Thread: Headers installed and temps under hood

Originally Posted by Colossus

Obviously you would think they would go up, but at that point you've probably wrapped the headers.

I was expecting they would go up due the increased surface area putting off heat, but stainless does not conduct heat as well as the stock steel mani's. I would guess that is what is keeping the temps down.

As far as wrapping them goes, that will never happen on my car. I did a lot of reading on this topic and I could not find any reputable source supporting wrapping headers. Wrap does not allow any heat to escape from the metal and causes it to deteriorate. It does not matter if it is stainless or mild steel, the result is the same. For the record, I didn't learn this info from a forum where we all know there is as much bad info as there is good info. I found tech articles in motorsports magazines and even header manufacturers saying that wrapping is a bad idea. One header manufacturer made a tongue in cheek comment to go ahead and wrap yours because then he can sell you another set sooner.

I'll be driving a few hours this weekend and getting the engine as hot as it's going to get without having a problem. I'll be watching the temps the whole time and posting back with more data on this subject.

Just wanted to post an update on this. I went to visit family this weekend and drove 2.5 hours non-stop. Obviously the engine was nice and heat soaked from a drive this long so I figured it would be a good place to compare against the data I got from the stock mani's.

Here's what I found: Driving at highway speeds, the engine compartment was running around 18 degrees hotter than ambient air temp. It didn't vary from this by more than 3 degrees unless I turned the air conditioning off. It would run about 15 degrees over ambient then. I watched the engine compartment temps after I get there and after I got home. Both times, it started to cool down once reaching about 65 degrees over ambient. Even though I got the engine hotter than I ever did while measuring temps on the stock mani's, I still ran colder while moving and about the same when shut down.

I started gathering this info under the assumption that the engine compartment would be hotter with headers installed and wanted to see if there was enough of an increase to justify ceramic coating. After what I have seen, I believe the lower thermal conductivity of stainless steel leads to lower engine compartment temps than stock mani's even though the surface area putting off heat is greater. I don't have data to support it, but I would assume ceramic coating would help this even more. My concern was running higher temps than stock and shortening the life of the plastic and rubber components under my hood and now I feel comfortable that I am no worse off now than I was stock.

I'm open to questions and suggestions if you have any.