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HomeTech Articles > Porsche Oil Coolers - Form & Function

Guest Technical Article:

Porsche Oil Coolers, Form & Function
Part II - Cooling Alternatives

Martin Schacht
schacht917@email.msn.com

     Potentially damaging Porsche 911 oil temperatures (Greater than 230 degrees F.) are especially noticeable if you drive in heavy traffic, or are a regular Club Racer, Time Trial or Slalom participant, especially in the summer months! What are your options if you have a 1974 through 1989 911 and you want to seriously address excessive engine oil temperature? It may depend on whether you subscribe to the dictum that factory parts are the only alternative, and aftermarket products suspect.

     For those pre-1985 911 owners feeling that Porsche factory parts are their only option, you have an alternative from the Porsche factory that will optimize oil cooling on your car over your present set up, the 1987 to 1989 Carrera oil cooling radiator system. Out on the road (And track) there are thousands of 1987-1989 Carreras and their oil coolers out there. The “active” cooler, with fan and a protective shroud enclosing the radiator, work well. But does it work well enough across the varied applications we drivers put our cars through, street, autocross, Time Trial, Club Racing? It depends.

      Let’s first look is involved in an installation of the 87 to 89 Carrera oil cooling system to an earlier car. The Carrera “active” radiator, as you would expect, is mounted directly behind the headlight in the right front fender of your 1974 or later 911. For 85 and 86 Carrera owners, with some minor modification involving factory brackets and a wiring loom, your oil radiators may be retrofitted and converted to "active" by incorporating the high output oil radiator fan introduced with the 87 Carreras.

     For owners of 1974 through 1983 911's wishing to install the 87 Carrera cooler and maintain the "old style" spoiler with the exposed fog lights, simply have the 1987 Carrera oil cooler mounting tab fabricated and installed on the upper right side of the spoiler. Depending on the year of the car, a radiator mounting bracket may need to be fabricated and attached to the back of the right headlight tub; it was necessary on my 1980 SC installation.

     Also, if the Carrera radiator to function to it’s full potential, it needs maximum airflow. On 1984 and earlier cars, it is recommended to notch the right underside of the front bumper to maximize airflow to the radiator. In addition, the horn must be relocated to accommodate the Carrera cooler; factory brackets are available.

     Should you wish to update your 1978-83 SC to the 1984-89 Carrera front end "look", replace the 1974-1983 valance with the 1987 Carrera valance. This valance has the recessed fog lights introduced in 1984 and the necessary mounting tab for the cooler. You will have to fabricate the tab if you stay with a 1986 or earlier valance. Also, a 1984 or later Carrera style windshield washer container will be needed. The pre-84 bottle is too large and won't fit.

     A caution for Porsche 1974-77 Porsche 911 owners contemplating converting a car delivered without a factory loop cooler. You will also need to purchase the hardware to get the oil from the engine to the cooler in the right front fender. This includes multiple sections of brass pipe as well as a right rear wheel well mounted thermostat that activates the cooler circuit when oil temperature reaches approximately 182 deg F. Note, a significant amount of heat transfer (cooling) is provided by the pipe which is lost if rubber lines are substituted.

     Once the Carrera cooler is installed, another option to consider involves the wiring of a dash mounted override switch for the oil radiator fan. It now becomes your decision to activate the cooler fan rather than having to wait for the factory thermocouple to activate the fan after oil temperature reaches 244 deg F.(Ouch, that’s hot!). With manual override, you must not forget to turn the fan on, that would be very un-cool.

     Parts for the conversion to the "active" Carrera cooler are all factory. In my experience, the oil radiator with fan and shroud will cost from $500 to $1,000 depending on whether you buy new or used. The Carrera 1984-86 valance is available used for about $200 and you must add a mounting tab to the right side. New, the 87 Carrera valance is about $275. Budget another $200 to paint the valance. The fog lights can be obtained for about $250 a pair, or you can wait and install them later.

     The remaining mounting brackets, hardware, relays, fan control harness, etc. will cost approximately $325 including about $80 for the new Carrera windshield washer bottle. Bottom line, your looking at a minimum of $1,500 in factory parts assuming you do all the labor yourself. The cost of the Carrera factory oil cooler conversion is similar to what you could expect to pay for a high quality aftermarket “Ruf” spoiler with hardware, cooler and paint.

     Concerning the labor: I had the conversion work on my 1980 SC, including addition of the override switch and wiring of the fog lights, fabrication of the upper cooler bracket on the rear of the headlight tub as well as installation of the 87 Carrera valance and needed windshield washer bottle done at a local Porsche repair shop. It took approximately eight hours. You can save a substantial amount on the conversion job if you choose to stay with your 74-83 valance.

     Some questions you may wish to consider, is it worth the expense just for some peace of mind? And, does the 1987 Carrera cooler perform to the point where the investment is worthy of consideration?

     To some, me included, the peace of mind factor is substantial. A cooler running engine will last longer and perform better, period! Plus, the upgrade may add to the value of your car should you ever sell it!

     Does the active Carrera cooler perform significantly better than the loop or an aftermarket (Turbatrol) fender mounted cooler? In my personal experience on a long summer road trip, as outside the temperature hovered at 95 deg F., driving my 1980 SC on the highway as well over steep grades, with the air conditioning on, the Carrera oil cooler conversion resulted in a dramatic improvement. At no time did the oil temperature exceed 205 deg F. Previously, in similar situations, first with the loop cooler, and later with an aftermarket (Turbatrol) fender well mounted cooler, the oil temperature gauge crept past the 220 deg F. mark.

     In heavy city traffic, the "active" Carrera cooler has demonstrated it can do the job. I especially enjoy having the option to activate the "non-factory" fan override switch whenever I the oil temperature gauge indicates temperatures in excess of 205 degrees F.

     What about performance of the "active" Carrera cooler in Slaloms and Time Trials?

     On a hot summer day with a one run PCA Slalom course, installation of the Carrera oil radiator with fan will just about guarantee that you'll run out of brakes before you get the oil temperature too high.

     Regarding Time Trial performance of the Carrera cooler, I ran a Time Trial at the Firebird International Raceway located outside Phoenix, AZ. Here track temperatures was approximately 90 degrees F. At no time at the event did oil temperature ever exceeded 220 deg. F. Note: at this event, I did have my right front parking light removed for additional air circulation.

     Next, consider these conditions encountered in a Southern California summer Time Trial. Track temperatures were between 95 and 100 degrees. I took the car out for the full 20 minutes, and for a few moments toward the end of the session, the oil temperature was up to nearly 250 degrees F., admittedly too hot. Other 911s and Carreras were getting as hot, some hotter, but much sooner and were pulling in the pits to cool down after as few as three laps around the course. At this point, I had made up my mind to replace the Carrera cooler with something better.

     By now I had gone through my “purist” phase. I had no reservation about changing the stock outward appearance of the car. I wanted wanting maximum oil cooling for Time Trials and would make no further compromises.

     In my experience, the Carrera “active" cooler provides significant, but not the ultimate, reductions in engine oil temperatures. The Carrera coolers work well in heavy traffic and moderately well in Time Trials and Slaloms. However because of my primary interest in participating at speed events, I ultimately went to the next step and installed a “Ruf” type spoiler and cooler.

     Before purchasing the “Ruf” spoiler and cooler for my SC, I observed these units in action at several Time Trials. Car with the “Ruf” set up, after 20 minutes of continuous track time, were running cool, seldom exceeding 200 deg F., usually lower. Non “Ruf” cars ran 20 to 30 degrees higher.

     For those interested in Time Trials and Club Racing, strongly consider installation of “Ruf” style spoiler with the center mounted oil radiator. Not only will you run cool, you also pick up front air scoops for your brakes. If you have a shop do all the work for you, you could spend approximately $1,800.

     To summarize, my history with oil coolers on my 1980 SC started with the factory loop cooler. With this set up, the car ran too hot for me and I wanted more cooling. Next, I installed Turbatrol aftermarket cooler, which was an improvement but did not provide enough cool under adverse Time Trial conditions.

     Subsequently, I installed the 87 Carrera valance with the “active” cooler: Still not cool enough for my taste. Finally, I installed the “Ruf” spoiler with center-mounted cooler. I had attained the cool I wanted. The trial and error had cost me but finally, I was cool.

     Bottom line, if you plan to Time Trial of Club Race your car, take the “Ruf” approach. I must add that the “Ruf” cooler was more than adequate for street driving as well. The only down side is the possibility of having the spoiler mounted cooler punctured in a parking incident. I have never experience this as I make it a rule to never parallel park a Porsche.

     Decide upon your budget and your short term and long term goals for the car. Do it, and do it right the first time

Back to Part II

Comments and Suggestions:
hierogk Comments: What are my options for improving oil cooling on a 1984 ROW Carrera made for Germany but living in Texas?
October 25, 2015
  Followup from the Pelican Staff: You can upgrade the oil cooler:

http://www.pelicanparts.com/techarticles/911_carrera_oil_cooler/911_carrera_oil_cooler.htm

Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Alex 85 Comments: What will be the best way to cool my 85 Carrera for heavy traffic and 93F. I had to park and wait for two hours until traffic cleared out. Alex
August 14, 2015
  Followup from the Pelican Staff: The factory fan and engine ducting should do it. Unless something is worn out. Are you having temp issues?- Nick at Pelican Parts  
Dale911Noob Comments: Is it normal for the passenger side front fender of my 1987 911 to get very hot to the touch after a drive? My engine is running great, and gauges indicate oil is cool, pressure is optimal, oil level is good. Is this hot fender just a function of how the oil cooler works to dissipate heat?
August 17, 2014
  Followup from the Pelican Staff: Check if one of the lines is resting on the fender. It shouldn't be super hot. - Nick at Pelican Parts  
pojefferson Comments: forgive me if this question has been answered elsewhere, but is there a specific correlation between the hash marks on my 1988 911 Carrera oil demo gauge and degrees Fahrenheit?

My next question will be what temp degrees or hash mark should I strive for. I recently modified by stock 3.2L engine to be 3.4L, plus twin-plug ignition, plus Steve Wong chip. While doing a PCA DE event at Watkins Glen, on a very hot day 94 degrees F, the attached image show my typical temp reading after about 10 minutes; but it never got any higher than this.
July 8, 2012
  Followup from the Pelican Staff: Looks like it's running a bit hot. I would shoot for the center of the gauge. If you want an accurate reading, try an aftermarket temperature gauge. - Nick at Pelican Parts  
944cruizin Comments: I was wondering a couple of things, I had a repair shop loo at my 1985 944, the said I'm having problems engine oil cooling housing or it could just be the gaskets but they won't know until they take the housing off. How can you tell if the housing is bad or if it's just the gaskets and how difficult is it to change?
March 22, 2012
  Followup from the Pelican Staff: The housing could be pitted or cracked. They want to inspect it once removed. This is good practice, if they told you gasket, then removed housing and found it damaged, would be harder to convince you that you need it. - Nick at Pelican Parts  
macbadger Comments: I found running a 10w50 synthetic oil reduced the oil and engine temp under heavy use on track on a water cooled engine, also an increase in the coolant to water rate also helped.
August 24, 2011
  Followup from the Pelican Staff: Thanks for the Info. We appreciate it. - Nick at Pelican Parts  
cjannelli Comments: I would like to upgrade my oil temp gauge to the numerical version on my 1989 Carrera. Does this require a different sending unit?
April 30, 2011
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799 and they can help figure out which part or repair kit you need.
- Nick at Pelican Parts
 
Fran Comments: I have a 2005 997 911 carrera cabriolet and have a concern re the oil temperature on a 85 degree plus day. Oil temp never varied from 200 degrees until last summer. On hot days the oil temp now will move quickly to 225 degrees and after getting out of traffic would drop back to 210. The dealer does not offer a reason. my concern is the sudden change from previously stable temps. Water temp remains stable 175
Can you help?
April 19, 2011
  Followup from the Pelican Staff: This is within normal range. I wouldn't be concerned. Keep up on your oil and coolant services and you should be OK. - Nick at Pelican Parts  
GRAHAM Comments: IM LOOKING FOR A OIL COOLER FOR MY 1985 PORSCHE 911 CARRERA
March 2, 2010
  Followup from the Pelican Staff: Try this link: https://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_ENGoil_pg5.htm#item18 - Nick at Pelican Parts  
993CAB Comments: I agree my statement leaves a lot open. I am looking at this as a preventative measure.

My car has 42k+ miles, is new to me and I have noted slightly elevated temps during spirited driving. I enjoy the car in the higher rev ranges 3500rpm+ after warm up and prefer this driving style. I am looking for a recommendation to provide the highest cooling capacity for the vehicle during spirited driving and auto crossing/DE next summer.

I want to address the cooling as my first mechanical modification. I believe that I can avoid the valve guide issue if I take preventative steps to run the engine as cool as possible at all times.

I am open to any and all suggestions. My perception may be incorrect. Perhaps this would be wasted dollars for little gain. I appreciate any advice and comments. Thank You, Mike
September 18, 2009
  Followup from the Pelican Staff: The valve guide issue is independent of cooling, although running it a bit cooler probably can't hurt. You're going to have to take care of the valve guide wear at some point however, almost all the cars have it. If you're just seeing slightly elevated temps during spirited driving then you're fine. The 993s aren't known for having cooling / overheating problems. I wouldn't worry about it right now, and just save your pennies for the top-end job that almost all 993s will need in the near future. - Wayne at Pelican Parts  
993CAB Comments: I am looking for the "best" max cooling solution for my 1995 993. The mechanicals are all stock. I simply want max cooling and would appreciate some advice. I am considering the RUF Cooler or the factory Turbo S cooler, but am very open to suggestions. Any advice will be greatly appreciated. Thanks in advance!
September 17, 2009
  Followup from the Pelican Staff: That's a bit of a broad statement. If your car is not overheating, then you probably don't need any additional cooling. Many times the fans and/or thermostats will fail to function properly, and it may be wise to look at these if the car is experiencing higher temps? - Wayne at Pelican Parts  
Ron Comments: I am trying to find an "engine rpm vs oil flow" chart and an "oil flow vs pressure drop across the oil filter" chart, or a chart showing the oil filter presssure drop at various engine rpm's, for a 1983 Porsche 911. Do you know if such information is available?
I have recently had an oil fiter issue that I am trying to resolve.
July 23, 2009
  Followup from the Pelican Staff: Shoot, sorry, I've never heard of anyone measuring oil pressure out of a filter while the engine is running. Do you mean oil pressure as a standard function of RPM? I think there's a table of that in our technical forums... - Wayne at Pelican Parts  

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