Ripzta

Is there any difference between wrapping a mild steel dp than a stainless steel dp? And what sort of wrapping and coating is needed?

zullo

Some folks claim that wrapping the downpipe can cause corrosion or rust. If so, I would have to assume that it is a bigger issue with mild steel. The most economical wrap is "header wrap" that you can find at Summit or Jegs.

DaveW

The bigger problem with wrapping a mild steel DP is that the steel will get hot enough to degrade it, and cause it to fall apart.

A better solution is a ceramic coating such as "Jet-Hot 2000" which coats both the inside and outside of the pipe, keeping it cool enough to live.

alberto_mg

^^ i call huge BS on that comment

why don't you do a search and read one of the many threads on this already?

DaveW

Alberto, if your comment was directed towards me, I respectfully disagree.

I have raced Formula Ford and Formula Continental racecars for years and have 1st-hand experience with this (the EGT's are similar, above 1500F).

In this type of installation, MILD steel primary pipes quickly fall apart if wrapped. They last much longer if not wrapped, and longer yet if coated internally. Stainless steel is much more resistant to heat, but even those can deteriorate under some conditions if only wrapped externally.

alberto_mg

It was.

Thanks for qualifying your comment then. Most of the time you hear people saying they heard something somewhere by someone who might or might not know what they are talking about. I can see how wrapping could contribute to greater stress, greater heating of the header metal and shortened life on a race car running flatout for 30-60 minutes.

However, I don't think it is as much of an issue on the street where you only see the extreme end of those temps on an occasional basis. Plus what is more important future degredation of a downpipe that can be replaced for ~$100 or decreasing the underhood temps by x amount and decreasing the heat relating aging of those components?

I vote for the later.

Given the info you provided, I withdraw my overeager BS flag but I think it still is a good idea to wrap it.

Back to one of the poster's original questions - I think you can use the same material for either downpipe.

DaveW

Alberto, I agree that reducing under-hood temps is very important. However, I always think of things from a reliability standpoint - if the header or DP fails, and I'm racing, I'm screwed.

Like you said, though, on the street, life of a mild steel DP, even wrapped, in normal use will probably be OK.

As a side comment, I just bought a used (mild steel) HKS DP (looks enough like a pre-cat to maybe fool the emissions police) and it's at Jet-Hot for the Jet-Hot 2000 coating as we speak.

rescueranger

iTrader: (15)

from what ive read .. i wouldnt wrap a mild steel dp .. cause the heat will destroy it over time .. now if you have a ss thats a different story .. get yourself some thermal wrap .. i think coating it is a better alternative .. i dont know if coating it and then wrapping is the best alternative .. can anyone comment on that? anyways .. i highly recommend at the very least wrapping your dp .. you will notice lowered under hood temps

alberto_mg

yeah, i'm gonna do that too eventually.

I think I might be PM'ing you Dave regarding formula cars. I've been racing karts for a few years and am considering moving up

NewbernD

iTrader: (1)

I'm not sure I'd wrap a mild steel downpipe that hasn't been coated. One of the big problems is not from the heat per se, but from moisture. When the pipe cools it traps moisture in between the wrap and the pipe. That plus the heat really accelerates oxidation/rust.

Sgtblue

iTrader: (16)

^Agreed. I've had mine wrapped for about a year on a street driven car with no issues, and the underhood temps dropped significantly (and it helped slightly with noise). There was a small area next to the O2 sensor where I couldn't get the wrap. Even on days when I've driven it pretty hard, or just got off the freeway I've checked but there was never any indication that it was getting red hot. I'm sure my DP will eventually fail whereas a SS one would still be going strong. But I think that day will be relatively far off. FWIW, I'm also running a Bonez HF cat and Greddy SP cat-back.
And Newbern, I searched and read other comments regarding concerns about corrosion. So last fall, after the wrap had been on 4 or 5 months I partially pulled it off. There was a light coating of rust, about as rough as 220 grit sandpaper, but nothing that gave me concern. My thinking at the time was my DP would likely outlast my turbos (a 65k car) and I'd worry about it then.
Basically, the benefits far outweighed either issue for me.
Just my .02.
Jim