Chiburbian's 01' Lots of potential, no follow-through build - Page 36 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 07-29-2017, 05:28 PM   #701
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Originally Posted by Chiburbian View Post
I did some troubleshooting today on the fans. I am still confused. Here is what I did:

Ran 14ga wire from negative battery terminal to the fan.
Ran a 14ga wire to an in-line fuse holder with a 15a fuse. From there it went to a switch rated for 60a. From there to the positive connection of the fan.

I then (with the motor and ignition off) switched on and off the fan. I had no problems. The fan turned off and no with no problems.

After that, I started the car. I switched on the fan and it came on with no sputter or stalling of the motor. I switched the fan off, and a few moments later switched it back on. The fuse blew.

I swapped the fuse with another 15a fuse and watched the fuse this time. On the first power up of the fan I could see the solder on the fuse melt but not break contact on the first switch-on. However, on the second switch-on the fuse blew again.

Why is my fan blowing a 15a fuse connected directly to the battery when the car is running but not when the engine ignition is off? I will buy another 20a fuse set on my way home tonight and put my meter in-line to see what the max amperage draw is under both conditions.

My plan going forward will be to slowly walk the ground supply and the power supply forward on the chain one link at a time to see at which point it causes the motor to stall.
WHat fans do you have? gauge sounds small for spal fans.

My SPAL fans I ran 10 gauge wires right off the alternator + terminal, 40A fuse for each fan, 50A relay for each fan. Ground goes to chassis near factory ground point under headlights, one on each side. The wires get warm running them on high. If I had 8 gauge wire I would have used that.

The reason you blew a 15A fuse with the engine running, but not when the engine is off is because the voltage was lower with it off, so less power was going through the fuse. With more voltage available, the fans were pulling more amps and that blew the fuse.

Electric motors typically pull 2-3x their normal current during startup, it's called inrush current. My spals spike around 120A each on startup. I designed and built a custom fan controller that PWM controls the fans to soft start them, and vary the % duty cycle as needed so that under normal driving, they don't pull much power and they turn on/off as soft as stock fans. But if things get hot, they can ramp up to 100% duty cycle and then move a lot of air.

The reason the motor didn't sputter with your new setup is because your wiring/fuse is limiting how much current they can pull, thus not affecting the battery voltage supplied to the coils/injectors as much as it previously did.
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Old 08-07-2017, 10:53 PM   #702
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I upgraded all the wiring to 10ga and used a 60a switch for testing purposes. I was blowing fuses up to 25a. 30a would survive, but it would cause my motor to die immediately, which placed me back at square one.

I decided to give fan controller a try. This is what I got: https://derale.com/products/electric...n-probe-detail

Essentially, it is a PWM fan controller that soft starts the fans and raises the fan speeds as the radiator gets hotter. I was initially resisting this because I wanted the car to control the fans 100% of the time, but the more I thought about it, as long as the fans come on at 195 degrees (for example) and allows me to force them on (for example, when the A/C is on), I am ok with that.

I laid all the ground work yesterday so we will see how it turns out tomorrow night when I put it in.

On a separate note, I decided to start messing with my A/C. I will post more about that soon.
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Old 08-14-2017, 03:20 PM   #703
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PWM fan controller installed. I have a couple problems with it.

First, it's intended to run off the coolant temperature of the radiator. They give you this probe you are supposed to thread through the fins of your radiator. I hated to do it, but I tried it. And it sucked. It didn't even give me discernible fan movement until about 200 degrees. Even then it was barely turning.

So instead I went with a sensor that reads the coolant temperature in the head. This results in two problems. First, the coolant in the head bares little relationship to the temperature of the coolant in the radiator during warmup, especially before the thermostat opens up. The second issue is that when the engine shuts off, the fans keep running until the ENGINE is below my set point and there is no coolant flow to move the coolant into the engine. I am worried that it will drain my battery and that I will need to install a relay.

Another issue is that at the VERY HIGHEST set point my fan starts spinning when the engine is only 155 degrees or so. This further compounds my "engine off" fan problem. I really hope I don't have to add a relay to turn the fan off. My solution will be to try and calculate a viable offset resistor that will adjust the usable range of the sensor. I want the fan to start to turn about 180-185 degrees. My ECU will then force the fan to 60% duty at 195 degrees and it will continue to rise in duty above that.

I will likely end up adding a relay either way so I can experiment with shutting off the fans at highway speed, but for now that's where I am.

I did drive it to work this morning so that was nice. It ran fairly well until I got to work and the draw on the fans caused the car to stall :(
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Old 10-28-2017, 01:41 AM   #704
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Some developments...

In order to get the fan to operate at a more reasonable temperature range in it's current incarnation, I created a resistor pack wired in-line that brought the resistance of the threaded temperature probe in line with the push in probe. An off-season mod will be to add a temperature bung to the discharge side of the radiator near where the lower hose comes out and I will move the sensor there.

Also, in the time since my last post it has gone from Chicago to deals gap and back and pretty much everything has been resolved. I am still not happy with how my tune seems to change as the car gets hot but I have a few changes in mind that should eliminate some possible weak links.

The big developments: My EFR6758 has been traded for the following:
  • (built) Engine will be professionally assembled by a person who has done it before (all parts provided by me)
  • Engine will be installed in my car and broken in according to best practices
  • All fabrication necessary to install my sensors will be handled as part of my agreement
  • Ducting in the front will be upgraded from my current coro-plast stuff to something a little nicer.
  • Assorted other projects until the money runs out.
This means that my car will keep the precision 4828 and current manifold/downpipe for the foreseeable future. It's ok though because it will still be a monster and I don't feel like spending the money necessary to really take advantage of the 6758 anytime soon.

The motor build should be done within a week or two, and all labor should be done by the time my car comes out of storage in approximately March. It may even be in the car and broken in within a couple weeks but it's getting cold fast and I would rather keep the stock engine in the car until we get all the supporting stuff done. I am thinking honestly that maybe I should do the v8roadsters getrag rear end swap as well as the new BMW trans swap before doing the EFR turbo kit. I feel like if I am going to be upgrading to "all-of-it" I will need all the supporting mods and maybe I should just save up money to get that stuff before I worry about swapping out a perfectly good turbo setup.

Upgrades this off-season:
  • Upgrade fuel pump wiring with a dedicated relay. Maybe PWM?
  • Upgrade to return style fuel system
  • Upgrade to e85 compatibility
  • Build muffler delete for fun
Motor build details:
  • 95'ish block with oilers deleted
  • 10.5:1 Wiseco pistons, 84mm bore
  • Manley forged rods
  • Boundary VVT oil pump
  • ATI fluidamper
  • NB2 oil pan and windage tray/girdle
  • VVT head, ported with +1mm oversize valves. Exhaust valves are inconnel
  • ported VICS intake manifold
  • LS2 coils
  • ARP studs for everything
I am also thinking of having my spare alternator rebuilt and re-wound to give a little more amperage.

Last edited by Chiburbian; 10-29-2017 at 01:22 PM.
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Old 12-17-2017, 03:25 AM   #705
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Started car the other day to get move some fuel through the system and give the battery some relief since I don’t have it on the charger. It’s now dripping coolant pretty steady from the area of the no. 3 cylinder on the drivers side. I’m hoping it’s just a loose coolant supply line for the turbo and not a cracked block from incorrect coolant mixture. :
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