Engine Cool-down Strategies for Autocross (Single Driver)

[RFB]

Originally Posted by Brzzee

Thanks for all the discussion in the different paths it has taken.

Refining the topic:

Is allowing the engine to continue running a better or worse solution than turning the engine off when parked then back on to make the run?

One point made was that other than more fuel burned, continuous running did not appear to make a difference.

Other thoughts?

My thoughts - turning off a hot engine turns off the cooling of fans, main rad, AND the extra rad (turn on heater core full heat - with interior fans blowing full blast and windows open).

A hot idling engine will cool down faster with coolant circulating than a giant piece of glowing pig iron sitting in the sun with no breeze.

Works for me , especially on Gran Prix style tracks after an excessive number of hot laps.

[CraftyObeseCrunchyKitty]

Originally Posted by RFB

...turn on heater core full heat - with interior fans blowing full blast and windows open...

A hot idling engine will cool down faster with coolant circulating than a giant piece of glowing pig iron sitting in the sun with no breeze.

I'll do this with the hood open if temperatures get too hot. Normally I just leave the engine on and the hood open. The coolant leaving the heater core returns to directly to the engine block, and, for the purposes of this discussion, serves as a second radiator.

[Ultramaroon]

Originally Posted by Locust

I thought installing oil coolers wasn't allowed in Street/Street Touring?

This has devolved into a discussion about air conditioning but there are still other things you can do to cool the car down.

1. Always pop the hood. Under hood temps get really high.
2. Spray your radiator, intake box, and engine cover with water.
3. Lay a bag of ice on top of your intake box.
4. Buy some high speed battery powered fans and point them at your engine, radiator, etc. (yes the legality of this has been checked).

Or you can just crank up the AC for free. ...with the hood up. This hasn't devolved into anything except a search for over-complicating a simple task.

[strat61caster]

There's a big difference between cooling down between track sessions and autox, half an hour+ vs. <5 minutes. Seems like some are talking about one and others about the other.

Shutting off between track sessions after temps have stabilized sounds like a solid plan when the car is going to be sitting for a bare minimum of 20 minutes (and in most cases more than an hour).

But for autox you've got to wait, what ~2 minutes for temps to stabilize, shut it off for 1 minute, than turn it on ~2 minutes before your next run so the engine isn't still trying to 'warm up' while you're trying to launch off the line? Maybe you've got long run groups and you're 10 minutes between runs, that's still about 5-8 minutes of engine off time max. I could see people leaning one way or the other and I won't say someone's wrong for shutting the car off, but man heat transfer is not a fast process, that's a >400 lb lump of aluminum you're trying to cool down, and I've already blown too many runs by forgetting to turn off traction control again.

[Brzzee]

Appreciate the comments. For autocross multi-run heats either way appears to work, with the sole advantage of continous running is not having to turn off the nannies with the pedal dance before every run.