I currently have my 3" DP wrapped with DEI heat insulation wrap. I did this to keep the oil pan and transmission cooler, and to keep the exhaust gas velocity as high as possible. I have seen some comments in threads, one by Dave Buschur, that indicates this may cause " premature failure" of the DP. I was wondering if this would just be due to higher exhaust temps and velocity thinning out the walls, or is it from cracking due to the higher thermal stress on the metal itself. Would it be better to ceramic coat the DP then wrap it? Kind of a pricey option. I would think the turbo would spool faster due to the increased exhaust gas velocity with the wrap. I have my test pipe wrapped also to keep the heat as far back as possible. Comments?

 

When your downpipe fails then ask this question. I have yet to have failure with wrapping the pipe and seeing other people with this issue.

 

how does a downpipe fail? other then the obvious hitting the oil pan or transfercase, but i would considering that the manufacturing failure.

 

when you insulate it, you have it retain the heat, as opposed to being the medium to transfer it to air molecules around it. The higher the heat and temp that a ferrous metal is subjected to, and the longer the sustained peak period, the faster it oxidizes (rusts, or breaks down). At sustained temps it will also tend to scale, so thin out by scraping off in layers.

Basically, wrapping it loses material and strength over time, and then it succumbs to the stresses of the loads or weights that it is bearing.

 

Heat wrapping and water will literally eat away the metal. I've seen this many times. That's why I don't heat wrap anything in a street car that needs longevity.

 

Unless you're driving through a lake, wouldn't the temperature of the DP evaporate any water that was in the heat wrap?

 

Just put a section between oil pan and exhaust.

Heat insulating downstream turbine will increase the velocity of gas but at the cost of pressure differential accross turbine yeilding a big loss.

Think of it like this, heat and pressure are proportional, how much pressure energy can be transfered to kinetic energy when there's pressure on both sides?

 

I have never had a quality stainless downpipe ever fail after being heat wrapped. Mild steel yes, but not stainless. If you are running a 3" DP on your Evo do your tranny a favor and wrap the DP (atleast) where it runs by the oil pan and trans.

 

^+1

 

It holds moisture and heat I also never use heat wrap.

 

The better the base material, the higher the temp is that the material will oxidize at a high rate. "Better" can be defined as, more Nickel in the stainless, etc.

 

I live by heatwrap,.. I wrapped my entire exhaust to the muffler when my car was full exhaust. I header wrapped the manifold as well. I also use heat shields anywhere heat can come in contact with intercooler piping.. My downpipe was pretty close to my charge piping to the intercooler. With the heatshield and an infrared gun it was a difference of 50 degrees compared to without it..

 

So, the Megan Downpipe... Is it worth wrapping?? What material is used in their piping??

I let my car idle and then wrapped my hand around it on bare metal... It wasn't even warm and/or hot...

 

I've been wanting to do this for awhile, just haven't had the time. What I plan on doing, and what others have suggested, is to wrap it, let it soak/expand with some heat, then when it cools spray it down with the high temp ceramic, which soaks in even more and also seals it away from water. Then you should be good for about 1600deg.

 

I wrapped my header and it got real ugly and brown