Courtshark

I ran my solo laps MUCH more gently than I had on the first session when I overheated; never got much over 5k, and I even shifted into 5th on the straights. The engine temps thanked me, though it still ran on the warm side. Probably never fully cooled down from the first run. Videos coming soon...

hacker-pschorr

Probably already been said, but yank the radiator and give it a good flush. Even on low mileage, well maintained 928's I've seen a lot of crud come out of them.

Local guy retrofitted a belt driven fan from an early car, he "fixed" the clutch so it was always on. Sure there is some engine drag, but he saw instant lower temperaturs at Road America with an S4.

Courtshark

Interesting thought on the fans; I could add a fan to the front of the radiator after the AC is off, perhaps, one that I can control with a cabin switch.

I'm planning to yank the radiator and soak it in a kiddie pool full of degreaser, per the race shop's recommendation.

docmirror

OK, back to cooling. It's been said by several different people, but maybe needs to be reinforced. The stock system, even when new is marginally able to handle the temps of track work.

What I would do if I were tracking:
1) Make all the recommended changes for the oiling system. Make them ALL, because rebuilding the engine after a 2/6 rod failure is 10x more cost.

2) Remove the AC condenser. Back flush the engine while hot. Get a new hi capacity radiator. Insure you have a tight water pump gap(impeller near block housing). Make sure all the components are fresh and working as designed, including the fans and the fan controller.

3) Use 75/25 distilled water/coolant. No wetter additive. If it gets cold, change it out for 50/50 in winter.

Keeping the big lump cool and lubed is a challenge for this car. It takes time and money to get it right, and when you don't it always costs more to repair it later.

Courtshark

I've heard lots of concerns with aftermarket rads for the 928 leaking, and that the Behr can be refreshed to function as well as those. Going to give that a shot unless someone can recommend a solid aftermarket upgrade that will last. A new Behr is, well, out of the question!

Tom. M

On the track...you typically don't use coolant.. just use distilled and some water wetter... but it depends on how hard core your DE/racing organizers are.

Also make sure the flaps are wired open so it allows maximum air flow through the rad..and make sure it's clean between your condenser and rad...sometimes lots of crap gets built up there..

Courtshark

It was 30 degrees when I awoke there Friday morning, so I'm glad ANTI-FREEZE was in the radiator.

hacker-pschorr

Agreed with everything except the aftermarket radiator, the stock one is just fine if working properly.

Mark Anderson has always used a stock radiator, none of us are generating that much heat with our stock 928's.

Not to mention Jean-Louis with his supercharged 10.4:1 compression EuroS race car, stock radiator and no temp issues. 1/2 of his radiator is blocked by an intercooler, he also has a good sized oil cooler.

If anything, I would get rid of the in tank coolers for the oil and trans. That's just dumping more heat into the cooling system.

My first DE with the 79, the corner workers at Road America built a snowman on the apex of turn 5. Something really worng about that.........

Drewster67

I went with two 10.5" puller race fans mounted to an aftermarket aluminum race radiator. I also sealed off the gap from the top of the radiator to the hood. If you have the stock air itnake tubes - you wont have an issue with air passing over the radiator.

I do run a mix of H20 and Royal Purple Ice.

davek9

Hi good insight on tracking 928, I plan to do at least one DE with our local PCA this spring.

As far as the cooling system goes, the stock system should keep ur eng cool unless your out and out racing, removing the AC stuff for weight savings would be good idea.

I've rebuilt a few "rebuildable" 928 rads and would not recommend soaking them in engine degreaser, could ruined the rubber seals, not just the end tanks seals.
Just flush it out w/ a radiator flush.

Dave

hinchcliffe

Mike Frye, that was the main reason i put you on there. Thanks for responding.....

DE's are not for Everyone, though just trying one can get you hooked.

Yes watch the temp gauge, even at watkins when it was 90 I was below the redlines. Maybe my temp sensor isn't working....... Never overheated. I just took out the rad when doing my TB and its amazing the bugs and leaves that get caught between the condenser and rad.

Court, you may be running SRF , high boiling point than ATE Blue/Gold how expensive was the fluid change? I've run Blue/Gold (each year the opposite color) and have not had issues. Again I'm not pushing 10/10ths more like 7/10ths.

Tracking doesn't HAVE to be expensive but it sure can get there quick. Where are my $1k tires...... $350 brakes pads..... If you plan on pushing the limit the price goes exponentially up.

hacker-pschorr

That's what we do, just fill and flush over and over until clear.

Don't some radiator shops have a dip solution for anyone that doesn't want to go through the mess?


/hate coolant, should just by an early 911.....

docmirror

That was not my experience with my stock working system in TX. Of course, my condenser had many miles on it, so it wasn't flowing air perfectly. I would prefer to have a cooling margin that isn't stressed, and with the age of the cars, there is certainly some stress on the cooling system. The engine also has a coating internally that reduces transfer efficiency.

Anyway, at the least, take out the condenser so you get full air flow.

Courtshark

Another video - day 1 session 1. Just learning the line...

Courtshark

More videos:

Day 1 Session 2, pt 1:
Day 1 Session 2, pt 2:
Day 1 Session 2, pt 3:
Day 1, session 2, pt 4:
Wheel view
Day 1, Session 3:
Side view
Day 2, Session 1:
Cockpit view
Day 2, Session 2, pt 1: