My buddy was telling me at the track, not to let my car cool off too much or else my Firebird will not be in closed loop. What temperature will my Formula reach (ideal) closed loop?
Ben
'89 Formula Firebird

 

when u race you will be at WOT, so it wont really matter, letting the engine cool down, espicially the intake, is a good thing, cooler=better. thats why u see the guys w/ bags of ice on their intake

 

the car not running at temp will still not run as well as a car at temp(oil flow, coolant flow, tranny fluid, differential fluid), so running the engine cold (save for intake) is still not good practice despite the fact it'll default to fuel tables at wot.

Now a good temp to run is 170. 140 is usually when closed loop occurs, exhaust temps though is affected by coolant temp so if its not running at temp the o2 sensor won't be running well

 

I agree with the first part but some of it doesn't compute. Oil flow isn't an issue unless you JUST started the car and it was sitting for a few weeks. Having cool coolant isn't bad, neither is having cool/cold diff fluid and as far as tranny's are concerned, I don't think it's an issue unless it's below freezing (air temp, not fluid).
Also exhaust temps don't have anything to do with coolant temp. An oxygen sensor should warm up in less then a few minutes, at least that's how long it takes mine to be accurate and that's without the air injection. It's still not a good idea to run a cold engine with no load and high revs, I just don't think it's that big of an issue except that the internal parts will age faster (rings that is).

 

at least in cold weather, overcooling can occur. Fall weather in the northeast is more than enough to cause it at speed. The o2 sensor only functions properly with exhaust temperatures in the 600+F range as I remember, if the cooling system is doing a hell of a job, intake, heads and block aren't running at temp, efficiency isn't there in the heads temps may not be there in the combustion then.

That's why closed loop is so high a temp (140 F) combustion is more efficient past that temp. Below that and you're really not getting all the power you should be getting.