Cummins 6BTA aftercooler

[DavidM]

500 degrees may be a little high, but the Cummins white paint on its turbo exit air piping will get scorched and turn brown if the engine is run hard routinely. So it does get pretty hot. Never measured it but it will burn your fingers if running near wot.

Why don't you think a heat exchanger with maybe 80 degree water running through it won't cool the air down to near that temp? That is what heat exchangers do.

David

 

[sunchaser]

In support of David's concern, I've seen turbos on large dirt moving equipment get red hot. It happens which is why EGTs, turbo temperature and turbo pressure are closely monitored and controlled. Another reason why non after cooled turbo engines are rated and fueled to achieve lower HP.

 

[smitty477]

500 degrees may be a little high, but the Cummins white paint on its turbo exit air piping will get scorched and turn brown if the engine is run hard routinely. So it does get pretty hot. Never measured it but it will burn your fingers if running near wot.

Why don't you think a heat exchanger with maybe 80 degree water running through it won't cool the air down to near that temp? That is what heat exchangers do.

David

Maybe as high as 300F but no where near 500F.
White paint discolors at fairly low temps - you can use an IR gun to see just how low.

"Never measured it but it will burn your fingers if running near wot."
We have measured a number of intake air temps before and after intercoolers with EGT gages over the years.
Burn fingers at 300F but no where near 500F.

"Why don't you think a heat exchanger with maybe 80 degree water running through it won't cool the air down to near that temp?"
At higher flow the amount of time the preheated air is in proximity to the low temp fins is limited - that and the fact the heat transfer capacity is fixed.
I have seen drops of 180F max on most any application we measured. (post turbo worked air at 280 max and , aftercooler output at 100-110)
I believe Tony a has measured some of this as well and got similar results.

"That is what heat exchangers do."
Similar to AC heat exchangers , oil coolers, air handlers etc all of the temp drops have to do with capacity and time spent along the cooler pathway.
The higher the temp and the less time spent along the cooler path the less temp drop. The lesser the total cooler capacity the lesser the temperature drop.

 

[smitty477]

In support of David's concern, I've seen turbos on large dirt moving equipment get red hot. It happens which is why EGTs, turbo temperature and turbo pressure are closely monitored and controlled. Another reason why non after cooled turbo engines are rated and fueled to achieve lower HP.

"I've seen turbos on large dirt moving equipment get red hot."
Of course - on the turbine side of the turbo.

 

[sunchaser]

"I've seen turbos on large dirt moving equipment get red hot."
Of course - on the turbine side of the turbo.

Smitty, not doubting your numbers. Maybe we could at least agree that bypassing a raw water cooled marine after cooler should correspond with an intentional lowered fuel flow. IE, keep the revs down to avoid the potential of burned valves or ??

 

[smitty477]

There are a number of posts on Boatdiesel and Tony's site on intake tempertaure drops across exchangers , here is a link to one.....

https://www.sbmar.com/community/topic/air-intake-temp/

 

[smitty477]

Smitty, not doubting your numbers. Maybe we could at least agree that bypassing a raw water cooled marine after cooler should correspond with an intentional lowered fuel flow. IE, keep the revs down to avoid the potential of burned valves or ??

Absolutely agree - I have had problems knowing what exact rpm or what exact fuel flow would be a limit without EGT's.
I have also had a personal problem with running any 4 stroke TI engine without EGT's.

 

[DavidM]

While I appreciate the support, I believe that the red hot turbo you note was a non jacketed, non insulated exhaust turbo. Those will get red under heavy load but don't necessarily have anything to do with the air side that we have been discussing.

David

 

[firehoser75]

Not a stupid question at all. My Fleming 55's has twin Cummins 6CTA. I run two maintenance schedules.

1) Check the anodes every 6 months
2) Every 5 years, flushing the sea water cooling system with Rydlyme to remove any limescale build up.

This has worked well since I bought the boat in 2003. In other words, protection at all times, flushing and lime scale removal every 5 years.

Greatpapabear,
You may not be doing the right maintenance to avoid having to replace the aftercoolers?? Read the following from an earlier post of mine, and follow up by reviewing the info on Tony Athen's site. He is an acknowledged Cummins (and other) marine diesel expert, who gives freely of his knowledge and experience.
"Freshwater flushing will save your engine's raw water cooling side, reducing the need to "fully service" all of the components (aftercooler, fuel cooler, gear oil cooler, and heat exchanger).

However, even with freshwater flushing (which I do after each run when there is a decent flow of "dock water" available), the aftercooler will still require a complete "off engine" strip down every 3-4 years and every 2-3 if you don't flush. This is because even running ridlyme etc. through it will not deal with all of the issues. You have several dissimilar metals in contact with one another in saltwater inside the aftercooler (causing corrosion), o rings that could fail allowing salt water into the engine, and the air side gets "gunked up" by the oil particulates that are present in any engine room's air to say nothing about any crank case ventilation system.
Tony explains all of this in great detail on the above mentioned website.
If left without the proper regular servicing, the internal parts will corrode (basically weld) together (ruining the entire unit $$$), the air side will gunk up and start to slowly air starve the engine, and/or the saltwater side could clog up leading to overheating, to say nothing about the potential for saltwater to enter the engine.

After the complete off engine servicing, the aftercooler should be "pressure tested" to ensure no leaking.
To freshwater flush, just replace the sea strainer cap with one that has a garden hose (shutoff) adapter installed. Search for info on Tony's site for photos and how to's. With my setup it takes me about 10-15 minutes from start of getting the hose out to when everything is put away. I don't think just draining the aftercooler will result in much improvement when compared to flushing.
Hope you find this useful"
Unless your aftercoolers are totally different than mine (on a Cummins 6BTA), you need to disassemble them periodically or they can fail badly over time due to internal corrosion. Again, see Tony's site he has some photos of the worst he has come across, and it is not pretty

 

[Baker]

G Read the following from an earlier post of mine, and follow up by reviewing the info on Tony Athen's site. He is an acknowledged Cummins (and other) marine diesel expert, who gives freely of his knowledge and experience.
"Freshwate:

I think Tony has done great things for the Cummins marine community. But his time is not free. I don't blame him...he does not suffer fools well....and I am one of them!!!

 

[greatpapabear]

Greatpapabear,
You may not be doing the right maintenance to avoid having to replace the aftercoolers?? Read the following from an earlier post of mine, and follow up by reviewing the info on Tony Athen's site. He is an acknowledged Cummins (and other) marine diesel expert, who gives freely of his knowledge and experience.
"Freshwater flushing will save your engine's raw water cooling side, reducing the need to "fully service" all of the components (aftercooler, fuel cooler, gear oil cooler, and heat exchanger).

However, even with freshwater flushing (which I do after each run when there is a decent flow of "dock water" available), the aftercooler will still require a complete "off engine" strip down every 3-4 years and every 2-3 if you don't flush. This is because even running ridlyme etc. through it will not deal with all of the issues. You have several dissimilar metals in contact with one another in saltwater inside the aftercooler (causing corrosion), o rings that could fail allowing salt water into the engine, and the air side gets "gunked up" by the oil particulates that are present in any engine room's air to say nothing about any crank case ventilation system.
Tony explains all of this in great detail on the above mentioned website.
If left without the proper regular servicing, the internal parts will corrode (basically weld) together (ruining the entire unit $$$), the air side will gunk up and start to slowly air starve the engine, and/or the saltwater side could clog up leading to overheating, to say nothing about the potential for saltwater to enter the engine.

After the complete off engine servicing, the aftercooler should be "pressure tested" to ensure no leaking.
To freshwater flush, just replace the sea strainer cap with one that has a garden hose (shutoff) adapter installed. Search for info on Tony's site for photos and how to's. With my setup it takes me about 10-15 minutes from start of getting the hose out to when everything is put away. I don't think just draining the aftercooler will result in much improvement when compared to flushing.
Hope you find this useful"
Unless your aftercoolers are totally different than mine (on a Cummins 6BTA), you need to disassemble them periodically or they can fail badly over time due to internal corrosion. Again, see Tony's site he has some photos of the worst he has come across, and it is not pretty

Hi Firehoser. Now that's really interesting. Thanks so much for the site and it's wisdom. I will certainly look into this, eagerly. I have an excellent Cummins engineer contact in the UK and will contact him shortly. Again - thank you. GPB