Internal cooler necessary with front cooler?

[sandiego]

The oil temp in my 2.7 liter track engine stays cool with a front cooler (protected by a Mocal thermostat). I'm putting in a 3.2 and am tempted to replace the internal cooler with a filter. Some of the newer cars do not have the engine mounted cooler, just front coolers with fans. Does anyone see a down side to eliminating the internal coolers other than overheating at rest?

[ted]

The 3.6 conversions normally don't have an engine cooler either.
With a couple of front coolers you should be alright.
I nice fan on the fender cooler like the one Chuck sells at Elephant racing would be a good idea if you drive on the street.

[armandodiaz]

What coolers are you planning on using?

One thing to keep in mind, the difference on the newer cars (964>) is, their front coolers are alot larger than the Carrera coolers.

[Bill Verburg]

One thing to keep in mind, the difference on the newer cars (964> ) is, their front coolers are alot larger than the Carrera coolers.

Also the air flow is far more efficient.

I use a single valance mount w/ my 3.8 RS temps are always under 200F

Quite few of the more savy racers are going to the 964/993 air flow pattern

i.e a single or dual side mount cooler w/ central inlet and wheel well outlet

[addictionMS]

I have been told the efficiency of the engine mounted cooler is much higher than that of a front cooler because it is cooling the oil after the air has settled out, the motor cooler in inline on the suction side, front coolers on the pressure side where the oils is full of bubbles from having just churned aorund in the motor.

something to think about, an equal sized cooler will not cool as much

Jim

[Bill Verburg]

Originally posted by addictionMS
I have been told the efficiency of the engine mounted cooler is much higher than that of a front cooler because it is cooling the oil after the air has settled out, the motor cooler in inline on the suction side, front coolers on the pressure side where the oils is full of bubbles from having just churned aorund in the motor.

something to think about, an equal sized cooler will not cool as much

Jim

That's true, and you have the engine fan blowing across it at all times

Bottom line, you do not need it w/ an efficient front set up. Traffic is a potential issue though

[addictionMS]

you do not need it w/ an efficient front set up

Agreed, I do not have on in my race car, I am running the block off and 15 degree oil filter, but I also have the front oil tank so I have more oil to play with

On our RX7 we did not have the clutch fan, normally used to blow air over the rad, worked great to reduce the losses, but if you forgot about it, and sat on pit lane too long with the car running (about 5 minutes was all it took) the temp shot up pretty quick. I don't think a 911 is as suseptable to the rapid over heating. But it is alway good to think about all angles before you commit to something

Jim

[armandodiaz]

Originally posted by Bill Verburg
Also the air flow is far more efficient.

I've heard this alot. Is it because of the way it's mounted? I'd be interested in this setup since I already have the C2 bumpers on my 85. Does anyone have anymore info on this?

[Bill Verburg]

The 964/993 use the very efficient central intake in the valance to pick up air.

After that it's just packaging, either put the cooler in the opening where it is somewhat vulnerable or rotate it and relocate to the sides where it is somewhat better protected but still recieves the full flow of cooling air. Ducting to prevent loss under the car is essential. The wider front on turbos and 993s aids in this regard, though 964s also accomplished it. There is no reason a narrow 911 front couldn't either as long as an appropriate size and shape cooler is used.

[304065]

Bill, do you have a photo of what you are describing?

[Bill Verburg]

964/993 coolers are oriented like this, this one is a second driver side cooler in a 964


This is the standard passenger side 993 set up

[Bill Verburg]

Here is an '80s Carrera setup w/ the sideways mounted 964/993 style coolers

Intake


Sideways mounted coolers, hard to see, sorry

[Bill Verburg]

Jim Newtons SWB beauty

[Bill Verburg]

Couple more views of a 964 setup from over on Rennlist

[dd74]

Wow - how cool is that? I imagine a cooler scoop operates more or less the same way as those bumpers by bringing airflow into the radiator cooler, right?

General question: in most cases, including bad traffic, do two coolers (mounted inside the fenders) generally keep temperature levels lower than just one? Or do lower temperatures occur with a specific engine like the 3.6 or a race car engine?

Thanks.

[AES]

Hey Bill, who's light blue Carrera is that?

[Bill Verburg]

Marty F., he just rebuilt the motor Ti valves etc. v. nice!

[Walt Fricke]

Originally posted by addictionMS
I have been told the efficiency of the engine mounted cooler is much higher than that of a front cooler because it is cooling the oil after the air has settled out, the motor cooler in inline on the suction side, front coolers on the pressure side where the oils is full of bubbles from having just churned aorund in the motor.

Jim

Not quite - the front cooler is on the scavange side. It has pressure (a surprising amount according to Henry Watts, who once measured it). But the scavanged oil is aerated as you say. The engine mounted cooler has even more pressure, since it is fed from the pressure side of the pump so it receives full oil pressure and maybe a bit more (it is closer to the pump than the pressure sender typically). But its oil should have the least air in it. Bruce Anderson mentions the surprising efficiency of a cooler on the pressure side of the pump circuit (if located out in the air stream?) in his book.

Unlike your RX7 experience, my front only race car doesn't overheat sitting on the grid idling and it has no thermostats (I suppose if I let it sit idling long enough on a hot enough day it would, but if the oil temps are up around 150F sitting there I don't need to let it idle long). This may be due to the fact that I run two Continental aircraft coolers, which are pretty massive, and with an exit up through the hood maybe there is even some convective air flow while the car is stationary.

On the other hand, our '84 Carrera (that model had no fan up front) which had a front cooler in addition to the engine cooler would run noticeably hotter oil temps if forced to idle in hot summer traffic. That was clearly a feature of that model, as Porsche later saw fit to add a fan. That heating always surprised me, as my 2.7 and later 3.0 didn't seem to have this problem. So I don't know just what to make of the engine mounted oil cooler, other than that I have no intention of removing it from the SC.

On a race car there is another reason to delete the engine oil cooler: leaks. Last weekend at a DE a guy had to replace his. He could do this because he had had the forethought to cut the fiberglass one piece engine cover (this was an older 911 without the separate cover for the oil cooler) at some point when he had the cover off. He noted that the factory didn't run engine oil coolers on their race engines, and posited their inability to avoid leaking (because of a crack in the finning or the like) eventually as one reason for this.

Walt Fricke

[Rob 930]

I'm interested in this topic too, with a 600+ Hp EFI 930 engine getting ready for installation in my 78 930 track/street car. My interest is in keeping the front of the car as stock looking as possible, though I do have an 84 and later front valence. I have removed the fog lights and cut away the supports for the foglights to provide openings on each side. The holes measure about 9 in by 5 in if I recall. I have recently done away with the engine-mounted cooler (and replaced with a 993 oil filter console) not because of leak concerns, but because I wanted more filtration for oil entering the engine. I currently have a Fluidyne double pass cooler in the RF fender, with a Spaal fan, but I'm fairly sure this will not be adequate by itself. My interest is in avoiding a center-mounted cooler, which requires a new valance, possibly some serious body work for airflow, and it is more vulnerable during off-track excursions.

I'm considering a second "wing cooler" in the left front fender, possibly a C2/993 style unit. I'd probably have to mount it at an angle, given how small that space is. It was very interesting to see the photos in this thread provided by Bill Verburg. I have not done any serious ducting yet, but I plan to do so in order to direct the air over the cooler(s) as well as possible.

At the risk of further hijacking this thread (I hope that my discussion is relevant to the original post), does anyone have any comments as to whether this will be sufficient? Is there a better choice than the C2 cooler? Any idea what the best source is for purchasing the right cooler?

[armandodiaz]

Rob if your mounting your oil filter on the engine, does that mean your rplacing your oil tank? What oil tank are you going with? I'd like to install one in the smuggler's box, but I don't like Smart Racing's version. Do you or anyone else have any other suggestions?