Not really, and we never had problems with them either... I think there was some plastic shielding, but nothing substantial...

Gary,

I inadvertently came up with a way to test your theory for the radiator temps in the winter. Block part of the radiator along a few cooling tubes. I did that on the tracker and my return temps shot up like crazy. I was attempting to see if I was right about the return temps re-closing the thermostat in the winter causing an overheating issue and while that was what i had happening it caused my mechanical fan to work so hard I had to figure out another way to fix it(never did). But, I'd actually blocked half of the radiator tubes so it was essentially bypassing on those and then re-blending on the other end.

I'd slowly block them and watch temps as it doesn't take much for the return. I suppose you could block across the tubes but i found along them to be more effective.

On a side note: If anyone decides to try that you'll want to block the tubes closest to the return line to the engine to avoid having untouched coolant passing over your transmission cooler.

I've started looking into WAI in my Accent. Seems cheap and pretty easy to try out (and reversable).

Really, it's the engine compartment getting too cold from an additional hood vent that impacts this thread, right? If the radiator were in its own separate compartment that'd be less of a concern. Also, a setup that can use all the cooling it can get wouldn't care either.

The wiki article on WAI suggests that the primary gain comes from the reduced air intake resistance caused by the computer opening the intake diaphragm more to keep the oxygen level the same. FYI.

https://en.wikipedia.org/wiki/Warm_air_intake

Thinking some more, a ventilated engine compartment wouldn't matter if one had the bypass valve / thermostat arrangement to keep the coolant inlet temperature from declining too much. That should be able to mitigate the increased engine heat losses sustained from the cooler ambient engine compartment temps, right?

I ran the WAI on my VX until I could feel the lack of power at greater throttle openings.

In the old carburetor days, without WAI the fuel atomization was so bad the fuel would not atomize and you got serious hesitation as well as black spark plugs. My 37 Ford ran like crap until I figured out that the exhaust crossover passageway under the carburetor was plugged up.

Nissan had a wire screen under the carburetor in the early NAP-Z engines to help with fuel atomization. The screen was heated.

With the advent of fuel injection and the end of high velocity air over a venturi, poor atomization became a thing of the past, but that does not mean that atomization is not improved by hot air coming into the engine.

Restricting air flow through the radiator area also has the effect of increasing the temperature of the air coming into the engine. Air density at 200 degrees is 80% of the density at 32 degrees. All turbo cars run better in cold temperatures, but without an intercooler any turbo has much higher intale air temps. In fact any surpercharged car has higher intake air temperatures due to the simple fact that increasing air density also increases temperatures.

Thats the reason your air compressor tank gets hot. Leave it overnight and let it cool off and all the moisture condenses in the bottom of the tank. I used to do this when I painted cars, let the tank cool off overnight and you din't have to worry about water in the lines in the morning when you painted the car. It also helped to let the paint flow in the summer because the air was cold whent came out of the lines.

Think of the heat content of air in degrees Kelvin, not farenheit or centigrade and its easy to understand the increased heat under compression.

WAI and higher coolant intake temperatures are reutilizing the heat normally lost to the atmosphere. Considering you only get an average of 18% of the heat energy in useful work, you should easily understand the significance of reusing even as small as 3 % of that normally lost heat energy. That amounts to a 14 % increase in efficiency of your engine.

The best way to control the coolant inlet temperature would be to have a system that read the incoming coolant temperature and adjusted the bypass to radiator outlet volumes to maintain the desired (approx 120 degree) incoming coolant temperature.

regards
gary

The possibility of damaging the transmission by blocking flow to the cooler lines is certainly a significant point dkjones.

I am assuming your tracker had a fan clutch (viscous coupling) that was hooking up more as a result of the increases temperatures over the bimetallic spring that controls the valving in the coupling?

I think in light of your added information it may also be a good idea to monitor the intlet coolant temperatures to preclude damage to an auto tranny if your car is so equipped.

In most cases, in winter temperatures the tranny coolant would probably not rise as much as it does in summer temps even if you blocked a significant part of the radiator. I remember the old early 70's Plymouth state police cars in Va had the cooler lines blocked off. Didn't seem to kill the trannys.

I AM NOT ADVISING ANYONE HERE TO MESS WITH THEIR TRANSMISSION COOLER SYSTEMS, THE RESULTS COULD BE VERY EXPENSIVE.

They say an ounce of prevention is worth a pound of cure. Best bet would be to install remote temperature sensors to minitor temps of both engine coolant intake and transmission fluid temperatures if you choose to block off a significant portion of your radiator surface area.

regards
gary

Then you could have the hood vents and try to reduce drag or,
alternately, there could be a separate system controlling louvers over the radiator, reducing excess radiator capacity and reducing drag.

This started as an aero question, so I wanted to tie it back in.

OK, had a chance to think more on the implementation details.

For a totally new design, the shutters seem superior.

For a retrofit, the design of the shutters get very tough, so a hood vent coupled with the radiator bypass control system seems easier. The control system should probably monitor not only cooling temp in, but also cooling temp out.

The third option is a remote radiator location, of course. That gives you more freedom to explore other options, bringing shutters back into consideration.

This all assumes that a grille cover can't be at a fixed position all the time with good results. Then that is the way to go, clearly. Many factors in that one.

Does all that seem to sum things up properly?

I totally agree and I go one step further: oil temps. Keeping the engine warm (coolant and oil) is the most efficient.


Yes, a warm engine, but not warm intake air.
Yes, more air means more fuel for more power but that also means less throttle opening to produce the same power. Smaller throttle openings means less air flow means less fuel added. Also, the cooler the intake air, the more ignition advance you get. The earlier you ignite the fuel the more complete burn you get. Warm air means risk of detonation so the ignition is retarded. Retarded ignition means less burn time and more fuel wasted.

Warm Air Intakes do not create better mileage. Read the test proof:
https://www.metrompg.com/posts/wai-test.htm