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Old 08-15-2017, 08:05 PM   #1
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Pyro readings on Cummins 6BTA

Ok...I am finishing up my panel project and gotta get some things squared away. One of them is the pyro gauges. What is the "normal range" of pyro readings??? I am talking while in the boost? I cruise in the 2200-2400RPM range.

My starboard engine runs at about 600 degrees at around 2400rpms. The port engine is showing 1000.

I did call Seaboard as that is where I purchased the gauge. One of their techs answered that it should be in the 900-1200 range...putting that 1000 degree right in the wheelhouse and the 600 degree reading a little "cool". He handed off the phone to Tony. Tony said the normal range is more like 350-750....putting that 600 reading right in the wheelhouse and the other engine a little on the hot side.

On the engine spec sheet it shows 905. It does not give a range or a max. But it is annotated that figure is at rated power....basically assuming WOT is what they mean.

Just wondering what kind of reading y'all are getting for people that have B series Diamonds with pyro gauges???
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Old 08-15-2017, 08:44 PM   #2
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Ok...I am finishing up my panel project and gotta get some things squared away. One of them is the pyro gauges. What is the "normal range" of pyro readings??? I am talking while in the boost? I cruise in the 2200-2400RPM range.

My starboard engine runs at about 600 degrees at around 2400rpms. The port engine is showing 1000.

I did call Seaboard as that is where I purchased the gauge. One of their techs answered that it should be in the 900-1200 range...putting that 1000 degree right in the wheelhouse and the 600 degree reading a little "cool". He handed off the phone to Tony. Tony said the normal range is more like 350-750....putting that 600 reading right in the wheelhouse and the other engine a little on the hot side.

On the engine spec sheet it shows 905. It does not give a range or a max. But it is annotated that figure is at rated power....basically assuming WOT is what they mean.

Just wondering what kind of reading y'all are getting for people that have B series Diamonds with pyro gauges???
1000 degrees seems a bit too high. Prior to adjusting my prop, I could get to around 800 degrees at near WOT on a CAT 3306, which the prop guy thought was an indication of over propping. Now with a flatter wheel, it is around 700 degrees. Do you reckon both wheels have the same pitch?
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Old 08-15-2017, 08:53 PM   #3
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JD's here, but before that Cummins 555's. Readings about the same for both brands, and doubt that it is engine brand specific. Assuming everyone is using F then I only see 900 when near full power. At my low speed/eco cruise its more like 400-450.

Try swapping your senders between engines. I suspect one of them at least is dodgy, perhaps both. I think the senders are quite cheap, so suggest that you replace both anyway.
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Old 08-15-2017, 08:57 PM   #4
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Do you reckon both wheels have the same pitch?
Props were redone 3 months ago... I gotta assume they knew what they were doing. Also, there is absolutely no other symptom...no black smoke on that side....no excessive fuel burn on that side.

I ask a theoretical question. Heat does not come out of nowhere. I would think heat in a diesel engine can only come from one thing....FUEL!!! Is there anywhere else it could come from?? In a gasoline engine, actually leaning the fuel can cause an increase in EGT. Can the same be said for diesel???
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Old 08-15-2017, 08:58 PM   #5
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Try swapping your senders between engines. I suspect one of them at least is dodgy, perhaps both. I think the senders are quite cheap, so suggest that you replace both anyway.
They are brand new. BUT, I will switch the gauges...not the senders....since that would be easier.
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Old 08-15-2017, 09:07 PM   #6
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I have a pair of those same engines

A bit less than 900 is normal for my properly proper boat at a cruise of 2500

At displacement speeds I see about 600
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Old 08-15-2017, 09:14 PM   #7
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I have a pair of those same engines

A bit less than 900 is normal for my properly proper boat at a cruise of 2500

At displacement speeds I see about 600

Hmmmmm....very interesting. Mine actually decrease to 900 at WOT.
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Old 08-15-2017, 10:05 PM   #8
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Hmmmmm....very interesting. Mine actually decrease to 900 at WOT.
Boy, that just doesn't sound right. More fuel + more work should mean higher exhaust gas temps, not lower. Have you checked air filters? You're an aviator, right? Reduce the fuel to air ratio, higher EGT, increase fuel to air, lower EGT. But maybe that only applies to gas engines? Just for kicks, perhaps remove the air filter on the engine with the higher temps to see if there is any effect?
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Old 08-15-2017, 10:06 PM   #9
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Hmmmmm....very interesting. Mine actually decrease to 900 at WOT.
I never really looked at that too much.

I can say with mine I cant get the EGT above 900 even fully loaded at WOT.

EGT seems to be based on load not RPM. If at WOT your boat is decreading in EGT then your load muct be going down.

At your cruise RPM are you on the "hump" of bow up, maximum drag, or are you over the "hump"

I run my boat at 2500 fast cruise, not because I like that RPM, but because I like the speed of 1415 kn ots which puts me "over the hump"
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Old 08-15-2017, 10:20 PM   #10
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Hmmmmm....very interesting. Mine actually decrease to 900 at WOT.
That is not uncommon with Cummins BTA's. Part-load can often produce the highest EGT's. The condition of the turbos, aftercoolers, air filters, exhaust backpressure, engine loading and many other factors I'm sure can all contribute to higher/different EGT's.

Like you, my owner's manual shows 905 F as max at WOT. I'm comfortable with anything below that number. The most important thing I look for are the temp and boost trends. Significant or sudden changes require investigation.

IMHO, you just can't have too much accurate information on these little white monsters.
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Old 08-15-2017, 10:41 PM   #11
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That is not uncommon with Cummins BTA's. Part-load can often produce the highest EGT's. The condition of the turbos, aftercoolers, air filters, exhaust backpressure, engine loading and many other factors I'm sure can all contribute to higher/different EGT's.

Like you, my owner's manual shows 905 F as max at WOT. I'm comfortable with anything below that number. The most important thing I look for are the temp and boost trends. Significant or sudden changes require investigation.

IMHO, you just can't have too much accurate information on these little white monsters.
Larry, you speak like you have pyro gauges. What do yours read at various RPMs?
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Old 08-15-2017, 10:43 PM   #12
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Boy, that just doesn't sound right. More fuel + more work should mean higher exhaust gas temps, not lower. Have you checked air filters? You're an aviator, right? Reduce the fuel to air ratio, higher EGT, increase fuel to air, lower EGT. But maybe that only applies to gas engines? Just for kicks, perhaps remove the air filter on the engine with the higher temps to see if there is any effect?
I asked that question above. I honestly don't think leaning out a Diesel engine would cause EGTs to rise. And after research, it is somewhat common for a drop in EGT at WOT. Maybe more airflow...who knows.
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Old 08-15-2017, 10:45 PM   #13
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I never really looked at that too much.



At your cruise RPM are you on the "hump" of bow up, maximum drag, or are you over the "hump"

I run my boat at 2500 fast cruise, not because I like that RPM, but because I like the speed of 1415 kn ots which puts me "over the hump"
Yeah, well over the hump. My hump is about 13 knots. 2400 yields about 18-19 knots. It seems to be a pretty happy spot.
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Old 08-15-2017, 11:52 PM   #14
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Larry, you speak like you have pyro gauges. What do yours read at various RPMs?
John,

At WOT, 3,025 rpm and 29+ kt, about 825. At high cruise, 2,550 rpm and 25kt, just under 900, and at econo cruise, 2,200 rpm and 21kt, I see 575 or so. I'm propped very lightly and the boat is not heavy. It is fully on plane about 13-14kt and is very sensitive to its large tabs. Good trim and running angle makes a big difference. Full-auto Bennett ATP's are next
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Old 08-16-2017, 07:55 AM   #15
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I do not have Cummin's engines but I have run pyro & boost gages on the last 3 boats with 6 cylinder 4 stroke turbo diesels. I have found them to be more valuable than any other gages on the boat. The EGT senders were always mounted immediately after the turbo outlet and the boost was read after the intercooler in the intake manifold area.
Readings are always within 950 max on the EGT with the gages beginning to move in the 1500 rpm area and builds to about 900 between 2200 and WOT of 3100. ON a really hot and humid day readings will rise to about 925 and when towing a larger RIB and maybe with a little bottom growth on a hot day readings will rise to 950 at max.
The gages always move in tandem with the boost gages so that they are just about equal at engine rpms that are within 25 or so.
I have always swapped gage sender lines at eth ages upon any installation to know that they are reasonably calibrated at the start.
Some things that will cause an EGT variations:
- sender not centered in exhaust flame kernel
- sender wires/connections not secure
- prop variances
- ambient heat and humidity
- a dozen barnacles on the prop or shaft
- air intake or boost
- exhaust restrictions due to design or condition
- Fuel or valve timing
- Poor injection patterns

IMO EGT and boost gages should really come on every marine turbo diesel 4 stroke.
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Old 08-16-2017, 07:57 AM   #16
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"My starboard engine runs at about 600 degrees at around 2400rpms. The port engine is showing 1000."

At this point when your EGT is really well out of balance what are your corresponding boost readings?
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Old 08-16-2017, 08:00 AM   #17
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I had a single 6BTA 270 (I repowered with it) in my previous boat.
My max EGT was around 925 F at WOT which was 2650 (50 over).
From my Dodge/Cummins pickup truck experience, leaning the fuel lowers EGT, while accelerating (or pulling a hill with a load) with black smoke (unburned fuel) increases EGT.
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Old 08-16-2017, 08:32 AM   #18
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I think the biggest thing out of all this is the large delta difference between the two, really need to sort that out and some OP's gave some good info on it.
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Old 08-16-2017, 08:46 AM   #19
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I suspect a gauge issue or sensor issue. 1000 sounds a little high, 600 way low for a 330 running at 2400.

Are you monitoring charge air pressure (boost)? EGT and boost should track each other closely between twins at same load

Are your tachs accurate and you know engines are in fact sync'd?

What rpm do both engines reach at full power?

Normal on lots of engines for egt to rise a bit at part load. At full load there is lots of boost and so the excess air in the cylinder, beyond what is needed for combustion, rises on a percentage basis. So more air going out that was not involved in a burn.

Also some boats settle at slow planing speed and that raises load.

You should swap gauges. Then if no change swap probes. Hopefully that is possible without making a hash of your cable routing job.
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Old 08-16-2017, 09:38 AM   #20
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"My starboard engine runs at about 600 degrees at around 2400rpms. The port engine is showing 1000."

At this point when your EGT is really well out of balance what are your corresponding boost readings?
Boosts are relatively low and within 2 psi of each other. 2400 is in the mid teens on boost.
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