Just started the car up after a 6 week down time - I changed to a Racing Beat dual muffler and wrapped my Pettit downpipe. Still have the stock cat, in good condition.

Started it up, after 2 min I lift the hood to let the smoking from the header wrap to clear, and I see ORANGE!! This is idle speed, 35°F garage. It has never done that before.

I've heard about it glowing in after a hard run, but this has me alarmed. I sure hope this muffler doesn't have any strange constrictions.

Dave

 

i've found a few threads about it, saying that sometimes at startup it gets real hot but cools down, and others saying it's a clog.

https://www.rx7club.com/showthread.p...t=red+downpipe

https://www.rx7club.com/showthread.p...t=red+downpipe

https://www.rx7club.com/showthread.p...t=red+downpipe

https://www.rx7club.com/showthread.p...t=red+downpipe

I'm debating whether to take it for an easy test drive...I'll be carrying my fire extinguisher, that's for sure.

Dave

 

how old is the cat on your car? if it's clogged it might be causing exhaust heat to build.

 

i think it's normal. my downpipe glowed orange after i started it up following my radiator hose project. it was cold out and i hadn't started it in a couple of weeks. it hasn't glowed again.

 

I don't know what to say. I wrapped mine, even overlapping about twice what the instructions said, but I never had it glowing.

 

I have the Pettit DP and Racing Beat Dual Tip. I have never seen my DP get red like that. I do, however have the Pettit high flow cat...

I don't know much - but sounds like you could have a clogged cat. I understand that the wrap is for keeping the heat inside the pipe for faster flow, less heat soak etc... but glowing at idle sounds a little extreme. Just my .02.

 

I don't see how your cat could be clogged or increased back-pressure. Your AWS is disconnected or you by-pass it by starting it in gear right G-man? A new dp has to "cure" like an oven sometimes, but glowing cherry consistently would be a serious concern.

 

A few things:

1) If you have an airpump on there, keep in mind that extra air is added to the exhaust. This adds oxygen to burn a rich mixture in the exhaust, thus raising temps. This is intentional, to heat up the pre-cat quickly (the AWS as previously mentioned).

2) A clogged cat will have the effect of cooling the exhaust. This is because the products of combustion cannot escape readily and do not burn; rather they absorb heat from combustion and reduce the amount of oxygen as a percentage of the gases, thus it cools the process. (This is the principal of EGR.)

3) The wrapping will retain heat in the pipe and bring it to incandescence much sooner; keeping the heat in is a good thing. It will improve the emisions performance of the main cat as well.

4) Stainless steel will show heat at a lower temperature and with less [time] exposure than will plain steel or cast iron.

5) Much of this system probably glows under normal, loaded conditions anyway.../ you just don't normally get to see it....

6) If you put the car into gear after starting it, as opposed to leaving it idle in neutral, this will force it to skip the AWS process.

Hope this helps..

 

Well I did take it out for a drive, and the glowing was gone when I stopped for gas. After getting home, I looked at it again, and it was very faintly red in the dark. Like Csefiroth0 said, I think it was a combination of oil/residue in the pipe, cold weather (block was dead cold), and letting it idle for 5 min that got it glowing. I may have forgotten to blip by the AWS, which I usually do.

I have to think the wrap is reducing the dp's ability to distribute heat and cool as well.

One other thing of note: I pushed it once, and got 12-13psi boost. Whoa - I know the weather is cold, but I guess I'm going to install an MBC. I won't be putting in a high-flow since I don't want to upgrade the ECU and fuel systems.

Dave

 

dave, did you have to take the dp off to wrap it?

 

I did to remove it: to clean off the gasket, have both ends of the dp flanges ground down, and replaced the bolts with new mazda studs and nuts.

So some of the smoking and heat might be from any anti-seize or lubricants that got on or in the pipe.

Dave

 

I wrapped mine while it was on the car.

 

That's odd. I have the same DP (unwrapped) and cat back with the stock cat and I've never seen it glow, regardless of conditions.

I can understand why you'd be concerned. I'd be beside myself. Heck, I was worried about the smoke after putting the DP and cat on, even though I was EXPECTING it.

 

i would think your cat was a bit clogged. the smoke is normal after wrapping but i dont think it glowing red is. was it day time or night time when you started up your car and saw it glowing?

 

It was a dark garage, at night. It wasn't really orange, had I been looking in normal light - maybe a dull red.

Is there anything more the checking for a clogged cat other than removing it, and looking for loose stuff to fall out or make a rattle noise? Because there is NOTHING loose in this cat.

Dave