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Smart quod bastardus
 
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glowing turbo headers

Started my car yesterday in the Michigan 20 degree weather to move the car out of the garage and let her warm up for a few minutes. The car never came down to a normal idle of 900-950rpm but stayed at about 1500rpm for 5-8 minutes.
My GSF headers that I installed last summer were actually glowing red at the collectors and leading up into the turbo exhaust housing. Is this normal or something to worry about, since I never noticed this while idling in the summer after the install.
There was no load on this engine at this time and the only thing that comes to mind on the cause is an overly rich mixture because of the cold weather here.
Any ideas, or is it the thin gage of the headers that have them running so hot that they glow red to the naked eye......I can imagine what they look like under boost and load.
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1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, B&B intercooler, Snow Perf water/meth injection, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.7bar max
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Old 12-17-2007, 01:21 PM
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How's your ignition timing?
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Old 12-17-2007, 01:22 PM
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Smart quod bastardus
 
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Should be ok, as I recently rebuilt the distributor and retimed it all.
I run about 5 degrees BTDC at 950rpm idle which gives about 24 degrees at 4000rpm.
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1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, B&B intercooler, Snow Perf water/meth injection, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.7bar max
---"When you're racing it's life! Anything else either before or after, is just waiting"
Old 12-17-2007, 01:30 PM
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I tried to find the old post I had read about this issue. I seem to remember it was being caused by a lean situation. I know that sounds odd, but people on the thread actually said extra fuel can act as a coolant? I may have read it wrong.

Here is one with a lot of possible culprits that I came accross in the process:

red hot headers
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1979 Porsche 930: 3.4L, SC cams, Twin plug, Leask WUR, Custom SSI turbo exhaust, Tial WG, K27HFS, and we can't forget the Zork (short lived depending on my homeowners assoc.)
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Last edited by AngM018; 12-17-2007 at 02:27 PM..
Old 12-17-2007, 02:13 PM
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I wondered the same thing years ago when I installed my first set of tubular headers on my original street 930 turbo but, with tubular SS headers it's completelty normal.

Bill

www.rudtnersracing.com
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Old 12-18-2007, 10:16 AM
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Cold weather leans out the mixture but it shouldn't be enough to make them glow red at the collector, but I'm no expert. Do you have an AAR? I have one and it kicks off high idle after 10-15 seconds in the summer and maybe 30-40 seconds in colder weather like yours. Maybe because it idled so long at a high rpm - combined with SS headers and a leaner mixture - that might be it. Is there a way to adjust the AAR? That seems like way too much high idle time. Might be a small air leak too. Retarded timing can raise exhaust temps too so maybe double check your distributor/timing.

I think Steve Weiner posted some shots of a 935 (1.5bar)dyno pull where you could almost see the turbine blades - white hot.

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Last edited by turbocarrera; 12-18-2007 at 01:30 PM..
Old 12-18-2007, 12:37 PM
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Glowing red at idle? Something is wrong. Ignition is retarded or there is huge amount of unburnt fuel igniting in headers.
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Old 12-18-2007, 01:44 PM
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Headers glow red for only one reason, there’s fuel burning inside. The two main reasons are a VERY rich mixture and late ignition timing - which doesn’t give the fuel enough time to burn inside the combustion chamber.

Test it for yourself, let your engine idle and crank the ignition timing back to the point where it barely runs, then get out the marshmallows and enjoy
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Old 12-18-2007, 02:51 PM
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Crotchety Old Bastard
 
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I addressed this issue on the thread referenced above.
The car in question was not far out of adjustment at all. The only change was going from stock Euro heat exchangers to B&B headers. The thin walled headers exposed the problem (by glowing cherry red) that only went away after exhaustive tuning.
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Old 12-18-2007, 05:51 PM
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Wo ist die Rennstrecke?
 
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Glowing red at the collectors? Wow - that's hot and that's wrong at 1500 rpm. I could buy into the idea of orange at the primaries just out f the heads. Also, why are you idling the motor for 5 - 8 minutes? That's a long time, even at freezing temps. Anyway, I agree with the others on timing.
Old 12-18-2007, 06:18 PM
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A 79 930 with dual nipple dashpot on the distributer idles at 5 degrees ATDC with the vacuum hoses connected. Worthy of glowing headers at 1500 rpm.
Old 12-18-2007, 06:50 PM
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Wo ist die Rennstrecke?
 
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I disagree. To glow dark red, stainless steel has to be nearly 1300 degrees F. For cherry-red, the temp has to be closer to 1600 degrees F.

Idle produces EGT's that will heat the tubes to about 350. Although I've never tested 1500 rpm, I have seen EGT's on my car at cruise (2200 rpm 10% throttle position) to be about 950 degrees. Well below the temp required to glow red.

If you're glowing red at the collectors (further down the pipes) at 1500 rpm, something's wrong.
Old 12-19-2007, 04:58 PM
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5 atdc...
Old 12-19-2007, 05:24 PM
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i put some customer supplied "going super fast" headers on a 79 930 last year and they also glowed red, at idle and otherwise. the old system never did. i put the old system back on as i didn't want the car to catch fire or something near them to burn up. consensus is they don't use a good quality stainless.
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Old 12-31-2007, 11:50 AM
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Crotchety Old Bastard
 
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The headers on the car I refered to were B&B. The temperature measured with a pyrometer was 1400*F at the heads. Glowing red at idle.
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Old 12-31-2007, 12:25 PM
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ZLP ZLP is offline
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Too much unburnt fuel. BTDT
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Old 12-31-2007, 05:39 PM
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