Something like this is all I'm using to drive a relay which powers the fan. Cheap, and reliable. http://www.jegs.com/i/Derale/259/167...oductId=758411

 

efans are easily in my top three list of mods.. right up there with $1200 re-gearing, and $375 custom tune SCT.... go figure, the efans ran me around $150 total, and if I weren't so **** about wiring, I could have gotten out of it for $70ish...

the delivery right off idle is real and present... right where you need it.. I could care less about RPM's above, say, 1500, the punch is right off the line, and the truck never got over 195* in any situation again..

 

360 ram motor gains 3hp and 9lbft of torque. did this to a just about stock 1500. search the forum i have a page that says the gains on mechanical fan removed. did think alternator would of pulled about 5hp.

 

I'm using the Cherokee recall fan. I need a better fan shroud for better cooling.. Using the AC adds about 10-15+ degrees and then if in traffic for too long she'll slowly creep up to 210... other wise she does awesome... I have it just mounted to factory shroud which is probably reducing the effectiveness of the fan greatly.

 

Okay, I can't tell if you're joking or ... nevermind. If you want to see that test, I suggest you find it. The rest of us will be too busy installing electric fans.

But, I will give you a hint. An alternator under zero load draws zero power from the motor. An alternator under full load draws the maximum power from the motor. So, given that a 60A draw costs 3 HP, and you have a 180A alternator drawing 120A of load, adding six 10A fans, or three 20A fans, or two 30A fans, will cause an increase in parasitic loss of ______ HP?

And my 2nd gen 96 RAM came with the standard 85A alternator, like every other RAM of the year that didn't add the optional high output alternator. Dodge did not feel that truck "needed" a 120-160A alternator "to run the various onboard systems" or it would have come with one standard. Plus, that alternator, like all automotive alternators, cannot put out anywhere near 85A at idle, yet the truck mysteriously still runs, the lights mysteriously stay lit, the heater mysteriously throws heat, and the stereo mysteriously still plays music. And there are plenty of computer-controlled cars sold today, in 2012, with 65A alternators.

The truth is the ECM systems don't draw that much power. They operate @ 5V (industry is moving to 3.3V), whick means every 1A @ ECM voltage requires 0.41A @ 12V . Most Factory Repair manuals won't even mention the draw, as it's considered insignificant. Anecdotal evidence suggests 3A @ 12V or so ... that's the parasitic draw of a completely shorted ECM on a car battery. The rest of the system ... ignition, spark, etc ... is identical to a carbeurated, coil and electronic distributor engine, which is lower than a points, coil and distributor engine.

 

That's the only time it should come on. Airflow through a (properly designed) radiator from vehicle speed is very good at cooling. The spinning fan begins to impede cooling at a certain mid-ish speed (starts to push back against the flow the rad can make just by vehicle speed) and a non-spinning fan will impede cooling at a higher speed threshold. So the fan should turn off above some low speed threshold, even if more engine cooling is needed. If you never ran the vehicle below, say 70 MPH, you would get better cooling with no fan at all. That is why you sometimes see race cars with no shroud, which is a big no-no on a street driven vehicle, and why cautions, pit stops and warmup laps cause overheating in race cars.

That's also why if you want the lightest, most efficient cooling system, you should look at quality fans such as SPAL (there are others; just an example) who give complete specifications. The "advertised" CFM ratings you see are at zero pressure drop ... in other words simulating driving when you don't need a fan. It's actually the CFM rating of the fan with no radiator in front of it.

I suggest that you want to know the CFM rating at about 5~7 inches of pressure drop, which takes into account the presence of a radiator in front of the fan, and is as close to typical of stop-and-go traffic situations when you actually need the fan as you're going to get. If you have a 3 or 4-row rad, the pressure drop could be higher than that even. (Adding a row, the 2nd row is 1/2 as efficient as the first, the 3rd is 1/2 as the 2nd and 1/4 as the first, and so on. Each additional row has the effect of making the rad less like a mesh and more like a piece of plywood for airflow through it and pressure drop behind it). With almost any rad, once actually installed in a vehicle, the bottom 1/4 or so does mostly nothing and the top 1/3~1/2 does most of the cooling. Cross-flow rads are the most efficient.

That low pressure drop value will also be the point where the current draw is the highest, and you want to know that number as well. Some fans have zero CFM under those conditions.

The above is all you really have to go on ... nobody ... not even OEMs ... have figured out how to measure the pressure drop behind a radiator with any accuracy in an actual road-going vehicle. They get all excited if the dyno-equipped wind tunnel, the road test, and the computer simulation are within +/- 10% 10 times out of 20, and that's after doing speed compensation that could be 15 MPH different between each test method (ie wind tunnel with dyno @ 30 MPH = road test @ 40 MPH). That would be considered "state of the art" results, and they don't get it often. Nor have they even settled on what tools to measure the pressure with ... every OEM uses different methods, and none are very consistent nor has one method stood out as better than alternatives. They're all equally bad.

I have an experimental fan system I am going to try in another vehicle, assuming I can find the room, which I think I can. Not going to spill the beans just yet (and maybe never) but so far it looks promising on paper. There is data that says it works, but with HVAC and Aircraft, not automobiles. I have never seen a car with this system, although with some levels or racing you never actually know what they're doing. The real world tests will prove it one way or another though. There is a lot of experimenting but little science to engine cooling. When 21st century computer modelling only gives you a good guess, you know the state of knowledge is, at best, only half there.

 

^^^ looking forward to hearing about it. That's what hot rodding is all about, trying new stuff, not buying bolt ons.