Is stock '73 911s cooler sufficient for track?

[logician]

Hi,

I'd like to know if the stock fender mounted cooler in a '73 911s would be sufficient for track (time trial) use? Sufficient for me means that the temperature would not exceed 245 degrees on a 100 degree day during a 1/2 hour session -- typical summer Thunderhill conditions.

I'm more familar with 3.2 Carreras, and know that the stock cooling needed modification to work under those conditions. But I was able to get the temperature under control by removing the right fog light, and adding some ducting to force more airflow through the cooler. In addition, I also used an elephant oil line. The 2.4 engine is smaller, but the trombone cooler in the '73 is also less efficient, and the airflow is different, so I don't know if the cooling situation might be worse.

So if the stock cooling system on a '73 911s isn't sufficient, then will elephant oil lines provide enough additional cooling? If not, then would a Mocal or other fender mounted cooler be sufficient. I know that the best solution would be to add a large center mounted cooler, but I would rather not do that right now if the fender mounted system will work for the stock 2.4s engine.

Any advice would be greatly appreciated!

-Juan

[k9handler]

I can say the trombone cooler that was on my 75 was not enough!
After a good 30 min on the track, she was at 250!
A mocal was installed and I never seen higher than 220 on the track after that, so every bit worth the expense...and since you already have the trombone installed it's quite easy to install.

[ttweed]

You might be all right with a stock 2.4S motor. The smaller displacement engines with MFI generally run richer and cooler compared to the later DME cars. However, 30 minute run sessions in 100F weather is pretty extreme. If you watch your temps and they start climbing above 240, just start short-shifting and stressing the engine less in the later laps. It's pretty amazing how much more heat you generate by running to redline on every shift. Or pull off and let it cool down if you're worried. I like Mobil 1 synthetic oil because of its higher heat tolerances. 250F is not too horribly high with synthetics, I don't think.

BA says anything larger than 2.4 will probably need remote cooling if run hard. Make sure your engine mounted cooler is clean. If it is gunked up with dirt and oil caked on, it will not be very efficient. Most of the cooling accomplished by the trombone cooler is thru the lines, so if you are close to marginal temps when you try tracking it the first time. I would guess that the Elephant Racing lines would be a good improvement.

Ya won't know until you ya go, so I say "charge on ahead!"

[pwd72s]

Apologies to Chuck here, but if you already have the factory hard lines, I'd suggest sticking with them, but replacing the trombone with a radiator...if still too warm after that, go with the elephant lines. After seeing the elephant lines on Evren's car, I'm impressed with 'em...