# Exhaust temps



## sternchallis (Nov 15, 2015)

Now that I am retired I start thinking about stuff.

We all took engine logs, and exhaust temps for each cylinder, I can understand that, but what was the Exh temp before the turbo charger used for as it was a mixture of several cylinders. Then there was exh temp from turbo.
Then the Chief averaged a days readings to put on his log abstract. 
So you could get ◇T across the turbo perhaps a measure of fouling of nozzle ring, I don't know.

Can anybody enelighten me.

When the Chief took all the voyage log sheets plus his abstract back to the office, did somebody sat on a stool go through all the figures as a penance or what! And then what. 
You often had those slow steaming voyages, which made the watches last forever and clagged up the system, doing more harm than good, despite an hour on the 12/4 pm watch to speed up, which probably did nothing after 23 hours at slow steaming.


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## david freeman (Jan 26, 2006)

sternchallis said:


> Now that I am retired I start thinking about stuff.
> 
> We all took engine logs, and exhaust temps for each cylinder, I can understand that, but what was the Exh temp before the turbo charger used for as it was a mixture of several cylinders. Then there was exh temp from turbo.
> Then the Chief averaged a days readings to put on his log abstract.
> ...


I am not sure of the answer, you are rattling my cage as an apprentice and combined Motor time? Somewhere I remember on the company doxfords and H&W opposed piston types 2 strokes with scavenge pumps/spaces, and turbo-blowers. In a two stoke the scavenge space [blown or pumped], could with faulty fuel valves become 'clagged up' with exhaust/post combustion crud and the temperature across a turbo blower may have been as you suspect [the temperature drop across the blower], giving a higher ultimate funnel exhaust temperature[ and the danger of uptake fires?],-indicate a fouled Blower, or poor injectors operation, due to leakage or any adjustment to cam alignment to improve engine BHP per cylinder, and a perfect combustion cycle.
By good sir this is one for the orals? If I failed: I wish the rest of you all the best.


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## uisdean mor (Sep 4, 2008)

sternchallis said:


> Now that I am retired I start thinking about stuff.
> 
> We all took engine logs, and exhaust temps for each cylinder, I can understand that, but what was the Exh temp before the turbo charger used for as it was a mixture of several cylinders. Then there was exh temp from turbo.
> Then the Chief averaged a days readings to put on his log abstract.
> ...


Fairly complete explanation here - http://www.dieselduck.info/forum/viewtopic.php?t=3310

The only additional comment I would add is that the "energy" is not solely accounted for in the temperature differentials and volumes. We must also consider the losses in travelling along the shaft to deliver the "work" done by the compressor.
As to chiefy and the abstracts - all were recorded in various forms by HQ but as you suspect seldom referred to unless there was a "problem". Might be charter speeds or future breakdowns which might be unexplained at the time - or perhaps wear rates whatever might give cause for concern at HQ in terms of out of the ordinary costs or delays or even the legals associated with chartering at the time. I am sure there may be abstarcts mouldering away somewhere in some long forgotten office just waiting for a student to bring fresh thinking to what and why some operations were carried out. 

Slainte


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## sternchallis (Nov 15, 2015)

Thank you chaps. 
I checked out the Canadian site, very interesting, though some was getting beyond my memory or competence.
It sounds like they are having problems with their Tickets, the Government making a mess of things as governments do. Manila Tickets, must be like the Bamboo ones from our time.


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## oldgoat1947 (Apr 5, 2018)

Re Ex Temps. The Temp Differential across the Turbo Charger is indicative of the efficiency of the T/C and cleanliness of the Exhaust system. If Either are fouled then the differential drops. Comparing Readings to the Original Sea Trial Readings gives a good comparison of Engine and T/C Efficiency. (Along with Exhaust and uptake pressures.)


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## sternchallis (Nov 15, 2015)

oldgoat1947 said:


> Re Ex Temps. The Temp Differential across the Turbo Charger is indicative of the efficiency of the T/C and cleanliness of the Exhaust system. If Either are fouled then the differential drops. Comparing Readings to the Original Sea Trial Readings gives a good comparison of Engine and T/C Efficiency. (Along with Exhaust and uptake pressures.)


Thanks 1947, that sounds more like it. Strange this was never mentioned in Chiefs or 2nds for that matter. I don't suppose C/Engs ever bothered unless was to tell the 2nd to waterwash the Turbos. Though this was often done in the middle of every long passage, then cards were taken.

I had to decarbonise a TC nozzle ring on a large MAN 4 stroke (58L same as QE2 generators) in situ using a solution of dhobi dust and water as we were having troubles. Suggested to the C/Eng about water washing the TC when we were at sea and he said the engine is too new , it won't be ready yet ( we probably could have saved the day if we had), we were still on the maiden voyage southbound. After we changed all the Exh valves sorted out the HOP, the MAN man said to waterwash every 4-5 days. After that no more problems.


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