GrossPolluter

iTrader: (1)

Free up space for more options of radiator, oil, and and intercooler mounting. But true, anyone looking for bolt in upgrades won't ever need that space open.

user 8202

Monopoly money?

Sorry, I own a rotary bruva .. lol

Aaron Cake

iTrader: (1)

Yes, it is. Stock thermostat temp is 82 (or is that 84?) degrees. With the stock fan, that's about where the FC runs.

Did you really just invoke the FD, possibly the worlds most unreliable vehicle (for reasons thoroughly related to heat), as an example of how things should be set up?! The same car that Mazda had to issue a cooling system recall for so that the fans continued to run after the car was shut off, to avoid boiling the coolant? Didn't that same recall also drastically lower the turn on temp for the fans?

clokker

iTrader: (2)

The FSM states that the FC thermostat BEGINS to open at 180° and is FULLY open at 203°.
I would contest the idea the Mazda intended normal operating temp to be UNDER the fully open thermostat temp and that 195° is dangerously high.

I'll defer to your greater experience though and accept that maybe my particular car is an outlier/freak.

Yup, I did.
Funny how Mazda screwed up and did exactly the same thing on the RX8, eh?

misterstyx69

iTrader: (142)

Should I run Regular Oil with a Stock fan,...Or Synthetic with an Electric Fan?

clokker

iTrader: (2)

Funny you should mention that.
I found that after installing the efan, my car required no oil at all.

Didn't think that was significant or I'd have brought it up sooner.

Rob XX 7

iTrader: (8)

premix it brah

GrossPolluter

iTrader: (1)

I usually drain my fan clutch and mix 2 stroke and synthetic oil, the filler is at the top.

I'm jk, oil has nothing to do with fans

clokker

iTrader: (2)

Unless you're Lexus.

Akagis_white_comet

iTrader: (4)

Clokker vs Aaron Cake in a debate about cooling, with reference to the FD...

Aaron is correct about how the clutch fan works. To put it in easier terms, think of the clutch inside the fan as a Torque Converter from an Automatic Transmission. Yes, it IS spinning at all times, but can easily be stopped with a single finger just like how the brakes on a car will stop the car at a red light.

As far as proper operating temperature is concerned, I'm agreeing with Aaron 99% on it. A stock S4NA's A/C fan switch triggers at 195 degrees (TII is 207 degrees), while the thermostat is open at 180 degrees. Before my 20B Conversion, I was running with a Taurus fan & Alt, triggered via the 195 degree thermoswitch. Although I did not have an external temperature gauge in an otherwise bone-stock car, the car never seemed to overheat IIRC. A modified turbo car is an entirely different story though...

Per the S4 FSM, the thermostat for both NA & TIIs begins opening between 80.5 degrees Celsius (176.7 Fahrenheit) and 83.5 Celsius (182.3 Fahrenheit) and is fully open at 95 degrees Celsius (203 Fahrenheit). The FD's thermostat is identical in this manner.

Most of us know that the FD's cooling system is essentially the gold standard for how NOT to do things. It is simply insufficient for the heat being generated and trying to cover for it with the fans just didn't work. For evidence of heat-induced failure, one needs not look further than the turbo control solenoids.

Aaron, could you please recommend a suitable activation temperature for an Electric Fan? I believe you state in your E-Fan Article that the thermoswitch should not fight the thermostat. Considering that FD owners benefit quite a bit from using a S5T2 fan thermoswitch, I think it would be to everyone's interest to know what is reasonable for their fans to come on at.

Per the FD's FSM, the fan thermoswitch should read as follows:
214 degrees: 0.5 ohms Max
226 degrees: 1 Mohm minimum

Although I'm not a fan of ECU-Controlled fans, I do see the merit in accurate, predictable control. But at the same time, it is not the end-all, be-all answer for everyone. My preference is to have a thermoswitch with a manual override switch in parallel. If I need to override the normal operation for any reason, I can force the fan on. Otherwise, it is controlled by the thermoswitch(s).

When I have time to translate the JC Cosmo's FSM, I'll report back with my findings. In 13B-RE form, it is essentially a FD with a FC radiator and clutch fan, so it should be quite interesting what Mazda states its thermostat and A/C fan switch should trigger at...

jjwalker

I am eagerly awaiting Aarons answer to your question akagis. If it where me, I'd set the fan to turn on at the halfway point between thermostat starting to open and thermostat fully open (which is about 87-90*C)

j9fd3s

iTrader: (3)

yes do, the 3 rotor has a very interesting setup.

its got two thermostats, one 92c, and one 82c. the 82c thermostat has an ECU controlled vacuum valve to turn it on and off. since its ECU controlled, there are 7 conditions where it operates, coolant temp, a/c on or off...

then it has a mechanical clutch fan, like the FC, although its bigger. in a ducted shroud.

then it also has an ECU triggered electric fan.

RotaryEvolution

iTrader: (30)

the RX8 also had plenty of coolant seal failures with the same engine sealing configuration as the 12A and early 13B, which almost never blew out the coolant seals and ran about 20F cooler. those early engines also used.... a mechanical fan.

hotter engine temps may help with efficiency but it also hurts reliability and adds to the "hot start" variable. when talking expansion and contraction, more is not better.

to the efan debate, i hate efans. at least i hate AFTERMARKET efans, the controllers which are saving your engine are usually unreliable and turn on erratically unless you set one up properly with a probe INSIDE the coolant flow ON the engine.

gxl90rx7

iTrader: (1)

ecu controlled e-fan all the way.. mine never turns on unless sitting in traffic. I have it set to turn on 195F, off at 190F

Aaron Cake

iTrader: (1)

Datalogs here are the key. A standalone equipped car running on the highway (so we're ignoring fans here) will run around 84 degrees with a stock thermostat. Give or take a degree or two of course. As logged.

Important to remember it is the thermostat which sets the temperature of the car, not the fan. The fan is just there to pull air when there isn't enough natural airflow. Which is why most new cars are also switching their fans based on speed and temperature.

An interesting experiment for people is to disable their e-fan then get the car to about 200F or so. Then turn on the e-fan (leave it on!) and immediately go onto the highway. The car likely won't cool down very well as the fan is a restriction. Turn off the fan and the temperature drops like a stone.

I typically set the fan-on point to 195 (F) and the off point to 188 (F). Staged fans are a bit different. Typically one fan will be set to come on at 190 (and with the A/C) and off around 186. Depends on the car though. If it cycles too much that can be adjusted.

The goal is to keep appropriate airflow through the rad to keep the temperature stable. Makes it much easier to tune.

Unless it's a stupid Microtech which only allows you to set the fan-on point (it cuts the fan off 5 degrees below) and only then in 2 degree settings. So I set it to 90C.

Thermoswitches drift and fail, and as a mechanical device, will wear our. Plus this causes all kinds of silliness when you want the ECU to control the fan, such as an A/C situation. And it means that you can't easily cut the fan at speed, which hurts cooling.

clokker

iTrader: (2)

Just a few days ago when I said my fan triggered at 195°, you responded:
It would seem we both consider 195° a safe temp for low speed fan operation.

You are absolutely correct about the fan on/highway test, the fan is a hindrance when the incoming airspeed is higher than the fan's suckage (*technical term*). That's why it's nice to have air relief flaps in the shroud as they mitigate this effect.

This phenomenon would also seem to be a strike against the stock mechanical fan, the shroud has no reliefs and (unlike an efan) the blades are never idle.

Just sayin.

Akagis_white_comet

iTrader: (4)

I like the way you approach it Aaron. To end the whole Thermoswitch Vs ECU Trigger debate, let's approach it this way:

If you have an unused output on your Haltech/Microtech/Megasquirt/Etc ECU, use it for the fan as Aaron Cake suggested. This method allows the ECU to override the activation temperature based on road speed, A/C activation or other conditions based on its software settings.

If you're using a stock ECU or don't have an extra output on your EMS, using a thermoswitch in the temperature range Aaron recommended will do the job. Doing it this way means the ECU CANNOT interrupt the fan's behavior based on road speed, A/C, etc.

I prefer to have some redundancy built into the circuit, hence why I suggest a Manual Override Switch wired in parallel to the Fan Trigger. One can consider it an onboard diagnostic mode that's available to the driver at any time.

Aaron Cake

iTrader: (1)

It is my mistake. I got a bit confused because the US uses Fahrenheit, unlike the rest of the world which properly uses Celsius.

Doing the mental conversion caused me to think 195F is hotter than it is. I've tried in later posts to translate into Fahrenheit for non-standard US readers.

The clutch fan freewheels. It's speed achieves equilibrium with the incoming air. In the same sense, the oncoming air cools the fan clutch which will disengage the fan once up to speed.

Dak

This is why I have always felt just fine using the Perma-cool "finger chopper" though many may not or don't like it due to it's lack of a shroud or ducting. At highway speeds there is nothing to interfere with airflow. This is where most of my driving is so it's a good fit. It is set up with a thermoswitch. Highest my temps have got was acouple of years ago I got stuck in traffic in Huntsville, Alabama in July( near 100F temp and they peaked close to 230F. I think it was more the radiator was maxed(stock size copper/brass replacment) than the fan being insufficent. I am going to intentionally go get in traffic on a hot day this summer to see how the Godspeed I just got does.

As to the original question I like the E-fan. Makes working on the front of the engine much easier. My clutch fan died years ago so I switched. Only wish I had my autometer gauge when it was functioning. As to the pros and cons to cooling I'll let you guys continue to hash it out.

As to the FD not kicking the fan on till 220. That is crazy on Mazdas part. No wonder they had so many problems. I start to worry if my temps reach 220 in traffic.

clokker

iTrader: (2)

I didn't realize anyone was even having that debate.

I wish I could find the source because I swear I've read that the thermoclutch operates in the 30-80% lock up range. It never fully disengages nor does it ever fully lock.
No matter, the differences would be trivial and hardly relevant in the real world.

Rob XX 7

iTrader: (8)

ill sound like a broken record and say again when its a NA car, especially with no AC its a much easier chore keeping the car cool


adding to what aaron said about electric fans on the highway- The design of the shroud plays a large part. I had a custom shroud that covered the entire radiator, so the only air that could pass through it had to come through the fan- this ran warmer on the highway.
I switched to a taurus set up, which the shroud doesnt cover the entire radiator- I feel this helped keep the car cooler on the highway. I keep meaning to install one or two of those rubber flaps in the shroud I feel they can only help things.

TonyD89

iTrader: (10)

Just a thought. A mechanical fan spins more stuff than an electric fan and with the battery in the loop, wouldn't that help performance? Not spinning more stuff? Inertia?

Aaron Cake

iTrader: (1)

A manual fan override is a handy thing to have when you are at the track. Just make sure to run appropriately heavy wire (12 gauge) to an appropriately heavy duty switch, assuming you are bypassing the fan relay completely (which is good redundancy).

There are many adjustable thermo switches made by Derail and the other vendors. Just avoid the cheap little mechanical silver type with a probe that sticks into the rad. In my experience they are unreliable and hard to set to any consistent temperature. The best types use a standard CLT (GM typically) which screws into the water jacket (drill and tap the water pump housing).

I also agree with flapped shrouds. If possible, it's the way to go.

If someone is curious as to how I would set up a cooling system, then Episode 27 of my Cosmo covers exactly that. Fan stuff is near the end where I install a Derale dual fan assembly with aluminum shroud, pressure release flaps and properly wire it up to EMS (MS3-Pro) outputs.

clokker

iTrader: (2)

I've consulted the FSM several times during this discussion and have a question for the thermoclutch fan advocates...

There is absolutely zero specific information about the specs or a test process for the thermoclutch in the FSM.
"Push fan with finger and feel for resistance" is as technical as it gets.

Unlike most other consumable parts on the car, I doubt people have been regularly replacing their thermoclutches, so chances are excellent that yours is a pretty old example.
Given that the fan is a pretty important component in a very critical system, short of buying a brand new thermoclutch, how can you feel comfortable depending on a part you can't test?

TonyD89

iTrader: (10)

Put a heat gun it, low setting, and see if it grabs.