Cheap reduction in engine temperature

[fireant911]

Yet another (cheap) mechanism to reduce oil temperatures… Although my engine has never run what I would consider ‘hot’, I have spent a great deal of time pondering the thought of removing excess heat from the cooling system in our cars. Some of these concepts have been successful while others have not. Yes, a proper oil cooler can greatly aid in this though not everyone has that sort of disposable income. Cheap and effective is the focus here.

Last week I was again studying the situation and noticed a source of heat on my car that I assumed could be rather quickly and inexpensively removed. Whenever I park my car in the garage I immediately open up my engine lid and place a box fan and a mouse cage fan at the rear of my to cool things down quicker. Upon doing this ritual last week I again silently commented to myself again about how much heat the bumper is picking up (Sherwood/ 911pcars had an excellent proposal on how to fix this issue I am lookin for a "heat blanket/shield"). I then felt of the engine cover (this piece runs width-wise to the engine, is facing the rear of the car, just aft of the lower pulley cover, underneath the engine support bracket, and passes the heater duct work from inside the engine bay to underneath the car) as I have done so many times previously. Of course, this engine cover was rather hot due to the close proximity to the exhaust muffler. More importantly, in my mind, was the location / closeness of the cooling air intake fan and shroud to this heat source. One could safely postulate that although huge volumes of air are being pulled through the engine yet this ‘convection oven’ residing directly below, and as heat rises, that the resultant effect would be a rise in temperature of the cooling air to one’s engine. This elevated temperature initial cooling air would limit the cooling possibilities that could be obtained – that was my theory.

Because of the testing I have done before, I had mounted a temperature probe inside my engine shroud and have been driving around with this configuration for the last year and a half. I was always amazed at the amount of temperature rise from the ambient air to the inside of the air shroud. Given this elementary lab consisting of my curosity, car, and attached temperature probes, I gathered some data. With my car in its normal configuration baseline readings were recorded: 85.6° F ambient temperature, 56% humidity, and steady state at 3,000 rpm’s (fully warmed up). This revealed a reading of 115.5° F inside my engine shroud. I then placed a layer of insulation that I had previously cut-to-fit this engine cover and repeated by basic experiment over the same identical course given the same conditions. To my amazement, I saw a reduction in temperature to 110.1° F. This 5° F drop in cooling air temperature produced a noticeable decrease in my oil temperature through a definitive reading could not be obtained due to the lack of increments on the oil temp gauge - but a decrease was easily seen. True, 5° F decrease in cooling air is not a great deal; however, the corresponding cost for this reduction was $2/°F – which is rather cheap. How much of an effect does a reduction of 5° F on cooling air have on the oil temperature??? I do not know though it does make a difference.

Points of concern if anyone possibly wishes to incorporate this idea into their own car: make sure than the insulation is firmly in place. You do not want to have the insulation pulled into the cooling fan since that could create a much bigger problem of higher temperatures. I used HVAC ductwork insulation for my experiment. This insulation was foil-faced on one side and 2” thick. I pieced together a cardboard template and placed this on top of my insulation and sprayed the outline to be cut. Then the cut insulation blanket was placed / neatly stuffed / positioned into place (some duct tape on the motor mount bracket was used for added security).

[Eric-325I]

Any pics?

[NEIN11]

You're experiment hints that you may have experience in programmable logic for HVAC/R. CPC, Novar, Danfoss?

[Duckworth]

I just tried a Pelican search for the 'Rubbermaid' solution....

It should have come up - but did not for me.



Are you familiar with it ?

[Grady Clay]

Try here:

“Rubbermaid Solution”


Best,
Grady

[fireant911]

Eric-325I,
I haven't been able to post pictures for months now??? Something has changed on the other end - I do not understand why...

Duckworth,
Yes, I am familiar with that suggestion but I would never do it that fashion. Though others may not agree, in my opinion, the actual cooling potential of the water is mostly wasted using this method. In order to maximize the efficiency of the ability of the water to cool the air it must be completely atomized. Psychrometrics is the science behind this ability and great amounts of heat can be absorbed with just a small amount of finely atomized water. Spraying water will cool the engine but at a much less effective rate given the same quantity of atomized water. Plus I am not an advocate of directing a stream of water at my alternator.

Engine Cooling With Water - Crude Evaporative Cooling

[johncmng]

How about mounting a nossle at the oil cooler that is located behind the motor? Also, will the water create a thermal shock to the metal. Won't the thermal shock stress the motor and maybe create microfracture? Or the Porsche motor is built that good.

[cmcfaul]

Under the Rubbermaid metheod. Wouldn't the water atomize as soon as it hit the heads / cylinders?

Chris
73 911 E

someone is always pimping that Rubbermaid soution :-)

[JP911]

This is an interesting idea. From a cosmetic standpoint I would prefer to place the insulating material on the underside of the engine tin with the foil facing the muffler.

[fireant911]

Originally posted by cmcfaul
Wouldn't the water atomize as soon as it hit the heads / cylinders?

Chris,
A crude example is spraying your lawn mower with a water hose immediately after shutting it off - yes, it steams (flashes to vapor) and does cool it down though this cooling is not being used as effective as possible. The atomization you are referring to is after-the-fact and not relevant when dealing with a psychrometric process. My purpose was to cool the air that is cooling the engine. In theory, if everything works properly, no water will contact the cylinder fins. The atomization will absorb the heat and the humidity will rise resulting in a decrease in cooling air temperature. In my testing previously I saw some remarkable decreases in temperature (10° below the ambient outside temp in the same engine shroud used in this other temperature reducing project). There are some limitations in the amount of moisture hat air can hold at various temperatures.

Originally posted by JP911
This is an interesting idea. From a cosmetic standpoint I would prefer to place the insulating material on the underside of the engine tin with the foil facing the muffler.

Jon,
Actually, that is my intent for phase II. I had no way to secure the insulation from underneath (plus the material I used originally is not designed for outdoor use). I have already eye-balled the new insulation material that I am planning to order from JC Whitney. This will be affixed from the underside. Sherwood's contribution of the muffler heat protector will be performed at the same time.