Bill Gregory

911's through 1989 have had a variety of auxilliary coolers, in addition to the engine-mounted cooler. The first auxilliary cooler was on the 1969 911S, and there were basically 3 variants after 1974: the loop cooler, the brass-tube cooler, and the radiator-type cooler. In most cases, for street driving these coolers work just fine. However, the demands placed on the engine while on the track can overtax the stock oil cooling capabilities. First, you need to know if you engine is running too hot. For temperature gauges with numeric temperatures, instead of "zones", if your temps go up above 250 degrees, you need to augment your 911's cooling capacity. For those with "zones" on their oil temp gauge, if you look from the right side onto the far left edge of the gauge, you'll see the degree centigrade temperatures that the zones correspond to. An easy upgrade, which takes less than an hour and around $70 in parts, is to swap out the "zone" oil temp gauge for a numeric gauge, which includes changing the oil temp sensor on the engine. Here's how do do it: First, getting the gauge out of the dash is simplicity itself: open the front hood, move the carpet aside behind the master cylinder, and push the housing with the oil temp/oil pressure gauges out of the dash. 4 small screws hold the oil temp portion in the larger housing. Old out, new in, change wires to new, push housing back into the dash. The second part requires replacing the existing temperature sender on the engine with the new, pre-1977, sender. The sender is on the right side of the engine where the cam oil line comes out at the base of the fan. You'll see a yellow/black wire attached to the end of it. Detach the wire, undo the existing sender, put the new sender in (don't forget the washer), attach the wire, and you're done.

So, let's assume you've just completed a driver education event, and your oil temps got into unfriendly territory. First, before installing or replacing your external cooler, be sure that your engine is in a good state of tune (not running lean, for example), that the airways to the pistons and engine-mounted oil cooler are clear, that one (if you only have one), else both thermostats are opening around 185 degrees, and that there are no kinks in the brass oil lines running to the external cooler. If these all check out OK, your next action depends on what you already have, and whether you want to upgrade in steps, or jump right to the valance-mounted cooler. The steps are: No cooler, add one. Loop cooler and brass-tube cooler, upgrade to radiator-style. The 84+ Porsche Carrera cooler is one option, as are coolers from Earl's, Mocal, B&B, and others. Already have a radiator-style cooler? Ensure that it's getting good airflow and/or add a fan. Sources of air come from the valance (84+ valances are shaped to flow more air to the cooler), or you can remove your turn signal on the track, or Paragon Products and Pelican Parts sell a scoop which replaces the right side marker lamp, or you can drill holes/cut out some metal behind the right headlight (removing the headlight at the track). Porsche and SPAL are two fan sources. Already have a working fan? Add a front valance that allows a valance-mounted cooler. There's a gaggle of front valances (I like the RUF polyurethane valance, as it has some flex, which can be important on a lowered daily driver), and B&B, RUF, and others make valance-mounted oil coolers. Some also adapt Honda or Mazda oil coolers. If you're customizing your cooling solution using Earl's, Aeroquip, or similar stainless-covered rubber lines, make sure you don't size them too small, as that can damage the engine. -12an is the minimum, and -16an is better. To hook up -an connectors to the Porsche metal oil lines, you can buy the appropriate metric-to-an adaptors from Pegasus Racing.

If your oil temperatures are too high, in addition to upgrading your cooling, you might also consider changing your oil to the appropriate grade of synthetic oil. Synthetics, like Mobil 1, can withstand higher operating temperatures than most dino-based oils.

Required statement: Written by Bill Gregory for the "Challenge", monthly publication of the Connecticut Valley Region, Porsche Club of America.

[ 04-06-2001: Message edited by: Bill Gregory ]

Bill B

Good stuff, Bill, keep 'em coming...

Leland Pate

Thanks Bill, I printed this out and will use it in the future.

JackOlsen

Bill, if you're looking for a charity case, I'd appreciate any suggestions you might have for keeping my little monster from getting too hot. I've already got two coolers in place, with improved ducting in place and more on the way. It's fine on the street, always, but not fine on the track (although it's been getting better with the incremental improvements that I've made).

Click on a small image for a bigger version.










[ 05-06-2001: Message edited by: JackOlsen ]

Bill Gregory

Jack,

Nice Pictures. Gotta get me a digital camera one of these days.

Keeping the 3.6 cool can be a challenge, as you're finding out. I don't know if you can duct enough air to the dual cooler setup you have, however. I know one person who used aluminum to build, in effect, a big tunnel to route all the air through the cooler so no air could flow around it, which helped on their 3.2L. They also had a larger outlet that they cut in their valance to flow more air through the tunnel to the cooler. The factory so-called stone guard that fit behind the Carrera cooler did much the same, while providing a path for the air to flow through the cooler.

The next step might be to mount fans on each cooler, much as Porsche did in, I believe, 1987. When I had the fender mounted radiator-type cooler with my 3.0L, I did all sorts of things to flow more air to it (cut holes in the valance, took out signal lights, etc). When I added the fan (I used an SPAL fan), that made a significant difference - I could see the temps go down when I turned it on (I used the fog light switch to turn the fan on). Alas, while it was better, it wasn't good enough, so I ended up going to the front mounted valance cooler, which solved the over heating problems.

carnut169

Bill, I am basically mechanically illiterate when it comes to all but the most basic routine maintenance- I rely on good people like you in hope of one day being able to properly diagnose my own problems and perhaps helping others as others have helped me. But… digital cameras I do know. Whenever you are ready to buy one let me know and I will be more that happy to give you some words of advice. If you were to get one now my vote would be for the Nikon 950. Takes great photos- and it is available on Ebay all day long for about $450.00. Also has a ton of features I will not get into here- but please let me know if I can help! Sean.

JackOlsen

Thanks, Bill. I've put an aluminum shroud around the passenger-side cooler, which also has a spal fan, and has had the battery box removed. I'm currently having the driver's side battery box reduced in size by about half (Stinger dry cell battery will still fit), and I plan on a shroud (and possibly another fan) on that side as well. While the new ventilated spoiler is getting painted, I added an aluminum scoop on the shrouded side, so that air would be forced through that cooler.



One question: can fans and ducting work to counteract one another? I wonder if having a fan on the second cooler will reduce airflow at track speeds (where I have the temperature problems) while helping in stop-and-go traffic (where I don't have any problems).

[ 05-06-2001: Message edited by: JackOlsen ]

Bill Gregory

Jack,

I always figured the fan was pumping air through alot faster than air could get to the cooler on it's own. Have you also sealed up around and next to the cooler, so air can't go around it? Just another thought on helping guide the air to the coolers.

Herr Cooled

Whoa.

[ 05-06-2001: Message edited by: Herr Cooled ]

JackOlsen

Yeah, I used aluminum to surround the thing, with heat-tolerant pipe insulation stuffed along the sides. As it is now (on the passenger side, at least), there's only one place for the air to go.

On my last track day, temps still got up to 251 degrees by my pyrometer. I'm hoping the better straight-through-the-bumper ducting, as well as the same treatment added to the driver's side cooler, will knock me down another 20 degrees.

The driver's side battery box gets cut out tomorrow. But the next track-day test won't be until the weekend of July 7 and 8.

Cary E

I'm on the same quest as Jack. I want to go to the track and run not over 220 degrees.
About the same as Jack. 20 minutes track time 240 degrees.

I'm in the process of changing out the supply lines from the engine to the front oil cooler. Come to find out when I removed the rocker panel one of the lines was crushed 1/2 closed. That should help.
Something probably everyone with cooling problems should look at. I couldn't see it from underneath.

I have a question : Can/will a later Carrera rockguard with its air seal be attached to my Terbatrol oil cooler to force all the air thru it rather than some escaping around it ?

TIA

Roland Kunz

Hello

Why not going the total way and threw out the rest from the AC and place the cell in the smugglers box. Then cut the battery boxes complete away.
Then you have enough space for direct flow and some duct work will make it more efficient.

If you go racing then use a RS frontdam with the cooler siting in the airstream. If you use a SCRS unit you will have two cooling ducts for the brakes too.

Your wheelhouse coolers will work better if you use the factory cover panels ( 2,0 - 2,4 ) Get the one and copy it for the other side. The louverd pans will cost flow but protect the fins. Porsche was thinking that the frontwheel will generate a drag at high speed spining and this will cause a ventury effect on the fins help draging air trough.

You can see a slight temp degrease if you compare it on the german highway. But low speed drag is nill.

There is to much turbulence for a foil streaming.

Two fans each side will help then even in driving.

Grüsse