Kentetsu

The only difference I see between our installs is the fact that you thought of running dual circuits (and I have just added that to my to-do list). They were all rusted up when I bought them, but I removed the motors/fans and soaked 'em in some good old muriatic acid for a bit. Still a bit pitted afterwards, but after painting they look decent at a glance...

Weren't all 1st gen MR2's supercharged? Funny thing is, the wife's van uses the same engine and supercharger. Fastest damn minivan I've ever been in!

Jeff20B/Mar3: That's a pretty old picture. New (used) motor is going in, and the old motor has been convinced to donate her oilpan screws, which I felt was quite considerate of her.

Thanks for the compliments guys...

ray green

iTrader: (14)

"The main point i made that no one seems to be getting is that the clutch fan DOES ENGAGE TOO EARLY, optimal running temp would at LEAST 90degC ~ ~240degF, but the clutch fan fights to keep the coolant around 78degC ~172 degF, which is unnecessary energy expenditure, and also the coolant is cooler than you want it because atomization improves with higher temperature!"

I've got to disagree with this, the clutch fan (a properly functioning "healthy" clutch fan) essentially never engages at all, except when you first start a cold engine (it engages for a short time, then let's go - not sure why this is since the engine is already cold).

But once the car is at operating temp the clutch fan just free wheels - it almost never engages (I know, I stick my finger in my fan on a regular basis):

http://youtube.com/watch?v=Oi7BANPkh-Y

My temp always holds steady at 180 degrees whether highway cruising or sitting in Atlanta traffic on a hot summer day, when it will occasionally kick in and do some work.

All this noise about lost horse power from the clutch fan dragging is just nonsense. The fan never drags, that's what the clutch is about.

Fan Clutch. Get it?

And if you guys keep this post going for another page I promise I will post my movie again.

Which I expect will happen.

Ray

Kentetsu

Hey, I just did it because all the cool kids were doing it.....

Jobro

iTrader: (2)

whops 92degC is about 200degF, I have to type in 240ADC in my megasquirt to tell it to turn on at 200F

bliffle

Huh? Where? I missed it.

djjjr42

I meant threads, not posts in this thread. I just read one a couple days ago where the guy measured on the dyno after every mod just to show the gains of each. I was really surprised by that the fan was so much.

ray green

iTrader: (14)

Maybe the fan was broken? Locked up or something?

When that fan clutch is engaged it does draw a lot of air - this is what it's so perfectly designed to do. So it probably does pull a bit of power for the few moments it's engaged.

But since a properly functioning fan clutch is almost never engaged, I don't see how it could be much of an issue. Certainly I've never noticed any power drag from the fan clutch on any of my 84/85 GSL daily drivers.

But maybe I'm missing something. Like Ken says, it the cool thing to do and that's not nothing. Maybe I'll give an efan a try.

djjjr42

This may have already been mentioned here but some other advantages of the efan are:

1)Your engine will warm up faster since the efan is off until your coolant reaches x degrees. The stocker still moves air when the engine is cold.

2)After the engine is hot and either fan would be running, you have the inertia of the clutch fan to drive along with everything else. I'm sure everyone is familiar with the loud whirring sound on the stocker. The engine is able to spin up a little faster with the efan in the lower gears.

Kentetsu

One thing to remember in regards to the dyno results; while on the dyno, there is no air movement over the radiator as there would be going down the road. This would mean that the stock fan would be engaged during the dyno testing.

Then again, the efan would also be running during testing, so the results would probably be valid in any case...

ray green

iTrader: (14)

These would only be a concern if the fan weren't working correctly, which I suspect is the case for a lot of people who complain about power drag and whirring sounds with fan clutches.

A properly functioning stock clutch fan will only engage for a few moments after a cold engine is started. For my current 84 GSL that's about 15 seconds, not nearly enough to affect engine warm up.

A properly functioning clutch fan makes no noise when it is not engaged. There is no whirring because the fan is not pushing air. In fact, the unengaged fan is free wheeling, so there is no drag at all.

However, if the fan clutch is stuck it will make quite a roar whatever the engine temp. I had this happen once in my brown 85 GSL, it sounded a little like a jet turbine with the hood up and you could feel the wind from several feet away. I fixed the problem by putting in one of my spare properly functioning fan clutches.

So this efan thing seems to be just another one of those urban myths.

djjjr42

Clutch engaged or not it still turns and moves air. Are you saying your fan doesn't rotate at all when your engine is cold, save the 15 seconds you mentioned??

Kentetsu

If you check out Ray's video, you can see that there's no real force behind the spinning blade. I don't think there's any realistic drag on the motor at that point.

However, consider the source of the power. With the clutch fan, it comes straight from the motor. So when engaged, it will affect the power output.

But with an efan, if connected to the battery (rather than straight to the alternator), the alternator will have all of the time the engine is running to replenish any charge that is used. So when the efan is running, you might not see any noticeable reduction in power, because the power requirements are "spread out" over the entire time the engine is running.

If autocrossing on a hot day, chances are that your clutch fan will be engaged at least most of the time. And 1st/2nd gear is what is typically used for autocross, and that is also where you can "feel" the biggest difference in power when using an efan. The difference may not be huge, but I strongly believe that it is there...

ray green

iTrader: (14)

It spins freely and doesn't move enough air to detect, therefore it is creating essentially no drag on the engine.

Have you seen this video?:

http://youtube.com/watch?v=Oi7BANPkh-Y

That fan is spinning pretty fast, but it isn't moving much air. In fact the ram air at even moderate speeds will be much more than the driven air, so that the ram air will actually spin the fan, rather than the fan pushing the air.

The only time that fan pushes air is on those rare occasions that the engine is working but not getting any ram air, like sitting in traffic or, I suppose, running on a dyno.

When there is no ram air there of course will be a tiny amount of "drag" on the engine even when the fan clutch is disengaged, but this is hardly the basis for concluding that fan clutches create unnecessary drag on engines (do you really need that immeasurably tiny amount of HP when you are sitting still?).

Like I said, the only time my fan clutch engages is during that brief start up and very rarely when I'm sitting in traffic on a hot day. Virtually all the time, when there is power to the rear wheels, the free wheeling fan is being DRIVEN by air, not driving it.

But if you really want to get rid of you fan clutch, please send it to me!

Ken, why do you always post 1 minute before I do?! And of course you bring up a good point, under more extreme driving that the rather spirited commuting I do, like racing or autocross, you certainly might want to have the extra power that a fan clutch robs when the engine needs that extra wind. As Ken points out, under these conditions the battery and alternator are powering the efan, so you are protected from the possible drag that might happen should the clutch fan engage.

djjjr42

Ray I've seen the video, and the fan is rotating until he sticks his finger in it. I can do the same with mine, the clutch is definitely not engaged at that point. What I'm saying is whether it is engaged or not, the fan is still moving air. You surely aren't suggesting that since the clutch isn't engaged and the fan is not moving as fast as it can that it isn't moving ANY air? Even just a small amount of air flowing will effect the engine's warm up time, period. For the most part I let my car warm up and the choke disengage before driving it.

The second point I was making regarding the whirring sound....those rare occasions happen more often than you'd think. Take for example:
Let's say you're sitting in stop and go traffic at rush hour. Or you're at a long traffic light and a guy pulls up next to you and revs his Honda Civic with a fart cannon and you want to teach him a lesson by giving him a taste of the 7. At any rate your fan engages since you've reached the temp for it to do so. Once you go to take off the fan will still be engaged ( the whirring will be heard) and thus taking away from potential power that would otherwise be going to drive the wheels. The fan won't disengage or be driven by ram air when you have not yet built up speed for it to do so. See what I mean?

Glazedham42

iTrader: (4)

So Mar3, are you going to do some dyno testing on this subject or did I misunderstand you?

ray green

iTrader: (14)

Well OK, it depends on conditions. So Mar3 will have to tell us exactly what's being dyno'd and how.

But for practical purposes, I generally don't race Civic's at stop lights and while I'm not opposed to having fun driving the highways, I generally stay within limits - ie, no racing.

Also my 84 GSL is very well maintained and has a recent radiator, so it's at 100% cooling efficiency. This might not be the case in some cars (we all know what a dying radiator is like, near daily overheating problems when the car is stressed).

So what I'm saying is that if you have a well maintained cooling system and aren't racing hondas a clutch fan will almost never be engaged, amounting to essentially no drag on the engine.

Therefore, since under normal driving conditions there is essentially no opportunity for gained horsepower, switching to an efan can not provide any gain in horsepower.

But even if my clutch fan came on a lot because of a honda racing habit or an afternoon at the auto cross, I still don't see how an efan could, in the long run, increase horsepower. This is because the power that drives an efan comes from a battery that gets its power from the alternator which gets its power, you guessed it, from a fan belt to the engine, just like a clutch fan.

In other words, you don't get something for nothing. You can only max out efficiency, which I suspect the fan clutch does best hands down.

bliffle

Actually, the moving air is spinning the fan, when driving at speed.

djjjr42

Ahhh Ray, I've so missed our debates!

Yes but normal driving conditions is different for everyone. We're talking about performance gains so that's why I made those points. If you never rev your motor above what the choke does upon startup and also try to squeeze 500 miles out of each tank of gas then no, you probably won't benefit from an efan.
A well maintained cooling system is irrelevant. If the car didn't need the fan except for extremely rare conditions then why would Mazda put it on there to begin with?
Forget racing or autocrossing. Ever go through traffic or a drive through restaurant on a hot day? Or had to wait for ages to pull out of a parking lot and then having to get into the throttle a little so that you can squeeze into that small gap in traffic that has miraculously presented itself? With the temps being what they are where we live, your fan is engaging a lot more than you think.
Yes there is a spike in the power drawn when the fan kicks on. However that is quickly taken care of by the voltage regulator. You don't feel your car losing power when you turn on the radio or operate your windshield wipers, do you? On a side note, I've switched over to a higher output alternator which has an amperage rating of about 150% over the stock one.

Toyman01

In my experience a fan clutch that is as easy to stop and turn backwards as the one in the video is worn out and has lost most if not all the fluid in it. I wouldn't try that on a new fan clutch. A properly functioning fan clutch has some resistance to slipping at all times, even when hot. I personally run a e-fan because I can't stand listening to a engine driven fan when they do engage. When engaged they pull 5-10 HP and when you only have 110+-HP to start with...... And the thought of having a 25+ year old piece of plastic turning 7000rpms makes me think of dents in the hood.

Jeezus

iTrader: (4)

I got a spare one around the garage somewhere, works great. I'll give it to ya when I see you again

Jeezus

iTrader: (4)

When the clutch is cold it is supposed to do that.

Toyman01

Also when hot.

djjjr42

Toyman I sent you a PM, we are having a SC RX7 club meet in Charleston tomorrow. I'd like to see another 1st gen at a meet, come join us if you can at Patriot's Point in Mt. P between 10-11.

Toyman01

PM sent, Can't make it Let me know when and where for the next one and I will try to make it.

ray green

iTrader: (14)

"also try to squeeze 500 miles out of each tank"

Not quite right dj, I usually settle for around 350-400 miles per tank and I have my fun, you can ask Stu how I drive. Like I said, about the only time my fan clutch engages is when I first start a cold engine, for about 15 seconds it whirs, kind of a nice sound, really, and every once in awhile, when sitting in traffic on a hot day. And even then it is hardly noticeable.

I never have even the slightest over heating problems, when driving hard or sitting in traffic. This is confirmed by two temp gauges, one stock and the other taking a reading at the thermostat housing - the both read rock steady at 180 degrees.

So if the fan clutch is worn out, it doesn't seem to matter much, does it? (And no, I'm not loosing any sleep worrying about my 25 year old fan blades puncturing the hood).

But out of generosity, we should allow that I'm driving a well maintained essentially stock 84 GSL, put together the way the Mazda engineers planned it, while many of you folks with efans have molested your cars to the point of putting in pistons. So efans, power robbing high output alternators and toggle switches that you can use manually to try to keep the thing running in traffic might in fact be useful, even necessary "upgrades".

Am I sounding like Hillary?