Post injection events = hot EGTs on 3rd gens ?
08-17-2005, 01:44 AM
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Post injection events = hot EGTs on 3rd gens ?
I'm seeing a recurring theme with these 3rd gens, that the EGTs are really hot. (http://www.turbodieselregister.com/f...8&page=1&pp=15)
I'm wondering what part the post injection event has in this. I assume the post fuel is being burnt in the combustion chamber just prior to or during the exhaust stroke and might this attribute to higher EGTs and if so, should the engine EGT limits be higher than one without a post injection event ?
Aside: the only thing that seems to make the EGTs go down is the 2 degree crankshaft position sensor mod. This reasons alone makes me want to test it, although my engine is completely stock. I consider the BHAF and Donaldson to be stock in my installation...
When I pulled hills with the PSD, I ran it on CC and I let the engine come down to 1700 RPM before I would downshift into direct. (1850 = 65MPH on a ZF6 in my truck.) I drove my Cummins the same way on a recent trip. In Quickserve, Cummins says "To obtain optimum engine performance on a grade, allow the engine speed to load down to near peak torque before shifting. This will result in an engine operating speed in the maximum power zone after the shift is completed."
I take this to mean that I can continue to allow my engine to pull down to 1700 RPM, in spite of any high EGTs I may be creating ? And if the grade is long, I could leave the engine at 1750 WOT indefinitely ?
It also says this:
"Do not operate the engine at full throttle operation below peak torque rpm (refer to engine dataplate for peak torque rpm) for more than 30 seconds. Operating the engine at full throttle below peak torque will shorten engine life to overhaul, can cause serious engine damage, and is considered engine abuse.
Cummins engines are designed to operate successfully at full throttle under transient conditions down to peak torque engine speed. This is consistent with recommended operating practices.
CAUTION
Do not operate the engine beyond the maximum engine speed. Operating the engine beyond the maximum engine speed can cause severe engine damage. Use proper operating techniques for the vehicle, vessel, or equipment to prevent engine overspeed. The maximum engine speed specification is listed in Maintenance Specifications (Section V)."
I'm wondering what part the post injection event has in this. I assume the post fuel is being burnt in the combustion chamber just prior to or during the exhaust stroke and might this attribute to higher EGTs and if so, should the engine EGT limits be higher than one without a post injection event ?
Aside: the only thing that seems to make the EGTs go down is the 2 degree crankshaft position sensor mod. This reasons alone makes me want to test it, although my engine is completely stock. I consider the BHAF and Donaldson to be stock in my installation...
When I pulled hills with the PSD, I ran it on CC and I let the engine come down to 1700 RPM before I would downshift into direct. (1850 = 65MPH on a ZF6 in my truck.) I drove my Cummins the same way on a recent trip. In Quickserve, Cummins says "To obtain optimum engine performance on a grade, allow the engine speed to load down to near peak torque before shifting. This will result in an engine operating speed in the maximum power zone after the shift is completed."
I take this to mean that I can continue to allow my engine to pull down to 1700 RPM, in spite of any high EGTs I may be creating ? And if the grade is long, I could leave the engine at 1750 WOT indefinitely ?
It also says this:
"Do not operate the engine at full throttle operation below peak torque rpm (refer to engine dataplate for peak torque rpm) for more than 30 seconds. Operating the engine at full throttle below peak torque will shorten engine life to overhaul, can cause serious engine damage, and is considered engine abuse.
Cummins engines are designed to operate successfully at full throttle under transient conditions down to peak torque engine speed. This is consistent with recommended operating practices.
CAUTION
Do not operate the engine beyond the maximum engine speed. Operating the engine beyond the maximum engine speed can cause severe engine damage. Use proper operating techniques for the vehicle, vessel, or equipment to prevent engine overspeed. The maximum engine speed specification is listed in Maintenance Specifications (Section V)."
08-17-2005, 11:23 AM
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Yes, post injection (used to burn of unburnt hydrocarbons and NOx) will inherently make your turbine inlet temps higher.
It was either that or run a cooled EGR system to control NOx. Which would you rather have?
Yes, advancing the injection timing will bring down your EGT's
I think that whole thing is basically the "disclaimer" that everything has nowadays to allow the manufacturer a "way out" of litigation.
Your ECM should be calibrated to know that you have exceeded either condition and react accordingly (i.e. if the engine knows you are lugging it, it should cut the power so you have to down shift). Overspeed is another phonomenon because you can manaully overspeed the engine going down a hill. Other than that scenario though, the ECM has a High speed governor that will limit engine rpm.
It was either that or run a cooled EGR system to control NOx. Which would you rather have?
Yes, advancing the injection timing will bring down your EGT's
I think that whole thing is basically the "disclaimer" that everything has nowadays to allow the manufacturer a "way out" of litigation.
Your ECM should be calibrated to know that you have exceeded either condition and react accordingly (i.e. if the engine knows you are lugging it, it should cut the power so you have to down shift). Overspeed is another phonomenon because you can manaully overspeed the engine going down a hill. Other than that scenario though, the ECM has a High speed governor that will limit engine rpm.
08-17-2005, 12:27 PM
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"Yes, post injection (used to burn of unburnt hydrocarbons and NOx) will inherently make your turbine inlet temps higher."
So whereas everyone was concerned about keeping things below 1300 before, the safe limit for a 600/610 might be a bit higher ? The big thing about EGTs was limiting the piston temp on the power stroke, right ? Now with the post event occurring late in the PS, EGTs aren't really indicative of what the piston is seeing during he peak combustion pressures.
"It was either that or run a cooled EGR system to control NOx. Which would you rather have?"
I'd rather have a post injection event ! No EGR cooler/valves, etc. Quickserve says the EGR engines weigh quite a bit more than the non EGR engines (equipped with a post injection event) and the EGR engines have a lot more sensors.
"Yes, advancing the injection timing will bring down your EGT's"
For the same work done by the engine that means less BTUs out the exhaust thus better efficiency. Very interesting.
"I think that whole thing is basically the "disclaimer" that everything has nowadays to allow the manufacturer a "way out" of litigation."
It might be a relic of the days of manually controlled engines too. Some drivers have funny habits.
"Your ECM should be calibrated to know that you have exceeded either condition and react accordingly (i.e. if the engine knows you are lugging it, it should cut the power so you have to down shift)."
Excellent to hear that. I'll let the RPMs drop and not worry. This is my first 5.9 and it is a bit different than the PSD. I'm a bit worried about lugging it too, but I am thinking the best fuel economy is at lower engine RPMs.
"Overspeed is another phonomenon because you can manaully overspeed the engine going down a hill."
Quickserver says 4200 RPM for 15 seconds is the limit. I'll be running an exhaust brake soon. Any problems revving to 3000-3500 RPM while braking ? Thats 65MPH in 3rd on my truck.
GREAT INFO BTW.
So whereas everyone was concerned about keeping things below 1300 before, the safe limit for a 600/610 might be a bit higher ? The big thing about EGTs was limiting the piston temp on the power stroke, right ? Now with the post event occurring late in the PS, EGTs aren't really indicative of what the piston is seeing during he peak combustion pressures.
"It was either that or run a cooled EGR system to control NOx. Which would you rather have?"
I'd rather have a post injection event ! No EGR cooler/valves, etc. Quickserve says the EGR engines weigh quite a bit more than the non EGR engines (equipped with a post injection event) and the EGR engines have a lot more sensors.
"Yes, advancing the injection timing will bring down your EGT's"
For the same work done by the engine that means less BTUs out the exhaust thus better efficiency. Very interesting.
"I think that whole thing is basically the "disclaimer" that everything has nowadays to allow the manufacturer a "way out" of litigation."
It might be a relic of the days of manually controlled engines too. Some drivers have funny habits.
"Your ECM should be calibrated to know that you have exceeded either condition and react accordingly (i.e. if the engine knows you are lugging it, it should cut the power so you have to down shift)."
Excellent to hear that. I'll let the RPMs drop and not worry. This is my first 5.9 and it is a bit different than the PSD. I'm a bit worried about lugging it too, but I am thinking the best fuel economy is at lower engine RPMs.
"Overspeed is another phonomenon because you can manaully overspeed the engine going down a hill."
Quickserver says 4200 RPM for 15 seconds is the limit. I'll be running an exhaust brake soon. Any problems revving to 3000-3500 RPM while braking ? Thats 65MPH in 3rd on my truck.
GREAT INFO BTW.
08-17-2005, 03:17 PM
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Originally posted by Superduty
"Yes, post injection (used to burn of unburnt hydrocarbons and NOx) will inherently make your turbine inlet temps higher."
So whereas everyone was concerned about keeping things below 1300 before, the safe limit for a 600/610 might be a bit higher ? The big thing about EGTs was limiting the piston temp on the power stroke, right ? Now with the post event occurring late in the PS, EGTs aren't really indicative of what the piston is seeing during he peak combustion pressures.
Our abort temp for turbine inlet (measured pre-turbo at the collector) is 1425. I've seen them run higher on dyno but you'll start to crack the turbine housing and exh manifold after awhile of cycling that hot. I actually haven't seen the hot gas fail a piston like you've mentioned.
"It was either that or run a cooled EGR system to control NOx. Which would you rather have?"
I'd rather have a post injection event ! No EGR cooler/valves, etc. Quickserve says the EGR engines weigh quite a bit more than the non EGR engines (equipped with a post injection event) and the EGR engines have a lot more sensors.
We agree here.
"Yes, advancing the injection timing will bring down your EGT's"
For the same work done by the engine that means less BTUs out the exhaust thus better efficiency. Very interesting.
I might get one myself.
"I think that whole thing is basically the "disclaimer" that everything has nowadays to allow the manufacturer a "way out" of litigation."
It might be a relic of the days of manually controlled engines too. Some drivers have funny habits.
"Your ECM should be calibrated to know that you have exceeded either condition and react accordingly (i.e. if the engine knows you are lugging it, it should cut the power so you have to down shift)."
Excellent to hear that. I'll let the RPMs drop and not worry. This is my first 5.9 and it is a bit different than the PSD. I'm a bit worried about lugging it too, but I am thinking the best fuel economy is at lower engine RPMs.
You'd be surprised by the numbers you'd get. Its more dependent on boost than engine speed. Take 40ish mph. I bet you'd get better fuel economy (or at lease the same) in 5th rather than 6th. Plus you'd already have power available if you have to get on it to avoid something/someone instead of having to down shift. This can really be important when towing.
"Overspeed is another phonomenon because you can manaully overspeed the engine going down a hill."
Quickserver says 4200 RPM for 15 seconds is the limit. I'll be running an exhaust brake soon. Any problems revving to 3000-3500 RPM while braking ? Thats 65MPH in 3rd on my truck.
right. I've gone down Loveland Pass at 3500 almost the whole way towing 12,000 lb trailer. I would not go over 3500. If you briefly pass it that's fine, but it its my truck I'll use the service brakes a little more to avoid spinning a bearing too hard. I love my exhaust brake though and it definitely extends your brake pad life.
GREAT INFO BTW.
"Yes, post injection (used to burn of unburnt hydrocarbons and NOx) will inherently make your turbine inlet temps higher."
So whereas everyone was concerned about keeping things below 1300 before, the safe limit for a 600/610 might be a bit higher ? The big thing about EGTs was limiting the piston temp on the power stroke, right ? Now with the post event occurring late in the PS, EGTs aren't really indicative of what the piston is seeing during he peak combustion pressures.
Our abort temp for turbine inlet (measured pre-turbo at the collector) is 1425. I've seen them run higher on dyno but you'll start to crack the turbine housing and exh manifold after awhile of cycling that hot. I actually haven't seen the hot gas fail a piston like you've mentioned.
"It was either that or run a cooled EGR system to control NOx. Which would you rather have?"
I'd rather have a post injection event ! No EGR cooler/valves, etc. Quickserve says the EGR engines weigh quite a bit more than the non EGR engines (equipped with a post injection event) and the EGR engines have a lot more sensors.
We agree here.
"Yes, advancing the injection timing will bring down your EGT's"
For the same work done by the engine that means less BTUs out the exhaust thus better efficiency. Very interesting.
I might get one myself.
"I think that whole thing is basically the "disclaimer" that everything has nowadays to allow the manufacturer a "way out" of litigation."
It might be a relic of the days of manually controlled engines too. Some drivers have funny habits.
"Your ECM should be calibrated to know that you have exceeded either condition and react accordingly (i.e. if the engine knows you are lugging it, it should cut the power so you have to down shift)."
Excellent to hear that. I'll let the RPMs drop and not worry. This is my first 5.9 and it is a bit different than the PSD. I'm a bit worried about lugging it too, but I am thinking the best fuel economy is at lower engine RPMs.
You'd be surprised by the numbers you'd get. Its more dependent on boost than engine speed. Take 40ish mph. I bet you'd get better fuel economy (or at lease the same) in 5th rather than 6th. Plus you'd already have power available if you have to get on it to avoid something/someone instead of having to down shift. This can really be important when towing.
"Overspeed is another phonomenon because you can manaully overspeed the engine going down a hill."
Quickserver says 4200 RPM for 15 seconds is the limit. I'll be running an exhaust brake soon. Any problems revving to 3000-3500 RPM while braking ? Thats 65MPH in 3rd on my truck.
right. I've gone down Loveland Pass at 3500 almost the whole way towing 12,000 lb trailer. I would not go over 3500. If you briefly pass it that's fine, but it its my truck I'll use the service brakes a little more to avoid spinning a bearing too hard. I love my exhaust brake though and it definitely extends your brake pad life.
GREAT INFO BTW.
08-17-2005, 04:49 PM
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Great answers, BigBlock2Stroke. That clarified a lot of stuff. It would be great if you could edit your post to clarify what you said...
I agree about the boost being too low at lower RPMs affecting economy. 40 MPH in OD is about 1500 RPM. Exhaust temps get pretty hot there.
What about the other end of the scale ? When is one over revving the engine ? I stumbled onto a Kenworth power spec guide recently and it told the operator when to shift and when to lug for best fuel economy. Why doesn't Dodge publish something like that ? For example, when towing up an incline I can run 2500 RPM in direct or 1800 in OD. Which gear is better for fuel economy ? Say I am running 3/4 throttle or better.
The power spec stuff is here: www.kenworth.com/KenworthPowerSpec.pdf It is a very interesting read.
I agree about the boost being too low at lower RPMs affecting economy. 40 MPH in OD is about 1500 RPM. Exhaust temps get pretty hot there.
What about the other end of the scale ? When is one over revving the engine ? I stumbled onto a Kenworth power spec guide recently and it told the operator when to shift and when to lug for best fuel economy. Why doesn't Dodge publish something like that ? For example, when towing up an incline I can run 2500 RPM in direct or 1800 in OD. Which gear is better for fuel economy ? Say I am running 3/4 throttle or better.
The power spec stuff is here: www.kenworth.com/KenworthPowerSpec.pdf It is a very interesting read.
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