Manually turning on high speed fan to cool down between staging (dragstrip)

[venom1997]

Hey guys I know of the high speed cooling mod where you tap into pin 46 light green purple stripe on the ecm harness passenger kick panel and run it to a ground. However is there another way to do this under hood? I removed all my A/c system and the harness to the high pressure ac switch is just zip tied out of the way it has 4 wires going to it and one I probed has 12 v with key on. Would I be able to jump anywhere on that harness to run the high speed fan?


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[9397SVTs]

You could put a relay near the fan, run the switched power to the fan and activate it with a fused toggle switch inside the car.

I did this on one of my cars and it worked great. I also added in a small LED, so I knew power was passing through the switch.

 

[I_like_turtlez]

You could put a relay near the fan, run the switched power to the fan and activate it with a fused toggle switch inside the car.

I did this on one of my cars and it worked great. I also added in a small LED, so I knew power was passing through the switch.

This is the proper way to do it, never splice into or jump pins, you can draw too much current and cause a fire; fuse &/or relay is a must

 

[venom1997]

This is the proper way to do it, never splice into or jump pins, you can draw too much current and cause a fire; fuse &/or relay is a must

I just did the high speed fan mod (grounding pin 46 on the ecm) its basically doing what the computer does naturally when the ac is on or if your coolant temp gets to the temp where it kicks your high speed on. It works great most guys don’t do it properly they use those crimp together splicers I soldered it makes for a solid connection and no chance to loosen. I’ve tested it now for the last couple weeks if just idling and not getting air through the radiator my temps will start approaching 185-190 (my low speed is set to come on at 190 and shuts off at 185) if I turn my high speed on at say 188 it takes about 20 seconds to drop back down to 166 perfect if you are in traffic and want to stay cool. Or at the drag strip and need to cool the car down between passes. Once the car starts moving the fan isn’t even needed above say 20-25 mph in my case


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[venom1997]

Being I have a non intercooled twin screw, coolant temps in the 160-170 range makes the car happy it really helps with iat temps pre and post


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[01yellercobra]

That's impressive it runs that cool and cools off that fast.

 

[I_like_turtlez]

I just did the high speed fan mod (grounding pin 46 on the ecm) its basically doing what the computer does naturally when the ac is on or if your coolant temp gets to the temp where it kicks your high speed on. It works great most guys don’t do it properly they use those crimp together splicers I soldered it makes for a solid connection and no chance to loosen. I’ve tested it now for the last couple weeks if just idling and not getting air through the radiator my temps will start approaching 185-190 (my low speed is set to come on at 190 and shuts off at 185) if I turn my high speed on at say 188 it takes about 20 seconds to drop back down to 166 perfect if you are in traffic and want to stay cool. Or at the drag strip and need to cool the car down between passes. Once the car starts moving the fan isn’t even needed above say 20-25 mph in my case


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I can see the benefit of manually turning on the high speed fan to cool down faster between drag passes

And good, whenever you're dealing with a circuit that goes directly into the PCM you NEED to solder & heat-shrink, those wires operate in mere millivolts/milliohms, it's easy to deep-fry a PCM

165F is honestly too cold, modern engines like these are designed to operate around 200-215F; below 180F you start to get condensation building up in the oil/crankcase, it'll often present as a white sludge under valve covers or on a dipstick

Engine efficiency also nosedives, closed-loop idle and operation occurs around 170F for most vehicles

Running a cooler thermostat was a popular trick back in the 1960's when every engine was cast-iron from top to bottom, they struggled with temps on hot summer days; our all-aluminum engines dissipate heat much faster by comparison(obviously boost will create a lot more heat)

You'll probably be fine as a dedicated drag car that gets constant oil changes but not sure I'd daily drive one this way

Last summer I was driving mine home stuck in traffic for 600 miles while it was 108F outside with a 26 year old radiator, I don't get the sensation these cars have cooling issues when naturally aspirated & maintained



Edit: What's your blower setup anyway, I meant to ask a while back. I think it would be pretty cool to "Terminator" my car, would hurt a lot of Scatpack's feelings

 

[venom1997]

That's impressive it runs that cool and cools off that fast.

I also removed all the ac stuff and condenser so I’m pretty sure it helps with air flow cooling the radiator and that reishe 4D thermostat is amazing it’s fully open by 170 and half open at 165


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[venom1997]

I can see the benefit of manually turning on the high speed fan to cool down faster between drag passes

And good, whenever you're dealing with a circuit that goes directly into the PCM you NEED to solder & heat-shrink, those wires operate in mere millivolts/milliohms, it's easy to deep-fry a PCM

165F is honestly too cold, modern engines like these are designed to operate around 200-215F; below 180F you start to get condensation building up in the oil/crankcase, it'll often present as a white sludge under valve covers or on a dipstick

Engine efficiency also nosedives, closed-loop idle and operation occurs around 170F for most vehicles

Running a cooler thermostat was a popular trick back in the 1960's when every engine was cast-iron from top to bottom, they struggled with temps on hot summer days; our all-aluminum engines dissipate heat much faster by comparison(obviously boost will create a lot more heat)

You'll probably be fine as a dedicated drag car that gets constant oil changes but not sure I'd daily drive one this way

Last summer I was driving mine home stuck in traffic for 600 miles while it was 108F outside with a 26 year old radiator, I don't get the sensation these cars have cooling issues when naturally aspirated & maintained



Edit: What's your blower setup anyway, I meant to ask a while back. I think it would be pretty cool to "Terminator" my car, would hurt a lot of Scatpack's feelings

Yeah I don’t daily this car it’s pretty much just a “mexico” trip if you know what I mean and it will be trailered to the drag strip so I’m not to worried about it. It’s a pretty decent set up considering it’s a tiny 1.5l kenne bell I had made a huge modification back in 2015 and re fabricated the blower I let to flow better just that alone and not changing the blower pulley jumped my boost from 9psi to 12 that indicated the factory kenne bell inlet was a huge restriction. In then upped the boost some more to 14 psi with the smallest pulley they make added 2 water alky nozzles one pre rotor and one under the blower into the hot side. I fabricated a bypass as well to cool it down. With the water alcohol spraying my IAT2 are about 100 degrees on a 60-70 degree day not bad considering I’m spinning the blower to 19000 rpm. If I don’t spray my iat2 gets 250-275. Before I did all of this the car made 450 rwhp, after everything it was just shy of 550 rwhp. I’m happy with it as it only weighs sub 3000lbs. In this current set up it will hurt hellcats feelings lol


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