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Old 07-01-09, 02:34 PM
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Temps/electric fan

Those with temperature gauges what readings do you see after some boosting on the highway?
What is your crusing temp at lets say a steady 60-65mph?

Finally what is your set up that you have?

IM trying to establish a baseline to see how im doing, currently have a Greddy FMIC, AC condensor, stock oil cooler, Koyo alum. radiator, electric fan with alum. shroud.

If I cruise along the fan regulates the temps, I run at about 190 or so, fan comes on, cools it down then it will come back up and so on and so on. If I boost the temps obviously run warmer.

Trying to figure out if I can set the fan higher and only rely on air flow.

Anyone know if thier fan is coming on at crusing speeds?
Old 07-01-09, 03:20 PM
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With the 195* switch I'm using right now (that actually switches around 200*), my coolant temps stay around 180-190* during highway cruising. This should be without the fan running at all, since it's proven itself to switch on at higher temperatures. Not entirely sure what temperature change I would see directly after a hard run at freeway speeds; I hit too much traffic going to/from work, and have only had an e-fan in for 2 weeks. Of course, it's the stop and go driving on surface streets that make you really need a fan. I had an adjustable thermoswitch stop working the other day mid-drive, and I was able to keep coolant temps at 217* or lower by just taking it easy between stoplights, with no fan at all running. This is with a TMIC and a Koyo radiator.

It's mostly going to be what temps you're comfortable with. Highway speed airflow is better than a fan anyway.
Old 07-01-09, 03:29 PM
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The thermostat has an operating range from 182-203 F, and at 203 it is fully open. I think it is reasonable then to say that the engine is safe anywhere in that range. My fan comes on at 187 F. During the winter the engine stays right around that temperature and the fan will cycle on and off some. That's the same as it behaved with the clutch fan under those conditions. During these really hot summer days, I am seeing about 195 cruising and 203 after boosting. This is with a shrouded e-fan and an FMIC with Fluidyne radiator.

You could definitely set the fan as high as say 190-195. Isn't the factory thermoswitch triggered at 195?
Attached Thumbnails Temps/electric fan-fc_temperatures.jpg  
Old 07-01-09, 05:43 PM
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Originally Posted by Rob XX 7
Those with temperature gauges what readings do you see after some boosting on the highway?
What is your crusing temp at lets say a steady 60-65mph?

Finally what is your set up that you have?

IM trying to establish a baseline to see how im doing, currently have a Greddy FMIC, AC condensor, stock oil cooler, Koyo alum. radiator, electric fan with alum. shroud.

If I cruise along the fan regulates the temps, I run at about 190 or so, fan comes on, cools it down then it will come back up and so on and so on. If I boost the temps obviously run warmer.

Trying to figure out if I can set the fan higher and only rely on air flow.

Anyone know if thier fan is coming on at crusing speeds?
Rob-my low speed is on a 200/185 switch. Switch is in the rad tank right next to the water inlet, BMF 3" Griffin radiator. My VDO temp sender for the gauge is in the thermostat neck of the water pump. FWIW most switches seem to have a 15* swing between on and off. Since my off is at 185* and the thermostat is just cracking at 183* my fan mostly runs on low speed all the time. Even on a cool night in the mid 60's the low speed fan will run pretty much continuous once it starts running. I really need a turn off temp of 190-195* or about 5-10* above the thermostat opening temp.

I tried an experiment a couple of weekends ago. I unhooked the fan sender, thus relying on the high-speed fan switched on by the A/C compressor. +100*f day. The traffic was pulsing from 45-75 mph (Dallas!). Temps slowly rose when the A/C compressor cycled off, came back down when the compressor cycled back on. (Yes, after the interior cools down my A/C compressor cycles on a 100* day-34* vent temps rock)

For grins, I switched off the A/C and ran it for several miles with no fan at all. The temps crept up to around 225* before I lost my nerve and turned on the A/C. The temps came down very, very slowly. This made me very very nervous, so I pulled over and put the terminal back on the fan sender. I won't pull that stunt again. On a day like that normally my temp will run at around 190-195*-low speed fan never turns off. Kick it a little and the temps will pop up to 200-210 then drop right back to the 190* range, all with the fan on low speed.

Expect the temp to jump when you boost-the engine is producing more heat plus the fmic is warming the air entering the radiator. The 2 +/- gallons of coolant act both as a heat transfer medium and a heat sink to absorb the peaks. Don't set your set point temps based on the boosting temps, or on acceleration temps. Set it up to work the way you want it to at steady state cruising.

Good Luck!
Old 07-01-09, 05:47 PM
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Originally Posted by RotaryRocket88
With the 195* switch I'm using right now (that actually switches around 200*), my coolant temps stay around 180-190* during highway cruising. This should be without the fan running at all, since it's proven itself to switch on at higher temperatures. Not entirely sure what temperature change I would see directly after a hard run at freeway speeds; I hit too much traffic going to/from work, and have only had an e-fan in for 2 weeks. Of course, it's the stop and go driving on surface streets that make you really need a fan. I had an adjustable thermoswitch stop working the other day mid-drive, and I was able to keep coolant temps at 217* or lower by just taking it easy between stoplights, with no fan at all running. This is with a TMIC and a Koyo radiator.

It's mostly going to be what temps you're comfortable with. Highway speed airflow is better than a fan anyway.
Nice temps.

You are running the TMIC-do you have an A/C condenser in the airflow or has it been removed? The reason I am asking is that Clokker removed his condenser on his N/A. He runs significantly lower temps for similar conditions than I do and those temps he quoted were with his stock radiator before he got Godspeeded...

Just curious.
Old 07-01-09, 06:08 PM
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it is believed by some that a stock radiator might cool better then a thicker one. My tuner is suggesting that I go to a stock radiator, and I have given thought to a stock FD radiator/dual fan set up.

I think the gauge in the car is throwing everyone off who is on my project, relying on just the stock gauge it is decieving because you dont see the gauge react with each degree like a aftermarket gauge, when you boost and look at the aftermarket gauge you see it react instantly.

I am almost starting to think that a thinner radiator might allow what air that flows to be able to be more efficient or that I might experiment with a different fan and shroud set up. SneedSpeed who sold me the shroud and fan set up claim thir shop vert that is run on the track has no cooling issues, maybe I am just being paranoid and should accept the fact that my car will never run the rock solid 180-190 it ran when it was stock NA with stock clutch fan.

BTW- I have a 180 degree thermostat in my car if im not mistaken.
Old 07-01-09, 06:39 PM
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Before wasting a huge amount of time with the SPAL FAN-PWM, when the e-fan was controlled only by a relay (and it's going back to that configuration this coming weekend) my temps were very stable. With a Fluidyne rad, biggish front mount and Pontiac 6000 fan the temps would stay at thermostat temp whenever the fan was running. I turned it on via the Microtech at 88 degrees and the Microtech automatically switches the fan off at 5 degrees lower then that which is about thermostat temp.

During 1/4 mile runs the car would warm up until the fan came on and then the temperature would be stable at about 88. On the highway, the fan is off and the car runs at thermostat temp no matter how hard I hammer it.

Oil temps are around 180 on the highway, around 200 in the city.
Old 07-01-09, 06:51 PM
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a oil temp gauge is what I want next, but I think when the engine is operating correctly the oil temps will mirror the coolant temps.

With the microtech cant you adjust when you want the fan to come on?
Reading your set up you also no longer have a ac condensor in the car correct?
Old 07-01-09, 06:55 PM
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My car never had A/C, a sunroof or any of that other fluff. Base model RX-7s are proper sports cars.

The Microtech will allow you to turn the fan on at any temp you want, but it will always turn the fan off 5 degrees below that.
Old 07-01-09, 06:59 PM
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Originally Posted by jackhild59
Nice temps.

You are running the TMIC-do you have an A/C condenser in the airflow or has it been removed? The reason I am asking is that Clokker removed his condenser on his N/A. He runs significantly lower temps for similar conditions than I do and those temps he quoted were with his stock radiator before he got Godspeeded...

Just curious.
My A/C is still in place, condenser and all. I just need to recharge the system, so it actually works again. If it were working, I'd expect to see some considerably higher temperatures with the A/C running. I'm sure it would be keeping my fan switched on at almost all times. The fan isn't set up with any kind of A/C bypass switch; it's just a relay & a 195/185 thermoswitch.
Old 07-01-09, 06:59 PM
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I understand now about the microtech. I think the wolf shuts the fan off at the temp you have it set, I dont think there is a variance because I would watch the hand controller and it would click the fan off at the precise temp.

I had to get the AC going again, when it hits 85+ degrees out the desire to sit in the heat and drive the car is not stronger then my desire to be comfortable.
The older I get the less I can tolerate it, I just want the car to feel like a factory car.
Old 07-01-09, 07:18 PM
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Originally Posted by Rob XX 7
a oil temp gauge is what I want next, but I think when the engine is operating correctly the oil temps will mirror the coolant temps.
Not really, at least in my car.
My water temps play peek-a-boo between 180-195°F (depending on traffic) as the fan desperately tries to cool to thermostat temp (low speed fan trigger activates at 194°).

Oil temp on the other hand stays fairly constant at @ 190°F and barely seems to move (sending unit located in oilpan).
In heavy stop-n-go traffic, temp will rise to 200° and takes a while to decrease once moving again.

Oil doesn't seem to shed (or gain) temp as quickly as water.
These results may be skewed due to sender location, I'm not sure.
Old 07-01-09, 07:28 PM
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Originally Posted by clokker
Not really, at least in my car.
My water temps play peek-a-boo between 180-195°F (depending on traffic) as the fan desperately tries to cool to thermostat temp (low speed fan trigger activates at 194°).

Oil temp on the other hand stays fairly constant at @ 190°F and barely seems to move (sending unit located in oilpan).
In heavy stop-n-go traffic, temp will rise to 200° and takes a while to decrease once moving again.

Oil doesn't seem to shed (or gain) temp as quickly as water.
These results may be skewed due to sender location, I'm not sure.
I see a lot of the same thing on my oil temp gauge, but my sender is located on the oil filer pedestal. It holds constant at 180* most of time time, but will creep up 200-210* at times if the fan isn't on, and I'm in traffic. It definitely takes it longer for the temperature to increase or decrease than it does with coolant. I've had my e-fan kick on and drop my water temps by 15*, but oil temps only dropped by ~5* in that same time.
Old 07-01-09, 07:38 PM
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Power FC turns the fan off 1 degree C below where you turn it on.
Old 07-01-09, 10:51 PM
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Originally Posted by arghx
Power FC turns the fan off 1 degree C below where you turn it on.
One degree is a pretty tight differential. Back when I was doing electromechanical environmental temperature controllers, we found that anything under 3* was very hard on the equipment and actually used quite a bit more energy with almost no increase in temperature stability. If the on/off are too close together, you get short cycle. The relay activation and fan startup happen way too often, reducing equipment life without a meaningful increase in temperature control. The 3* does not directly correlate to our cooling systems, but the principal does apply.

If the differential is too large you get temperature overshoot and too large of a temp swing. I think the 15*f /10* C swing on my summit sender is too large. I see mild overshoot at times.
Old 07-01-09, 10:56 PM
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Originally Posted by Rob XX 7
it is believed by some that a stock radiator might cool better then a thicker one. My tuner is suggesting that I go to a stock radiator, and I have given thought to a stock FD radiator/dual fan set up.

Yep, that is a distinct possibility. Each additional row is has progressively less heat rejection capacity, thus a diminishing marginal return occurs when the rad gets thicker from additional rows. I think that I have read the realistic limit is 4 rows-beyond that there is not much theoretical gain. Additionally, if the radiator has more fin surface area (thicker) but less airflow, it could reject less heat. Griffin makes a big deal claiming to design the fin spacing to maintain the airflow. That is one reason I wanted to use a Griffin rad. I am running significantly lower temps with the griffin than I was with my old all metal stock replacement rad. Additionally, there currently are 5 rows of tubes at the bottom of my rad that pass from inlet tank to outlet tank that are not covered by my Taurus fan. That makes 5 out of 40 or 12.5% of the rad that gets NO airflow from the fan. I will be changing fans, maybe this weekend. The Mighty Mark VI fan is a perfect fit on my rad covering 100% of the core. It's a beast and pulls approximately the same amperage as high speed on the Taurus fan.

Originally Posted by Rob XX 7
I think the gauge in the car is throwing everyone off who is on my project, relying on just the stock gauge it is decieving because you dont see the gauge react with each degree like a aftermarket gauge, when you boost and look at the aftermarket gauge you see it react instantly.
I have the same paranoia issues. I never worried about my temps before I installed the accurate, responsive VDO gauge. Maybe Mazda was onto something with that crappy S5 gauge...

Originally Posted by Rob XX 7
I am almost starting to think that a thinner radiator might allow what air that flows to be able to be more efficient or that I might experiment with a different fan and shroud set up.
More efficient and higher capacity are not necessarily the same thing. A thicker 2-row rad will almost certainly have higher heat rejection capacity (total heat rejection) but will be less efficient (heat rejection capacity per square inch) than a thinner single row radiator.
Old 07-02-09, 06:00 AM
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We have access to some REALLY large Ford fans and shrouds, I think they came off crown vics or something, they are quite impressive looking. I have to measure one up though and see how its going to do.
Old 07-02-09, 08:24 AM
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The FD radiator is a BAD IDEA! Have you ever seen one? They are smaller than what I had on my old 88 GTU. They are garbageand can barely cool a stock FD, which is why FD owners like to ditch them immediately. From the factory they are mounted forward at a funny angle, such that they always leave air in the system. So Mazda had to design an air separation tank, which always fails because it was made of plastic. When I look at the FD cooling system (rad, oil cooler, and don't forget the POS intercooler) I am stunned at how inferior it is to what came on the non turbos just one model year prior. The fans don't even turn on until over 100 C (!) on that car with the A/C off, and the thermostat still cracks at 82 C like the 2nd gen cars.

The stock FD fans are fine but they are multi-speed units, which adds wiring complexity that you don't really need. they are controlled by 4 relays from the factory.

1C is a tight differential
that's true, but I have no way to adjust that aspect of the control logic. and with a turn on temp of 86 C (turn off at 85 C) it effectively runs all the time unless I am idling for a long period. That would not work so well from an OEM design perspective but this is a weekend car that sees a couple thousand miles a year. the Power FC control sure beats those ghetto radiator probes that everybody uses.

Honestly I wish I could have kept the stock fan, but there was just no room for the shroud and I had already had one fan clutch fail on me. I tried hacking up the shroud to fit some stuff but that didn't work out so well.
Old 07-02-09, 09:22 AM
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come to think of it the wolf must shut it off a few degrees below, otherwise it would constantly cycle.

Dont know what I was thinking, lol

I was more interested in cruising speeds and temps, that is when airflow plays its role, sitting in traffic your going to need your fan and in that department my set up does fantastic. Its the highway air flow I would like to improve, or I could just be over analyzing things
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