High speed fan only

[eighty6gt]

I've been doing some searching and poking around, I'd like to wire in a 2013 GT500 cooling fan on my car and have the factory low and high speed triggers run an 85 amp continuous duty solenoid which will run full battery/system voltage to the fan with a custom harness. Additionally, I'll have a switch inside the car to ovveride and run the fan as required to cool the car at a stop, or to help pull air through my intercooler hot side rad.

I can't see a downside - at highway speeds the air flow through the rad will still be higher than with a fan on high in town. The thermostat will control the engine's temp. The only issues would be NVH from the fan running on high, which I won't mind, and possibly running the charging system into the hole. At a minimum I could upgrade the alternator to a 2010. It seems to me the load of the fan on low with the resistor in line would be similar to the fan on high.

 

[redfirepearlgt]

1.) Are you trying to supplement the existing cooling fan with an additional or are you wanting to replace the existing fan with the GT500 fan?
2.) Are you seeking to install an over ride inside the car that will allow you to toggle the fan on/off regardless of PCM demand strategy?
3.) Why would you need an 85amp solenoid to do the job of a control relay?

It is possible using a 40 amp rated control relay to do what you seek to do. It would require to be done properly 2 relays or at least one dual contact relay. The wiring sequence would be such that when the switch inside the car is on, the PCM control outputs are removed while direct voltage from the battery feeds the fan at full speed. When the switch is off the relay releases and reapplies the signals to the fan from the PCM to once again operate under PCM control. IN addition to this the PCM strategy can be altered to turn your fan on at high speed much sooner than currently as well which would help your process. Being the GT500 fan is a direct swap out according to what I have seen, the rated fuses for the factory fan (15a on low speed and 40a on high speed) are sufficient enough to handle the GT500 fan. Therefore a 40 amp contact rated control relay with dual contacts will suffice.

 

[eighty6gt]

I'm looking at replacing the existing fan with the GT500.

The plan is to have the factory fan relays/circuit trigger the new system. Low or high speed ECU controlled relays close it, and so does a switch inside the car. The left hand won't know what the right is doing. If the override switch inside the car is on the ECU can do whatever it likes and the fan will remain on.

I don't believe it would be necessary to isolate any of the triggering circuits. They'd all be in parallel.

I wanted to try a solenoid as it's $35 and is rated for continuous duty at double the amperage. Might have an easy life.

Obviously a lot more current flowing with the high speed side. I need to look into how motors load in series with resistors and the resulting draw.

 

[46addict]

I don't think it's possible to have both. It would be simpler to have the high speed activate at a lower temp, as mentioned before. Or bypass the AC compressor and turn on Max AC from inside the car to have the fan on. Buy some spare fans because having it on more often will burn out the motor. At least the OEM GT fans did for me. I am on my third fan.

 

[eighty6gt]

Thanks for the info, I was wondering if the fan motor itself had a duty cycle other than continuous. I didn't think so, but it seems that's the case.

 

[redfirepearlgt]

Knowing the current draw of the GT500 unit is going to be the key. Some have claimed they have measured 35 amps being drawn with the GT500 fan in high speed. That is still within the tolerance of the 40 amp circuit for the factory setup, but may be pushing it a bit. Generally in electrical applications 75-80% load on a circuit is max. Therefore 32amps would be max draw at 80%. It may be beneficial if the current wiring size would allow to up the fuse to a 50 amp on the high side vice the factory 40amp fuse and 20 amp on the low size vice the 15 amp fuse.

By using a dual relay in the circuit you would be able to provide max current to the fan while isolating the output voltages from the low and high speed relays being driven by the PCM which IMHO is better than what you are thinking. In the industrial realm this is referred to a hand/auto strategy which gives direct full on override availability to the operator or returning the circuit to auto control. Isolating one control circuit form another is just good clean common sense in the electrical world. But its your car do as you wish.

I don't know your setup or why more cooling is needed but you must have a reason. I was able to obtain additional cooling simply through adding a 170 degree thermostat and having the cooling setpoints in the tune lowered so the cooling fan comes on earlier. Even in 90+ degree weather at WOT the temps don't go much above 207 on my FI setup. I thought about a larger radiator but was told it would be over kill for my application so I just went with what was recommended. Should the fan crap out its a direct swap out.

Have fun...and stay cool

 

[46addict]

By using a dual relay in the circuit you would be able to provide max current to the fan while isolating the output voltages from the low and high speed relays being driven by the PCM which IMHO is better than what you are thinking. In the industrial realm this is referred to a hand/auto strategy which gives direct full on override availability to the operator or returning the circuit to auto control. Isolating one control circuit form another is just good clean common sense in the electrical world. But its your car do as you wish.

How would one go about isolating the output voltages? Is it just a matter of adding a relay and switch in the existing circuit?
I don't have an electrical background and I'm having trouble visualizing this.

 

[eighty6gt]

This is to address a very specific circumstance - the car rotting in traffic and losing intercooler function. The OEM fan with the way I have things set up will draw a lot of air through the 2013 GT500 hot side radiator.

I plan on running all new fan wiring - I'll find a substantial ground. I am doing to add a painless/? hot point under the hood as my factory connection is getting a little crowded with the intercooler pump/fuel system wiring, wideband wiring, etc. 10 ga at a minimum on the load side.

 

[redfirepearlgt]

Yes. The relay will have two pairs of contacts. Route the high and low to the normally closed side of each pair. Route the high/low side of the fan to the common point of the contact pair. Route the override voltage wire to the normally open side on the high side pair. When the switch energizes the relay both pairs of contacts will pull closed opening the NC side and completing circuit to the NC side. This will route your output directly to the high side input on the fan while keeping the PCM controlled outputs isolated so they can do as they wish. When the switch is flipped back to off you are now giving full control back to the PCM regardless of what strategy is active. Would be a great idea to use on of those red flip covers on the switch as well so that it has to be opened to turn on the switch to bypass and then flipped closed turning the switch off and insuring the switch can't be bumped back into manual over ride accidentally.

Hope this is what you are trying to accomplish.

 

[lito]

I have this fan in my car, I barely use high speed on it, ever. (even in our hot climate).

The low speed fan beats the old fan low speed out of the water.

Just control the settings on the tune for that and it should be running when you like it.

Need good shielding so the fan will be efficient on pulling air thru the heat exchanger.

Check you fuse box for overheating and having known issues down the road.

Is not unusual of having the fan running for other things different than the radiator, it runs for the AC condenser even when ECT is low.

 

[redfirepearlgt]

This is to address a very specific circumstance - the car rotting in traffic and losing intercooler function. The OEM fan with the way I have things set up will draw a lot of air through the 2013 GT500 hot side radiator.

I plan on running all new fan wiring - I'll find a substantial ground. I am doing to add a painless/? hot point under the hood as my factory connection is getting a little crowded with the intercooler pump/fuel system wiring, wideband wiring, etc. 10 ga at a minimum on the load side.

gotcha. IS this the car with the series intercoolers ganged together that you were experimenting with last fall? Or is that another guy? Just curious.

 

[46addict]

Yes. The relay will have two pairs of contacts. Route the high and low to the normally closed side of each pair. Route the high/low side of the fan to the common point of the contact pair. Route the override voltage wire to the normally open side on the high side pair. When the switch energizes the relay both pairs of contacts will pull closed opening the NC side and completing circuit to the NC side. This will route your output directly to the high side input on the fan while keeping the PCM controlled outputs isolated so they can do as they wish. When the switch is flipped back to off you are now giving full control back to the PCM regardless of what strategy is active. Would be a great idea to use on of those red flip covers on the switch as well so that it has to be opened to turn on the switch to bypass and then flipped closed turning the switch off and insuring the switch can't be bumped back into manual over ride accidentally.

Hope this is what you are trying to accomplish.

I assume this requires splicing into the PCM pinout wires and not the wires going from the fan resistor to the fan motor?

 

[eighty6gt]

gotcha. IS this the car with the series intercoolers ganged together that you were experimenting with last fall? Or is that another guy? Just curious.

that was someone else.

The other reason I am considering doing this is to preempt the failure of the stock relay block and controls.

 

[46addict]

^I believe his user name is pentalab?

And yes doing this to bypass the stock relay block is a good idea on its own. The factory setup in the 05-09 cars have fried the BEC connections (fuse box) before blowing a fuse.

 

[07 Boss]

Just food for thought, have you ever thought about an electric H2O pump? I drive my boosted car all summer here at sometimes +115* and never has my cyl temp gauge ever gotten to the middle of the gauge. In fact it always stays a notch or two below the center where it used to sit. Adding the max coolant flow of the pump while the engine is at idle or low rpm's seems to work better than adding air flow. Just saying.

I have actually sat in the staging lanes with my engine idling and observed the gauge get cooler as I sat there. Most cars get hotter sitting like that because the pump is flowing at is minimum rate when you actually need it to flow more.

 

[eighty6gt]

I'm already using the electric pump from the 2013 GT500.

 

[redfirepearlgt]

^I believe his user name is pentalab?

And yes doing this to bypass the stock relay block is a good idea on its own. The factory setup in the 05-09 cars have fried the BEC connections (fuse box) before blowing a fuse.

Think you're right. Gettin old. LOL! Heck I am old. ROFL