Pictures from weekend @ Willow Springs, too hot - questions... Options

[siverson]

I spent the weekend at the NASA event at Willow Springs. It was pretty fun, and a very fast track - 125 on front stretch, about 105 or so on the back stretch. Turn 8/9 right at about 90/100 mph. Yowzers. I had never driven on that fast of corners before.

It think it was about 105 degrees out too, and my car started to get too hot in the afternoon sessions. I actually had to stop the 20 minute run sessions early. I was quite surprised by this, as I had previously been concerned that the car is running too cool on the freeways. Hmmm...

I'm running a 3.6 with a front mounted Mocal cooler that's 20x6x2 or so. Another 914 there had a 4.0 (from a 3.6) with the factory C2 cooler under the rear trunk AND a front mounted cooler that was 16x6x2 or so.

I think my DME programming might still be a little off (too lean) contributing to the heat. I'll have to check it out.

Does anyone have any real world experience with the GT engine lids? Do they really make a cooling difference? Anything else to consider besides fuel/timing and engine lid before I start cutting away for a second cooler somewhere?

-Steve

[Jack Olsen]

It's not easy to keep a 3.6 cool. The cars they were designed for were able to generate really good airflow through the cooler. It's hard to tell from the pictures: did you cut outlets for the cooler airflow down below the shroud? On a 3.6-swapped 911, air is sometimes vented back up, through the hood, or to the sides and into the wheelwells.

You can also add an engine-mounted cooler from a 3.2, assuming you've eliminated the power steering pump.you

Oh, and a fan helps. I don't know why (considering the speeds you can get up to at Willow), but it does.

Dash-16 lines are the safe choice for track applications. Some guys swear your engine will cook with just dash-12. I run dash-12, into two fender-mounted coolers, in my 911. On days as hot as this weekend at Willow, I need to pull both headlights so the buckets can function as addiitonal air scoops. It's not an issue in street driving at all.

I wish I had gone with dash-16.

Another cooling problem comes from the heat sink effect after you shut the car off. The 3.6 liter cars would have the heater blower keep running air through the heat exchangers after the motor was turned off. When you swap a 3.6 into another tub, you generally lose this automatic function. The exhaust cooks the heads, and you see more leaks.

But enough about cooling. That much motor in that light a car has got to be awesome at a track like Willow. What kind of times were you running?