Thinking of going e-fan

[FerociousP]

Originally Posted by Pete_89T2

The spec for the temp switch shown in the FSM diagram in my post says "off below 194*F" and "on above 207*F" Since it's a switch, that is either on or off, that's Mazda's way of writing a spec with a tolerance. So in other words, it should switch from off to on somewhere between 194*F and 207*F.

That's probably a good temp to trigger an e-fan, as most OEMs run similar temps. What temp does Mazda set the e-fans on the FD & RX8's to kick on at?

I figure I can wire a toggle switch to that check connector in the circuit diagram to run the fan at will if needed.

Pete, you are correct that it is a switch, but wrong in its function. It won't switch somewhere between 195-207. It will purposefully switch on at 207, and continue to run until 195. Otherwise, the fan would just constantly switch on and off as it transitions above and below 207. Most mechanical thermoswitches (i.e. not ECU controlled fan switches) operate this way. That is why in a standalone ECU setup, you have a on temp and an off temp, specifically for this purpose.

In this case, the thermostat has an operating range from 180-203. Meaning, below 180, it is shut. Above 203, it is fully open, and therefore becomes ineffective at regulating engine temp above 203. (A 180deg thermostat is typically used when you want a 190-195 deg operating temp). The fan's job is to bring the temperature back into this operating realm, which is why it brings the temperature down from its own starting point.

FDs have a complicated "4-speed" config using variations of its two fans, while the rx8 has two fans for a "2-speed" setup. IIRC both the FD and Rx8 have settings around 207-210 with more fans/higher speeds engaging at even higher temps. The reality is, is that OEMs don't want fans running during driving unless they can help it. They'd much rather the thermostat do the regulating, which is why the temp settings are relatively high for our comfort.

Personally, on my Cobb for the rx8, i set the fans to come on at 205. On my turbo vert I kept the stock clutch fan while I had it, even with my Haltech easily able to control a fan. It just worked.

[RETed]

My 2 cents...

I have gone through horror stories with electric fans...
I'm very paranoid when running just 1 fan.
Electric fans will fail.
I've had them fail on the street, and I've seen them fail on the track.
Either or will ruin your day.
I'm a firm believer that you should be running twin fans.
Luckily, Spal makes one - I believe Be Cool rebadges these things?
It's like 2800CFM for twin 13" units?
(I don't see it on the Be Cool website. )
The downside is that these things pull some serious current.
Minimum 15A - 20A *per* fan.
Can you imagine running both of them just idling???
Yeah, upgrade alternator is a must.

As for the numbers...
IME, the stock thermoswitch used to switch on around 225F indicated on my SPI water temp gauge.
The gauge, calibrated down to actual temp via an IR gun, is around -10F in those ranges, so actual was around 215F.
I used to run it triggered directly by that stock switch...
...until it FAILED.
The switch would be intermittent and then one day, it just stopped turning on the fan.
Yes, the circuit was isolated via a Bosch 30A relay.
Luckily, I always run a manual switch, so that saved my ass.

Currently, I have a *single* fan (I've got the Spal / Be Cool sitting on the side) triggered by my Haltech E8.
(i keep one eye on my water temp gauge all the time when I drive.)
Turn on is a lofty 230F and turn-off is at 205F.
I don't want the stock thermostat "clapping" due to too low temps, so I try and float it 10F higher than it's rated at.

IME, things don't get toasty until the temps hit 240F - 245F.
At 240F - 245F, you can SMELL the engine burning - good visceral sign that something is WRONG.

Yes, people will balk at those numbers, but I will stand by my experience.
We've had our race cars run up to 250F - 260F intermittently without puking seals.
This is not possible, right?
I'm living proof that I can run at those kinda numbers.
I've been running my Haltech E8 like that for the past 5 years so far...

I've got these numbers up on my website here:
http://fc3spro.com/TECH/MODS/EL/GAUGES/wtemp.htm


-Ted

[Pete_89T2]

Well folks, I decided to scrap the e-fan project and ordered a new fan clutch from Rockauto. Good thing I did, because I got the last one they had on wholesaler closeout for $39, and when that one sold, they jacked the price up to $169!

Anyway, my primary motivation for going e-fan was to clean up the engine bay and improve maintainability/access. The problem is that when you have a thicker than stock aftermarket radiator, the stock fan & shroud become a PITA to R&R when you use all the stock fastener points for the shroud like I did. The thought occurred to me that if I modify the stock shroud mounting points (i.e., relocate some, make all fasteners easier to get to), I could make it a lot easier to R&R the shroud & fan when needed. More to follow if I figure this out.

[GySgtFrank]

Originally Posted by Pete_89T2

Well folks, I decided to scrap the e-fan project and ordered a new fan clutch from Rockauto. Good thing I did, because I got the last one they had on wholesaler closeout for $39, and when that one sold, they jacked the price up to $169!

Anyway, my primary motivation for going e-fan was to clean up the engine bay and improve maintainability/access. The problem is that when you have a thicker than stock aftermarket radiator, the stock fan & shroud become a PITA to R&R when you use all the stock fastener points for the shroud like I did. The thought occurred to me that if I modify the stock shroud mounting points (i.e., relocate some, make all fasteners easier to get to), I could make it a lot easier to R&R the shroud & fan when needed. More to follow if I figure this out.

IMO You're much better off staying with the mechanical fan if you can. As Ted says, electric fans fail, ...regularly. Usually if the mechanical fan quits turning so does the engine, no problems. The V-mount bubbas just haz ta take their chances.