My resto-mod project is finally on my mind and in my time budget again. Because of the shear weight of this rig it is mandatory that it be powered by its engine instead of being pushed around by a fork lift etc. I am wearing the guys in the body shop out with its foot print and its lack of maneuverability.

My build is a 2002 *E*550 chassis with a 1955 *C*600 Cab in place where the Econoline cab was once. The 7.3 Powerstroke and E4OD were repositioned downward a few inches and backward from the radiator support about 3feet. Basically the under the hood area of this COE is a front trunk its so devoid of anything. Most of the engine is under the floor of the C 600 cab. Currently this is the beginning stages of a tilt cab in place. and as current it tilts about 30 degrees. It does not tilt more than that because the lower part of the front edge of the fender makes contact with the front tire. If I modify/flared the fender that might solve that contact issue so the cab can tilt to 90 degrees. But that tilt thing is for another time.

This thing needs to run. It needs its POWER STEERING it needs not to overheat while moving it around a body shop. This needs to be done first so we can next cut it down from its current 30 feet length to about 18 feet. Did I mention Im wearing the guys thin because its a long, heavy hulk?

There is no problem using the original radiator from the E550 it fits fine. I havent tried to see if that statement is true when the radiator shroud is attached now that I am sitting here thinking/writing about this.

A few days ago I zip tied the radiator in place and was pleased that it fit between the cross beam that gives the frame strength and the front grille supports. That factory cross beam which looks like a 3" diameter Pipe welded from one frame rail across to the other is likely to cause me to mount the radiator higher than its currently zip tied in place status to actually allow the shroud to fit also.

Until now I thought I was being cute using the old ruined radiator to test fit everything. You know I didnt want to bang around a clean radiator and also thought it would be nice not to have to lift as much since I was just test fitting...Darn...now I dont know about the shroud...oh well that will have to wait for me to get the shroud from storage and trapes across SD County to where the truck is to see what's with that.

Ok back to what prompted me to post.. The engine sits far back of the radiator. support area That means its still attached mechanical fan sits very far away. It appears that an electric fan or fans are going to be the way to move the air past the radiator. Question: One LARGE electric 16inch electric fan or two 7inch electric fans? The one large fan might have the advantage if it fits under the original shroud....Is there a particular brand or style of electric fan that I should only consider in your humble opinion(s)?

Next Question: what would be the best way to plumb the radiator to the engine with the distance between the two? I once had a Toyota MR2 I think they used copper pipe that had radiator hose on each end of that pipe to run the distance from the front ("Frunk" area) where the radiator was to the rear where the engine was. Ironically that MR2 distance thing is almost the same as what exists for this truck's radiator and engine...

Constructive criticism and your suggestions for my above questions are what I am seeking...take care y'all!

 

Is the first gen RX7 yours or a customers? I've had a few, fond memories. Built my first road race car out of one.

I would go with a single fan, maybe one with multiple speeds.
For the coolant, whatever metal pipe of the proper diameter would work. Aluminized exhaust pipe with a bead rolled into each end would do the trick.

 

That's a picture from when my project lived in that building where it had the cab transformation. Its 3 years ago...That RX7 was a race car that one of the other tenants of the building was working on for his client. That other tenant (Eddie Y) is a serious race addict. You shoulda seen his Blown GREMLIN before he launched it to a 90 degree ready to travel to space thing that didnt end well when gravity said " now come back here" He's building another one....(I just found a picture of it that in the post now...Ive owned two of those RX7 first gen cars my self they were a kick to rev like crazy...good little car.

Thanx for your suggestion especially about the multi speed capability I hadnt thought of that....yet....I also like the idea of aluminized exhaust pipe this thing looks like hell now but eventually it will be nice.. so some nice pipe work will be good.

.its in the body shop so that a 1956 cab can be grafted to its cab to make it a 4 door crew cab.

The goal is to make a tow pig out of it...I want to hook an Airstream to it an GO!

Eddie Ybara's Gremlin prior to the wheel stand incidence dummy "forgot" to reinstall the wheelie bar that was with him that day....ooopps...

 

Why keep the shroud if not using the mechanical fan? The electric unit should be mounted directly on the radiator. I think there should be no use for the shroud at that point.

 

The viscous clutch driven engine fan doesn't run all the time. It loafs along, consuming only a couple of horsepower, until it is really needed, where it is estimated to consume 27 horsepower to drive it at full tilt.

You propose using electric fans close coupled to a radiator (and I assume also an AC condenser, an oil to air transmission cooler, a power steering cooler, and a charge air cooler, if you choose to add one to your E series engine while you are at it.) Keep in mind the number of heat exchangers layered in this stack, and the thickness of the aggregate of their cores... as each exchanger adds static pressure, or restriction, that the electrical fans must pull or push air through. Restriction = resistance that the fan must overcome with horsepower.

1 horsepower is 745.7 watts, so 27 horsepower expressed in watts is 27 x 745.7, which equals 20,134 watts of energy to match the stock engine driven fan pulling a similar amount of air through a similar amount of restriction under similar load in similar ambient and operating temperatures.

Automotive electric fan motors are typically rated at 13.5 volts DC. A typical DC motor has a peak efficiency of 80% at it's best... which is when it is already turning at the optimal operating rpm at which the ratings were derived. But motor efficiency isn't static... it is best represented by a curve, where a motor is radically inefficient in the milliseconds of start up, and can thus consume 60% more current than when it is humming up to speed.

So to calculate how much electrical power is needed to have on tap, we need to look at steady state current consumption during peak operating efficiency, as well as peak current demand at start up. Through the use of predictive fan controllers, the fan operation can be ramped more efficiently, but let's see what what kind of current demand might be called for.

If peak DC motor efficiency is at 80%, and it has been determined that 20,134 watts of energy are needed to move similar volumes of air, through similar static pressures of restriction, then to factor for less than 100% efficiency, we need to have 25,168 watts on tap at peak operating efficiency, because 80% of 25,158 equals the 20,134 watts required to match 27 HP.

If peak current can spike to 60% more current demand for a few milliseconds at fan start up, then 25,168 plus 60% = 40,269 watts of transient start up power demands (This can be worked down with intelligent fan controllers, but lacking these controllers, the power to brute force drive the fans should be accounted for).

25,168 watts divided by 13.5 volts equals 1,864 amps of current required at peak operating efficiency.
40,269 watts divided by 13.5 volts equals 2,983 amps of current that could transiently be demanded to spin up the fans, without intelligent and thermally predictive ramp control.

Focusing on just current required at peak efficiency... 1,864 amps is a lot of amps. The stock alternator is only putting out 110 amps. Dual alternators? 220 amps. High amp alternators? 240 - 400 amps. That's still an approximate deficit of 1,500 running amps of current to produce the horsepower needed to match the power of the engine driven fan driven at full tilt.

The engine driven fans have a blade width and pitch that 13.5 vdc electric fan motors simply do not have the torque to turn.

When shopping for automotive and racing electric cooling fans in the aftermarket, a comparison is commonly made of the CFM ratings between fans. Yet these CFM ratings are quoted in free air, with no radiators in front of them creating static pressure restriction that the fans have to fight to pull or push air through. Nevermind 4 or 5 heat exchangers in a close coupled stack.

Instead of doing away with the shroud of the engine fan, it may be better to consider creating a smooth walled, fully enclosed, cylindrical tunnel with a larger diameter radiused edge hyperbolic funnel-like entrance (visualize a celestial black hole) from the back side of the radiator to the engine fan.

Electric pusher fans in front of the radiator stack can supplement cooling air flow given the separation of the heat exchangers from the engine fan, but any electrical fan capable of moving the same amount of air through the same amount of restriction as the engine driven fan, is impractical to deploy due to the electrical power needed to drive such a fan.

Lighter duty cycle engines, with less heat rejection requirements, less heat exchanger restriction, less gross vehicle weight ratings, etc... can and do make use of electric fans to the exclusion of any engine driven fan. But in this particular application, electric fans are no match for the engine driven fan when needed at full tilt.

"Cool" project, btw!

 

^^^^^ I feel like I spent some time in school.

Any questions??? Just raise your hand.

🙋🏻‍♂️

 

No kidding... thanks for the electro physics efficiency lesson Y2K!