Under Trunk Temp., Addition to Oil Cooler Thread. Options

[Olympic 914]

So on the Oil Cooler thread the suggestion was made to place a thermometer under the trunk to check the temps to determine possible difference for cooling efficiency.

I don't know if anyone had done this before. So I broke this off into a new thread for future reference.

One of the Oil Cooler threads

http://www.914world.com/bbs2/index.php?showtopic=347075

So yesterday I did this.

Using a Wifi endoscope taped to a magnetic tool holder with a thermometer.

Placed parallel to the Setrab oil cooler to sample the air temp without the fan blowing directly on the thermometer










And went for a drive. My GF rode along to monitor the temps and take notes.

The outside temp was 80 rising to 85 yesterday.

Idling in the driveway the temp rose to 125, after 2 miles of two lane roads 30mph it had dropped to 120.

at 4 miles stop and go it was still 120, Oil temp 200 CHT 340

onto a two lane road for 11 miles with speeds from 30-50 mph air temp was between 118 + 120 deg Oil temp 212 CHT 322

at this point I stopped for 2 minutes to mimic sitting at a long light or in traffic.
the air temp rose to 140 deg Oil temp 210 and CHT 337

Pulled onto 4 lane and accelerated up to 70 mph. After 1/2 mile the air temp had dropped to 125deg oil temp 209 and CHT at 370.

mostly level with some slight grades.

Turned around at 23 miles

Air temp holding at 125 deg Oil temp 213 CHT 330

The battery was low on the endoscope and I had turned it off on the way back, and when I turned it back on I discovered that the duct tape had loosened and I lost my thermometer.

My setup is a 2056 9590 cam Djet. , Oil cooler is Setrab 119 fanpack 180 deg oil thermostat and 190 deg sensor for the fan. Exhaust is SS HEs and a Triad muffler.

When running in normal summer heat the fan runs constantly.

If any one else decides to do this Please add your results here.

Tom

[GregAmy]

Conclusions? Eh, I'm not gonna make any declarations based on such a small data set. I was surprised kow baked that area between the heat exchanger and transaxle is; I expected some level of radiant shielding from the heat exhanger shroud itself, especially since there's air constantly flowing through there.

There seems to be a lot of stagnant air under there, too. If there was strong airflow then the exhaust heat would be carried away better and the forward temp probe would have pretty much stayed as solid.

In the interest of science, I flipped on my interior heat with the fan, to see if any additional airflow would cool the general airflow under there, and dump the hot air into the cabin instead of out the heater valve. Zilch, zippo. Ddid not affect the temps by even one degree.

I was also surprised at the minimal difference in air temps between the cooler inlet and outlet; I expected not only a higher delta but a higher overall exit temperature. 30F delta is not a lot, making me wonder how I can make it more efficient. Plus, it highlights the significant importance of the inlet temperature flow; if I could get the inlet closer to ambient instead of 130F then I'm confident it would affect the oil cooler temperature a whole lot more. This whole exercise shows how effective the front coolers are, and is making me rethink my support of rear-mounted coolers...but front coolers are such a major PITA on a street car...

Oh well! Digest the info, lemme me know what you think. And if you have some other places you'd like to see my try, I'm open to ideas.

BTW, I may try this again later today when it's hot as blazes, just to see how 15F ambient affects it. Depends on whether I hit the beer early or not...

[BeatNavy]

This is good stuff. Thanks for posting. I just finally got a chance to read and digest.

This whole exercise shows how effective the front coolers are, and is making me rethink my support of rear-mounted coolers...but front coolers are such a major PITA on a street car...

I'm getting on board with this sentiment, Greg.

Rear mounted coolers can probably do the job under the right conditions, but they'll never approach the heat displacement of front coolers (which are a PITA...or at least require cutting).

[GregAmy]

I never got motivated to try it out later in the day (beer). And today has been hot as f....udge.

Rear mounted coolers can probably do the job under the right conditions, but they'll never approach the heat displacement of front coolers (which are a PITA...or at least require cutting).

The problem I primarily have with front-mounted coolers is I really, really, really don't like having engine-pressure oil all the way to the front of the car, all the way through a thermostat/cooler system, then all the way back to the engine. There's just too much opportunity for pressure loss and introduction of air into the system.

Dry sump? Sure, no prob, there's a stage to drive the engine oil and its circuit is local, and another stage to drive the oil forward and then into a sump tank. I use a 2-stage CB Performance dry sump on my race car.

I know "it's done" but I don't like it in concept. So I run an aft cooler on the street car. It seems to do the job (I may try a Track Night in America event later this year to see if it's "enough").

[porschetub]

I never got motivated to try it out later in the day (beer). And today has been hot as f....udge.

Rear mounted coolers can probably do the job under the right conditions, but they'll never approach the heat displacement of front coolers (which are a PITA...or at least require cutting).

The problem I primarily have with front-mounted coolers is I really, really, really don't like having engine-pressure oil all the way to the front of the car, all the way through a thermostat/cooler system, then all the way back to the engine. There's just too much opportunity for pressure loss and introduction of air into the system.

Dry sump? Sure, no prob, there's a stage to drive the engine oil and its circuit is local, and another stage to drive the oil forward and then into a sump tank. I use a 2-stage CB Performance dry sump on my race car.

I know "it's done" but I don't like it in concept. So I run an aft cooler on the street car. It seems to do the job (I may try a Track Night in America event later this year to see if it's "enough").

Well done Greg,my experience with thermo couplers indicates your reading should be pretty accurate,wow never expected those temps for one minute.
Wonder if anyone has removed the rear valance to see if there is a drop in temp as per the Porsche factory race cars or was that done for another reason (IMG:style_emoticons/default/confused24.gif) .
Cheers for your efforts.