<VV> Re: Porsche cooling

[Crawford Rose]

The oil cooler is a popular addition to the front fenders of Porsches because they overheat. They sell a lot them for the cars that weren't factory equipped with them, I guess before 1978 or so. As far as the five and 11 blade fans, well isn't that what we are arguing about with the 60, 62-62, and mag fans? I can only tell you that many 911 cars are typically overheating and running 300 degree oil temps in performance apps just like Corvair people. I know that my experience was representative because the Porsche repair shop told me that it was and had the ready fix fior sale, a fender mounted cooler.  Heat sells radiators!
Crawford
  ----- Original Message ----- 
  From: JVHRoberts at aol.com 
  To: crawfordrose at msn.com ; virtualvairs at corvair.org 
  Sent: Tuesday, July 31, 2007 9:01 PM
  Subject: Re: <VV> Re: Porsche cooling


  There were a few Porsches with problems, yours being one of them. The time period you're talking about, for some bizarre reason, Porsche went from an 11 blade fan to only a 5 blade fan! The idea was to crank up engine temps for improved emissions. Needless to say, the 11 blade fan became a VERY popular retrofit. 
  This is a well known issue from about 1971 to 1978. 
  Given that some 911s, turbos in particular, were belting out over 400 HP and staying plenty cool, I'd say your 911T experience is NOT representative of most Porsches. 

  In a message dated 7/31/2007 9:44:52 P.M. Eastern Daylight Time, crawfordrose at msn.com writes:

    It is unfortunate that Porsche has such a good reputation for cooling 
    because it isn't so much truth as belief. When I was 19 y.o. I owned a 72 
    911T which was the base model with iron cylinders. During a PCA sponsored 
    dinner out of town we convoyed by Interstate 55 to have dinner about 40 
    miles away. We all did 90-100 mph and my car began to seriously overheat 
    after about 20 miles.  It had the dry sump cooling system but not a remote 
    oil cooler.  Now, the engine had 90,000 miles on it at that time but the car 
    was not able for sustained high speed runs in stock condition.  Later when I 
    had the engine rebuilt ($6,800 in 1985) I had the recommended Porsche 
    aftermarket oil cooler installed in the right front fender and that seemed 
    to resolve the overheating problems at highway speeds.  The moral of the 
    story is that the 911 fan did not cool the engine enough to overcome high 
    load conditions. 911 flat sixes with iron cylinders do overheat unless there 
    is additional cooling. Many improvements in aluminum cylinder technology 
    such as nikasil plating were vital to exceeding 3.0 liters without 
    overheating.  There are a number of factors but the fan is not the 
    determinant. Yet, I'd think that  a 911 fan would cool my Corvairs o.k.
    Crawford 






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