On track days I see some guys with engine hoods up, down, or up with a fan from the top, or the bottom.
After hard track session, or at the drag strip what is really the best way to cool engine and also how long to let it idle?

TIA tom

 

Tom
For the 996, if possible I like doing 2 extra cool down laps to cool down the drivetrain, and brakes. Then 2 minutes idling at the pit for turbos. I don't like having the engine lid up because that would take away the cooling affect of the fan unless there's wind.

 

Leave the 996tt hood down so the fan is efficient at
extracting air. After a track session I'd idle the car for
3 minutes. I'd think about a spray bottle to cool down
the radiators too if your engine temperature is any
higher than you see it in the street.
Joe

 

This topic has been covered many times before. Opening your engine lit will actually INCREASE the temperature of the engine in the short term compared to keeping it closed and running the engine lid fan. The fan draws air into the engine compartment from the top, forcing air downward, past the headers which allows the heat to escape out from under the car. Opening the lid automatically creates a chimney effect and the extreme heat from the bottom of the engine will force it's way upward, increasing the heat of the top of the engine. Logic says to blow from the coolest part of the engine towards the hottest part of the engine, which in this case in top down. You should also run you frobt fans at high speed for 5 - 10 minutes which will drop coolant temms by as much as 30F. Spraying water on radiators will also speed cooling up.

 

At our track, Brainerd, there is an off track "loop" we do that takes
a few minutes (low RPM driving), and you touch the brakes once or not at all. Then for us
it has always been park without using brakes if possible (no E-brake), and
then idle for 3-5 minutes (with all hoods closed).
MK

 

at drag strips to cool down in between passes i've used a bag of ice on top of the intake manifold, not sure that'd be possible on the porsche boxer's though

this reminds me of a funny story though, I did a canyon run about 5 years ago w/ a HUGE group and there was a guy in a yellow 996. We all pulled over for a cool down and the 996 guy opened his front hood and walked away. I asked what he was doing and he said cooling the car down

 

Cooling his battery

 

Thanks for the replies, and good info. What about blowing cool air from a large fan with the hood up instead of relying on the tiny OEM fan, or is cool down lap, idle times three minutes and keep the hood closed the answer?

thanks again for the answers......

 

The engien fan is more than enough to cool the engine. Just install a switch so you can turn it on at will. Don't make things more difficult that they have to be.

 

The 996 is much less of a concern than the other earlier air cooled. Also don't even come with under engine cover.

 

and he owns a 996... lol!

 

At the track we usually bring a few fans and pop this lid- letting the engine cool

I would idle the engine down for about 5 minutes - before shutting off-
A cool down lap does help also..

 

Fabryce, that's what I thought was better and what I also used to do, until I read all the above posts, I think I'll go with the above majority, I may have been over thinking this one!

 

I dont know how hard everyone is pushing there cars- But you want to avoid heat soak with the engine.. I have talked with many engineers in regards to this and they all agree that idling down the engine for 5 minutes is best to get the temperature of all the fluids down.

We run a high speed fan blowing down on the engine -lid popped open
and another one under the car..blowing up at the engine.

You really want to get as much of that hot air out as possible.


Maybe, I'm being overly cautious but - I dont like taking chances with 75k race engines

 

thanks Fabryce, sounds like best way!!!!