Exhaust manifold temperatures

[tcslr]

How hot does the exhaust manifold get? I’ve measured block and other locations. I’ve read they can get up to 1200-1600? That would be dull red - I’ve never seen that condition. 
 

[Matt Harwood]

LOL

 

[37_Roadmaster_C]

I was going to say what Matt showed......

[c49er]

400-500 degree's is what I typically find when doing random checks on my cars and trucks...40's, 50's MoPars.

Mine don't glow red though.

[Guest]

Way back when, We installed a 283 into a boat. Not having the money, we used the stock manifolds. At night, under full throttle, they glowed cherry red even though there was no motor cover on it!🍒

[John Byrd]

I always thought this was a beautiful photo with those red hot manifolds, ...Ford might have "enhanced" it, but I've always wondered about the story that goes with it.

[tcslr]

Matt,

what engine is that? How long had it been running?
thanks all. Learn something new everyday
tom

[hook]

On 12/29/2021 at 9:31 PM, tcslr said:

How hot does the exhaust manifold get? I’ve measured block and other locations. I’ve read they can get up to 1200-1600? That would be dull red - I’ve never seen that condition. 
 

Here is the running temps of a Franklin Air Cooled engine. I have seen the manifold on model A Fords glow red many times. It's a dull red, not like that 427 photo and you could only see it a night when it was dark and you were running in excess of 45 miles per hour.

[Mark Gregush]

If it is glowing, could be a timing issue or running too lean.

[hook]

23 hours ago, c49er said:

400-500 degree's is what I typically find when doing random checks on my cars and trucks...40's, 50's MoPars.

Mine don't glow red though.

I bet it does at 55 mph. Even my model A's would stop glowing when I stopped. I could only see it glow through the heater hole in the firewall.

[c49er]

Hope not. Running too lean.

[avgwarhawk]

5 hours ago, Mark Gregush said:

If it is glowing, could be a timing issue or running too lean.

I have seen this in rich running and clogged catalytic converters. 

[Mark Gregush]

We had an old Case combine with air cooled motor. Not something you really want to see out in a dry grain field, but running at full load, the manifold glowed a most cheery red!

[Akstraw]

When I was a teenager first tinkering with old cars, my Model A exhaust manifold would glow red.  Then I learned it was a timing issue.  Advancing the spark made it run cooler, and no red manifold.

[Matt Harwood]

On 12/30/2021 at 9:04 PM, tcslr said:

Matt,

what engine is that? How long had it been running?
thanks all. Learn something new everyday
tom

 

It's my 1935 Lincoln K V12. Long story and you can read about it below, but basically it would take 8 gallons of coolant from ambient temperature to 220 degrees in about three minutes. That particular photo is a still from a video (the red glow wasn't visible to the naked eye) of the engine running for about three minutes. Thought we had it licked when we found the water pump wasn't moving any water, but it turns out the timing chain was off by two teeth. Fixed that and then bent all the valves doing a compression test. All the sordid details are here:

 

 

[Terry Harper]

The idea that an engine runs hot because of a lean mixture is assuming that the extra fuel in a rich mixture somehow cools the engine. It does not. It actually causes the engine to run much hotter.
 

The extra fuel in a rich mixture results in a much longer burn event, due to lack of oxygen. Thus combustion isn’t confined to just the combustion chamber but extends into the cylinder. In fact This slow combustion can extend well into the power stroke if not through.

 

As the piston moves down the bore more cylinder wall area is exposed to the heat of the slow burning (overly rich) combustion gasses thus transferring heat to the block and to the coolant over a much greater time and vastly increased surface area thus the engine runs hotter. And yes, cause much hotter exhaust gasses (still burning) which in turn cause the manifolds to get rather warmer than they should be.

same with late timing. More cylinder wall is exposed to a slow burning fuel/air mixture which was not compressed enough to combust rapidly or completely. Thus more time for heat transfer over a much greater surface area as well and of course causing the exhaust manifolds to get excessively hot as those still burning gasses exit through them. 

 

 

 

 

Edited January 1, 2022 by Terry Harper (see edit history)

[paulrhd29nz]

I have an EGT sensor in the manifold of Cummins 24v. On a long grade it gets to 900 deg. A gas engine would be much hotter I would suspect. 
that Franklin drawing shows the Exhaust valve stem at 1300 deg.