Too HOT?

I own a 1981 911SC, with a rebuilt 3.0, that I autocross once or twice a month. When I first bought the car it had a new style (without numbers) oil temp gauge. I put in an old style gauge (with numbers) and a old style sending unit. I see operating temps (under load) that are fairly low (less than 180 F)during normal driving. However, when I autocross, the load temps go up to 210, and at idle they can get up to 250. Is this normal? Some of the other 911 owners at the events think it is normal and others think the car is going to blow up. When I leave the event and head home the temps go right down to near 180 again. Is it ok to run this hot or not? The car does have a external secondary cooler (tube type in the front right side fender). Should I install an aftermarket cooler to replace the tubular cooler?

I lost my 911 hand book for the moment. Any way If I remember correctly 250 is too hot. Where were you running on the old gauge.

The old sending unit was not working. That was one of the reasons I changed the gauge and sending unit. I know that 250 is to hot, but when people talk about running too hot, does it mean under load or at idle. Somewhere I read that 250 was not that hot when it comes to idle temp, but one should avoid conditions that would cause you to idle a lot. So I just do not know what to think.

That is definitely too hot during the autocross/track events! It is also why a lot of street/track drivers retrofit the later Carrera cooler with the fan. And, unless you plan to do a bunch of fabrication and adaptation yourself, a used Carrera setup is definitely the way to go!

Even the fabled Turbatrol cooler recommended by Bruce Anderson has been reported to be inadequate for track events! Of course, the Turbatrol doesn't have any kind of shroud or fan ... it might perform better if those were fabricated and fitted like the Carrera cooler setup.

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Warren Hall
1973 911S Targa

What about one of these?





[This message has been edited by Matt Holcomb (edited 10-21-2000).]

Has anyone had any success getting the Carrera cooler and its fan and shroud in the front fender of a 69-73 car? I've got the cooler in, but not the shroud and fan.



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Jack Olsen
1973 911 T sunroof coupe

Jack,

How much clearance between the back side of your cooler and the front edge of the tire? I suspect a pair of fans mounted BEHIND the cooler blowing out through the modified shroud might be easier to fit and make work! That '73 fender and body profile may be too different from the Carrera shape to be practical. How about cardboard, cut to fit, then the shape transferred to aluminum, or maybe fiberglass? I have a pair of 6.5" fans that are about 1.5" thick ... add 0.5" for the louvers, and your need a minimum of 2.5" clearance back to the tire for my idea to work.

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Warren Hall
1973 911S Targa

To mount a carrera cooler in an early
body car, you have to do the unthinkable.
Cut out your right battery box, seal the
hole and box in the bottom. This is what
I did on my 72. Porsche makes a bottom
bracket mount for the cooler for around
$30. It helps if your handy with a welder
or have a good friend who is. My 911 sees
a lot of track time here in Colorado and
this modification was a must, along with
the toggle switch on the fan. I also cut
into my headlight bucket to send more air
in. Made good use of the Wurth rust proofing
paint in the process as well.

It's not at all unthinkable for me to cut metal on this car. It's not a restoration.

I haven't taken the cooler off to see exactly what is in my way (having too much fun driving it), but I'm considering a two-pronged approach. One is to allow air to move around the battery box, starting from the horn vent, and ending up at the cooler (with some fabricated aluminum pieces working as a shroud around the cooler itself). Then, also cutting the rear side of the battery box out, mounting a pusher fan in the space, and possibly turning (and securing) the passenger side battery sideways (or biting the bullet, losing the new O.E.M. batteries and putting in an Optima, or a Stinger, in the driver's side box) and letting the fan draw air through the trunk (would this be too restricted an air source?) when the pusher fan is switched on.

Or maybe the whole battery box should go. Of course, that would mean taking off the fender, which makes me worry about damage to the paint. And time. I've got track time booked for a week from Monday.

On the street, it seems to stay reasonably cool (I'm putting the old-style sender in next week so I can get accurate readings), but it does heat up when stuck in traffic for long periods -- so I think a fan is a must. I have a Spal 7.5" pusher that's less than 2" thick, including its mounting assembly.

Does my plan sound viable? Or should I take the whole fender off, go for the big operation, and have my battery box surgically amputated?

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Jack Olsen
1973 911 T sunroof coupe

Black, what I was getting at, I was wondering if you were seeing these high temps. prior to the gauge and sending unit change. I guess you sort of answered that when you said the sender was not working. the answer would be you don't know. I just wanted to rule out the "indicated" high wasn't just due to the switch and maybe a mismatch.

To mount a Carrera cooler on a early
car, it is much easier to remove the fender.
There are about twenty small sheet metal
screws and one spot weld to get the fender
off. You might be surprise what you find,
as this is a notorious rust breeding ground.
Upon reassembly, you will need to get some of this Porsche seam tape that runs for
about $15. Once your fender is off, get
a sawsall to work on the battery box. You
are correct that the horn grill does provide
air, but with the battery box in place,
this air is obstructed. HTH.

Find out what your actual temps are first...buy a hand held pyrometer and see what the temps are....the pyrometer also works well for tire temps...