[dataway]

To be honest, I think a properly designed electric setup is the overall best way to go. My 2011 GMC truck with HD cooling, HD everything ... has no mechanical fan and I have never seen it ever go over thermostat temp even for a second.

No constant parasitic draw, less noise (most of the time), lighter, and probably easier on the water pump as there is no fan shaft. And, as you say, it's cooling specifically WHEN you need it regardless of engine rpm.

But then the truck has a huge frontal area, big radiator, plenty of room under the hood, lots of flow at highway speeds. It's all about what a vehicle was designed to have. A GTO has in comparison a tiny frontal area, smaller radiator, and a large, high hp engine .... it needs a LOT of air flow, more air flow than the vast majority of electric setups can provide and limited space to work with.

Just imagine for a moment if some GM engineers decided they wanted to create an electric fan setup for vintage vehicles ... pretty sure it would work, probably way better than the original OEM mechanical fan.

Like most things ... implementation of the technology is as important, or more important than the technology used.

[Formulajones]

I did a bunch of real world testing in this area and came to my own conclusions.

Test subject was dads GTO with a 700hp 571 pontiac. Always ran cool with the stock clutch fan and shroud setup and a 4 core copper radiator.
When he wanted to step up to an aluminum radiator he wanted to try electric fans, mainly to remove the parasitic losses from a driven fan blade. (He's a HP junky)

I found the shroud construction is more critical than any type of fan used. If the electric fan setup is too close to the radiator and blocking large sections of the radiator impeding air flow it's just not going to work well. Air flow through just the fan area is simply not enough and turning the fans on to try and pull air through those tight blocked areas doesn't work well enough. Cutting openings in the shroud and installing rubber flaps with the idea that air will push through there at speed also doesn't work well enough.

What happened was an engine that normally ran in the 160's to 175 degrees now would climb to 190 and stay there with the electric fan setup. Even at highway speeds the fans would kick on and run constantly trying to pull air through the radiator, that was because too much of the radiator is blocked with the electric fan shroud setup and even the fans running full speed couldn't pull enough air to overcome it going 70 mph.
It did work well sitting still and would cycle the fans on and off but that scenario was only 30% of driving.

So I pulled the electric off, put the stock shroud back on with a 7 blade clutch fan and immediately the car ran cool, almost cold. Even when it's over 100 degrees here it never gets over about 182 sitting still idling. Once moving it's in the 170's and when it's cooler outside it'll run in the 160's no matter what you do, and highway speeds aren't a problem anymore.

You really have to spend a ton of money for a well designed electric fan setup to work properly. It's doable but at that point of the testing dad said screw it, the clutch fan does a great job, will never really fail, and in the end he has enough HP anyway he's not going to miss a few ponies. Running cooler in Arizona is way more important.

[RocktimusPryme]

Originally Posted by dataway

To be honest, I think a properly designed electric setup is the overall best way to go.

Oh I agree. I don't even think that is in question. Cost-effectiveness could be questioned, but for absolute effectiveness, I don't think a reasonable argument could be made that a mechanical fan is superior. And I say that as someone with clutch fans on most of my old cars.

I have long been considering an electric setup on my Firebird. I have a Terminator X, and I feel like Im wasting capability by not using it to control fans. I struggle a little at dead stops on hot days. But because I do a bit of bracket racing occasionally, I would really like the ability to cool it down with the electric fans between runs.

I like the way you explained the delta math between the higher thermostat stuff. Its not rocket science but that was a concise explanation that makes sense to everyone.

The modeling in general is an interesting concept. Im a process improvement specialist so I would like to see Pareto style analysis on how much each factor (Radiator size, fan airflow, engine CI etc) should be weighted. So people would know which thing to attack first. For instance, rather than fighting fans, would people be better off modifying their radiator support to fit bigger core section radiators.

How much does CI matter, VS power output when it comes to cooling? Do some common V8s just have better designed coolant passages in the engines? Lots of questions.

I think Im more educated than the average gear head, but I still encounter anomalies.

My 462 Pontiac has a Cold Case, a factory style shroud, with an HD Clutch and a 19.5 inch fan. Its fine most of the time, but will temp creep a bit on hot days at a stop.

The trash old stock 455 Olds in my catalina has a new, but chinesium aluminum radiator, NO SHROUD, 18" clutch fan and runs dead on the 160 thermostat in hot weather. In cold weather its hard to get it to the 160. Ive been meaning to swap it to a 180.

Do Olds engines inherently cool better? Or does the Pontiac making probably 3x the power make it generate more heat even in normal driving?