Holley Sniper EFI + Dual cooling fan wiring help

Hijinx · Feb 23, 2021

I need help installing dual spal fans onto the Holley Sniper EFI system. I purchased 2x Mr Gasket Relays PN #40100G. From what I am able to understand…

1. I need to connect the sniper light blue wire to pin 85 on one relay & the sniper light green wire to pin #85 on the second relay.
2. Pin 86 on both relays go to the battery +
3. Pin 87 on 1 relay goes to Fan 1, pin 87 on the second relay goes to Fan 2. Both grounds on the fan pigtails go to battery ground.
4. Pin 30 & Pin 87A are un-used…

Is this all correct? Or does Pin 30 go somewhere?

Zeppelin264 · Feb 23, 2021

You are close. Just read the diagram. A relay is a switch of power on/off. You engage it with your "switch wire". So 30 goes to Battery + ( I suggest fused battery power), 85 is ground (Anything will work here), 87 isnt used(This is a constant 12v and no switching) and 86 is your EFI wiring trigger. If you are running two relays then I believe you'd Daisey chain #86 into both relays. On a normal setup.

But the Sniper is using this as a grounded switch, so it's all backwards. Ground becomes your trigger wire.

The Sniper EFI electric fan ground wires (pin C, light blue - Fan #1 & pin D, light green - Fan #2) trigger the relay coil − (terminal #85). Yes, terminal #85/Ground is the industry standard for good quality relays, with or without a diode. Sniper EFI instruction manual: LINK - page 17 & 50.

Electric Fan #1/#2 relay terminals (ECU ground signal scenario):
#85 - Ground signal from ECU Output.
#86 - Fused +12V power to relay coil.
#30 - Fused +12V power to relay contact.
#87 - +12V power to electric fan.
#87A - Not used in this application.
Terminals #30 & #87 can be reversed.

And this diagram might help too.
https://electronics.stackexchange.com/questions/167277/ground-trigger-on-relay

451Mopar · Feb 23, 2021

Someone will post a schematic, but #1 looks correct, the sniper triggers on the low/ground side, so whatever those wires colors are they would go to the relay socket 85 (White wire.) This can be smaller 18-AWG wire
#2, relay pin 86 (Black wire) goes to positive power, but you could use switched power from the key and also have a small 5 Amp fuse. This can be smaller 18-AWG wire
#3, relay pin 87 (Yellow wires) go to each fan as stated. This should be larger 10-AWG wire
#4, relay pin 30 (Blue wires) go to full un-switched battery power through 25-30 Amp fuses. This should be larger 10-AWG wire

Don Frelier · Feb 23, 2021

#10 AWG is kind of overkill for the fan.
A good quality #14 should be fine. Like an MTW stranded copper wire.

Hijinx · Feb 23, 2021

#2, relay pin 86 (Black wire) goes to positive power
#4, relay pin 30 (Blue wires) go to full un-switched battery power

is there a difference between these two? both get connected to the battery? i'm sorry not too sure what the difference is between positive power and un-switched battery power... when it comes to electrical stuff i don't know much. Thinking positive power may mean when the key is on? and un-switched means constant power like direct from battery?

diesel_lv · Feb 23, 2021

For a Spal fan, they pull a lot of amps at startup and about 25amps constant. I have run dual Spals before and will only use 10 ga wire from battery to #30 and from #87 to fan. I have used a 40 amp fuse on battery hot but changed to a 40 amp breaker. I changed because my fuses didn't blow, but the plastic would melt. The amperage creats heat.

Screenshot_20210223-200734_Amazon Shopping.jpg

This is what I used so leads were covered.

451Mopar · Feb 24, 2021

Don Frelier said:
#10 AWG is kind of overkill for the fan.
A good quality #14 should be fine. Like an MTW stranded copper wire.

The 10 AWG wire size is really looking at the 30 AMPs the relay can supply and the larger fuse size, more than what the fan pulls.
Using a 30-Amp fuse on a 14 awg wire is almost redundant because the 14 awg wire may become the fuseable link.
Usually the distance from the relay to fan is short, and most Spal fans pull less than 15 Amps (except for the large 18" Spal fan that can pull over 30 Amps.)
So a smaller size wire could work (with a smaller 20 amp fuse). I think the fan wiring is usually smaller, only about 12 or 14 AWG? it likely depends on the specific fans current draw.
The only down sides to a larger wire is cost, weight, and harness size. Electrically, the larger AWG is lower resistance and can handle higher currents.
Use automotive Cross-linked Polyethylene (XLPE) wire SAE-1128 spec (-51C to 125C temp rated) it is not much more cost. I usually use the GXL insulation thickness as it looks closer to the original wire insulation thickness. The thinner TXL can be use also, but my be less abrasion resistant if not in a loom.
The MTW wire mentioned will work (-25C to 90C temp rated) but is PCV, which can melt at the higher temperatures.

There are even better wire types like MIL-W-16876 Stranded silver plated copper wire, Extruded Polytetrafluoroethylene (PTFE) insulation.
100' of 14 AWG, black color is $223.00
Same in PVC is $22.00
Same in GXL is $25.00-26.00

https://www.hotrod.com/articles/build-relays-right-way/

Don Frelier · Feb 24, 2021

I don't disagree that a larger wire is better, just not necessary.
The connections are probably the weak point not the wire.
The wire is sized for the load X 1.25 not the fuse size.
A #14AWG 90DegC wire in free air is rated at 35Amps for 40DegC.
Yes it gets derated as the temperature goes up.
I've been running two fans on my Charger for 5 years on an old vacuum cleaner #16 wire from the scrap pile.
I'll check them this spring, I'll bet they are fine.
But my fans only run maybe 10 minutes at a time they go off driving down the road.

451Mopar · Feb 24, 2021

Just trying to say that the Higher spec GXL wire is not that much more expensive.
In the majority of auto wiring, the fuse is only to protect the wire going to the component, not the actual component.
I often run smaller sized wires too, just need to be aware of the application (acceptable voltage loss) and deratings then fuse it correctly.
Recently installed a Sniper EFI, it came wired with 10 AWG wire to the fuel pump. Part of that may be the long run length?

Just a recent observation on wire gauge, I am starting to use less 14 AWG, and more 16 & 12 AWG. Most of the lower current circuits are fine on 16 or 18 AWG which is usually the smaller wire terminal and seals, and the higher current stuff is usually 10-12 AWG requiring the larger wire terminals and seals.

Hijinx · Feb 24, 2021

The relay comes with 2 different sized wires (12 and 18 gauge wire), i am going to match the wire that came with it. I also installed a fused box (circled below) which has 30AMP fuses. Now, again if one of you guys can confirm this... Pin 30 is going straight to the battery (fused box)...

What is the difference between "#86 - Fused +12V power to relay coil." and "#30 - Fused +12V power to relay contact." are they both going to the battery? or is 30 going to battery and 86 to a "key-on" power source?

Don Frelier · Feb 24, 2021

That's alot of bling under the hood.
Your gonna need sunglasses to work on that thing.

Hijinx · Feb 24, 2021

Don Frelier said:
That's alot of bling under the hood.
Your gonna need sunglasses to work on that thing.

That's why i left the hoses black, to provide for some shade... ;)

Hijinx · Feb 24, 2021

Ok just got off the phone with Holley Sniper tech support, according to them... using 2 relays and having the fans come on/off at the same temp is the best setup.
Pin 85: Sniper light blue / light green wires one to each relay.
Pin 30: Goes to the fan's
Pin 87: Goes directly to the battery with a 30AMP fuse in between
Pin 86: Key on / switched 12 volt source.

Hope the dude is correct... hate to turn the car on and hell and damnation happens all over the place...

diesel_lv · Feb 24, 2021

Since your Sniper uses a grounded signal, the #86 can go to either a keyed on or direct to battery using the supplied 18ga wire. #30 is the direct power lead to #87. This "requires" direct battery using the 12ga supplied wire w a fuse or circuit breaker. It goes like this, #85 links to #86. One triggers the other, positive to negative. If you have a positive trigger, you have a negative on the other n vice versa. Once triggered, it closed the switch connecting #30 and #87 which is the main power to your fans. I am sure your Holley Sniper instructions go into great detail on wiring for fans. Even my ghetto Fitech gave great instructions for the fans.

451Mopar · Feb 24, 2021

Hijinx said:
Ok just got off the phone with Holley Sniper tech support, according to them... using 2 relays and having the fans come on/off at the same temp is the best setup.
Pin 85: Sniper light blue / light green wires one to each relay.
Pin 30: Goes to the fan's
Pin 87: Goes directly to the battery with a 30AMP fuse in between
Pin 86: Key on / switched 12 volt source.

Hope the dude is correct... hate to turn the car on and hell and damnation happens all over the place...

Pins 85 & 86 goto the activation coil. The smaller 18 AWG current creates a magnetic force to change the high power switch position of Pin 30 from Pin 87a to Pin 87 (on a 5-pin relay.) You can swap the polarity of Pins 30 and 87, if you never use pin 87a and don't want power on 87a in the normally closed position.

The polarity of the coil pins 85 & 86 only matters if the relay has a protection diode in it.

Here is a decent link with diagrams of the relays:

https://www.swe-check.com.au/editorials/understanding_relays.php

I staggered the on/off fan temps in the EFI software so the fans don't activate at exactly the same time/temperature.

Holley Sniper EFI + Dual cooling fan wiring help

Hijinx

Well-Known Member

Zeppelin264

Well-Known Member

451Mopar

Well-Known Member

Don Frelier

FBBO Gold Member

Hijinx

Well-Known Member

diesel_lv

Well-Known Member

451Mopar

Well-Known Member

Don Frelier

FBBO Gold Member

451Mopar

Well-Known Member

Hijinx

Well-Known Member

Don Frelier

FBBO Gold Member

Hijinx

Well-Known Member

Hijinx

Well-Known Member

diesel_lv

Well-Known Member

451Mopar

Well-Known Member

Similar threads