PWM fan conversion.

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HCP2311

HCP2311

Joined
Apr 18, 2024
Threads
11
Messages
54
Location
USA
I am pulling my 1FZ to send off for a rebuild and while it's out I've decided to upgrade a few things. One of the projects is a PWM controlled electric fan. Originally I planned on building a PWM controller circuit from scratch. (Which isn't difficult if you enjoy things like that, and I'll do a write-up later on it) While I was hunting for a new radiator with a shrouded fan I came across a PWM controller circuit made by Mishimoto that does 90% of what I want. (Universal Pulse-Width Modulated (PWM) Fan Controller - https://www.mishimoto.com/universal-pulse-width-modulated-pwm-fan-controller.html)

I still have to add a monitor circuit and a timed override switch, I'll talk about that in the write-up.

The radiator I went with was: Alloyworks Radiator Shroud Fan 4Row fit 93-97 Toyota Landcruiser 80 SERIES/Lexus LX450 4.5L - https://www.alloyworksplus.com/products/radiator-shroud-fan-4row-fit-93-97-toyota-landcruiser-80-series-lexus-lx450-4-5l

The questions that still need answering are this:
1) Mishimoto recommends tapping the radiator for the temp probe, Alloyworks recommends getting the coolant temp from the engine.

Should I tap the radiator, or piggyback off the 1FZ stock temperature probe?

2) The FSM states the operating temperature of the 1FZ-FE is 167-203, the thermostat valve opens at 176-183.
Should the PWM controller start the fan at 176?
The PWM controller is also tied to the AC and when the AC is on the fans run at 30% regardless of engine temp.

3) I am going to add a timed Killswitch for the fans. (For water crossings) I'm stuck between 15, 30 & 45 seconds. I realize that seems short, but my thought process on it is if than fans are submerged then the water body is probably cooling the radiator below the target temp so after the timer is up the fans should be off and if the fans are not submerged then it's a moot point. This question actually goes back to the probe location. If I tap the radiator it's more likely that the river crossing will lower the temp enough to kill the fans. (I think anyway) The 1FZ probe is just below the intake manifold iirc and less likely to be exposed to water from the crossing.
 
Wow, that fan/radiator combo is cheap...wish I knew about it for my LS swap.

I would think measuring radiator temp would be better than engine temp for running the fans.

With the former, you can be proactive in cooling the radiator down before the engine gets hot, while the latter would be reactive to the current engine temps.

Alloyworks suggests "turn your electric fan on at 185 degrees and shut off at 165 degrees"

This makes sense to me.

but since you have PWM capability, I suggest a ramp up curve for when the radiator temp rises from 165°F -> 185°F. Max fan speed at 185°F, and then until the radiator cools to 165°F.

Looking at the Mishmoto doc, it shows a ramp up fan speed. Setting 4 is nearly what I just described. You can play with different ramp up profiles, which is cool.
 
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My opinion; if you do tap the rad for temp do it near radiator inlet so you get as close to engine temp as possible OR at cylinder head INTAKE side..cause heat rises..

For kick on temps match as close to thermostat open temps because that is what regulates cooling function of radiator. For kick off temp I would say 10deg below thermostat temp..

I would also. (As I did) Put in a manual override fan switch. My AUX trans fan is completely controlled by switch because I have tapped temp for transmission from trans to cooler line.
 
I'm running a new stock rad on my LT swapped 105.

The engine runs cool with the two PWM fans. It's reading of the head on the L83 engine. works great.

If it's good enough for Saudi Arabia weather. It should be good enough for you.

I'd recommend keeping the stock rad for ease of maintenance down the road.
 
Man, for the cost of that Mishimoto controller you might as well get a $350 Microsquirt which would give you so much more capability.
I am a big fan of OEM PWM fans (pretty much all Euro cars after about 2004-5 use this tech), but you usually need to be able to figure out the frequency/duty cycle they need on your own.
 
I say moniter the temp at the block, that's the part you want to keep in temp range. The radiator is just the part that is doing the cooling.

If the circuit is always powered the fans will run after the vehicle is shut off and the temp rises from heat soak. This will keep the motor in a good range. Where the rad will cool off very quickly and leave the engine temp high.

This is a normal situation with heat soak but why not make it better when you can.

If the #RollBuild has cooling issues I will probably go this route. Thanks for sharing
 
Outsane said:
I say moniter the temp at the block, that's the part you want to keep in temp range. The radiator is just the part that is doing the cooling.

If the circuit is always powered the fans will run after the vehicle is shut off and the temp rises from heat soak. This will keep the motor in a good range. Where the rad will cool off very quickly and leave the engine temp high.
Click to expand...

Well I didn't think about that. I'm wondering if the electric fan is going to be able to provide any kind of actual cooling to the block compared to the much larger clutch fan. The electrical fans are basically useless without shrouds so I'm not sure how effective they will be at pushing air across the engine.

I wonder if an engine bay vent might not be a good idea. A simple on/off circuit could be piggybacked off the stock temp probe to help void air from the engine bay when the vehicle is off. I'm a little concerned about having the complete cooling system and warning light rely solely on just the one stock probe. If it fails I would lose cooling AND the temp warning.
 
If I may express my opinion; you are going to a whole lot of trouble to fix what isn’t broken.
IMG_6854.png


Toyota provided a boss cast into the water outlet pipe for drilling and tapping a hole to add a temp sensor.
 
baldilocks said:
If I may express my opinion; you are going to a whole lot of trouble to fix what isn’t broken.
Click to expand...

Agreed. Started down this road with my hdj81. Decided it wasn't worth the effort, and loss of reliability, to much trial and error on a critical part.
Get it wrong and cook the engine, it's a big mistake.
 
The OEM setup is very robust with it’s double fan belts.
The only thing I like about an electric fan system and the ability to shut it off during deep water crossings.
 
baldilocks said:
If I may express my opinion; you are going to a whole lot of trouble to fix what isn’t broken. View attachment 3641939

Toyota provided a boss cast into the water outlet pipe for drilling and tapping a hole to add a temp sensor.
Click to expand...

I drilled/tapped a port shown in the pic as well, mainly for a mech temp sensor for a mech temp gauge that used to live in the engine bay. It's been abandoed for a better part of a decade by now. I'd think this would be good place for sensors for other applications as well.

My turbo added a lot of extra heat not only to the engine bay but also the coolant temps hovered north of 210deg as normalcy. I finally bent over and bought a Ron Davis radiator and all is good now. I've never actually seen temps this low on my Scangauge 😁 since the turbo install.

I'm also running a Blue fan clutch with 15k fluid, IIRC.
 

This guy used the same type of combo radiator and fan. He had to upgrade to better fans. Just an fyi.
 
All this looks good guys, thanks. I knew going into this that some people would feel like its an over complication, and I know some people swear by clutch fans. I don't know why this 1FZ overheated, I just know that 5 out of its 6 cylinders are toast so I'd like to remove any possibility of overheating again. Plus I'll be the first to admit that I demand a lot of any vehicle of mine so I try to be preventative when I can. The PWM controller can output up to 50amps, the current fans I have are both 12v 90w so they are about 7.5amps each. If they are not getting the job done I can always go up the ladder. Like I mentioned earlier I want to add in a bit more functionality to the circuit, namely a dummy-resistant kill switch for water crossings and a feedback to know when the fans are on. The fans I have now do not have built in Tachs, so reading the fan speeds would require a bit of leg work; either a hall-effect sensor (I don't like that personally) or a complex logic controller to read the negative side of the fan circuit. (That's a little counter-longevity imo) I've settled on a simple LED to let me know when power is reaching the fans, and I can just puts eyes on them if I'm concerned.

For the kill-switch it looks like I'm going to go with a momentary-on pushbutton switch to trigger a NC (Normally Closed) delay-on-release relay. This will actually end up being a chokepoint in the system as the relay I found that I liked for its timer is only a 30amp relay. The fan indicator will just be an LED in parallel to the fans with a resistor. I'll drop my scratch notes below, let me know what ya'll think. I currently have a number of segments set to ground out, but I may bundle them and send them directly back to the battery to reduce the number of fail points. I also haven't settled on a push-button switch yet. I'm considering 3D printing a nice dash insert that that would hold the LED and the switch.

74985_drawing.webp
 

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Auxiliary Fan Install

Fan kits available at the link below Land Cruiser Products - LCP ► Remove the 5 screws holding the grill in place and remove ►Remove the lower bolt on the center support bracket ►Remove the rear bolt holding your aftermarket bumper on. If you still have the stock bumper you will most likely...
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Seems like a good idea to me. For sure put the temp sensor in the radiator or engine INLET pipe that's how Toyota did it from the factory on their FWD cars that used only electric fans. the engine temperature is regulated with the thermostat. You want to regulate the temperature in the radiator. Of course Toyota put the temp sensor location in the radiator outlet pipe this is a great place to put the gauge temp sensor, they didn't engineer it for electric fans. as others have said you will need some serious CFM might be worth adapting a euro car fan to it. most of these have big CFM, readily available. there are controller's made just for them too. the fans you linked are 90w some of the Mercedes fans can draw 1000w
 
TheBussman said:
Seems like a good idea to me. For sure put the temp sensor in the radiator or engine INLET pipe that's how Toyota did it from the factory on their FWD cars that used only electric fans. the engine temperature is regulated with the thermostat. You want to regulate the temperature in the radiator. Of course Toyota put the temp sensor location in the radiator outlet pipe this is a great place to put the gauge temp sensor, they didn't engineer it for electric fans. as others have said you will need some serious CFM might be worth adapting a euro car fan to it. most of these have big CFM, readily available. there are controller's made just for them too. the fans you linked are 90w some of the Mercedes fans can draw 1000w
Click to expand...

Yeah I'm a little skeptical of the fans, I'm going to run them for a bit and see how they do. I want to switch them for fans with built in tachs so if they are not cooling well that will just be the last straw for them.
I have a diesel ML320 and can confirm Mercedes needs a kw fan. 😂
 
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