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Discussion Starter · #1 ·
A friend of mine, who skippers an Alloy megayacht, recently gave me a tour and was expounding upon how he uses the exhaust temperature gauges to give him optimal performance on his engines with variable pitch props. I have been thinking of adding a temperature gauge as well, since I have a Gori propeller with "overdrive" functionality and think I can use that and the exhaust temperature to ensure that I don't overload the engine and also get the maximum performance from my diesel.

Has anyone here either done this or heard of it being done on a smaller (75HP Yanmar) engine?
 

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the pointy end is the bow
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Highway truckers monitor their exhaust temperature for performance and monitorning for problems. When we used to troubleshoot engines, we would watch the temperature for each exhaust manifold for temperatures either on the warm side or cool side.
 

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You got it Zanshin. EGT monitoring is a very good way of monitoring your engines efficiency. When you learn what you are doing, you'll be able to diagnose lots of engine, and drive line problems also. Combine this with a coolant sensor, vacuum gauge, throttle position sensor, and you can visualize what your ears and nose and toes are telling you. Record all your base lines, and track changes. For those who don't want to plumb in the various sensors, but still want to play, Infrared thermometers are available to the general public at reasonable costs ($100) just point and shoot, presto temp. readings where you could never reach! Perfect for the clogged heat exchanger.
 

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BUT the trucks dont water cool there Exhaust or Exhaust manifold :) and try and keep that comparment cool for saftey


And O2 that lived through a bit of water sensor was one of the big problems on gas powered EFI boats that are moving to Cats in 2010 and the ones they use on big Outboards require far more looking after than auto units
 

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Discussion Starter · #5 ·
Interesting replies, thanks. I talked with a Yanmar service rep here (in St. Martin) and he convinced me that going to the effort of drilling/welding a mounting for a gauge, then doing the wiring would be too much work; I should just see what Revs (or %age of max revs) I get in "overdrive" mode and compute it from there. I like the idea of using an infrared temperature gun and might look into finding one here - but I will have to find a "target" on the engine exhaust that will give me a correct reading prior to cooling.
I think I will put more effort into located volume in the boat that can be used for additional fuel tank(s) and might just convert one cabin to fuel storage using those waterbed like flexible fuel tanks. The specific background to the fuel question was that I would like to sail for Horta from the Caribbean next week using the rhumb line route and the weather isn't quite ready - so I will most likely need to use the engine as I will be sailing on a bit of a schedule.
 

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Zanshin, I know there is a thread around here of someone whom uses the IR Temp gun. and they have painted several dots in strategic locations to monitor engine temps. I think it may be SailingDog, if not I'm sure he will know which boat it is. Even if you are monitoring exhaust gas at your heat exchanger, you will still benefit from monitoring the EGT. You will learn that the idiosyncrasies of your engine as it warms, and settles into its operating temp. Over time as your heat exchanger fouls, water pump wears, coolant ages, etc. You will be able to monitor the temps of the various locations, recorded into a spreadsheet. In time temp reading will change as problems slowly arise. In the long run you should be well informed and prepared in advance for any preventative maintenance. I do realize you originally wanted to RUN your engine at a specific EGT. but you can also use engine temp. to do the same thing, also the data available will probably reflect the sensors the engine was manufactured with, (coolant versus EGT.) Hope this helps.
 

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Courtney the Dancer
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Most ships run a dry exhaust, like trucks, so you would need to plumb it into a location before where the cooling water enters. Pyrometers in trucks are used to keep from overheating while pulling hills, and it's pretty dramatic how fast the temp can go up if you keep your foot on the throttle when the RPM's start dropping if you don't downshift. If you are properly propped you should never have to worry too much about it in a sailboat (especially if you don't have a turbo), your coolant temp alarm should alert you to an overheating situation before you do any damage even if you don't have a temp guage (most Yanmars ?). I could definitely see an advantage to having a Pyro in a tug boat with variable pitch prop, or any large diesel engine for that mattler.
 

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So if you had access to this information what would you do with it??
 

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From driving my share of diesels, having a water temp and EGT guage can be good. Both measure parts of the overall equation of what will or will not harm an engine. Sometimes the water starts to go sooner than the exhaust, but usually I found the exhaust to go quicker towards the too hot end of things before the water was even close to hitting something to be worried about. Especially if you are pushing limits.

On the other hand, not sure if on my boat it would be worth the effort as it is in the trucks I use for work.

marty
 
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