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Old 02-21-2018, 06:43 PM   #1
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EGT and Boost Gauge..is this necessary?

Doing winter service and though about adding these.

What does the info these gauges do for me?
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Old 02-21-2018, 07:41 PM   #2
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Doing winter service and though about adding these.

What does the info these gauges do for me?
After I blew up a 790hp 892 (burned a hole through a piston), I installed EGTs and never pushed the engines above 950 F EGT and never burned up another engine. The thing is, the EGT can go from 950 (borderline) to fatal very quickly, so unless you are keeping a continuous eye on the EGT's, you may not notice before it is too late. Even a murphy gauge style alarm may not be sufficient if your boat, like mine, has so many identical-sounding alarms that that it takes 30 secs to figure out what is wrong. (My current practice is to immediately pull the throttles back to low rpm until I figure out the problem.)

That said, both EGT's and boost gauges will help you detect problems early just by telling you when things are off the base line.
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Old 02-21-2018, 07:48 PM   #3
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After I blew up a 790hp 892 (burned a hole through a piston), I installed EGTs and never pushed the engines above 950 F EGT and never burned up another engine. The thing is, the EGT can go from 950 (borderline) to fatal very quickly, so unless you are keeping a continuous eye on the EGT's, you may not notice before it is too late. Even a murphy gauge style alarm may not be sufficient if your boat, like mine, has so many identical-sounding alarms that that it takes 30 secs to figure out what is wrong. (My current practice is to immediately pull the throttles back to low rpm until I figure out the problem.)

That said, both EGT's and boost gauges will help you detect problems early just by telling you when things are off the base line.
Gotcha
So where would I learn the safe operating values (temp and boost) for my engine?

Or are they standard for all diesel motors?

they are Yanmar 6lya 370's

Thanks so much!
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Old 02-22-2018, 06:11 AM   #4
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Most eng mfg attempt to have the owners power the boat with a prop for a sport fish or to tow water skiers.

The engine is propped for max RPM at WOT , wide open throttle.

This is their desire to never overload the engine , which helps get the engine past the warranty period .

It works for them as they do not pay the fuel bills or have to live with the noise , and if the engine lasts long enough , its not their concern.

Some folks prefer to operate the engine efficiently , with long service life and low on board noise a consideration.

The real answer is a CPP a controlable pitch prop , but these are expensive , and require knowledge to operate the vessel safely.

An EGT gauge allows an owner to install a drive setup that although more efficient , MUST be operated within the engines limits.

So EGT and boost are required.

The newest boats with computer controlled injection systems can be operated with no fear of harm , the computer knows the engine limits.
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Old 02-22-2018, 07:11 AM   #5
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I just installed some on my boat...Cummins 330B
It just gives you an idea of what is going on in the engine. Yanmar should be able to tell you values. WIth that said, I have struggled to find values for my engines. Probably the best values are those that are running the same engines with the same instrument.
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Old 02-22-2018, 07:17 AM   #6
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In my experience, the boost gauge is more valuable (and easier, more reliable) than an EGT gauge. I have a boost gauge on my helm. Both really tell you the same thing: what is the engine load. I know with clean bottom I get 11-12psi boost at cruise of 2000rpm. Anything higher and something is not right. EGT would tell me the same thing.

There are engine problems that the EGT will tell you that boost will not, but usually those have other rather obvious symptoms.

Also, I sea trial lots of boats and many with EGT gauges, the gauges do not work or are obviously inaccurate. Delicate probes and wires and electrical gauges take a toll from the marine environment.

Cummins publishes EGT post-turbine for their engines at full power, rated rpm. If numbers match there, all is good. Note that as you drop down to cruise rpm, it is not unusual for EGT to rise as air flow reduces and specific load goes up. I kind of cringe if cruise is over 1000F at turbine exit.
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Old 02-22-2018, 07:36 AM   #7
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In my experience, the boost gauge is more valuable (and easier, more reliable) than an EGT gauge. I have a boost gauge on my helm. Both really tell you the same thing: what is the engine load. I know with clean bottom I get 11-12psi boost at cruise of 2000rpm. Anything higher and something is not right. EGT would tell me the same thing.

There are engine problems that the EGT will tell you that boost will not, but usually those have other rather obvious symptoms.

Also, I sea trial lots of boats and many with EGT gauges, the gauges do not work or are obviously inaccurate. Delicate probes and wires and electrical gauges take a toll from the marine environment.

Cummins publishes EGT post-turbine for their engines at full power, rated rpm. If numbers match there, all is good. Note that as you drop down to cruise rpm, it is not unusual for EGT to rise as air flow reduces and specific load goes up. I kind of cringe if cruise is over 1000F at turbine exit.
On a Cummins 6b I would be pulling the throttle back if the EGT's were at or near 1,000 immediately post turbo. This is based upon many Cummins owners inputs over many seasons. We have added pyro and boost gages to 3 boats we have owned and helped others to add them on many occasions - maybe 2 dozen more engines or more.
I find them to be priceless for many reasons:
- baseline for healthy engines that are propped correctly
- real time monitoring of dangerous operating parameters
- great for seeing degradation over time (bottom growth etc)
- ability to balance engines and read props
- real time diagnostic tool

The pyro and boost gages have 'detected' lines wrapped around props, barnacle growth, small slits in flew turbo hoses, intercooler buildup , etc. All while at the same time protecting those engines - great gages that are very cheap to install DIY.
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Old 02-22-2018, 07:39 PM   #8
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On a Cummins 6b I would be pulling the throttle back if the EGT's were at or near 1,000 immediately post turbo. This is based upon many Cummins owners inputs over many seasons. We have added pyro and boost gages to 3 boats we have owned and helped others to add them on many occasions - maybe 2 dozen more engines or more.
I find them to be priceless for many reasons:
- baseline for healthy engines that are propped correctly
- real time monitoring of dangerous operating parameters
- great for seeing degradation over time (bottom growth etc)
- ability to balance engines and read props
- real time diagnostic tool

The pyro and boost gages have 'detected' lines wrapped around props, barnacle growth, small slits in flew turbo hoses, intercooler buildup , etc. All while at the same time protecting those engines - great gages that are very cheap to install DIY.
Wow
thanks for the info
very useful

I am going to reach out to Yanmar
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Old 02-22-2018, 07:42 PM   #9
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Originally Posted by Ski in NC View Post
In my experience, the boost gauge is more valuable (and easier, more reliable) than an EGT gauge. .
As you point out, EGT typically drops at higher rpms, while boost does not. So, EGT helps you find the best / avoid the worst rpms better than a boost gauge alone can.
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Old 02-22-2018, 07:45 PM   #10
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As you point out, EGT typically drops at higher rpms, while boost does not. So, EGT helps you find the best / avoid the worst rpms better than a boost gauge alone can.
I have to process this

Not getting my head around this completely but it sounds like i need to
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