So in two different posts, you state that an aluminum radiator will drop the temperature 20 degrees over a factory copper/brass unit.
You state above you keep records and analyze the data.
First, we note that you failed to note the ambient conditions and most know that you cannot make a comparison of a heat interchanger without maintaining the same ambient air temperature across the unit. We also know that performance falls off as the ambient air temp increases and the delta between the fluid temp inside and the air temp outside decreases.
Second, we note that you changed radiator, fan, and shroud so we have no means of attributing any verifiable improvement to a given component because you made a number of changes in an uncontrolled environment. In other words, you have put apples, oranges, bananas, and a few coconuts into two different baskets and then claimed your cholesterol went down ten points because of the aluminum basket.
Third, we note that last year you were still complaining that your car was running hot after the changes and we pointed out that your electric fan was too weak even tho it was advertised at 2800 cfm. As evidence, we pointed out how few amps you claimed it was pulling which is typical of the cheap fans that claim high ratings but don't produce when put up against the radiator where it has to pull against a high head pressure. Compare this to a quality fan such as a Spal or a factory fan that is rated at a similar flow but pulls a lot more amps. Or, simply hold a piece of paper six inches in front of the radiator and compare the pull between a quality electric fan and a cheap one with equivalent ratings. As a comparison, I run dual Spal 11" fans on one of my cars. They weigh 12.5 lbs and pull an honest 2780 cfm. Compare that to your 4 lb fan. It's all in the motor size.
Fourth, last summer when you were complaining about the car still running too hot, we suggested you fill the radiator with plain water and use a surfactant like the one from Royal Purple or RMI-25. I believe you went to a 20-80 mix instead and added Royal Purple's Purple Ice. What did you claim? Was it a 15 deg drop?
Fifth, you don't mention anything about the transmission cooler. I would like to assume that you were still running the the transmission fluid thru the radiator in the interest of keeping the playing field level. I know that when I don't route the transmission fluid thru the radiator and use only an external cooler, my coolant drops 10-12 degs on a hot day.
Sixth, you claim that you used an old, rodded out factory style in the comparison. After 6-8 years, any test of any radiator, no matter what it is made of, will show improved peformance from the new one because the bond between the fins and the tubes deteriorates and affects the heat transfer from tube to the fin/airstream.
Now, my idea of a hot day is anything over 100 degs. I live in west Texas and it was 102 degs last Monday and Tuesday. Unfortunately, this is pretty normal and we usually have at least 90 days in a row above 100.
Now, for the rest of you, I strongly believe in CROSSFLOW aluminum radiators. In no way am I saying you should run a vertical flow factory style copper/brass unit if you need a replacement radiator unless you are trying to maintain factory stock appearance. A crossflow aluminum radiator will typically present more core area to the air stream so it offers better cooling opportunity in spite of its lower thermal efficiency with regard to material. A good crossflow radiator will also have a couple of rows of tubes that are 1-1.25" wide that are rectangular in shape rather than being oval shaped like a brass/copper unit. This presents more area for the air to touch as compared to the brass/copper where the air tends to focus upon the peaks of the oval tubes. Again, this offsets the thermal inefficiency of the aluminum. The big tubes don't get plugged up as easily as the smaller brass/copper tubes which is a benefit plus they allow for much more turbulence in the water flow meaning that more of the water surface actually touches the aluminum. A good high volume pump that keeps the water pressure up makes this work better.
I run a big three pass aluminum radiator on my faster Buick and I run a regular Griffin crossflow on my Challenger.
So again, I am not debating the merits of Aluminum vs copper/brass factory units-only Bob's claim that a an aluminum radiator will drop coolant temps 20 degs without any qualification or evidence of controlled conditions where improvement can solely be attributed to the material that the radiator was made of. His own posts demonstrate that he made a lot of changes in varying conditions and one cannot single out the radiator and make such a statement.
Now for your latest link supporting your fan claims. The first thing I noted was that he picked up about 3 hp going to synthetic oil and I recall you having a snit because we dared challenge your claims that you picked up 60-70 hp by switching from conventional oil to synthetic and, as usual, you did not present any performance data to support your claims but you posted a link or two to some ad or such to back up your claims. According to this guy's test, you just lost about six tenths of a second of performance.
With regard to his fan tests, he did not put the fans in front of a radiator and they were performed in a static environment. He noted as much as a 45 hp loss on one of the fans but as he did not present dyno curves with the attendant ambient conditions, I am not sure if this was a calculated number that took his engine down to 315 hp from about 360 hp, or what. It was an interesting test, but I am not sure what it meant.
We know that on the average muscle car, 10 hp is worth close to 0.10 seconds in the quarter mile so a relatively minor change is documentable, if that is a word. I would be interested in anyone's real world data that can support a 17 hp difference in performance from a fan swap and even more so, a 45 hp gain. If so, there will be a lot of electric fans suddenly installed.
As far as your Yugo comments and your attempts to run away from trucks and stick only to cars. That says a lot. A truck loping down the road is doing a lot of work and can easily be compared to a 500 cubic inch in a car that weighs 1800 lbs less driving the same speed. It's making a lot of heat and the factory went to a mechanical fan to deal with it. It's not about being stuck in the past 40 years ago, it is about dealing with reality.
