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???

Baker said:

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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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?

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.

Delfin said:

Do you reckon both wheels have the same pitch?

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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???

Insequent said:

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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They are brand new. BUT, I will switch the gauges...not the senders....since that would be easier.

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

ksanders said:

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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Hmmmmm....very interesting. Mine actually decrease to 900 at WOT.

Baker said:

Hmmmmm....very interesting. Mine actually decrease to 900 at WOT.

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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?

Baker said:

Hmmmmm....very interesting. Mine actually decrease to 900 at WOT.

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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"

Baker said:

Hmmmmm....very interesting. Mine actually decrease to 900 at WOT.

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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.

LarryM said:

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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Larry, you speak like you have pyro gauges. What do yours read at various RPMs?

Delfin said:

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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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.

ksanders said:

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"

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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.

Baker said:

Larry, you speak like you have pyro gauges. What do yours read at various RPMs?

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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

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.

"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?

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.

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.

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.

smitty477 said:

"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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Boosts are relatively low and within 2 psi of each other. 2400 is in the mid teens on boost.

Ski in NC said:

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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The boat is underpropped. I can reach 3000rpm on a 2800rpm engine. There is absolutely no black smoke and in the 900 hours I have owned the boat, I have never seen black smoke nor absolutely no soot of any kind on the transom. Boost is relatively low and within 2psi of each other. Yep, I am going to switch wires at the gauge first. Switching probes would indeed make a "hash" of the installation. I think I might even just take out the probes and reinstall them to make sure they are seated or whatever...

Baker said:

The boat is underpropped. I can reach 3000rpm on a 2800rpm engine. There is absolutely no black smoke and in the 900 hours I have owned the boat, I have never seen black smoke nor absolutely no soot of any kind on the transom. Boost is relatively low and within 2psi of each other. Yep, I am going to switch wires at the gauge first. Switching probes would indeed make a "hash" of the installation. I think I might even just take out the probes and reinstall them to make sure they are seated or whatever...

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Does the high EGT engine have the low boost?

What are the boost and EGT readings at that rpm you had recorded?

The boat may be underpropped but if the gages are reading correctly we need to find the issue with the high EGT.

smitty477 said:

Does the high EGT engine have the low boost?

What are the boost and EGT readings at that rpm you had recorded?

The boat may be underpropped but if the gages are reading correctly we need to find the issue with the high EGT.

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Yes we do. The low boost is the low temp engine. Like I said....there are no other symptoms but I will get to the bottom of this. Headed to the boat now.

Ok...went to the boat and started looking around. I realized there were fused plugs on the pyro probes that allowed me to switch probes quite easily. Took the boat out for a test ride....no change. So it isn't the probe. But while I had the floor torn up, I left it torn up to allow me to get some temperature readings with the laser thermometer gizmo. The temps on all "representative surfaces" were almost identical and matched the "cooler" gauge. The other gauge reads almost perfectly twice of the other one????

Anyway, will switch the wires at the actual gauge on the flybridge next. That probably won't happen until tomorrow or Saturday. The identical temp readings with the gun are giving me a little peace of mind. I realize that is not the exhaust flow. But if there is a 500 degree delta on the gauge and it were "real" I would assume I would see a significant delta on the temp readings..regardless of what the actual readings were.

Really smart move using a infrared thermometer!

At 2400 what are you reading for boost in psi?

Ski in NC said:

At 2400 what are you reading for boost in psi?

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About 14psi on the port. About 12 on the starboard. Slightly low??? I needed to get the props tuned and did it about 3 months ago. I actually added an inch of pitch and probably could have done another. Before the addition, I would get damn near 3100. Now I am at 3000 +/- 25. The boat left the factory with 23x27. When I bought the boat the props had to be done and I was shooting in the dark(and with prop calculators). I went 23x24 to be conservative. I am at 23x25 now. I have never seen black smoke(I am sure I could force it) and have never had soot on the transom. The "inside" engine will load up in a turn and boost climbs about 3-4psi on that engine in the turn.

Could they have sent me 1 24volt gauge and 1 12 volt gauge??? It is just bizarre that one gauge is almost exactly double of the other. I know the final answer will be when I switch the wires at the gauge.

12 and 14psi means you are in a happy spot load wise. I would not worry about the 2psi differential, they are never exactly the same.

Those x2 readings would be consistent with one sender being single-station and the other dual-station. Maybe check that....