Why? Partly because I just don't like the idea of an unshielded portion of the exhaust system passing very close to the oil pan and partly because I just like automotive projects. The part of the exhaust I'm talking about is where the flex joint is, just under the pan. The flex joint part is probably shielded somewhat, but there is a bare section of pipe just in front of that.

What? Thermo-tec adhesive backed radiant heat barrier. I cut a piece that's about 4x5 inches long. It's tricky to get back there since the pan is curved and the exhaust is very close. The pan is also not flat (not a perfect portion of a cylinder where it "wraps" around the exhaust). I neded to cut some slits to get it to lay flat. I rubbed the area down with isoporpanol first. If I did it again I'd probably cut the piece wider and maybe wrap it a little around the sides of the pan a little.

Notes: I've used this stuff before on other cars. The fiber glass backing and reflective face can stand the heat with no problem. The adhesive is only rated to 300 deg F and dies after a while. We'll see how long this stays.

-JL

 

Looks like a good idea. What would've been a good measurement is to do some hot-laps on a racetrack before and after the insulation was added, measuring the oil and coolant temps to see if there's a tangible difference.

 

A couple of quick blasts through the gears generates enough heat for the edges to start pealing on the thermo-tec adhesive-backed barrier. I used some aluminum tape to secure the edges and it's holding pretty well.

I also couldn't resist trying one of these heat shields (see pic) on the downpipe itself. It only covers maybe 120 degrees (as in degrees of a circle, not temp) of the surface of the pipe, but that's enough to reflect much of the heat away from the oil pan and transmission.

I know, there're not a lot of people complaining about heat related problems in these areas, but what can it hurt.

-JL

Edit: I'm one of those who wrapped my aftermarket SS downpipe on the WRX. Underhood temps were noticeably cooler. It was no longer like putting my head in an oven every time I opened the hood. There were several reported cases in the WRX world of failed inner CV joint boots from the heat of an unshileded aftermarket downpipe. It was like 6" away if I remember correctly. Just a data point.

 

Good idea, jlevy. Another small tweak added to the list of plans. Now if only the car was here...

 

Header wrap is an outdated technology. The wrap holds moisture and can cause the metal underneath to erode, even if it is stainless steel.

If you really want to reduce underhood temps and keep the heat in the piping, I would recommend getting the exhaust coated with a thermal barrier.

 

That is a good idea. I bought a used set of manifolds for the WRX, ported them and sent them to Jet-hot to get coated. I saw around a 200 deg drop in surface temps as measured with a laser pyrometer at idle.

| also wrapped my SS TXS downpipe on that same car. For an "outdated technology" it seemed to last pretty well for more than 4 years, one HPDE event, lots of full throttle, and countless rainy days. I'd also rather change a failed exhaust component than a CV joint or whatever I'm trying to protect from the radiated heat.

-my 0.02

edit: I guess to phrase it another way, if I had the time or extra exhaust components laying around then I would send them out to have them Jet-Hot coated without another thought. It seemed very durable and did reduce the surface temps. Plus the coating is on the inside of the pipe as well as the outside. To me that's the real benefit. I'd really like to do this on the MCS exhaust manifold eventually.

Note the Thermo-tec heat shield I'm using isn't really a wrap - it's designed to have like 1/2" of air gap between the pipe and shielding material. Hopefully it won't decrease the durability of the exhaust tubing too much, if at all.