Open Headers w/ cool temps

Its starting to cool off a little quicker here than anticipated. I currently only have open headers on my V6. I have heard a lot of different opinions on this but was curious as to what to follow. Will running open headers during cool temps do any damage to my engine. If it does what would the cut off be on lowest temp that would be safe to run it in. I plan on getting a full exhaust put on in the next week or two so it won't be getting run in terribly low temps. Headers are new as are gaskets. Torqued to proper torqueness.

 

Only when you turn the motor off will there be a problem. If you look at some of the old drag racer photos, they stuffed tennis balls in the pipes to exclude cooler air so the valves didn't warp or crack. I think you are on the right track, but I can't give you a temp to work with, just go and have the exhaust done.

 

No, it won't hurt your engine but may damage your ears. If you could get cold air to blow across an exhaust valve right after you shut it off you MAY be able to warp the valve. If you have a few inches of pipe on the port it just isn't going to happen.

 

I think that's mainly to keep foreign material out. If you ran a blown Chrysler down the strip, shut it off and stuffed tennis balls into the zoomie pipes you would have melted tennis balls.

 

Where are you getting away with running open headers without getting arrested?!!

I've never heard of open headers damaging an engine. The chance of a blast of cold air making it up 3 feet of hot pipe is a bit crazy IMO.

 

I or others I know have never had any problem that have run open headers in Jeeps over the last 35 years.
andthere's been some very cold nights at the dunes.

 

I would think open headers wouldn't be any kind of problem in any temperature . tubes are long enough no cold air will reach valves

 

Define 'warm' and 'cold' air.

To us the difference might be thirty or forty degrees. Does a valve capable of running at 2000ºF know the difference between 60ºF air and 90ºF air, and commit suicide if the ambient air is 2% cooler?

 

In and around that exhaust port the temperature isn't going to drop like a rock, the coolant has stopped flowing and that head casting is going to take it's time cooling off, there just isn't a rapid enough change to create a breeze. Heat goes to cold, and if any cool air did drift in the head is going to be giving up heat to it like a mother before it gets near the valve, it's not going to care if the air is 40 degrees cooler than it was yesterday. Just for the sake of conversation, you guys do know that heat doesn't rise?

 

I would be more concerned with fuel metering with open headers vs. full exhaust system.

 

I ran zoomies for years on drag boats and never had any problems with the valves. Like Nick said above.....more of an issue with jetting.