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I made a few efforts to bring the stock BMW fan under the control of the GM ECM, but I didn't get anywhere with it, so I went ahead and ordered this beast in. It's supposed to move 4,000 cfm, so it should keep my "daily driver" setup cool just fine. I'll wire it up so the primary will come on at 210 or so and the secondary will come on at 220. It pulls over 49 amps with both fans on, so hopefully I'll just be running one most of the time.
I'll need to modify the shroud to get it in there, but it should look good once it's all in. You've probably noticed by now that the build has slowed to a crawl again. Another school year has begun, so much of my attention will go back toward helping my students toward a successful year of mathematics, but because I'm so close to being able to drive it, I am having a hard time leaving the car alone, so even though things are happening slower, they are still happening. And I guess that's the important part.
May want to consider a pwm variable speed controller - that'll minimize current draw as the controller only spins the fans fast enough to keep the car at its set point....also soft starts and stops to eliminate the "shock" to the system of that big draw hitting. I only use the stock ecu relay activation to trigger a high temp warning light. Using a dual 11" fully shrouded SPAL unit on mine. They rarely run more than 30% of max. And you can set the temp much closer to the t'stat controlled temp - with stock 187F t'stat on mine I see pass-side head temps of 195F under cruise. Set the fan controller at 200F - so my operating temp band width is only about 5F. Fwiw
Edit - rumors abound that pwm control is available in some of the gm ecu's....no idea how to go about figuring that out. Probably have to use the square root of three or something. lol
I've had one from these folks performing flawlessly for 15 years. Controlled my twin 11" SPAL's as well as a 6" fan on an oil cooler. Although with the LS3, I put the oil cooler fan on a switch/relay. The aluminum block transfers heat to the oil much more quickly than the old cast iron V8 block I had in before did -- and letting the oil cooler run most of the time works better now.
We even modded a VDO/Volvo 52mm tach with the turbo boost gauge face and created a "fan tach" of sorts -- tells me how fast the cooling fans are turning. So I can see the gauge ramp up when they come on, and ramp down when they go off. There are also provisions to activate the fans when the A/C is on, etc.
For the record, I'd go DCC. But I've been holding a grudge against Derale for a few decades since some of their ancient (80's) controllers I bought were broken right out of the box.
You have a good point. I was reading reviews on the Derale unit last night and people are not having the best luck with them. I'll have a look at the DCC unit.
I had the earliest generation of the DCC unit - and 15 years later still flawless service. Keep in mind - set point should probably be around 15F higher than whatever t'stat you're running -- assuming the t'stat is on the inlet like on my LS motor. My OEM 187F s'tat on the inlet results in driver's side head temps of about 196-197F under cruise with enough air moving to not need the fans. So I set the fan temp at 202F - 5F above the head temps I was seeing. So my temp operating band only varies from about 196F - 202F under all circumstances. I have the fans set to turn at 75% speed when the a/c clutch engages --- and even in the summer heat, this results in head temps staying right at 195F all the time when the A/C is on. So I have the unusual situation of the car running it's coolest when the A/C is on....nice.
Just a very small update. I ordered the pwm right about the time that the last post was made. I just got it in the mail last Friday from DCC. Talk about slow shipping. Now I can button up the rest of the wiring and possibly take it around the block. But who knows when that will happen since the weather has grown cold again and I am working like crazy. Ill cross my fingers and hope for the best as far as getting to drive this thing before next summer.
Question for anyone who might have an idea for what I could do for my tcc control wire for my ecm. Most cars have 12 volts running through the switch when the pedal is up and 0 when it's down. Some have 0 when its up and 12 volts when it's down. But not BMW. My car has 12 volts when it's up, then when you push it down the voltage drops to 0 and goes right back up to 12 volts while the pedal is still down. Anyone have any ideas?
On my e36 swap I didn’t even hook up the brake switch wire for the tcc. I’ve been driving it for 4 years and it works perfectly fine. You wouldn’t even know it wasn’t hooked up. The tcc unlocks when the throttle is 0% anyway.
I went ahead and hooked a relay into the brake power wire. The computer seems to know that I am pushing the brakes and idles down slightly in preparation to be put into gear. But it's nice to know that I didn't have to go to the extra effort.
I had some time yesterday and the weather was nice and warm, so I wired up the pwm and mounted it on the radiator fan shroud.
Not the prettiest wiring job, but it rests neatly out of sight underneath the radiator cover.
You'll notice that I'm slowly getting the wiring for the rest of the engine bay under control. Just a few more wires to run to the gauge cluster (I think I have an idea for making the speedo and tach work, time will tell if it's successful) and I will be able to clean up the rats nest of wiring near the pcm.
Got the first drive in today. Still has some lifter tick, but man those germans know how to create a nice interior experience. It's like Christmas time every time I bring the gauge cluster to life. So many pretty lights.
Nah. I did hose it down, but didn't have time to give it a wipe down. The PWM works nicely. Kept the temperature right at 198 degrees. I have one gauge that actually work...the fuel gauge. I'm going to try a few things out. If all else fails, I'll go with either a digital gauge tablet or aftermarket gauges.
Glad fan is under control....that was one of the nicest operational pieces I've ever added to a project car. So much tighter operating band of temps. I ended up placing all of the Volvo/VDO gauge senders in various locations (engine, rad, oil cooler plumbing, etc.) and just using the stock analog gauges. But if yours ran off the Bimmer Bus - switching them out may be easier.
Nice! Just keep us posted since I recently picked up an E61 and couldn't care less for the N52 that's in it currently.
Be sure and post a build thread when you rip the guts out of it. I love seeing the ideas that other people come up with. That way I can steal the good ones when I go through and revise my own designs on the car.
I have to agree on the pwm. It took quite a while to get it shipped out to me, but I would say it was worth the wait as I don't have to worry at all about the cooling system.
08-25-2017, 10:48 PM
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