The quest for cool

Well, those of you following the development of Black Beauty know that oil cooling was a big concern. In taking it out on the track last weekend, even with the dual oil cooler arrangement, I was still getting temperatures close to 250 degrees. I was not running the fan, and there was no ducting in place to direct air into the fenders to move over the coolers. On the street, it's impossible to get the car very hot, but on the track I'm still concerned.

TRE Automotive in North Hollywood is going to verify for me that my oil pump is working correctly, and that there isn't a pressure relief valve allowing oil to bypass the cooling circuit (if this is even possible on 964 engines) or that I don't have an obstruction somewhere. Assuming the system itself checks out all right, I'm going to definitely use some aluminum to block off around each cooler, and also put some ducting to direct air up in there. I'm considering getting a fiberglass front "S" spoiler and cutting two holes in it, for ducts (like the RSR brake ducts) to feed the new shrouds for the coolers. Any suggestions or ideas would be appreciated on this.

And since the front two fenders now house oil coolers, my air conditioning and transmission cooling needs are going to be taken care of in the rear driver's side fender. A scoop-type duct is going to draw air in ahead of the rear wheel, sending it over (and through) a small cooler for the transmission, and then to a 964 AC condenser that will fit in behind the wheel, sort of in the position where the oil tank is on the other side. By the time the AC is up and running, heat from the cat test pipe should be a non-issue, since I plan to switch to headers. There will be a second condenser up in the factory position under the nose. The rear condenser for this model was originally in the decklid, but that's not doable with the 964 lid on my 911.

That's the plan, at least. As always, I'm interested in opinions. If everything works correctly, I should be able to keep all of my major components (driver included) cool this summer.

------------------
Jack Olsen
1973 911 T (3.6) sunroof coupe
jackolsen@mediaone.net

Jack, my personal vote would be to add yet another Oil cooler. Shoot, you've got two...why not three???

You need to be the first person on this board to break the 20 qt oil change record.

Just throw one horizontally and put an RS air dam on up front.

You know,...some day when you all threw with you modifications (if that'll ever happen) we are going to want to know exactly HOW much money you've put into that georgous car.

Not me - I keep expecting him to become one of those guys who puts $20k into a car and then sells it for $10k when he decides he's just got to have a Boxster S!

Just kidding,
Emanuel

------------------
Emanuel Brown
1983 911 SC Targa
http://home.att.net/~epbrown01/91183.jpg

The key for cool oil is airflow. The wheelwells have poor airflow no matter what you do. I have 1 (5 1/2 X 2 1/4 X 20) B&B oil cooler in the front spoiler of my 76 Carrera with 3.6 transplant, temps are always at 80C street and can get into the 90's on a hot track day. Traffic can be an issue though and it was a pain to mount, this is why I always reccommend a good wheel well cooler(with e-fan) and a small spoiler mount in series, each compliments the others strengths/weaknesses.

Jack, I know this may sound simplistic, but what do the *other* guys (with similar sized engines) run to solve this problem? And what about turbos....don't they cook their oil?
Having been to Willow Springs for an AMA race in the Summer, I can understand your concern.

------------------
Doug
'81 SC Coupe (aka: "Blue Bomber")
Canada West Region PCA
members.home.net/zielke/911SC.htm

Not me - I keep expecting him to become one of those guys who puts $20k into a car and then sells it for $10k when he decides he's just got to have a Boxster S!

Dibs!!!

You're in real good shape with coolers. You just need to force feed a lot of air through them. I know you really like your front spoiler, but it may need to go. Build shrouds for the coolers and ducting to them. You need air my man.

I have used the 993/964 front mount oil coolers in all of my projects. They are considerably larger than the early versions and have shrouding to ensure that the air passes through the cooler and not around it (and they are not very expensive to pick up). To fit in an early car, you will need to mount it at an angle, but it will fit. You may need to replace the factory fan and install a PAL version which is thinner.

I have run this setup with a C2 Turbo engine (no engine mounted oil cooler) in earlier cars and did not have heating problems. I did install the 965 hard lines, soft lines and thermostat.

If heating is still a problem, I would add a second one with the same configuration on the drivers side with a 964 AC condensor (someone sells mounting hardware which will allow a 993/964 oil cooler and condensor to share the drivers side front fender).

As for the rear quarter AC condesor...I would be concerned about damage from stuff flying off the wheels...by the time you install enough shrouding to protect it, you will dramatically limit the airflow capabilities.

Also make sure that the fans are drawing air through the coolers...

Have you considered changing the thermostat?

Another consideration is the ribbon on the 964 decklid...As this part often wears and breaks, cooling to the engine compartment is dramtically reduced since the air doesn't enter the engine bay. When they installed the engine, did they keep all of the engine tin, and is the engine gasket in good shape?

You should have adequate oil cooling with the configuration you have...

David

Not that I have any experience in this matter, but I think the front mounted oil cooler, in an RSR bumper is the best way to go...

I am guessing you are doing the fender mounted coolers because you do not want to slap on a large RSR with a central duct for an oil cooler...

Also I think at the exspense of preserving the geogeous look of your car, you may not be able to achieve some of the goals you have set out...I can't imagine what your car's balance will be with added oil coolers, moved a/c condensors and tranny coolers...and moving these parts to the outer most corners of your car...after moving all parts, a corner balance may be in order...

My opinion...make your blk beaut your daily driver...sell the jag, buy a good 70's tub and make it an all out racer...then buy an SUV and a trailer to take it to the track...not that it is my money, but I think this way you do not have to try to balance preservation of the cars look and trying to extract peformance.

There is something definately wrong in that you are running 2 oil coolers and the 3.6 is still running hot...you may want to play around on photoshop and give your car an RSR bumper and see ho you like it, hey it may strike your fancy...

Thanks, everybody. I understand that the RS front bumper and cooler arrangement would probably solve my problem in one fell swoop. But that's my last resort, since I don't like the look of it on a street car.

Ducting is the next step, I think, pending confirmation that the oil circulation system is all right mechanically. (Is there any possibility that my pressure release valve is not closing fully, allowing some hot oil to go to the cooling loop, but some to go right back into the tank? After all, on the track, with the engine over 6K, the oil pressure has got to be approaching its max.)

I'm thinking two holes cut into a fiberglass bumper, each ducted to a cooler shroud. On top of that, I'm considering an additional (removable) scoop that feeds into the same duct, peaking out underneath the spoiler, feeding into a Y-shaped duct leading to the shroud. The idea being I'm not going to have to worry about clipping curbs when I'm at the track, and it's where I need the most cooling. On other days, I can cap the Y-shaped portion of the duct or even leave it open. Street driving hasn't produced any problems.

I do have a space in the ribbon on the spoiler, so I'll fix that. I think I also might have a gap in the engine sheet metal where the power steering pump would have been. I'll see about plugging that and the (engine sheet metal) hole for the heating duct as well.

Once again, the Pelican board proves its value.


------------------
Jack Olsen
1973 911 T (3.6) sunroof coupe
jackolsen@mediaone.net

Have you looked at the correct RS bumper for your car? I had one on my '72 and thought it looked great(dark blue), in addition the space between the bumper bottom and tub can easily be sealed at the bottom so that all of the air which enters through the central grill is deflected left or right into the coolers, this is not as efficent as having the coolers directly behind the grill but it worked well enough on my 72S. Don't forget to seal the top, bottom and sides of the cooler itself.
Unfortunately there is not enough room behind the grill of the RS bumper to mount anything but the smallest cooler there without modifying the tub. This mod would consist of cutting the oem vertical front of the tub and rewelding a piece which is angled back ~45 deg at the bottom. There will no longer be room for a full size spare.
An additional plus is the lighter f/g bumper will reduce the polar moment of the car making turn in much crisper.

Okay, I figure this is a good chance to learn so, I have a question:I know that to much heat is bad.And I know that the thermostat is measuring the oil temp, right?I guess that when oil gets too hot it doesnt lubricate to well, which is bad. And I also guess that when metal gets too hot it tends to bend, which is very bad in an engine.Also the engine in our cars users oil to cool it.So there in lies the question.

When we worry about engine cooling are we worrying about the ability of oil to lubricate or about the metal getting to hot?

I suppose it is a bit of both, which is why we had the head studs pulling problems on 2.7s etc... (Which I gather is due to different thermal expansion properties of components, which is slightly different).

So what is the deal with the newer engines?
How hot can they run?
Does it depend on the type of oil?
Is 250 too hot as Jack is worried about?
If its running to hot whats the worst that can happen?
How hot is too hot?
How long will the engine last at 250?

Porsche ran engines similar to ours at Le Mans for 24 hours, so why is it difficult to make ours run for half an hour on the track?

Actually thats a lot of questions, but I like to know what the point of something is. And there seems to be a lot of issues with regard to cooling.


Sorry for all the questions, but I just sold the Porsche and Im thirsty already!

Alex.

Engine temp and oil temp are two different things. You can have too high of cylinder and head temps but have cool enough oil and vice versa. High oil temps are a problem concerning lubrication and premature engine wear. Too piston and cylinder head temps can cause meltdown and piston seizure/scuffing. The reason street cars have probs at the track is because most of them have increased horsepower over stock. More power = more heat, so more cooling capacity is needed.

------------------
Tyson Schmidt
72 911 Cabriolet
92 C-2 Cabriolet

Just wondering, Jack, do you have any fans mounted for the two fender coolers? What type of coolers are they? Are they the radiator looking type (like Mr. Griswold's) or those tube looking things? Not that I'm an expert but I would think two radiator looking oil coolers with fans would help. Then you can preserve the Black Beauty look.

------------------
Jeff
1976 911S

Hi Jack. I love the car and your postings! It does sound a bit odd that it gets hot. The fact that your car is weighing in at not much more that Mike Tyson and the 3.6 (unless your foot is flat on the floor the whole time) is designed for dragging fairly heavy 964s around the place so should not be working that hard and should be running cool. Even on the track.

So do the oil coolers feel really hot (hot as hell) when touched by hand. Meaning that the oil is circulating ok and not a thermostat problem.

Is the temp gauge reading correctly - again same as above, check the oil coolers hot as hell.

And... Is it something else wrong like ignition timing, that's making it run hot.

I know the above ideas/suggestions sound a bit simplistic and I know you are great mechanically to build the machine to start off with, but it's nice to find an easy fix instead of more drama and more money.

Bill, '79SC

Bill, my last resort will be exactly that -- using the RS bumper as a dual air duct, running air to the two fenders. But before I resort to that, I think I'll try a fiberglass "S" bumper, with holes, ducts and an additional air scoop on each side.

Alex, I figure a newer engine (made of more modern materials) and synthetic oil (which suffers less temperature-induced breakdown) should mean that a handful of ten minute stretches north of 240-degrees won't mean the end of the world. However, they're close enough so that I don't want to see them ever happen again. I'm going to have the oil pump, fuel lines and pressure release valves all checked (as much as possible without cracking the engine open) when it's out for the current transmission work. I'm hoping that it's a still-air issue, and that generous ducting will solve the problem. I'll also check the ignition timing.

Jeff, the two coolers are both radiator-type. One is a Carrera cooler. The other is a Turbatrol cooler, with a fan. However, I wasn't running the fan (it works with a switch) until I noticed the temperature during the second of two runs. I had heard somewhere that with high speeds, the fan could actually reduce airflow to the cooler. This seems like nonsense to me now. 964 oil coolers have a fan and a very efficient design. I suspect that there was very little air movement inside the fenders, and that the fan -- if running the whole time -- would have helped.

Here's what the cooling setup looks like. Click on the thumbnail for a larger view.



Bill: Yes, both coolers were extremely hot to the touch. But if a pressure-relief valve were stuck open, I'm told (but no one's confirmed for me that this could happen with a 964 engine) that a much smaller quantity of oil could be going to the cooler, with a similar quantity going back to the tank. If this is the case, my coolers might be working fine, but not getting a shot at all of the oil.

I've done some minor pieces of mechanical work on the car, but the swap was done by someone with a lot more skill (and time) than I have. Unfortunately, he -- my mechanic -- died shortly after finishing the swap, so my new mechanic and I are going to have to get to the bottom of this.

------------------
Jack Olsen
1973 911 T (3.6) sunroof coupe
jackolsen@mediaone.net

Alex,
The early cars seals were another weak area. Temps as hot as 250-260 on a modern car (3.6 from '93 in this case) while not desireable are perfectly ok(with good synthetic oil). That temp on an early car would have been considered frightening(the seals would give up and the car would leak like a seive). Optimum temp for racing is ~200F + or -10(they get frequent oil changes). Optimum for street use is 220F + or -10 the street temps should be higher for emissions and more importantly to boil off condensates.
Turbos have their own set of problems not only do they tend to run hot but they have an additional tender spot at the compressor shaft. One end of this shaft is exposed to 1000F + and the other end (3 whole inches away) is at intake manifold ambient ~100F. For this reason turbos absolutly require the use of synthetic oil and frequent oil changes. While I don't have a Porsche turbo I do have an Audi twin turbo, 250F is considered normal for oil temp, they also advise the use of a lighter weight oil to keep the turbo shaft well lubricated even at particularly low ambients(-20F here in the Northeast)
The pulling heads are related to a combination of heat and the inherent softnss of the magnesium alloy used for the 2.7 cases. If the cases are timecerted and steps are taken to keep temps under control and modern seals are used then those engines can be as reliable and leak free as the newer ones.
The snapped head studs on the 3 liter cars are attributable to heat and corrosion of the studs.
Porsche race cars are just that, Race Cars they may look similar to your car but they are very different in key, but not always obvious ways.

Just a silly question, but what about the remove the head lights and then cut a hole into the head light bucket trick??? of course for track use only

This reminds me of the old Yoshimura GSXR's air/oil cooled endurance bikes. They mounted a auxilary coolers everywhere on those things. You may want to run it with the headlights removed and see if your problem is air flow related.

http://www.pelicanparts.com/ultimate/Forum3/HTML/007668.html

Oil temps in a 911 over 235, under racing conditions, will cause premature engine wear - even 10 minute stretches. Oil temps at or over 250 under racing conditions means an engine rebuild is in your future, even using Mobil 1 - take it from me, I know. Jack, I think your idea of ducting a fiberglass S spoiler may work - I have seen that done on other cars. What has been tried and tested and will work under your So Cal desert in summer conditions is an RS spoiler with extra large cooler and duct opening with changes to the front tub to allow air to exit easily (or installation of two fans pulling air out from directly behind the cooler). Part of your challenge is the ambient temperature you run in - staying cool will require additional measures beyond what might suffice elsewhere in the country. Best of luck - see you in Cambria?

Randy W