Cooling fan upgrade comparison: Explorer 11-blade fan and HD clutch versus SPAL 19" 850-watt electric brushless fan

[Steel City 06]

I'm glad this got addressed, because it's the biggest reason I might actually consider this mod.

Since gasoline engines are only about 30-35% efficient, and of the total power input about 30% goes out the radiator and the other 35-40% goes out the exhaust, it really is about 1:1. 5hp saved becomes about 3700W or 12,700BTU/h reduction in cooling system load.

I think this could be why you can find all over the Internet, people who claim to have fixed a highway overheating issue by replacing a fan clutch.

There's a lot of unknown variables but it wouldn't be completely out of the question for 5hp to be worth 10F of ECT. I base that assuming it probably takes about 60hp to maintain highway speed, which is ~153,000 BTU/h, and if the fan is 5 of that hp that gets rid of 8% of the required LMTD, which is will show up primarily in the difference between the ECT and the entering air.

An easy way to calculate horsepower required in steady state is simply MPG. A gallon of gasoline has about 45 horsepower-hours of heat. If we assume a 33 percent efficient engine, then we get about 15 horsepower-hours useful work out of a gallon of gas.

If you get 15 mpg at 75 mph, you are consuming 5 gallons per hour, or an average engine output of about 75 horsepower-hours per hour, or simply 75 horsepower. This is also roughly equivalent to the heat you need to dissipate.

Also useful for determining fuel consumption due to electric use. If we assume the alternator is 50 percent efficient, then we get about 7.5 horsepower-hours of electricity out of a gallon of gas, or about 5.5 kWh.

 

[freedom_in_4low]

An easy way to calculate horsepower required in steady state is simply MPG. A gallon of gasoline has about 45 horsepower-hours of heat. If we assume a 33 percent efficient engine, then we get about 15 horsepower-hours useful work out of a gallon of gas.

If you get 15 mpg at 75 mph, you are consuming 5 gallons per hour, or an average engine output of about 75 horsepower-hours per hour, or simply 75 horsepower. This is also roughly equivalent to the heat you need to dissipate.

Also useful for determining fuel consumption due to electric use. If we assume the alternator is 50 percent efficient, then we get about 7.5 horsepower-hours of electricity out of a gallon of gas, or about 5.5 kWh.

I like that approach and it seems probably a more accurate way to get there because there's one fewer layer of calculation involved.

I used 40% as a ballpark Load I remember seeing in the OBD2 scanner, which as I'm sure you know is calculated based on the MAP and TPS. 40% of 235 lb-ft is 94, which is 57hp at 3200rpm and I rounded up to 60 because I didn't think my math called for more than 1 significant figure. If I just remembered wrong and load runs closer to 50% then my number would line up very close to yours.

 

[Steel City 06]

Very interesting article. Thanks for digging deep and sharing with us.

One thing worries me a bit. I'm not sure I want to put this additional full-time load on my electrical system, say 30 amps (normal) to 70 amps (extreme conditions). How capable is the OEM alternator for handling this load?

Highest peak I measured was about 60 amps flat at running voltage (14.3V). Engine off it will be higher, maybe closer to 65 amps due to the lower voltage.

I do have a Durango alternator, specifically the 180 amp Remy alt. This is a good thing to consider when looking at this fan.

That said, the brushless fans are way more efficient than the aftermarket brushed fans (like Mishimoto, SPAL brushed series, etc.) you find all over the internet. Think of it like the Milwaukee Fuel tools compared to their cheaper non-Fuel counterparts.

 

[Apparition]

Now you have me thinking I’ll use this fan. I need to figure out how it’ll play with my 6.2 LS3, seems it may actually make things easier since I’m running an LS harness and ECU but I need to do some digging. Thanks for posting it up, didn’t realize it was an option.

 

[Steel City 06]

Now you have me thinking I’ll use this fan. I need to figure out how it’ll play with my 6.2 LS3, seems it may actually make things easier since I’m running an LS harness and ECU but I need to do some digging. Thanks for posting it up, didn’t realize it was an option.

The ECU simply needs to offer a PWM low signal, meaning it switches to ground (floating otherwise) at I think 100 Hz or 128 Hz. The function on SPAL OEM fans is reversed from their aftermarket brushless fans as a means to discourage people from repurposing OEM fans, so you won't be able to use a SPAL aftermarket controller. Both take PWM low at the same frequency, but in OEM fans, min PWM yields max speed, whereas aftermarket, min PWM yields min speed. But given you have a GM ECM, it may indeed be able to provide the correct signal.

So you certainly may be able to skip the external controller altogether. You'd just need to find the correct ECU pin and hook it up, and tune in the fan control details.

 

[NashvilleTJ]

Now you have me thinking I’ll use this fan. I need to figure out how it’ll play with my 6.2 LS3, seems it may actually make things easier since I’m running an LS harness and ECU but I need to do some digging. Thanks for posting it up, didn’t realize it was an option.

Don't worry, Ryan. LS = Low Power = Low heat. Stick a cheap Chinese 10amp fan in there and call it good.

 

[Mike_H]

Don't worry, Ryan. LS = Low Power = Low heat. Stick a cheap Chinese 10amp fan in there and call it good.

You saw the picture of it sitting in the crate still, after about 3 years, right? I'm not going to get into the LS vs hemi thing, but I do know an engine in the crate doesn't need a whole lot of cooling!

 

[Apparition]

You saw the picture of it sitting in the crate still, after about 3 years, right? I'm not going to get into the LS vs hemi thing, but I do know an engine in the crate doesn't need a whole lot of cooling!

I only ordered it 2.5 years ago. It took a year to show up and I’ve been busy since. Plus my reason for a second Jeep has been unable to wheel.

 

[Jezza]

The horsepower loss from the factory fan is actually something I want to test on my TJ. I was planning on doing some dyno pulls with the factory fan and clutch, then trying to lock up the clutch, and then with no fan connected similar to running an electric. Has anyone tried to use the JK fan? I like the idea of the brushless, but it seems complicated and expensive compared to the old school electric fans.

 

[Steel City 06]

The horsepower loss from the factory fan is actually something I want to test on my TJ. I was planning on doing some dyno pulls with the factory fan and clutch, then trying to lock up the clutch, and then with no fan connected similar to running an electric. Has anyone tried to use the JK fan? I like the idea of the brushless, but it seems complicated and expensive compared to the old school electric fans.

The brushless is actually way simpler to set up than an old brushed fan. No relay required. You simply hook it to battery with a fuse or circuit breaker. The only "complex" part is providing a signal to tell it what percentage of speed to run. (You could easily do this with an Arduino and a transistor without much trouble at all.)

The older brushed fans you were limited to 2-3 speeds using mechanical relays, or you'd have to use solid state relays to amplify the PWM signal to the entire power supply to the fan.

 

[D's Jeep Wrld]

The brushless is actually way simpler to set up than an old brushed fan. No relay required. You simply hook it to battery with a fuse or circuit breaker. The only "complex" part is providing a signal to tell it what percentage of speed to run. (You could easily do this with an Arduino and a transistor without much trouble at all.)

The older brushed fans you were limited to 2-3 speeds using mechanical relays, or you'd have to use solid state relays to amplify the PWM signal to the entire power supply to the fan.

Heck doesn't Derale make a PWM fan controller for their fans ? I've see it a few times and it pulls temp. Readings with their sensor you can adapt or use your stock one and etc. iirc.

I wonder if Spal makes their own PWM fan controller that makes it a "seamless" system persay,or like you said and make your own controller.....somehow
But hey the lingenfelter seems to do the trick! As long as it works

 

[freedom_in_4low]

Heck doesn't Derale make a PWM fan controller for their fans ? I've see it a few times and it pulls temp. Readings with their sensor you can adapt or use your stock one and etc. iirc.

I wonder if Spal makes their own PWM fan controller that makes it a "seamless" system persay,or like you said and make your own controller.....somehow
But hey the lingenfelter seems to do the trick! As long as it works

I believe he addressed that in an earlier post, that virtually all, if not all the aftermarket controllers use a PWM signal that is inverted from what his OE fan uses with respect to min vs max PW to convey min vs max speed.

 

[Steel City 06]

I believe he addressed that in an earlier post, that virtually all, if not all the aftermarket controllers use a PWM signal that is inverted from what his OE fan uses with respect to min vs max PW to convey min vs max speed.

Correct.

The Derale PWM controller is specifically designed for a brushed fan, and contains solid state relays to amplify the signal to the entire fan power supply. In essence, it's not providing a signal to tell the fan - it is literally throttling the whole power supply for the fan. If you tried to do that to a brushless internally controlled fan, it either wouldn't run, or it would fry it very quickly.

The SPAL aftermarket brushless fan controller will in fact run a SPAL OEM fan, just not in a way you'd really want. The fan would turn on at 100 percent once the low temp was reached, and then slow down to 5 percent as the temperature heats up to the maximum setpoint.

The other thing I don't care for about the SPAL controllers is that the temperature bands are very narrow and are not adjustable. 165 to 185 might work in our application, but would lead to a LOT of temperature cycling. Realistically you'd probably have to plug that into the heater core circuit instead and just eat the wasted fuel from spinning the fan on the highway.

The Lingenfelter is probably one of the best aftermarket fan controllers I've seen. It will run OEM SPAL brushless fans, aftermarket SPAL brushless fans, and pretty much anything else that accepts a PWM signal as a function of temperature. Just have to turn a switch to the right position. So you could use it to drive an OEM electric water pump the exact same way, or even something for the exhaust. If you pair it with a sufficiently large solid state relay, you could easily set it up to drive cheaper brushed fans (of any brand) as well, just with less efficiency and airflow. It also has widely adjustable min and max temperature setpoints, and you are also not bound to a particular temperature difference between the two. Might get more versatility with an Arduino and custom firmware, but that would take hours of coding to get right.

 

[freedom_in_4low]

Correct.

The Derale PWM controller is specifically designed for a brushed fan, and contains solid state relays to amplify the signal to the entire fan power supply. In essence, it's not providing a signal to tell the fan - it is literally throttling the whole power supply for the fan. If you tried to do that to a brushless internally controlled fan, it either wouldn't run, or it would fry it very quickly.

The SPAL aftermarket brushless fan controller will in fact run a SPAL OEM fan, just not in a way you'd really want. The fan would turn on at 100 percent once the low temp was reached, and then slow down to 5 percent as the temperature heats up to the maximum setpoint.

The other thing I don't care for about the SPAL controllers is that the temperature bands are very narrow and are not adjustable. 165 to 185 might work in our application, but would lead to a LOT of temperature cycling. Realistically you'd probably have to plug that into the heater core circuit instead and just eat the wasted fuel from spinning the fan on the highway.

The Lingenfelter is probably one of the best aftermarket fan controllers I've seen. It will run OEM SPAL brushless fans, aftermarket SPAL brushless fans, and pretty much anything else that accepts a PWM signal as a function of temperature. Just have to turn a switch to the right position. So you could use it to drive an OEM electric water pump the exact same way, or even something for the exhaust. If you pair it with a sufficiently large solid state relay, you could easily set it up to drive cheaper brushed fans (of any brand) as well, just with less efficiency and airflow. It also has widely adjustable min and max temperature setpoints, and you are also not bound to a particular temperature difference between the two. Might get more versatility with an Arduino and custom firmware, but that would take hours of coding to get right.

Is it a purely proportional control or does it use integral and derivative?

 

[Steel City 06]

Is it a purely proportional control or does it use integral and derivative?

I believe proportional. PID would be very difficult to program in this case due to the rapid fluctuations. We're creating a pretty rapid negative feedback loop, compounded by the fact that both the fan and the thermostat are reacting independently.

Modern ECMs actually predict cooling needs in advance by following engine load rather than using PID. Many of them have electric thermostats that are ECM controlled. Some ECMs don't even have a set coolant temperature and set the target temperature based on load. So it might run 240° on the highway at low load for fuel economy, but 180° during high load to allow more advanced timing without detonation.

 

[freedom_in_4low]

I believe proportional. PID would be very difficult to program in this case due to the rapid fluctuations. We're creating a pretty rapid negative feedback loop, compounded by the fact that both the fan and the thermostat are reacting independently.

Agree. I tune PIDs a lot and they can be hard enough to someone that understands how they work. I don't like it but sometimes you have to settle for "at least the continuous oscillations aren't full scale". There are some tuning techniques out there but they would be difficult to execute on a vehicle without a dyno and HVACR loads don't change anywhere as quickly.

Modern ECMs actually predict cooling needs in advance by following engine load rather than using PID.

That's cool, we do the exact same thing, but based on compressor load. Some companies call it "feed forward". We do it primarily for system stability, because rapid changes in a refrigeration circuit lead to undesirable things like a $20k compressor trying to compress things that aren't compressible.

Many of them have electric thermostats that are ECM controlled. Some ECMs don't even have a set coolant temperature and set the target temperature based on load. So it might run 240° on the highway at low load for fuel economy, but 180° during high load to allow more advanced timing without detonation.

Yeah, I've had a couple of those. I didn't pay much attention to it until the plastic housing on my Mini cracked and I had to pay nearly $200 for a thermostat. After that I looked at some live data and saw what it was doing with the coolant temp. None of my current vehicles do any of that stuff so I didn't know if it was becoming commonplace or just BMW doing BMW things.

 

[astjp2]

I may have to run a mechanical fan on the brown bomber, the spal setup I have is not cutting it on a hot day.

 

[Steel City 06]

To get an idea just how efficient the 19" SPAL fan is, I've been watching the operation with the current control scheme and measuring the amperage whenever I get a chance.

At an outdoor air temperature of 85 degrees and with the AC on full blast, the steady state idle power consumption of this fan is only 4.6 amps, out of a possible 60+ at the maximum end. (This is taken with the engine fully warmed up after driving for about 20 minutes.) Meaning the HVAC blower is literally drawing more power (6.5 amps) than the radiator fan, even though the radiator fan is operating three coolers (power steering, condenser, and radiator) versus the single exchanger (evaporator) for the A/C.

If we use the fan affinity laws based on the fact that running amperage is about 4.65 amps out of a possible 60 maximum, then we can estimate that the fan is running about 1,450 RPM (out of a maximum of 3,400 RPM) and pulling on the order of 1,700 CFM, and bringing the radiator coolant outlet temperature down to around 140 degrees F.

With the A/C off, there simply is too much airflow even at the lowest state, meaning the fan cycles on and off at it's minimum state (~20% shaft speed), indicating that 800 CFM drops the coolant outlet temperature below 130F. It tends to stay off longer than not, indicating that probably 400 or less CFM is needed to maintain this state.

On all of my driving, I have never once approached the top speed of the fan when leaving it in automated control. Granted, I have not driven it in temperatures higher than about 90 degree weather. However, I would be quite confident in trusting this fan in significantly hotter weather. Not only is there a lot of headroom left in terms of CFM, but there is also a lot of heat rejection capacity left in the radiator, given that the coolant outlet temperatures are still quite low.

 

[NashvilleTJ]

To get an idea just how efficient the 19" SPAL fan is, I've been watching the operation with the current control scheme and measuring the amperage whenever I get a chance.

At an outdoor air temperature of 85 degrees and with the AC on full blast, the steady state idle power consumption of this fan is only 4.6 amps, out of a possible 60+ at the maximum end. (This is taken with the engine fully warmed up after driving for about 20 minutes.) Meaning the HVAC blower is literally drawing more power (6.5 amps) than the radiator fan, even though the radiator fan is operating three coolers (power steering, condenser, and radiator) versus the single exchanger (evaporator) for the A/C.

If we use the fan affinity laws based on the fact that running amperage is about 4.65 amps out of a possible 60 maximum, then we can estimate that the fan is running about 1,450 RPM (out of a maximum of 3,400 RPM) and pulling on the order of 1,700 CFM, and bringing the radiator coolant outlet temperature down to around 140 degrees F.

With the A/C off, there simply is too much airflow even at the lowest state, meaning the fan cycles on and off at it's minimum state (~20% shaft speed), indicating that 800 CFM drops the coolant outlet temperature below 130F. It tends to stay off longer than not, indicating that probably 400 or less CFM is needed to maintain this state.

On all of my driving, I have never once approached the top speed of the fan when leaving it in automated control. Granted, I have not driven it in temperatures higher than about 90 degree weather. However, I would be quite confident in trusting this fan in significantly hotter weather. Not only is there a lot of headroom left in terms of CFM, but there is also a lot of heat rejection capacity left in the radiator, given that the coolant outlet temperatures are still quite low.

Would you get cooler A/C temps if the fan was at max during operation?

 

[Rickyd]

Would you get cooler A/C temps if the fan was at max during operation?

@freedom_in_4low ?