Autocross - do you leave your engine running between runs?

[Ugly John]

Like the title says, do you leave your engine running in between runs?

The last time I was out it was about 98 degrees, and I was worried about just shutting down the engine. Plus my son was also driving my car so it was not sitting still very long. I was opening the hood most of the time, but I'm not sure if that really helped much.

Suggestions? What is best for the health and well being of my motor?

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[BlackBoostedStang]

I turned mine off and popped the hood but that meant the cooling system wasn't on. I'd say go either way. Leaving the car on might be best though. The worst I got was drag racing actually, I would pop my hood and leave the car running. I lowered my intake temps from 130 to 106 what that method and gained 0.2 seconds and 2 mph

 

[ArrestmeRed]

I usually shut mine off in accessory mode with the a/c blasting. That with the hood open cooled everything off quickly.

 

[Static_LV]

I leave it on between runs.

 

[EFI]

Why are you worried about the engine when shutting down?

Shutting down/restarting is going to be a minuscule amount of "wear" especially compared to what you do to the engine during an actual run. I wouldn't worry about it.

Extremely cold starts are the ones that are the toughest on the engine. When the block, oil and all components are at sub zero temps that's when the wear starts. Restarts at operating temps is nothing.

 

[jabrax]

Why are you worried about the engine when shutting down?

Shutting down/restarting is going to be a minuscule amount of "wear" especially compared to what you do to the engine during an actual run. I wouldn't worry about it.

Extremely cold starts are the ones that are the toughest on the engine. When the block, oil and all components are at sub zero temps that's when the wear starts. Restarts at operating temps is nothing.

I don't think stopping and restarting the engine is the concern. Many people cool their cars down before shutting down after hard runs. Example cool down laps.

 

[Ugly John]

I guess I should have clarified a bit. No, I am not worried about the wear involved in shutting down and starting the engine. Instead, I am unsure if shutting it down very soon after a hard run would be worse for the engine heat wise, instead of leaving it running so that the radiator could cool it down normally. I was seeing my CHT getting close to 220 after a run, and was worried shutting it down and cutting the coolant flow would cause problems.

 

[dontlifttoshift]

We leave it run with the hood open for two reasons.

1. If you shut it off it heat soaks and you end up with cylinder head temps over 220 for your next run.

2. We don't have to do the advance track dance more than once. It is too easy to forget so we turn the advance track off for the first run and leave the car running until the end of the heat. We have never had the advance track come back on during a run using this method.

 

[wildcatgoal]

In AutoX you don't get a cool down lap. But I don't see why your car would get so hot in an AutoX - aren't they like... 40-60 second laps tops like one at a time?

Either case at my last track day we got a cool down lap and then I parked it hood open. Car never really went above 225 anyway.

 

[EFI]

But I don't see why your car would get so hot in an AutoX - aren't they like... 40-60 second laps tops like one at a time?

I kinda agree with this guy...I think you're making too much of it and worrying for no reason. You aren't overheating the car that much to necessitate extra measures to cool it back down. The radiator ain't gonna cool off the engine that much just sitting still especially in 95* weather, so you're just unnecessarily heating it up by continually running it. Pop the hood open and let it be.

Plus, your most concerning heat soaking should be off the IAT and not the engine itself. As long as you keep the hood open you should be fine with that.

 

[SteveW]

If you are codriving just leave it idling between runs. If anything you won't forget to turn off Advancetrack between drivers and throw away a run.

It can get pretty busy doing the driver swap and easy to forget something.

 

[BmacIL]

It depends on how your club runs. With the two I go with, you'd just be wasting gas. If you're concerned about temps just open the hood between runs to prevent heat soak. There is extremely little wear when starting a hot engine that was running only 10-15 mins prior. The oil doesn't drain down that fast and most surfaces still have a decent enough film to prevent wear.

 

[chedder]

At the track we have always, during cool down, turned the heat all the way up and fan on high to extract heat from the cooling system. Brings down engine temps pretty fast.

 

[chedder]

Forgot to add...throw away those plastic engine and rocker arm covers. Let the heat OUT!

 

[kz]

I let it run for a minute or two with the hood up after I pull into the grid, then shut it off - but I never have a co-driver so have some time between the runs.

The point above about Advancetrac dance is a good one, haven't happened to me recently (doing all the switches became the habit) but last year I did the run in a Normal mode with everything on - unintentionally

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