2.7 CIS w/Webers&Headers - Do I need a front mounted oil cooler?
 

With the three day weekend upon us and rain in San Diego, I am considering swapping engines and need the voice of experience on this issue.

I have a completely rebuilt 1977 2.7 CIS motor stting in my garage that I want to install in my 1969 911 chassis. It is my understanding that the amount of heat generated with the 2.7 in combination with the thermal reactor exhaust system and lack of a supplemental oil cooler was the primary cause of the lack of reliability with these engines.

I was planning to install the engine in the car for daily driving with Weber carbs. The engine has the stock CIS cams. I am going to use headers with the block off plates so there will be no loss of air flow to the heat exchangers. I also have a ducktail spoiler that seems to push more cool air into the engine compartment

Does anyone/everyone think this will probably be adequate in an early chassis? How about for an occasional track day?

I get the impression that a lot of 2.7s with early exhausts are getting by without using a front mounted oil cooler? Is this true?

I have an oil cooler, but I just don't have the hardline plumbing to put it in right now and I don't want to use the draped Aeroquip hose route. I will install it by summer and certainly before and desert adventures though.

Thanks in advance for your advice and help.

Rich

I know that RufBlackBird (Jeff) in Hawaii runs a 2.7 CIS car without a cooler. In that hot climate his car used to always run cool. He had custom headers and when I was on vacation I saw his car, it never ran hotter than 180ºF.

I was amazed that he didn't have an external cooler. He doesn't seem to visit the Pelican BBS much these days, but maybe he'll be able to tell you what his secret is.

My 2.7 has a trombone external cooler and I might try installing my new Carrera cooler this weekend. Australia's summer heat is unforgiving! We had 115ºF the other day... :(

Rich911E,
I have a '77 with a 2.7 CIS. I'm running SSI Exhaust with ALL emissions taken off. I was running with a trombone cooler in New Hampshire summers and it was running way too hot when stuck in traffic on 90+ days. I just installed a Carrera cooler with fan for next summer. Remember I ran hot with no thermal reactors and no air pump, oh yeah I took the AC out also. I highly recommend that you put an exterior cooler, preferably the finned cooler.
Tom

I forgot to mention that my car is a Euro model (no air pump etc) and hence has SC-style heat exchangers (no reactors) and the A/C has been pulled.

Rich,

With headers, yuou will probably be above 175 hp DIN. The factory decided that the 1969 911S needed a cooler at 170 hp. 'Nuf said? I suppose it depends on how spirited you drive ...

Time for a Cool Collar . . .

Thanks everyone for the input.

Adam and Tom: Your experience sounds spot on suggesting the a cooler is necessary. (115 degrees -- ouch! I'm staying in San Diego.)

Warren: Your thinking was the same as mine (170 was the factory's limit) but I was thinking the S may have been designed with more sporting events in mind. But given Adam and Tom's experience it sounds like it is as much a factor in daily driving as on the track.

It sounds like we have a consensus here that, absent something unusual, I need to mount the oil cooler and run the lines before the 2.7 installation. I have the finned cooler and I just need to get some aluminum tubing and get started making the lines to run under the car. I'll use Aeroquip in the fenderwells but I hate the way Aeroquip droops under the chassis.

Again, thanks everyone for the help and the benefit of your experience.

Rich

Rich911E,
An alternative to the factory hard oil lines are the finned versions from Elephant Racing (Chuck Moreland). Your plan to make your own from aluminum tubing is a worthy project. However, make sure these are protected from the misplaced floor jack or hydraulic lift pads.

Depending on your power level (stock vs modified) and the ambient temperature, you may need a fan to promote air flow through a fender-mount cooler to keep the temps within reason. A cooler in an RS front bumper opening is even better - better air flow and no fan required.

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

I don't think aluminum is the way to go.. has been discussed around here before.. maybe a search for more good info

I don't think aluminum is a good choice of material. Like copper, aluminum work hardens and becomes brittle. With vibration and chassis flexing the tubes will likely crack and fail. This is one reason the factory went with brass.

Then there is the substantial challenge of obtaining proper fittings to afix to the aluminum. And getting the proper bends will likely take multiple iterations.

Of course I am a bit biased towards the Elephant Racing finned oil lines. It was no small challenge to design an manufacture those puppies.

Chuck,
Yeah, I guess a couple of 10' continuous lengths of rigid hose is subject to some flex from the 911 chassis. For longevity they should be made out of a more suitable material like ..... elephantanium :-)

I was thinking more like short lengths of aluminum tubing would be acceptable for oil line as long as they are supported/clamped at regular intervals. A/C rigid lines are typically aluminum and are normally subject to many times the pressure found in a pressurized oil line.

Rich911E,
Let's not reinvent the wheel. I think you'd be pretty safe with either the rigid lines from factory or Elephant Racing.

Sherwood

Be sure to use line and Aeroquip fittings that have at least a 19mm or 3/4" ID. If you have an OEM oil cooler special adapter fittings are required to go from the Aeroquip to the DIN oil cooler fittings. At some point it may just be easier and more cost effective to just buy the OEM hard lines or Elephant lines. Some people like the plumbing challenge though. Cheers, Jim

Thanks for the advice. I was planning on using the aluminum for the lines simply because it would be easy to weld the aluminum AN fittings onto the line. However, it sounds like the factory hard lines are the way to go. Maybe I need to go down to the boneyard this weekend and see if any are available.

I don't think the stock 2.7CIS motor will generate enough power (unfortunately!) to require a fan. I was going to rely on the airflow through the horn grill with some aluminum/fiberglass ductwork to make the airflow more efficient from the horn grill to the cooler.

Thanks again for all your help.

Rich

Rich, you might consider removing the battery box to improve airflow.

Sherwood, although aluminum is used in AC plumbing none that I've seen run a solid aluminum line the length of the car. They are rubber hoses going front to rear.

Chuck:

I was thinking about doing removing the battery box, but I really don't want to cut up the car too much. I will try standard oil cooler and if necessary add a fan. If that combination doesn't do it for a mostly stock motor, something is wrong.

I understand the work hardening problem with aluminum, but do you think that they would flex that much? Perhaps if they were mounted in a flexible mounting bracket (sort of like the rubber hangers for exhaust pipes but a bit more tidy) it should avoid the problem with stressing the aluminum. I could fabricate some brackets with large rubber grommets for the line to pass through. I want a nice clean 90 degree bend into each wheel well from under the car to minimize any potential interference with the wheels.

Mostly, I just want to have something that looks clean under the car. I had also thought of making a U shaped box-channel out of steel, fasten it to the bottom of the car and then run the Aeroquip lines through it (analogous to the transmission tunnel inside the car). This seemed a bit extreme and the exposed metal lines do dissipate some heat without relying solely on the oil cooler.

Thanks again.

Rich

Voice of inexperience: do the original cooler lines run behind the rockers, i.e. are they visible from the side or not? I will probably be adding a cooler this summer, depending on how much heat the motor generates in its new configuration, but I'd rather not have cooler lines hanging down if I have an option.

They're mostly behind the rockers. I seem to recall one of the OEM hard lines shows slightly, especially the jog that goes under the jacking tube. The line is black though and doesn't look unsightly. Jim

Here is a twisted idea, instead of putting a cooler in the front can you put a cooler in the rear lid? In the Corvair world I have seen many oil coolers mounted to the engine lid. I would think with the ducktail you would get enough air flow.

Comments, Thougts, Ideas?

The problem with coolers on the lid is circulating heat flow. The cooling air for the engine is being inducted in through the grill. One has to make sure this air doesn't get pulled through the oil cooler first and preheated. Like the lid mounted A/C condenser situation. Might be an issue while stopped or in slow traffic. If arranged properly the lid mounted cooler could work but I'd wonder about the air drag. Jim

What is wrong with trying to improve air flow to the engine oil cooler. I have read countless articles about it not doing the job and the need for an external cooler but, never an idea to improve what the car comes standard with. It would seem to me that if you could channel some air in a duct to the engine cooler area it would be of benefit.