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Old 08-24-2015, 02:53 PM   #1
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Default Re-thinking this whole Fan Shroud thing (FM Stg 2 airflow kit)

So I've been having some difficulty getting my car to not stall out with the two large Spal fans on the Flyin Miata Stage 2 Airflow kit. Fans are wired in parallel, and I've just ordered a delay module for the secondary fan to see if it'll ease the initial draw.

Just yesterday, the circuit breaker that comes in the upgraded harness/relay (for NA6) stopped working and coolant temps shot up to 225 with only one fan working.

Now, these shrouds aren't divided so the working fan did a great job of grabbing air from the adjacent space without drawing much through the radiator/ac condenser. I'm wondering if it's worthwhile to either have a strip of metal welded between the fans (in the shroud) in an effort to isolate one from the other or if I should just ditch the entire setup and go for a slightly larger single fan with slightly less flow.

I'll be adding hood vents in the next week which will help, or so I hope, but if one of these fans fail, is this really an effective cooling solution?
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Old 08-24-2015, 03:06 PM   #2
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why did you wire in parallel?

your MS is trying to control two separate fan relays...


your MS also has lots of code to tune for these sorts of situations... like the the voltage idle duty % code, or the adaptive timing. You can also just have only the a/c fan run when the a/c turns on instead of both, but you've basically disabled that function.
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Old 08-24-2015, 03:14 PM   #3
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I thought that's what all the cool kids where doing?

I just followed FM's instructions when I installed it at the time. Also A/C hasn't been hooked up yet and wasn't quite working as soon as I installed the MS3. Changed AC relay, Fan relay and have a new compressor, but have been waiting for new AC lines as the r12 and r134 compressors are just slightly different enough for the old lines not to work.

Even if I let the A/C fan wiring trigger the aux fan, this doesn't seem like it'll function unless both fans are on at the same time as these fans are sharing the same pocket of space. I don't think I have space for stock shrouds given my filter location.
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Old 08-27-2015, 08:19 PM   #4
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Quote:
Originally Posted by psyber_0ptix View Post
So I've been having some difficulty getting my car to not stall out with the two large Spal fans on the Flyin Miata Stage 2 Airflow kit. Fans are wired in parallel, and I've just ordered a delay module for the secondary fan to see if it'll ease the initial draw.

Just yesterday, the circuit breaker that comes in the upgraded harness/relay (for NA6) stopped working and coolant temps shot up to 225 with only one fan working.

Now, these shrouds aren't divided so the working fan did a great job of grabbing air from the adjacent space without drawing much through the radiator/ac condenser. I'm wondering if it's worthwhile to either have a strip of metal welded between the fans (in the shroud) in an effort to isolate one from the other or if I should just ditch the entire setup and go for a slightly larger single fan with slightly less flow.

I'll be adding hood vents in the next week which will help, or so I hope, but if one of these fans fail, is this really an effective cooling solution?
I run bigger fans that you do, and my RPMs are rock solid when they turn on, less than 50RPM dip and my fans pull 70-80 Amps. And I don't have control of the factory idle valve either!

Use the timing feature to throw timing at it when the idle dips. Huge help.

I also wired in a vacuum solenoid that opens when the fan turns on (just wired it in) and sized the orifice so that the extra air brings the engine RPMs up back where they were with without the fans on. So fan turns on, manifold psi goes up, timing swings forward to catch the idle, then RPMs level off and timing goes back to say 16* where without the fans it was 10*.
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Old 08-31-2015, 04:55 PM   #5
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To the OP: I used to have this problem and it was because my alternator belt wasn't properly tensioned. The fans would kick on and my car would lose its mind. Tightened the belt to the proper amount and it was suddenly silky smooth.


Out of curiosity, how do you guys get around blowing fuses with larger than stock fans?

I remember it being an occasional problem the last time I had the car running.

I also run a 5 inch fan on the oil cooler off the same line as the ac fan, but I don't think it pulls much juice.
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Old 08-31-2015, 05:08 PM   #6
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To the OP: I used to have this problem and it was because my alternator belt wasn't properly tensioned. The fans would kick on and my car would lose its mind. Tightened the belt to the proper amount and it was suddenly silky smooth.


Out of curiosity, how do you guys get around blowing fuses with larger than stock fans?

I remember it being an occasional problem the last time I had the car running.

I also run a 5 inch fan on the oil cooler off the same line as the ac fan, but I don't think it pulls much juice.
I rewired mine with 10 gauge wire, 40A fuses, 50A relay.
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Old 08-31-2015, 06:00 PM   #7
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Quote:
Originally Posted by AlwaysBroken View Post
To the OP: I used to have this problem and it was because my alternator belt wasn't properly tensioned. The fans would kick on and my car would lose its mind. Tightened the belt to the proper amount and it was suddenly silky smooth.


Out of curiosity, how do you guys get around blowing fuses with larger than stock fans?

I remember it being an occasional problem the last time I had the car running.

I also run a 5 inch fan on the oil cooler off the same line as the ac fan, but I don't think it pulls much juice.


This wasn't a fuse, there was an inline 30A breaker to power the relay for the auxiliary fan.

https://www.flyinmiata.com/support/i...fan_wiring.pdf


Either way, my main concern wasn't with the fan so much as the shroud not being split between the fans themselves. If one fan did fail for whatever reason, cooling is compromised no matter how wonderful the other fan is working.
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Old 08-31-2015, 06:14 PM   #8
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Regarding flow, I noticed the huge gap between spal fans and the radiator a few years ago... so I used some 90 degree angle aluminum (one inch per side) around a sheet of thin aluminum to build a shroud that blocked off the airflow except through the radiator vanes. When I have it off the car in a few days I'll post pics. It's crude and held together by rivets, but it works and is lightweight and sturdy. I don't remember if I put a divider in the middle between the fans, but it wouldn't be very hard.
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Old 08-31-2015, 06:16 PM   #9
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I rewired mine with 10 gauge wire, 40A fuses, 50A relay.
You can just plug in bigger fuses and relay to the stock fuse box or you just wire them up separately? I'm afraid of making too much of a rats nest, though I suppose I should have stopped before the COPs.
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Old 08-31-2015, 06:19 PM   #10
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Did you have your fans mounted independently, floating over the surface of the radiator? This is boxed in and sealed around the perimeter relatively well, just nothing between them. Either way, I'll just have to modify the thing if I have time, all the while assuming both fans stay working at any given time.

Or sell, recoup losses, run one fan direct on the radiator and hope the hood vents take care of the rest
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Old 08-31-2015, 06:46 PM   #11
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Quote:
Originally Posted by AlwaysBroken View Post
You can just plug in bigger fuses and relay to the stock fuse box or you just wire them up separately? I'm afraid of making too much of a rats nest, though I suppose I should have stopped before the COPs.
I ran a new system. I wouldn't modify the factory system, it's all designed around the current of the stock fans. I believe the fan wires are 16 gauge on my 99. They are tiny...
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Old 08-31-2015, 10:51 PM   #12
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What did you use for the switched 12v power?
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Old 08-31-2015, 10:55 PM   #13
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What did you use for the switched 12v power?
I rewired my car, so it's all new. Switched +12V comes from the key like any other car.
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