Ironman404

88 N/A Vert

So my fan is in bad shape - the shroud had been loose and rubbing on it for who knows how long before I bought the car. Had to remove the shroud because it was toast.

I'm looking at just buying a high quality aftermarket electric fan kit - increased cooling and free up a small amount of horsepower.

Anyone else here done the same? Thoughts? Recommendations? Favorite color?

WondrousBread

You will not receive increased cooling or free up any [real] horsepower. The stock clutch fan freewheels when not in use, and it does not suck up much power anyways. The stock clutch fan also moves a huge amount of air (somewhere in the region of 2900-3100 CFM) The safest bet is to buy another clutch fan, and keep the stock cooling system intact. The only compelling reason to remove it is if you need the space for something (intercooler, turbo intake ducting, etc) which you most likely do not as you have an N/A. As your alternator is only 60 Amps, you will need to upgrade to the 90 Amp S5 alternator, or the FD alternator, or the popular Ford Taurus alternator as well to run the fan.

Popular fans are well documented, but the easiest, cheapest, and most effective way is to get a Fiero, Taurus, or Contour fan (search for the exact years).

Frankly, unless you are unable to source a replacement clutch fan, there is no compelling reason to get an electric fan.

Aaron's website documents how to properly install a fan, and also why a fan upgrade on an N/A rx7 is not really necessary. Google search "Aaron Cake Rx7" and his website will pop up. If you cant find it, I'll go link it for you.

Ironman404

Well damn...that clears things up lol! I guess I just need to get some new fan shroud for the stock fan. I'm sure my buddy that's doing some other custom fabrication work for me can just make one out of aluminum.


THANKS!

WondrousBread

That actually sounds cool, maybe post a picture when it is done

Just letting you know, the FAQ in this section and the Rx7 section of Aaron's website both provide lots of information regarding servicing, common faults, and things to watch out for with your 7.

Have fun with your Vert

JerryLH3

iTrader: (11)

You will want to get a shroud on there as soon as possible as it is necessary to help the stock mechanical fan pull air through the radiator.

littlebit421

Out of all the FC that I have owned or my friends have owned I have never had an issue with the cooling properties of the stock system, even on some turbo 2 that my friends have had. now granted these were mostly stock vehicles with maybe with an open style air filter intake and exhaust. I actually had a friend try to put an electric fan on his tii and it didnt perform as well as the stock and he went back to the factory set up. If your cooling system is up to par then you shouldnt need to even change the radiator as even the stock one is pretty stout.

Acesanugal

iTrader: (5)

I've got a fan shroud I could sell you. Pm me if you need and we'll work something out.

clokker

iTrader: (2)

I disagree...you want an efan if you want a fan that actually responds to coolant temp.

Not true.
The stock fan clutch never freewheels and never fully locks up.

There is no plausible defense of the stock fan that says it's "better" than an efan, the most you can say is that it's simple and it works OK.
A properly configured efan is inherently superior- simply due to its better, more accurate control system.

littlebit421

ITS ALL ABOUT THE CFM'S MAN THE CFM. The only down fall I would see with an Electric fan would be the electrical draw on the system. <---- just part of discussion.

Acesanugal

iTrader: (5)

And we're debating a topic that has been covered five thousand times already because....?

Children please.

FrankV702

iTrader: (14)

In my old 90 vert that I did a cosmo swap on, I used a Zirgo 3000cfm cooling fan.. I found a shroud on jegs that fit perfect for it, and I controlled it wth a SPAL PWM controller. Worked awesome. I live in Vegas and never had any heat issues with it.

littlebit421

Ive got the pop corn ready for the great debate round 2

WondrousBread

I'm going to preface my following statements by stating that you are probably aware of much of this information given that you run an E-Fan in your car.

The clutch fan is adequate for a stock N/A and has fewer points where it could fail. Barring the fan or shroud being damaged by some kind of debris (or in this case, the fan hitting the shroud) or the clutch failing (which does happen), there is no other way for it to really fail. Not that an E-Fan is particularly complicated, but it does involve more parts (at least one relay, a fuse, wiring, an electric motor) and still has the fan blades and shroud just like the clutch fan.

The first question with regards to energy efficiency is "Which is more efficient?"

I would imagine that an electric fan is inherently more parasitic to the system than a clutch fan, as it is doing the same job (ie, moving the same amount of air) but has a more complicated energy transfer system.

Clutch fan:
E-shaft>Water Pump Pulley>Viscous Clutch>Fan blades

E-Fan:
E-shaft>Alternator (kinetic energy becomes electric potential)>Electric Motor(electric potential becomes kinetic)>Fan blades.

Unless the E-Fan almost never runs, or fan blade design has advanced so far since the advent of the clutch fan in question that it has made up for the lost efficiency, it should be less efficient to run an E-Fan than a clutch fan of comparable output. Therefore a clutch fan is superior in the respect of efficiency.

Which then brings us to the far more important question "How often does the fan run, and for how long?"

In this respect the E-Fan is the obvious superior. A properly wired E-Fan will run only when the temperature is creeping in low speed situations. The addition of variable speed means you can wire your fan to run at only the minimum speed required to suit the situation, and you can relay it for a bypass so it runs when you engage Air Conditioning, thereby eliminating the little condenser fan in Rx7s so equipped.

The clutch fan does, however, freewheel. When my car is cold (as in early-morning starts after not driving since the previous day) I can spin it by hand. If I warm it up in the drive way, I can hear the airflow increase as the clutch begins to grab. Once warm, the clutch is relatively grippy. The clutch never locks because I assume if you redlined a hot engine and the clutch was locked the fan blades would explode from the stress of spinning at that high a speed.

The clutch fan does provide a small drain then even when not strictly in use, but I don't believe that this accounts for the lost energy efficiency of the E-Fan. It isn't truly engaged as such, just causing a slight drag.

I can't provide any testimony as to how often the E-Fan engages as I don't have one, so I'd be interested to know how often you hear your fan engage in low speed creep situations or on hot days. If it almost never engages, than perhaps the lost efficiency IS accounted for by the fact that it runs infrequently and I'm talking out my a** for saying otherwise.

The best way to test the clutch fan vs an E-Fan would be fuel consumption data over an extended period, first with the stock fan and then with a properly implemented E-Fan. I cannot provide this data as my clutch fan seems fine and I have no current plans of changing it out for an alternate setup.

However in the case of this thread, he asked what E-Fan he should install to provide increased power and reduce temperatures, and the answer (in my opinion of course) is none. The clutch fan does not cause enough drag to reduce power by any measurable amount (to my knowledge), and an E-Fan should not cool any better than the clutch fan. Therefore the cheapest and simplest option is to get a shroud and keep the current setup.

clokker

iTrader: (2)

Allow me to provide some anecdotal evidence gathered over the last eight years.

For context, I have a Godspeed alloy radiator, an 18" Lincoln two speed fan/shroud, Volvo control relays, a twin trigger (195/210°) BMW temp switch, VDO temp gauge and an upgraded alternator (110a)

In my normal daily driving, I'd say the fan is off approximately 99% of the time and ALWAYS off at anything over 40mph or so. During the course of my last road trip (3500 miles) I'd bet the fan was on for less than 15 minutes total, most of that in Chicago traffic
There is absolutely no question that from an efficiency perspective, the efan is a clear winner.

I'd say that energy consumption is hardly the most relevant asset the efan has though, it is much more directly responsive to coolant temp changes than the thermoclutch, which gets its info second hand (from air temp off the rad).

I have run basically the same control setup for years now and have never so much as blown a fuse (30a) and in fact, can't remember the high speed ever kicking in.

I'd guess that the majority of efan failure stories are the result of crap components and/or shoddy installation.

I should also note that I'm sort of a Luddite- my car has manual steering, no AC, manual windows, locks and seatbelts...basically I wanted as simple a car as possible and even so, I consider an efan not just a worthy, but a critical FC upgrade.

WondrousBread

It's true that the E-Fan is more responsive than a thermoclutch.

However, I think maybe the fact that your car is simpler mechanically (with regards to the installed options) makes the E-Fan a better option for you than for people with options installed. My car has Power Steering, Air Conditioning, Power Windows, and I installed power locks.

In a low speed creep situation such as navigating in the parking lot on a hot day, stop and go traffic, or a drive-thru, my Seven is working to propel the car as well as power the steering and sometimes the Air Conditioning. As for the windows, sunroof, and locks, they aren't really relevant in this situation as they aren't really in use.

If I had an E-Fan installed, I think it would run almost all the time at idle or in low speed creeping, so it would be a pretty inefficient setup for me.

However, I can see that the E-Fan would probably not run as often for you because the car is under less load in the same conditions.

Unless someone can chime in regarding an E-Fan they have installed on a fully optioned out Seven, and the amount of time it spends running, I can't really contribute anything more than conjecture at this point.

scathcart

Dyno's say otherwise.

No, it does not freewheel. Not even close.

source? Or else a made up number.

While he would need an upgraded alternator, those quoted amperage numbers are false.

There are several compelling reasons. It's usually due to cost and complexity of wiring in an appropriate controller that this is not reccommended.

Dak

Of the things listed the A/C is the only thing that would effect cooling. I have power steering and an E-fan and it works fine. Unfortunately my A/C doesn't work so I've no input on that other than with the right fan that will be fine as well, as you can find in other threads with turbo guys with A/C and E-fan and no problems. On a brass stock replacement rad. in traffic in summer I could see temps creep up to 210F or so. With the Godspeed Rad. I don't think I've seen it go above 195F to 200F. This also is with the Perm-a-cool "finger chopper" which is completely un-shrouded. https://www.summitracing.com/parts/prm-19115/overview/ This works for my application as my driving is probably 80% - 90% highway and country roads so my fan rarely runs. It's controlled by a thermo switch. I've had this setup about 15 or 16 years. Only had one problem referenced in this thread: https://www.rx7club.com/2nd-generati...blown-1108393/ where the fuse holder melted after 15 years.

Besides nobody mentioned the most important reason. It clears up so much space and looks much better.

Dak

Yep. S5 is 80A and did fine for me 'till it died. I'm now using a 626 alt. that's rated at 90A.

WondrousBread

As I mentioned, you may want the space for something else or you may not be able to source another clutch fan. However, on his otherwise stock N/A the only compelling reason I can think of is what Clokker stated, which is the precision. I personally find the clutch fan adequate in this regard too, but that is simply my opinion and not fact.

When mine is cold, it is fairly close to freewheeling. You can easily stop it with your hand. When warm, it grips. I think the misconception that the thermoclutch does not self-adjust to the situation stems from the fact that most people pay the part no attention until it has already failed. I had one before that was stuck in the "slightly grippy" state. Did not freewheel when cold like my current one, did not grip enough to cool properly. Replaced it and have had no issues other than my stock temp gauge being incorrect (unrelated).

"Some estimations have been made that it is approximately 2900 CFM at 2600 RPM using software modeling." - Aaron Cake: The Myth Of The Electric Fan

The Myth Of The Electric Fan

My statement was 2900-3100cfm (given that it had been several months since I read the article I gave a ballpark estimate). The number is not "made up". As for his source, the provided hyperlink on his site seems to be broken.

The Bosch AL394X from my S4 is rated at 60A as I stated:

https://www.summitracing.com/int/par...x/applications

The S5 alternator is apparently 80A, not 90A. My bad.

Source? Rather, one specific to the Rx7? I can find some evidence for other cars that horsepower has increased (I think somewhere it was by 4 or 5 horses, which is not insubstantial) but never on an FC. Also, the time when power is gained is once again when the E-Fan is not running, and a properly working thermoclutch fan should be [almost] freewheeling under those conditions.

WondrousBread

I actually said directly below that list of electric components that only A/C and Power Steering would affect load in this situation. I listed the other items to contrast my car to Clokker's.

I can see no reason why power steering would not increase heat in a parking lot as it does in fact create engine load. Though definitely not as much as A/C. I do appreciate that input though, as based on your experience it does not impact cooling in any significant sense.

You are correct about it clearing up space and looking better. Why did they choose a creamy beige colour for the fan anyways? Why not black?

RXSpeed16

iTrader: (41)

Because camouflage is not a good color scheme for something that is referred to as a "Finger Chopper"

Dak

Yeah, I somehow missed that

I don't disagree that it is a load on the engine. I just don't think the heat from it, if any, is significant, but it sounds like we agree on that.

I think every clutch fan I've seen has been an off white beige color.

WondrousBread

Touché

ramses666

iTrader: (1)

I would say that both the stock clutch-fan & the electric fan both suffer from the same in-efficiency. Namely, that neither one are used at all under normal "Moving Conditions" & that Both offer zero benefit for performance, other than being Deleted if possible. What if the movement of air could actually be used for some strange, but beneficial purpose when not needed for non-performance related cooling issues?

I believe most people are trapped in the useless & played-out modes of the past & couldn't think their way out of a box of tissues.

But then again... this forum is always somewhat brutal at times... I might be convinced into sharing the Home-Depot Super-Hacked Cold-Air/Fan Replacement Intake for a Lame NA... But that would be giving away the Secret Surprise Ending... I still need some bicycle parts & a few super-flux capacitors...

Get a New Fan Shroud & a Proper Stock Fan & Flush the Junk out of your System. The Rest is a Luxury or maybe an Upgrade, but Not Required or really noticeable. You should never neglect to re-install the under-body covers & various air ducting doo-dads, as Mazda actually went to some kind of trouble to actually put them there.

If you make modifications, then you're kinda working against yourself, unless your upgrades are from deleting emissions & restrictions & then you will be fighting the Stock ECU & restrictive MAF, as well as the fuel system.

Quake in Fear! & Rightly So!

clokker

iTrader: (2)

Your definition of "performance" is too narrow to define anything but a dedicated track weapon...in the real world, cars must be able to deal with hot, no movement situations and that ability is definitely within the performance criteria that should apply.

It's easy to "think outside the box" when you willfully ignore reality.