that sounds like very good MPG's from something that big on a carburettor! I have a 1992 19 foot E350 7.5L high roof van which weighed 7550 lbs. On the first 1000 mile trip after picking it up I averaged 11.6 mpg at 60 mph on the straight bits. That is from a much lighter vehicle than yours, and with EFI! I have not checked it since fitting headers or any of the other mods though.

 

There are some but they are used mainly for drag racing to cool the engine between runs
I would not recommend them for a daily driver and more importantly, neither do the manufacturers.

 

There have been some serious developments for this unending project, so I thought it appropriate to resurrect older thread. As the reader may have noticed, I had been contemplating a radiator swap along with the transition to electric fans. Well, a detailed discussion with the local (highly respected) truck radiator shop lead to a recoreing of the stock radiator and the addition of a Moroso overflow tank. The consensus was that the original (super cooling package) radiator was better than any current downflow unit and at least as good as any of the F350 crossflow radiators. The acknowledged exception of the double pass crossflow was discussed and passed over as at least requiring a high volume water pump and offering an un-required additional thermal capacity.

About this time we entered the High Sierra hot summer period with ambient temperatures of 105F at mid-day. I was idling in stop and no-go traffic with AC blasting on just such a day when I saw my aftermarket water temperature gauge go to 215F and continue to climb. I quickly shifted to neutral and brought rpms up to 2500 and the temperature slowly went down. Slowly, and with no roar from the mechanical clutch fan. Well, I replaced the clutch fan with a severe duty Hayden unit and installed a 7 blade fan (upgrade from the 5 blade stock unit). Everything tested out fine but I never heard the fan kick in hard. A few months later, I embarked on a 9,450 mile round-the-USA tour with the beast and again encountered the over 215F thermal problem again repeatedly in the Southwest. Always very slow or stationary road speeds, very hot ambient and AC on. It seems the clutch fan has to see air from the radiator temperatures of 225 to 230F to lock up. Well before this the AC performance declined rapidly. As a result, the electric fan upgrade is back on and I'll detail that in the next post to keep this to a digestible length.

 

Near the end of 2016, I tested several aftermarket fans with a real Air Flow Measuring Device (anemometer) and was stunned to see how fictitious the advertised numbers really were. After following the adventures of others on the internet, I too concluded OEM electric fan packages were far superior to the aftermarket group except for the very most expensive. The most highly regarded OEM fan assemblies for electric fan swaps are the venerable Lincoln Mark Vlll, the Ford Taurus, the Ford Contour and the Ford Windstar. The Mark Vlll is the most highly regarded, is a single fan with 18" blades, can pull more than 4,500 cfm (I measured 4,810 cfm on my bench) but the fan motor projects 6.42" from the face of the radiator core and therefore occupies the same volume as the fan pulley without fan. The other serious issue using OEM fans is the lack of any CFM data for nearly all candidates. The Taurus fan is also a single fan with a smaller fan blade and is rumored to flow about 4,000 cfm as apparently does the Contour dual fan setup. Unfortunately, I have not been able to find the original posts giving the source of these flow numbers, so my scientific background treats them as anecdotal at best. The Taurus fan projects about 6" from radiator but the Contour only projects out 3.55". The most extensively used OEM fan assembly for electric fan swaps is the Ford Windstar unit. The Windstar 99-03 version dual fan assembly flows a measured (Dorman replacement specs) 4,403 CFM (I measure 4,588 CFM) operating in the high speed mode and drawing 37.5 amps total for both fans! Unfortunately, the Windstar OEM unit has two different fan projections. The passenger side fan motor projects 3.93" and the driver's side motor comes out 6.0" from the radiator core. There is also a Windstar unit from 95-98 production with nearly identical dimensions.

For my 1982 E350-based motorhome, there are two serious interferences with these fans. The end of the fan pulley (without fan blade and clutch assembly) is 4.72" from the radiator core. Also, the AC pulley for the York AC compressor is 5.5" from the core. The AC pulley is in exactly the same physical space as the driver's side fan motor. Crisis! However, armed with my CAD programs and laser measuring tools, I found that the shroud could be manipulated to just clear the AC pulley but it would be dangerously tight. Then I noticed that while the OEM units in the junkyards had the two different sized motors, the replacement units available from RockAuto and other vendors showed two versions, one of which had the same depth motors on each side. An extended conversation with Dorman over their 620-131 fan assembly resulted in confirmation of the thinner unit. The tech rep pointed out that they had addressed several concerns and made improvements to OEM designs as warranted! I have now personally measured the Dorman 620-131 (replacement for the 99-03 Windstar Fan Assembly) at 3.94" (100mm) projection of motor end cap from radiator face. This unit will slide into the radiator area without any interference or impact on belt changing access.
This is important because many individuals have labored extensively (publishing detailed How To posts) to swap a second pass side motor for the longer driver's side component.

A last issue in this post is that of shroud size compared to the dimensions of the radiator core. The shroud area for the Windstar assembly (29.5"Wx17.4"H) is 513.3 sq. in., the Contour assembly (24.2"x15.8") area is 382.4 sq. in., the Mark Vlll (18.5"x22") is 407 sq. in and the Taurus (18.5"x23") is 425.5 sq. in. The radiator core for the 7.5L engine in my beast is 29.1875" wide by 21.125 " high for a surface area of 616.59 sq. in. The factory Windstar assembly covers 83.25% of the radiator core. The width of the Windstar shroud exactly matches the radiator core of the E350 (the cited dimensions are to the outer surface of the shroud and the material thickness of the shroud is 3/16"). In the height dimension, 3.75" of the radiator core will be unserviced by the Windstar shroud. There are extended discussions about permitting open flow for highway cooling unimpeded by the shroud. I'm not yet finished here. I'm currently looking for the shroud from an E350 with the 7.5L engine so that I can meld the two shrouds together.

I'll address the question of control of the fans (I'll use PWM units to individually address each fan) in a following post.

 

interesting info

 

At one point in time, I had a 79 Ford Ranger, 460CI, 3/4T, short bed, crew cab.
I was leaving the Great NW and heading to Alabama.
It had dual caliber pistons on the frond disk, huge drums in the back.
Had the radiator rebuilt by a very old and reputable radiator shop in the Tacoma area.
It was the stoke dimensions, but 4 cores.
They told me to run Prestone water pump lube and water in the hot months, and swap it for antifreeze mix in the cold months.
The first time i filled the rad, it took a full 5gal water can of water and then some.

When we left to drive to the AL, we looked like the Beverly Hillbillies.
I buddy of mine helped me make an extension on the rear end to tow our car, and support a 12' cab over we were to pick up in Cali, which weight just about a ton. Good thing I had the adjustable helper springs on it.
I welded up a tire mount on the front to hold the spare. The rims were new, and didnt have any slots in them as a stock rim would.

Loaded up the 6 of us, the cab over camper, hooked up the Colt wagon full of household goods and headed off cross country just as summer was coming on.

Long story short, that monster never broke a sweat nor over heated. granted the national speed limit was 55 at the time.

I used to laugh sometimes in the humidAlabama summers.
The engine bay would get so hot, i could easily pull the insulation off the wiring it got so hot, but that engine never overheated running the water and lube...Wish I still had that truck!

 

Aha, overheating memories! My version is that of my first car $25, 1952 Ford, summer 1960, pushed into the driveway by my Dad's friends. 2 months later the flathead V8 was operational (memory says Friday morning around 10 AM). I immediately decided to do a road test from my home town in Pennsylvania Highlands to my aunt's home in Butler, PA. My mother insisted I take a plastic jug for the radiator - just in case! In the event, I often (on that tour) made almost 20 miles before blow-overs. Scrambling down the creek and river banks to fill that jug burned the memory of that trip - and the need to check for leaks before commencing the drive - firmly into a deep place!

 

On to a minor discussion of the fan controllers needed to complete the transition from mechanical clutch drive to electrical fan cooling.

To start, I have to review a few key features of the Windstar dual fan assembly. To begin with the two fans measure 15.5" and 13.5" in diameter, the gap between the fans in the central area of the shroud is 0.5", the large fan has three terminals, the small one has two and there is no internal baffle between the two fans. Inspecting the Ford Windstar Factory ETVM, shows that there is only one power line to each fan and that power line spliced at the power input point. The ground lines are also joined together at the ground junction. As a result (despite the 2 input power wires to the larger fan) these fans were wired by Ford to be operated simultaneously. The wiring diagram shows one low speed fan circuit that is operated by a low speed relay with power fed through a dropping resistor and a 40A fuse. The high speed circuit is generated by a dual set of relays operated simultaneously and fed directly from the battery through a 60A Maxi-fuse. The choice of high or low speed operation is made by the PCM based on temperature and AC requirements. I was surprised by this arrangement, because I just assumed the smaller fan was to be activated by the AC and otherwise was called on to supplement the larger fan which was the primary fan. Analogous to my Jeep Cherokee! OK, not so as further established by the lack of a baffle between the two fans in the shroud (otherwise if operating independently, one fan would draw air through the radiator AND through the non-operating fan opening). The two fan sizes were chosen by Ford as simply the largest they could stuff into the shroud dimension. So I need a fan controller to handle dual fan operation (37.5A total at full speed) and possibly start-up surge (less than 60A slow fuse response).

After exhaustive research on the internet commiserating with a depressing litany of frustrating failure I was able to develop a list of possible candidates for the task. I began here with the conviction that the real advantage of the electric fans lay in their ability to provide just the level of air flow needed for a given thermal situation and nothing more. Air flow is a function of of the fan speed and incoming air velocity (car speed), so this calls for a variable fan speed controller which is defined as a Pulse Width Modulated (PWM) controller. This controller sends a series of 12V pulses of different time widths at a very high frequency. The net effect is to turn on and off the fan so quickly that it doesn't have a chance to slow down between pulses and the fan settles into a speed which rather averages the pulses to an effective power applied. Vary the effective power and the effective speed of the fan changes. Clearly this involves electronics in which MOSFET transistors serve as high speed relays. For those uncomfortable with 21st century silicon, relay controllers are available that result in two speeds - high and low.

My list of current vendors (here, the internet is depressingly out of date - the latest posts are more than 2 years old) include the Hayden 3655, the Intellitronix N4000i, the Flex-a-lite (FAL) 33055, the DeRale 16795 and multiple units from Radio Research (AutoCoolGuy.com). The units previously offered by SpalUSA and DCControls have been withdrawn from the market. FAL offers several different "Kits" which include either the 33055 controller or an older design (30332) packaged with inadequate wiring and connectors. Inadequate wiring and connectors are also featured by Hayden, Intellitronix and DeRale. No wiring and connectors are supplied with the AutoCool units. The inexpensive Intellitronix controller has no provisions for supporting AC compressor triggered operation and features a non-existent technical service line, so it vanishes from my list. The internet reviews all show poor design, inadequate engineering to handle underhood temperatures and high failure rates either at purchase or within a few months of operation. The DCControls unit was well respected but is no longer available. (References on request).

As a result, the field, for me, reduces to the controllers supplied by Radio Research (aka AutoCoolGuy). These are available to support single to multiple fan loads of 50A, 85A, 125A and 200A. More amps require more MOSFETs to support the load. For a given load, say 40A, the more MOSFETs, the cooler the controller will run and the longer the effective lifetime. Their PWM controllers eliminate the start-up current surge, which readily destroys relays, by a "soft start" by which the fan motor is triggered on at a very low speed for microseconds and then rapidly ramped up to desired speed. This feathered start-up is a sharp contrast to applying the full 12-14.4V at the battery to the fan windings. The fan motor (as are most) is a carbon brush contact device so high current pulses directly degrade reliability.

The Auto Cool controllers also offer a unique AC feature. Then the compressor on signal is delivered by the AC controller, the Auto Cool unit will turn on the fans (if otherwise off) at the speed you select (I'll use 50%). Then, if the thermal requirements of the engine/radiator so demand the controller will over-ride the AC startup speed and ramp up as necessary. These controllers also include a Fail-Safe feature that you can trigger 100% fan speed whenever needed or should the controller fail.

Based on the above, I chose the AC III controller rated at 125A with its 6 MOSFETs in studied overkill. I will use Auto Cool's unique temperature sensor (a thin sheet of brass with thermal sensor) inserted under the radiator output hose and on the radiator's metal output pipe. This is in contrast with other vendor solutions of a thermal probe inserted in the radiator fins. Finally, I'll add a few voltage level trigger circuits to turn on LEDs in my custom gauge panel to tell me just how fast the fans are running (to help keep driver alertness at a high pitch!).

 

 

What kind of price is that controller and a part number? Usually a sensor that will trigger the relay off and on at certain temperatures is used. I really like the sound of not running the fans at full speed if not needed. Maybe less wear and tear on the alternator and fans. I'm looking at the contour fans for my Mustang with a 514 in it. Great info on your write up.

 

Your statement is correct for the single or multiple relay approach. Often, the "sensor" is actually a thermal switch with a specific on and off point built into the design. Here with the PWM controller, you can literally dial in a radiator temperature independent (as long as you have excess thermal capacity in the cooling system) of the engine temperature. For example, lets use an engine with a thermostat marked 180F. This generally means that the the thermostat will open within +/- a few degrees of 180F and will be fully open at 185F give or take. This generally gives a engine cooling jacket temperature of about 190F.

With the ACIII controller, the thermal sensor measures the temperature at the radiator outflow port (the lowest radiator liquid temperature) which is the input thermal mass for the engine thermostat to work with to maintain the engine's desired temperature. As a consequence, one often finds that the engine water jacket temperature is maintained very close to the nominal thermostat temperature.

In the conventional system, the temperature is measured either in the intake manifold water jacket or the thermostat outlet port. If the radiator temperature is maintained at this higher value, the engine operating temperature must be higher (often 10F or more) than the thermostat temperature. As a result, anytime the engine sees a significant increased load (climbing a long grade for example) it will dump more thermal energy into the cooling system. The temperature of the recirculating fluid will have to spike until the the radiator can dissipate the additional thermal mass.

In the PWM case discussed, the mean radiator fluid temperature is less than the thermostat equilibrium value and it can adsorb the additional thermal mass without the same level of impact.

With the ACIII controller, you dial in the temperature you desire (in my case I'll set it to 10F below the thermostat value) and as long as there is sufficient air flow available from the fans and the vehicle frontal velocity, the engine water jacket temperature will remain constant.

The detailed installation instructions and diagrams as well as the design characteristics can be found on the autocoolguy.com site. The ACIII controller cost me $199. The 620-131 fan assembly cost $105. A replacement E350 460 fan shroud to cut up cost $20. The factory wiring for the Windstar fan from the local Picknpull came to $5. Additional wiring and connectors racked up about $15. Flowers for the wife after apologizing for the mess I made with the Dremel tool - I shouldn't say. My time - well, I'm retired!

 

As you can tell, I'm a fan of the Speedhut stuff! After doing the custom gauge cluster, I noticed in my peripheral vision the Speedhut clock I had put in the dash next to the radio had a white face with black ticks and numerals! My custom gauge cluster is done in black face with yellow ticks and numerals. This was unacceptable. Called Speedhut. They replaced the clock gauge face with matching black background and yellow ticks/numerals for $15. This, nearly 10 years after purchase.

 

Interesting reading! What size alternator you have?

I have a 95 E350 shuttle bus with dual AC setup(chassis compressor AND rear unit compressor) and has a 200amp alternator. That big alternator can barely charge batteries with the rear AC running. I measured around 85amps draw with 3 condenser fans and 2 evaporator fans running! I was going to go electric fans but can't due to that much current draw. I replaced the clutch fan and here in Florida at stop lights I can hear and feel that fan clutch kick on.

Never had over heating problems till last November the radiator blew a seam and dumped the coolant. Now with new radiator and tstat, found water pump gasket bad(probly the cause of this not so much fun)..
Now with new water pump, stupid bolt broke off(just only one!) and now have to take the timing cover off... all the while fighting that 2nd AC compressor that's in the way.

 

I run a 140 amp 1-wire alternator from Summit Racing on my 7.5L. When I lived in the LA area, I had access to an alternator rebuilder that would pack the alternator with all the diodes the unit could carry giving a 210A capacity out of the same unit. Unfortunately, in Northern Nevada I haven't found a similar capability. To run the electric fans, I think you need at least a nominal 100A alternator assuming a 60% of capacity draw as a normal long term operating load.

Looking at my engine bay and all the components stuffed in there, it must be a nightmare working around two AC compressors! I have toyed with replacing my York compressor with a Seltec unit when the York gives up the ghost, but according to the power tables, the York compressor only consumes 5 HP when running full out. Switching to the Seltec would only reduce that to 3.5 HP and a 1.5 HP gain isn't worth the hassle until full failure.

 

Just a quick correction on my comment about HP consumption of the York compressor. I went back to my notes and found several citations where the York compressor actually uses 12 HP when running. The Sanden/Seltec rotary units use 3.5 HP. That 8.5 HP delta puts the AC compressor back on my modification list!