What is acceptable low RPM full load for OM616?
What is acceptable low RPM full load for OM616?
11-06-2022, 01:03 AM
#3
1978 300D, 373,000km... OM617.912 with a Holset HX30W, 7.5mm IP, 711.113 5 speed (project car, 7 years off the road and counting ;/)
1977 250 270,000km (parts car)
1977 300D (ex 280) 500,000km
1981 240D 498,000
1975 HJ45 ???,000
2001 2.8TD Rodeo 4x2 - 456,000 - DD
There is no point going much below the peak torque figure (2400 when stock) if that's any help...
1978 300D, 373,000km... OM617.912 with a Holset HX30W, 7.5mm IP, 711.113 5 speed (project car, 7 years off the road and counting ;/)
1977 250 270,000km (parts car)
1977 300D (ex 280) 500,000km
1981 240D 498,000
1975 HJ45 ???,000
2001 2.8TD Rodeo 4x2 - 456,000 - DD
11-08-2022, 07:00 AM
#4
I have a few Cummins powered trucks and they seem to use more fuel when operating at peak torque and thought there may be a correlation with fuel consumption and making torque.
Above all, I didn't want to cause any problems with the OM616 running it too slow.
Well the engine is in a different vehicle, so it may have different sound characteristics then the sedan. It is nice and quiet running at 1800 RPM, has plenty of torque to move along on flat ground without any problems (evident) and I was hoping that is was getting high fuel mileage in the lower RPM ranges.
I have a few Cummins powered trucks and they seem to use more fuel when operating at peak torque and thought there may be a correlation with fuel consumption and making torque.
Above all, I didn't want to cause any problems with the OM616 running it too slow.
11-13-2022, 03:04 PM
#5
The engines always were very short geared in vehicle applications, how tall is the gearing in your application?
1978 300D, 373,000km... OM617.912 with a Holset HX30W, 7.5mm IP, 711.113 5 speed (project car, 7 years off the road and counting ;/)
1977 250 270,000km (parts car)
1977 300D (ex 280) 500,000km
1981 240D 498,000
1975 HJ45 ???,000
2001 2.8TD Rodeo 4x2 - 456,000 - DD
There is a BSFC chart from the 1978 OM617A SAE paper, but I doubt that would be of use with natural aspiration
The engines always were very short geared in vehicle applications, how tall is the gearing in your application?
1978 300D, 373,000km... OM617.912 with a Holset HX30W, 7.5mm IP, 711.113 5 speed (project car, 7 years off the road and counting ;/)
1977 250 270,000km (parts car)
1977 300D (ex 280) 500,000km
1981 240D 498,000
1975 HJ45 ???,000
2001 2.8TD Rodeo 4x2 - 456,000 - DD
11-16-2022, 11:14 AM
#6
(11-08-2022, 07:00 AM)m37 I have a few Cummins powered trucks and they seem to use more fuel when operating at peak torque and thought there may be a correlation with fuel consumption and making torque.
Above all, I didn't want to cause any problems with the OM616 running it too slow.
what´s up.
well that is a very interesting question!!! one that i didn´t hear for very very long time...
Diesels from this "era" usually did not had a TQ limiter governor, altitude compensation and such ...but that was not the case in MB automotive engines, as my understanding goes all automotive IP in MB automotive diesels had this type of GOV, its called a Speed GOV, and they incorporate a TQ limiter. To avoid untrained driver ´s WOT. if driver uses WOT but the engine canot hold the load, it decreases max fuel under load, to limit consuption and smoke, so as undesired high temps from not leting it breeth.
as any other diesel from the "era" without the TQ limiter, keeping it with a slight marging will always benefit consuption.
Be aware that Cummins from this era , as an example, do not have a speed GOV, therefore they tend to use more fuel if driven in WOT and full load conditions, smoke more , and heat up more, and when taken to altitude this may even result in very high heating, and eventually premature damage.
this can be told by any trucker from the 70´s...
FD,
Powered by tractor fuel
(11-08-2022, 07:00 AM)m37 I have a few Cummins powered trucks and they seem to use more fuel when operating at peak torque and thought there may be a correlation with fuel consumption and making torque.
Above all, I didn't want to cause any problems with the OM616 running it too slow.
what´s up.
well that is a very interesting question!!! one that i didn´t hear for very very long time...
Diesels from this "era" usually did not had a TQ limiter governor, altitude compensation and such ...but that was not the case in MB automotive engines, as my understanding goes all automotive IP in MB automotive diesels had this type of GOV, its called a Speed GOV, and they incorporate a TQ limiter. To avoid untrained driver ´s WOT. if driver uses WOT but the engine canot hold the load, it decreases max fuel under load, to limit consuption and smoke, so as undesired high temps from not leting it breeth.
as any other diesel from the "era" without the TQ limiter, keeping it with a slight marging will always benefit consuption.
Be aware that Cummins from this era , as an example, do not have a speed GOV, therefore they tend to use more fuel if driven in WOT and full load conditions, smoke more , and heat up more, and when taken to altitude this may even result in very high heating, and eventually premature damage.
this can be told by any trucker from the 70´s...
FD,
Powered by tractor fuel
11-18-2022, 04:23 PM
#7
(11-08-2022, 07:00 AM)m37 Well the engine is in a different vehicle, so it may have different sound characteristics then the sedan. It is nice and quiet running at 1800 RPM, has plenty of torque to move along on flat ground without any problems (evident) and I was hoping that is was getting high fuel mileage in the lower RPM ranges.
I have a few Cummins powered trucks and they seem to use more fuel when operating at peak torque and thought there may be a correlation with fuel consumption and making torque.
Above all, I didn't want to cause any problems with the OM616 running it too slow.
I'm not knowledgeable on mercedes, just some on diesels in general, but generally peak torque usually corresponds with the MOST efficient use of fuel per HP made. The correlation between fuel consumption and making torque is only that fuel = torque, your foot all the way down is whats deciding how much power and fuel to inject in a diesel - as long as there is enough air to allow combustion. (if there isnt it turns smoky)
As a rule all truck diesels are built with BIG bearings and intended to turn slower to get heavy loads moving. The Mercedes is not a truck diesel and doens't have a truck like torque curve and i'd be hesitant to grunt it around that much, I doubt it would be good for the bearings. It seems to have more in common with the older detroit diesels where you had to rev them to get decent power unlike other big truck diesels . Every engine has a range where it's designed to run, and by what i can tell the mercedes would prefer a higher range than most truck diesels. This would become more important as power modifications increased torque everywhere and loads exceeded stock.
That said countering my own advice om616's at stock power levels seem surprisingly tame for power output and I wouldn't be too worried if that's all it was doing, not power boosted or towing or something. Looking up elsewhere if the torque peak starts at 1800rpm i'd try to not let it drop below that personally.
futureswap
11-18-2022, 04:23 PM #7(11-08-2022, 07:00 AM)m37 Well the engine is in a different vehicle, so it may have different sound characteristics then the sedan. It is nice and quiet running at 1800 RPM, has plenty of torque to move along on flat ground without any problems (evident) and I was hoping that is was getting high fuel mileage in the lower RPM ranges.
I have a few Cummins powered trucks and they seem to use more fuel when operating at peak torque and thought there may be a correlation with fuel consumption and making torque.
Above all, I didn't want to cause any problems with the OM616 running it too slow.
I'm not knowledgeable on mercedes, just some on diesels in general, but generally peak torque usually corresponds with the MOST efficient use of fuel per HP made. The correlation between fuel consumption and making torque is only that fuel = torque, your foot all the way down is whats deciding how much power and fuel to inject in a diesel - as long as there is enough air to allow combustion. (if there isnt it turns smoky)
As a rule all truck diesels are built with BIG bearings and intended to turn slower to get heavy loads moving. The Mercedes is not a truck diesel and doens't have a truck like torque curve and i'd be hesitant to grunt it around that much, I doubt it would be good for the bearings. It seems to have more in common with the older detroit diesels where you had to rev them to get decent power unlike other big truck diesels . Every engine has a range where it's designed to run, and by what i can tell the mercedes would prefer a higher range than most truck diesels. This would become more important as power modifications increased torque everywhere and loads exceeded stock.
That said countering my own advice om616's at stock power levels seem surprisingly tame for power output and I wouldn't be too worried if that's all it was doing, not power boosted or towing or something. Looking up elsewhere if the torque peak starts at 1800rpm i'd try to not let it drop below that personally.
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