Pics of damage to the car....
https://www.rx7club.com/se-rx-7-forum-35/charleston-sc-feb-2nd-meet-bbq-725769/page3/

 

Freakin' Cadillacs....that's what did in my 1980 RX7 also......well, I hope the crazy lady makes it and I hope you have a good body man, the leading edge on the roof line is gonna be tough but at least it didn't end up like this...




Bottom line: Is An Electric Fan That Much Better Then The Original Belt Fan?

Answer: Yes, if the goal is a rear wheel horsepower increase. You will always see anywhere from a 5 - 10 % increase in rwhp from this modification alone.

 

But, if you claim that the advantage is a percentage then that would mean:

1. A 100 hp car would gain (for instance) 10 hp, or 10%

and,

2. A 800 hp car would gain 80 hp (again, 10%).

Who ever heard of a clutch fan that required 80 hp to run it? I'm telling you, you can't use a percentage to reflect the gains...

 

Are electric fans better? Yes and no.

Does the electric fan cool better? Yes and no.

Does the electric fan run better than the clutch fan? Yes and no.


There you have it folks. /thread

 

At 800hp the gain would be quite a lot more than 10hp. Probably not 10% but significant.

Like I said, it's the same reason drivetrain losses are expressed as a percentage. As hp increases frictional and inertial losses increase. The more torque going through the gearbox and diff the harder the contact between the gears and more friction. Likewise, the faster you try to accelerate something such as the flywheel or clutch fan the more inertial losses there are.

It may not be exactly a percentage but there's no way it's a fixed number either. It's physically impossible. Think about it, let's say an engine is rated at 200hp. A drivetrain loss of 15% (30hp) means it would make 170rwhp. Off idle, one could expect the engine to make about 30hp. That means it would be making 0rwhp. See how that's impossible?

 

Both are basically correct. Ken is correct saying that the fan driven at a FIXED speed would take the same power in either case. We'll assume that the range of RPM is the same for both engines. Where the difference in power comes in is in the inertial part (acceleration). More power = quicker acceleration and therefore more loss because you are using energy to spin up the fan blades quicker. This is the same principle as a lightweight flywheel. The lightweight flywheel does not add power or reduce drivetrain frictional losses, but reduces rotational inertia and allows the engine/car to accelerate faster (and decelerate faster too when you let of the gas).

In the results, some things bother me. For instance, in the article that Mario posted, you see basically a fixed increase of power over the whole RPM range (like 19 RWHP). Now on the dyno for the FC, you'll see at low RPM, there is no difference between clutch and e-fan. As you go higher, the difference increases. This is more believable than the article that Mario posted. I think that most people would agree that the faster the clutch fan is spun, the more power it is going to take, right? Whereas the e-fan is usually operated at a fixed speed (ON/OFF). There are controllers, but even in that case, the difference would be negligible if these results are correct. What I am saying is that the e-fan will use 1/3-1/2 HP at most, the dyno is saying that the clutch fan is using say 13+HP. This means that either e-fan off, on or anywhere in between, the difference in the peak power is basically the same. That is to say, the difference between the two dyno curves should be the power used by the clutch fan and the gap between them should increase w/ RPM.

 

You are wrong, simple as that....Let's see...if we use 5% from THIS part of my post you ignored while you were seeing red, "see anywhere from a 5 - 10 % increase", on that 800 hp mill, we get a 40 hp gain, which is not far from the 43 hp gain Car Craft got off their 5.0 L tests.

Hmmmmmm...

As you go higher, the difference increases. This is more believable than the article that Mario posted.

There is no such thing as consensus to establishing the Truth. Yet another "simple as that" Truth in itself.. It doesn't matter if people find it hard to believe, there are the dyno numbers back-to-back. THAT IS THE TRUTH. Gravity doesn't care if you believe in it or not, either......I'll play Devil's advocate here...I find it hard to believe you could take a mechanical clutch fan off a rotary and then set up an Efan in 5 minutes. Can the two both be in the engine bay in an FC? I know in an FB or SA, there is no way that is possible physically unless the Efan was a pusher.



I think that most people would agree that the faster the clutch fan is spun, the more power it is going to take, right?

See? That's the point I was trying to make with my 7600 rpm "dare" but the nay-sayers are saying that ISN'T the case with the mechanical clutch-style fan......I dunno...now that I look at your nuke rods avatar, it dawns on me that the clutch may be losing the energy as HEAT.

 

That's pretty much exactly what I said. Since we're talking about horsepower gain we're not really interested about what happens at a fixed speed. I suspect there would be increased frictional losses through the fan clutch at higher hp and rpm as well.

 

Mario: It seems that for the HPP article, the power increase only make sense of the stock fan was at max speed by 3600 RPM and just remained at that speed for the rest of the test. That is the only way that I can see that the power difference would be fixed over the RPM range. Also, what helps the difference to look constant is that Pontiac is tested over a smaller RPM range than the FC. You are correct. The clutch type will lose energy as heat through the viscous coupling of the an. The slippage allowed between the waterpoump speed and the fan speed would result in heating of the fluid. This loss is much less than going clutchless and spinning the fan at whatever speed the waterpump is at.

I would find it interesting to run a test on just the mechanical fan to determine its power consumption. I'm talking not on a car, just the fan. I know of a simple but accurate way to do it. I would like to do this experiment if I can find the time to do it. I think that it would be interesting and could accurately tell us what our fans consume. That way we could measure the power use over clutch engaged or not, different rpm, etc.

REV: Basically there is two components to the loss. 1. Drag, 2. Inertial. If the acceleration is slow (say 5th gear on highway), the inertial part is small and the drag will dominate. In this case, the power used by the fan is fixed no matter the application. If revving or low load, then the inertial part could be important.

 

Sorry to bring this back from the dead, but I just did the conversion to the e-fan and I'm very pleased with the results. I would've stuck with the clutch fan but the belt was slipping and making that high pitched, embarrassing squeal above like 2k rpms, even with a dual pulley setup. I tried another clutch fan and had the exact same results. I had even convinced myself that the water pump bearing must've gone bad, from using the darn yoohoo belt, so I replaced the water pump. Again, same results. So, I got a procomp 14" fan from ebay with a derale controller, mounting kit, and push-in thermostat for less than $65 delivered. It idles so quiet now, and the engine gets up to operating temp faster than before! And yes I can feel a little acceleration improvement on the old butt dyno in the lower gears. Also I get to hear the noise from the engine instead of a whooshing fan sound. Damn cool. What's also neat about the controller is that you can set up an additional switch that works independent of the fan's push-into fin thermostat, so you can turn the fan on from inside the car if the temp starts to creep up before the thermostat turns it on. I chose to do just that. I also did something else that's pretty cool, and that was rather than wiring the thermostat to switched ignition power, I did it to a battery circuit. So now the fan keeps running after the ignition is off, until the temps cool down enough for the thermostat to turn it off! So things under the hood are subject to less heat soak after a drive. Now let's see a clutch fan do that!
Assuming that you have a good battery, I'd recommend the last part to anyone with an e-fan. After a spirited run (which most of mine are) on a nice 75ish degree day, the fan only ran for approx 5 minutes after I parked her.

 

Interesting. How much current does the fan draw?

 

12 amp draw on the fan. What's also interesting is that I tried another run and then left the hood up after parking it, and the fan continued to run for even less time. Then within a minute of closing the hood, the tstat kicked it on again for another 2 minutes. This gives an idea as to how hot it actually is under the hood when there's no airflow.

 

here ya go
https://www.rx7club.com/1st-generation-specific-1979-1985-18/installing-ford-taurus-e-fan-886968/

 

Not sure if my SA can spare another 12 amps... probably would have to wait until after I upgrade my alt.

 

I would have kept my clutch fan, but the space freed up was necessary as my HKS manifold pushes the T04 5" away from the radiator. I had to shop around for a low-profile filter to put on it. It sucks that I'm sucking my intake air through the radiator (maybe it will act as an additional fan?), but it is what it is. Also, just installed a brand-new FD 100 amp alternator as fan kicking on at night with the Porsche fuel pump running would make my lights dim (I was running a S4 alternator). So, maybe the additional .5 hp that the FD alternator consumes offsets the clutch fan deletion.

Does the electric fan make any noticeable difference when you are pushing 400 RWHP? Probably not. It does install cleaner andgives you more space. I have not had any heating problems so far. In fact, my engine is running so cool that I installed an aftermarket water temp gauge in addition to my oil temp gauge. Never goes past 180. Now, come the summer, that may change but I have both a TII and the GSL-SE fan, clutch and shroud that can easily be reinstalled if necessary. The only problem is that I will have to cut the shroud to make it work.

 

Another satisfied customer! But, and I hate rain on your positive story, it should be duly noted that the efan is only cooling the water in your radiator once the engine is off. If you had an electric water pump, then you would be cooling the whole circuit but the battery would be taking quite the beating from those two motors. Better make sure they're yellow top Optimas.

 

I been using a Zirgo 3600 CFM with no problem. I do use a temp control sender that turn on at 160 degrees F. I also add a manual switch inside the car to turn it on and off. On long cold driving I turn it off with no problem, especially on the freeway. Driving on a cold night e-fan off is at 160 degrees F. On driving to Shasta, California up north on August, the heat was 95 to 100 degrees and driving up the mountain. My St-Ports with the Zirgo E fan run at 190-197 degrees and I was pretty happy, it did not even went half way up on my stock temperature gauge. Freeway traffic stop and go on a hot day its at 185 degrees. So far for 10 years E-fan has work for me. As far as HP I don't feel any difference.

The Zirgo fan is a 16 inch that also cools down my oil cooler. Sweet deal for the price of one.

 

so would a single 16 inch fan be better than say two 10 or 12 inch fans (depending on which would fit)?

 

In what I have been using all this years, yes I have check on 10" and 12" CFM, the Zirgo 16 inch with 3600 CFM fits better on my car. The 10" and the 12" did have problem on making sure if fit better. Its been so long ago when I did research. I think the 10" and 12" E-fan don't make enough CFM to add to 3600 CFM. I actually use back then a 3000 CFM. Now I'm using the latest from Zirgo 3600 CFM. I guess they stop selling the 3600 I can't find them. But the 3000 CFM works good too. That is what I use first. There is one that makes a 3600 CFM in Ebay for $120 he has a 100 feedback so it looks like he got satisfied customer.
http://cgi.ebay.com/ebaymotors/16-IN...#ht_762wt_1140 Good Luck!

 

right but coldnt you use two 8, 10 or 12 inch (depending on what will fit side by side) that push 1500 to 2000 each? so it would be 3000 to 4000 total.

 

Your right you can use 2 12" e-fan, if you can find a 2000 CFM. For sure in the 8" or 10" there is none with a high CFM. I have been using one 16" e-fan ever since I took the stock clutch fan. I also like to use one relay for one fan. E-fan wire for one fan is cleaner. Just make sure its over 2800 CFM its best for the rotary engine.

Also if you go to Ebay link that I send earlier look at the feedback for that 16" e-fan for 3600 CFM. All the positive feedbacks are mostly V8 owners that needs strong e-fan.

 

You are correct in stating that the only coolant getting cooled by the fan is in the radiator. Engine on or off. But everything else under the hood is enjoying the breeze too, or so I would think. Hey while we're at it, let's get an electric oil pump going too, hehe.

I've recently thought about maybe tapping into the tstat on the pump housing to get a more precise time for the fan to kick on. I think that one switches the choke magnet too. Right now my temps get to about 40% up on the gauge before the fan comes on, whereas before it never got above, say 30%. Even though its still in the safe zone and hasn't risen any higher than that, I think I'd prefer it to stay as cool as it has been running. Any thoughts on this?