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Headers installed and temps under hood

S

Silver GTP

New member
I installed my modified SSAC headers yesterday. (no sinktrap and a cat welded in) :th_mechanic: Took longer than I thought it would due to some mistakes on my part, but it's installed and running without any codes. I might have a slight leak on the v-band clamp, but that shouldn't be too hard to fix. I didn't take any pics yet and probably won't. I think everybody on here has seen enough pics of these style headers.

I started a thread a while back about ceramic coating headers and it left me with a few questions that I wanted data to prove or disprove. I bought a remote grill thermometer a month ago and have been monitoring my underhood temps. I put the probe near the throttlebody figuring it was up higher where heat wants to go and would give me some idea how hot it was in the engine compartment. When the car has been running for long enough to get everything good and hot, it reads about 30 degrees hotter than outside air temp while driving. It gets to about 50 degrees over ambient air when hot and idling without moving. It can get to 60-80 degrees over ambient about 5 mins after parking it when hot before temps start to drop. After installing the headers, I drove it for about 30-40 minutes and saw about 25 degrees hotter than ambient air while moving. I parked it and let it idle in the driveway when I got home and only saw about 40 degrees over ambient while idling. I want to watch the temps for a while and gather more data, but my initial conclusion is that stainless without ceramic coating does keep more heat in the pipes and does not cause more underhood heat than stock manifolds. Ceramic coating may be even better, but my concern was cooking things under the hood over time and now I'm not as concerned anymore. I"ll post updates on this if anybody else is interested in the final conclusion of my testing to determine the effect of headers on underhood temps.
 


good work. someone actually doing research and getting data on their own is pretty well unheard of nowadays. ill give you props for that.
 
i'm with bio... glad to see someone is doing their own research rather than asking questions.

sub'd for the results of your tests.
 




Colossus said:
Obviously you would think they would go up, but at that point you've probably wrapped the headers.
Click to expand...

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.
 
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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.
 
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