RS oil cooler install on '73

speedo · speedo's Garage

I wondered if anyone has a simple parts list for "plumbing" a spoiler mounted oil cooler into a '73 tub with a 3.0 SC motor. Most of the threads deal with the upgrade to a later model car that already has the hard lines going to the front fender. And most "kits" include the cooler, lines and hardware to connect to that system. I want to minimize the fittings, connections and run lines under the rockers directly to the cooler up front, and then back to the motor. I'm not convinced that the way to do it is to first run hard-lines as far as they'll go up to the wheelwells and then connect to the short lines that go to the cooler and then reverse the route from the cooler with the flexible short lines back to the hard lines and back to the motor. Sounds like spagetti to me! So...guys, who has done it, what do I need...fittings, (size, I guess I need AN12 for the correct flow), and connections to the metric motor, length of flexible hose etc. Since I won't have Deco panels on my RS, I'll need to hang the hose under my rockers...what kind of brackets do I need...should they be welded to the underside of the floor? And lastly, manufacturer suggetions for the cooler...built-in thermostadt or external, and is there one whose dimensions will allow me to hang it behind the RS front spoiler (from our host) so that I don't have to carve up the front panel to get enough air flow through it. There are a lot of RS conversions running around...and more being built that I would imagine this could help out a bunch of us. Lets hear it !

911pcars · 11-01-2003, 06:59 PM

The threads on this subject are already pretty exhaustive, but here goes:

I'd use the factory thermostat and hard lines or Chuck's Elephant hard lines. It's a lot cleaner install from wheel well to wheel well than flex hose. In addition, you'll need 2 new hoses at the rear; both go to the thermostat; one from the oil tank, the other from the engine. You may or may not need a metric adapter fitting at the tank. There was a thread a couple of days ago on the correct numbers for these factory lines.

In front, you have a choice of AN-type hose and fittings to connect the hard lines to the front cooler. The factory manual shows the routing and clamping specs along the rockers and inside the wheel wells. If you want to be really trick, run hard lines inside the rocker structure so it doesn't show at all. It's more protected as well. However, this requires sheet metal surgury.

With hard lines routed in the usual location, you'll need two 30mm by -12 or -16 AN fittings and about 2.5' of AN hose (total) between the hard lines and the cooler. I used (2) straight and (2) 45º AN fittings and -12 AN hose, but this depends on the inlet/outlet fittings on the cooler.

You have a choice of Setrab (Mocal), Earls or other brands of coolers. The max. size depends on the available space inside the RS bumper. I have an Earls 25012 cooler. You'll have to fabricate a mount or adapt manufacturer brackets to hold the cooler in place. Mounted in this location, there's minimal space for exit air out of the cooler, but except for a dedicated track car, there seems to be sufficient air flow to manage the oil temperature. On a hot day, I don't see more than 200ºF oil temp. with my 2.7. Others report similar results. If you have to cool more than 3.2 liters or if the engine produces prodigious power, you may need an additional cooler or two in the usual fender locations w/add'l air inlets punched into the body. If your plumbing needs go beyond a single cooler, you may also have to use larger hose (-16) and/or a combination of larger hard and flex lines.

Others will chime in with their experiences and suggestions as well.

Sherwood
http://members.rennlist.org/911pcars

Steve Marshall · 11-01-2003, 07:23 PM

Can't remember all the fittings we used, but we ran soft lines thru the heater ducting in the longitudinals on a 68 911L to a fender cooler and it worked great. No lines on the exterior to get damaged and soft lines have got to be easier to run than hard.

Elombard · 11-02-2003, 04:17 AM

I catn find the link right now. But if you go to the BAT inc. web site they have a downloadable catalog on 911 cooling. I learned alot. It is mostly for race cars but if you dont mind the aero quip it works on a street car too.

Elombard · 11-02-2003, 04:29 AM

I catn find the link right now. But if you go to the BAT inc. web site they have a downloadable catalog on 911 cooling. I learned alot. It is mostly for race cars but if you dont mind the aero quip it works on a street car too.

dean · 11-02-2003, 05:32 AM

I just bought a Mocal from BAT. I wouldn't recomend the Mocal or BAT. The Mocal looks very shody (failure to remove flux before painting resulting in the paint coming off). And BAT has terrible cust. service and they increased the price without telling me.

That said I would use -16 hose because -12 is smaller that what Porsche used

speedo · speedo's Garage

...why wouldn't it make sense to use a thermostadt integral to the cooler of choice? Then, you would be able to run the rear lines directly back to the motor. Or are the thermostadt characteristics that much different? I'm reluctant to run the lines through the heater ducts as I have already repaired the rockers and have NO interest in opening them back up again.. Is the basic argument against running soft lines under the car...the fear of "speed-bumpitis"? I mean ,what is the maximum exposure there under the floor pan...maybe an inch lower than the pan?

cary · 11-02-2003, 07:43 AM

Chuck or Dave at TRE will set ypu up with what you need.
Dave even makes the replace piece for behind the valance if you really want to do it right. Or you need MAX cooling.

Bill Verburg · Bill Verburg's Garage

911 aux. tstats also incorporate a pressure relief valve that will protect the aux. cooling circuit from overpressure conditions. I strongly urge you to use the factory unit and factory or Elephant hard lines. -12 is fine -16 is better

The '73 and earlier cars have less room for a spoiler mounted cooler than the later cars. I would modify the front of the tub w/ a TRE RSR piece and a cooler specificly designed to fit in the very limited space.

On a pre 964 car the aux. cooler doesn't have to be particularly large as it just takes up the slack when the engine mounted cooler runs out of capacity.

atr911 · 11-02-2003, 11:31 AM

What about a whale tail mounted oil cooler? I'm sure its been thought of before but any info on this? In my case, I'd be considering it with a 3.6 but i'm sure it could be used on an earlier engine aswell. Obviously woudln't work on turbo car or car with A/C, but seems like a good idea for any other, think of the SIZE of the cooler you could put up there.

Adam

911pcars · 11-02-2003, 02:55 PM

and the hot air from the cooler cools (?) the engine.

Sherwood

atr911 · 11-02-2003, 03:35 PM

Hmm true enough.

DOH!

Adam

911pcars · 11-02-2003, 03:53 PM

Adam,
That's okay. Engineers must deal with this with turbocharger intercoolers (air-to-air cooler); but this is mostly a packaging dilemma. There's no other place to put an intercooler and still keep it close to the engine.

Sherwood