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Re: Glowing exhaust manifold
Posted: Wed Oct 29, 2014 4:31 pm
by Crazyswede
RadioFlyer wrote:I actually brought it up on Saabnet last night for the heck of it and a guy said something similar:
"The first time you see it seems shocking , but that is how hot they run! I remember popping the hood of my 1979 900 turbo and thinking the thing will melt! Most big diesel trucks have a "pyrometer" which measures the exhaust manifold temperature. That high temp is the reason many people leave the engine running awhile after a long pull to cool down. I always marvel at how the gaskets/diaphrams/o-rings survive the temp."
I don't know if I would agree that that's how they normally run, but maybe it's just that it seems more shocking when viewing it in the dark? I'm still concerned that it happens during pretty normal interstate speeds and even non-interstate speeds. Would an intercooler help at all?
intercooler will likely make it worse. The intercooler is going to cool the intake charge thus allowing you to run more boost.
Re: Glowing exhaust manifold
Posted: Wed Oct 29, 2014 8:17 pm
by hutch
My crappy n/a 8v has a metal duct directing air from the drivers side over the exhaust manifold, you could try to add something like that and see if it makes a difference?
Re: Glowing exhaust manifold
Posted: Wed Oct 29, 2014 10:59 pm
by Crazyswede
hutch wrote:My crappy n/a 8v has a metal duct directing air from the drivers side over the exhaust manifold, you could try to add something like that and see if it makes a difference?
That duct was intended to pull heat off of the exhaust for the intake to help the car warm up faster in the winter.
Re: Glowing exhaust manifold
Posted: Thu Oct 30, 2014 12:07 pm
by Geoff
RadioFlyer wrote:"The first time you see it seems shocking , but that is how hot they run! .."
I tend to agree for the most part. The old turbos are pretty sluggish and inefficient, which leads to extra heat. Those early manifolds crack often to (heat + shape). I used to check my '85 (newer, somewhat more efficient turbo than B engines) when I'd get home from work and it was usually glowing real bright. Even on nights when was taking it easy and wasn't jumping it the manifold would glow a little. I've only seen my '97 Aero glow a little bit.
Re: Glowing exhaust manifold
Posted: Thu Oct 30, 2014 7:45 pm
by tirediron
for what it's worth, I have never, ever seen the manifold glow on my 2.1 n/a race car. either on LH or t5.
however my buddies '93 9k n/a race car glows all the time. that's the bastard child LH with direct ignition.
same exhaust between the two. 2.25" to glass pack race muffler.
Re: Glowing exhaust manifold
Posted: Fri Oct 31, 2014 5:52 am
by Jordan
It's definitely more of a turbo thing that happens. The manifolds are so dense that they hold the heat much better too. The MSS header I have on my 99 is almost cool to the touch in 5 or 10 minutes, while the turbo manifolds stay hot for hours.
Re: Glowing exhaust manifold
Posted: Fri Oct 31, 2014 9:51 am
by SwedeSport
Like this?
Re: Glowing exhaust manifold
Posted: Thu Nov 13, 2014 10:06 pm
by RadioFlyer
I think i might have figured it out. I had heat wrapped the manifold to try to protect he battery that kept melting and the intercooler that I was planning to install on the passenger side. The other day I cut the heat wrap off and ran it hard at night to see if it glowed. It was nice and cool. I think it was a combination of slight mis-timing and heat wrap.
Re: Glowing exhaust manifold
Posted: Fri Nov 14, 2014 7:41 am
by Geoff
Yeah, heat wrap is insulation so it prevents the manifold from cooling as quickly, therefore keeping the manifold hotter. So if it's close to glowing without being insulated it will really glow when it is.
I never had good luck with that heat wrap, it always stunk when it got hot.
Re: Glowing exhaust manifold
Posted: Fri Nov 14, 2014 7:54 am
by Crazyswede
Geoff wrote:Yeah, heat wrap is insulation so it prevents the manifold from cooling as quickly, therefore keeping the manifold hotter. So if it's close to glowing without being insulated it will really glow when it is.
I never had good luck with that heat wrap, it always stunk when it got hot.
Heat wrap tends to be good for performance and bad for whatever it is wrapping's longevity. But it tends to be used in a race application where part longevity is not an issue. A better option is ceramic coating.
Re: Glowing exhaust manifold
Posted: Fri Nov 14, 2014 7:58 am
by Jordan
We use it so we don't burn all of our arm hair off when we have to bring a car in to service. Other than that, I think it is counter productive.
Re: Glowing exhaust manifold
Posted: Fri Nov 14, 2014 9:07 am
by SwedeSport
I wrapped my MSS header. It rusted out within 2 years.
If you drive the car in the wet, wrap is bad... holds moisture.