and the noid won't work. Hence the "failed" or "faulty" noids of the past. The newer ones draw more current because they are stronger.
Look at it like a 4 cyl car going up a hill. It's takes everything it's got to try and make it, whereas a V8 will do it with little effort.
Having said all that, the FPSS on a 3-5 amp line would work ok. (still not the greatest, but ok). The micro switch inside the FPSS isn't rated for more than that. Putting it on a high current noid will eventually arc weld itself inside or just toast it completely.
j/k. The reason for both is that different noids draw different amounts of current. The little ones with 20 ga. wire probably aren't drawing more than 3-5 amps. Which may be fine if everything inside the noid is clean and the pressure is perfect. A little too much pressure or a little dirt in the system and the noid won't work. Hence the "failed" or "faulty" noids of the past. The newer ones draw more current because they are stronger.
Look at it like a 4 cyl car going up a hill. It's takes everything it's got to try and make it, whereas a V8 will do it with little effort.
Having said all that, the FPSS on a 3-5 amp line would work ok. (still not the greatest, but ok). The micro switch inside the FPSS isn't rated for more than that. Putting it on a high current noid will eventually arc weld itself inside or just toast it completely.
04-17-2007, 02:44 PM
#3
Originally Posted by Matt Kennedy
I find this along with one other related aspect - the size of the solenoid wire leads - confusing. If the solenoids do draw as much current why is it that the manufacturer wired with them with tiny, skinny, little 20 or 22 gauge (or whatever) wire leads? If they draw that much amperage wouldn't they use something much more substantial. Doesn't that seem strange to you?
Thanks,
Matt
The other thing to remember, is wire size also depends upon the length of the wire. You could have a noid with 20ga wire, but only 6" of it, and have it be fine for the current. Now move the noid 6' away, and you'll need a larger gauge wire to handle the same current draw. This is why its good to run 8' of 10-12ga wire to a bottle heater in the back of the car, from the battery up front, even if the relay only uses, say, 16ga wire from the relay to the heater elemet.
