The fan shroud improves the effectiveness of the fan. I was going to say efficiency but I'm not 100% sure about that. But the shroud helps the fan apply negative pressure to the entire surface of the radiator.
Air goes through all of the radiator with or without a shroud, think about it. The air would have to be solid to not turn the corner after it went through the radiator and hit the shroud.

R.

I refilled the radiator with distilled water and Justice Brothers Radiator Cooler (RC/22P) and Justice Brothers Cooling System Protector ( CSP/1P) to give me the best cooling and resistance to electrolysis.

I always thought distilled water was best also, but after some research I ended up using drinking water (purified by reverse osmosis) and No-Rosion which is probably similar to what you are using to protect the aluminum radiator. He said it would also bring the temp down 10 degrees, but it didn't.

Here's an excerpt from their site. I'm not an expert by any stretch, and I'm not saying it's gospel but it sounded plausible...


Q. Should I use distilled water as coolant?
A. Yes. But only in a 50/50 mix. Distilled water should not be used as straight water coolant, because it can cause damage to system metals. The reason has to do with how distilled water is created. During the distillation process, water is vaporized into its gaseous phase, so all impurities are left behind. These impurities include a number of minerals, including calcium and magnesium, the two components of hardness. The water is then condensed back into its liquid phase, so the resulting liquid is pure water. In fact, some of the purest water on earth. The problem is that distillation strips impurities from water, resulting in water molecules that are electrochemically imbalanced. So distilled water will actually strip electrons from the metals in a cooling system as it attempts to rebalance itself electrochemically. This can result in damage to metals in a cooling system. Using distilled water in combination with 50% antifreeze effectively cuts the amount of distilled water in half. By compounding with glycol, it will not cause damage to metals in a cooling system. For this reason, it is safe to use distilled water in a 50/50 mix.

Q. What type of water is best to use as straight water coolant?
A. Reverse osmosis (RO) water. Rather than stripping impurities from water, RO filters them through a membrane. The resulting water is electrochemically stable, and not harmful to metals in a cooling system. RO water is every bit as pure as distilled water, but without the risk of electrochemical stripping of electrons from system metals.

Q. Where can I find reverse osmosis (RO) water?
A. At the local supermarket. Look for DRINKING WATER, which is available in gallon bottles. But do not confuse it with SPRING WATER, which is often high in mineral content. We have performed extensive testing of major brands and generic brands of bottled drinking water, and found that it is almost always composed of RO water.

Q. What are the benefits of using purified water, such as distilled or RO? A. It lacks the impurities of tap water. Without impurities, its ability to function as an electrolyte is greatly diminished, thereby minimizing damage from electrolysis. It contains no hardness, meaning it will not form scales and deposits that can cause overheating. It does not contain other damaging contaminants, such as chloride or sulfate. And importantly, it enhances the overall performance of No-Rosion, allowing it to more effectively function and provide the full range of benefits that it has been engineered to provide.

http://www.no-rosion.com/

I agree to get water that is mineral free. The calcicum is what is really bad.

I have heard that about distilled water. But I couldn't find anything else that was labeled mineral free.

I saw RO water at the store. But it didn't see on the label that is was mineral free. Maybe it was my mistake. My first priority was to stay away from the minerals. Maybe I'll go back and look at the labels and look around.

I never really understood this type of test, seems to me that a liquid that was really bad at absorbing heat would read a LOWER temp, and the heat would just dissipate another way. Can't believe there is a way at these temps to absorb heat at one rate, and dissipate it at another rate.

So I got it all together and tested it. It was 92 degrees in my garage when I started it up.

I figure if I went this far, I was really going to test it. I've been a S-O-B to this car for 19 years, why should I stop now ....


I let it idle for 25 minutes not moving it an inch in the garage!


The front of the car was 1 1/2 ft from my washer and dryer. So no wind to help it. Even though the garage door was open, after 25 minutes my eyes would tear up if I stayed in there too long. After 25 minutes, the car raised the temp in the whole garage to 98 degrees.

RESULTS


1) After 10 minutes idling, temp measured on heat gun was 160 deg. at the temp sender.




2) After 25 minutes idling, temp measured on heat gun was only 203 deg. at the temp sender. Turned it off and no boilover whatsoever. I didn't think that was bad given the extreme abuse. It was a fricken nauseous sauna in there.


I think it did really well for such an extreme test ??

Here's a picture showing the suction of a paper towel on my grille at idle and the ambient temperature there.

it would cool better if you got that paper towel off the grille.


Do you have a lower air dam on the car?