How hot would ceramic coated headers get at idle? I'm looking to purchase an IR thermometer and need to know what heat range I should get. The car is LT1 with a 385ci 11.3:1 compression motor. I'm in the process of tuning my individual cylinder fuel trims and I'm basing my adjustments on the header temps.

 

no responses eh....i just went and got one that goes up to 1610 on ebay. that should be plenty. thanks.

 

doesn't really matter what temp they are, for what your doing you just need to make sure they are all within the same temp range when measured similar distances from the exhaust flanges on each primary

if i had to guess i would say in the neighborhood of 600-900 degrees

 

yeah i was just trying to see how high i needed the ir thermometer to be. i got the one that measures up to 1610 so i'll be fine. i'll probably be able to do my off idle icft's too since it can measure so high.

 

dont know if it helps at all but my buddy at work last summer had one and when the car was warming up all of the primaries were at right about 600*

 

this was a stock internalled LT1 though. im interested to do the same thing to my current car now but i dont have the thermometer

 

i did this to my car temps were in the 400s. three cylinders looked to be off. cylinder 1 was way off in the 200s which leads me to believe there is a problem with that piston or injector. I'll be taking my injectors to get cleaned and performing a compression test to see where its at compared to cylinder 2 which seems to be fine.

 

one thing to keep in mind when using this method, the way headers are bent, ground on, welded and even coated in areas can cause a bad reading on the IR thermometer. cylinders with a sharper bend than the one next to it will heat faster, not only because of the bending process, but exhaust gas wont move away from the cylinder as easily, creating a hot spot. Depending on how they were bent/ how far, the metal can be stretched thin. if you are using someones old headers were dented and pushed out, and you bought them, they are stretched thin and thats a hot spot. if they are dented and filled with some type of material other than the substrate, that spot will be inaccurate. There are a lot of variables there, your only method to trust on an expensive motor would be individual cylinder pyrometers IMHO. IR guns are good for a quick check on a motor to see which cylinder is dead and cold...

 

even using this method, if you took a header, ran 3 pipes straight out 3 feet and one pipe out 2 feet, bent it at a 90 and ran it another foot, the pipe with the 90 will be hotter, even if fuel trim is dead nuts with the pipes next to it.

 

well i took the injectors to get cleaned and the guys said they were in pretty good shape. that worries me since i thought one would be pretty fouled as cylinders 1 and 2 were way off (over 150 degrees different). looks like i have to keep searching for what may be the issues. im trying to fix some split blms. seafoaming the motor to find if there are any leaks is next.