Ahmet

This is somewhat of an open ended question but I would appreciate any input...

Today I noticed that my headers/cross over pipe were glowing bright red/orange after only about 15 minutes of cruizing @80ish mph.

It had only been running for 20 mins or so prior to this the whole day, and I did not dip in boost at all during that time. I have no idea if this is normal, but I would not imagine so. The headers are wrapped in header wrap, but not coated in anything and they were glowing bright enough to be seen through the wrap... I don't recall them ever emitting this much light (they did glow a bit immediately after a hard run), does humidity, etc. play a role in their visible light output? They certainly felt much hotter than I've ever seen them before, but unfortunately I did not have a laser thermometer handy...

Anyway, comments?
Ahmet

pk951

I can tell you that mine do not glow bright red after cruizing down the highway.

Here is what i did all my piping is wrapted ,as an experiment i tied them with tie wrap as of two weeks ther'e still not melted! Plus i tied them with wire just in case.

Hans

Running lean???

At full load I would expect them to be hot enough to light a cigar but at 80 mph for only 20 min???
TakeCare.

jimbo1111

Maybe the O2 sensor needs replacement. A clogged cat would also do that. If you still have one.

951kid

Probably because you have the headers wrapped, the heat that would normally be pulled off by passing air is held inside the wrap and caus your headers to glow. I'll bet if you took the wrap off and drove in the exact same manner on the same day the headers wouldnt glow.

Isnt the purpose of the wrap to keep heat in anyway?
my $.02

Sam Lin

That's normal inside the wrap.

Sam

Ahmet

Last year I got up to 160 (going through 2nd till near top of 5th @full boost), pulled over immidiately and popped the hood, on a dark night it was NOT anywhere near this bright...

A little puzzling...
Ahmet

Ahmet

I've got two range colder plugs than stock in anticipation of a bunch of other parts that were going to go on this car, but I ended up selling them seperately. Anyway, I think if the spark's weak enough combustion may still be taking place in the headers (infact the headers/collector were red hot, but not the cross over pipe, turbo or anything beyond that).

Anyway, thanks for the input thus far. I'm ofcourse open to further input. I will post an update after changing the plugs.
Ahmet

turbite

You were going 160 on a dark night?

tazman

One other thing to keep in mind when you are at low load you run more advance which = hotter exhaust temps. Cruising at low loads I usually see about 1400 deg exhaust temps and when I do a full throttle run it goes up into the 1500 deg range. So I think they got red hot because of heat soak and if you would run the same amount of time at full throttle high load you would get the same effect.

Danno

Also the stoich mixture of 14.7:1 that's generated at steady-state cruising will be a lot hotter than the full-load mixture of around 12.0:1 (about 300-400 degrees).

Tomas L

Is that really correct?
More advance = earlier ignition = more time to complete combustion and transfer heat to the combustion chamber wall.
Less advance = less time to transfer heat, combustion may still appear in the exhaust pipe = hotter exhaust temp.
Performance chips probably has retarded ignition in the midrange to get faster spool up from the hotter exhaust, Right Danno?


Tomas

Dan87951

I had a clogged cat that caused that problem. Does your car feel slugish? Man the moment I replaced it with one of Tim's 3" testpipes it felt like I gained 50HP because my cat was so clogged.

tazman

HMM your logic dose sound right I was thinking along the lines of the combustion not being completed and the extra fuel keeping the air cooler. I doubt anybody is going to comment on the timing on their chips and give their secrets away. I guess it has more to do with what Danno said.

v944god

I think something is clogged. Most likely cat.