Sanity Check- food for thought- EGT vs RPM
Sanity Check- food for thought- EGT vs RPM
When towing up long hills, I figured it would be better to down shift to a lower gear thereby raising RPM and decreasing the torque demand on the engine. BUT -whenever I do this my EGT goes significantly higher than if I leave it in the higher gear and add fuel?? This has me very confused and seems counter intuitive?
I have a pre-turbo pyro, stock electronic injection pump w/6mm elements. Full 3" exhaust (with low back pressure) VNT turbo pushing 1.75 bar boost (about 25Psi), with a very large air to air intercooler. I try to keep EGT below 1200F continuous. On long hills with a heavy load, I can be in 3rd gear 2500 RPM and have EGT at 1100f @ 22Psi, but loosing speed. If I downshift to second, RPM will go to about 3500, boost to 25 psi but EGT will shoot to 1400f almost immediately? If I upshift back to third and add throttle (essentially lugging the engine, I boost will go back to 25psi but EGT will not go to 1400F unless I really stomp on the pedal but even then, it takes longer for the EGT to climb from lower RPM.
It seems to me, that higher RPM with lower fuel flow seems to produce higher EGT than lower RPM with greater fuel flow? Does this make sense?
Also- I'd love to hear what others consider safe continuous EGT for the OM606 - pre-turbo of course.
Thanks
J
I have an OM606 turbo with DSL1 controller on my pickup. When I tow, I notice a something that has me a bit confused???
When towing up long hills, I figured it would be better to down shift to a lower gear thereby raising RPM and decreasing the torque demand on the engine. BUT -whenever I do this my EGT goes significantly higher than if I leave it in the higher gear and add fuel?? This has me very confused and seems counter intuitive?
I have a pre-turbo pyro, stock electronic injection pump w/6mm elements. Full 3" exhaust (with low back pressure) VNT turbo pushing 1.75 bar boost (about 25Psi), with a very large air to air intercooler. I try to keep EGT below 1200F continuous. On long hills with a heavy load, I can be in 3rd gear 2500 RPM and have EGT at 1100f @ 22Psi, but loosing speed. If I downshift to second, RPM will go to about 3500, boost to 25 psi but EGT will shoot to 1400f almost immediately? If I upshift back to third and add throttle (essentially lugging the engine, I boost will go back to 25psi but EGT will not go to 1400F unless I really stomp on the pedal but even then, it takes longer for the EGT to climb from lower RPM.
It seems to me, that higher RPM with lower fuel flow seems to produce higher EGT than lower RPM with greater fuel flow? Does this make sense?
Also- I'd love to hear what others consider safe continuous EGT for the OM606 - pre-turbo of course.
Thanks
J
Getting my TCC engagement/balistic shift programing and fueling has somewhat raised them at lower RPMS, this is so it doesn't buck while in lock up, this has raised my egts to 450 celcius. That is at 10 psi cruising at 100 km/h 28% throttle in between 1.9 lambda to 1.4 while maintaining lock up on slight grades.. And to get it to come out of lock up I have to stab the throttle and that momentarily brings it to .983 lambda for a second, but that is quick so it isn't noticeable on the egt gauge. If its on a flat road, I can cruise at 1.980 lambda to unreadable on the gauge and lower than what my egt gauge will read too...
The newish AEM wide-band may give you additional insight as to what is going on. BTW my EGT probe is in the EGR port on cyl six. Also with a ghetto laggy compound that doesn't start to light until 2500 rpm. My settings are always changing on the Baldur and my quick4 controller for further refinement. A VNT turbo would make my life easier....
Not really much advice but just some data to bounce around...
I get up to 700 Celsius at around 4500-5300 rpm at around 30-34 psi. That equates to 1.120 Lambda on my truck with some noticeable black smoke.. That is giving her climbing up a hill. My truck is basically towing all the time. Its probably close to Gross vehicle weight as an escalade esv full of camping gear. I keep an eye on the EGTS and let off if it climbs more..
Getting my TCC engagement/balistic shift programing and fueling has somewhat raised them at lower RPMS, this is so it doesn't buck while in lock up, this has raised my egts to 450 celcius. That is at 10 psi cruising at 100 km/h 28% throttle in between 1.9 lambda to 1.4 while maintaining lock up on slight grades.. And to get it to come out of lock up I have to stab the throttle and that momentarily brings it to .983 lambda for a second, but that is quick so it isn't noticeable on the egt gauge. If its on a flat road, I can cruise at 1.980 lambda to unreadable on the gauge and lower than what my egt gauge will read too...
The newish AEM wide-band may give you additional insight as to what is going on. BTW my EGT probe is in the EGR port on cyl six. Also with a ghetto laggy compound that doesn't start to light until 2500 rpm. My settings are always changing on the Baldur and my quick4 controller for further refinement. A VNT turbo would make my life easier....
Not really much advice but just some data to bounce around...
BTW- i gte no black smoke at all under boost. But I can easliy hit 1400-1500f egt under high rpm with a heavy foot.
is your 606 basically stock? If I tried to rum close to 30psi of boost, I got valve float around 4700 rpm. DId you have any issues with valve float?
BTW- i gte no black smoke at all under boost. But I can easliy hit 1400-1500f egt under high rpm with a heavy foot.
Do you have an exhaust pressure gauge? That would be a good way to see the turbo working too hard at 3500rpm/25psi.
Why not try 3500rpm and ~ 15psi? Jumping up to 25psi and 3500rpm should be a ~75% increase in HP, which seems excessive if you only want a little more to maintain speed uphill.
What turbo? Sounds like the turbo isn't as efficient at that higher RPM resulting in higher compressor outlet temp. Plus higher RPM and higher pressure both mean more mass for the intercooler to cool, so higher intercooler outlets temps. All of that is going to result in higher EGTs.
Do you have an exhaust pressure gauge? That would be a good way to see the turbo working too hard at 3500rpm/25psi.
Why not try 3500rpm and ~ 15psi? Jumping up to 25psi and 3500rpm should be a ~75% increase in HP, which seems excessive if you only want a little more to maintain speed uphill.
(08-01-2021, 06:25 AM)jav1 is your 606 basically stock? If I tried to rum close to 30psi of boost, I got valve float around 4700 rpm. DId you have any issues with valve float?
BTW- i gte no black smoke at all under boost. But I can easliy hit 1400-1500f egt under high rpm with a heavy foot.
I have a dieselmeken 7.5mm injection pump. Running my in tank fuel pump regulated to 15 psi. The stock turbo is compounded with an he351cw. I am only running that little boost as my transmission controller detects slip at around 100 mph when it is making full boost. My intercooler is also under sized. It is from an Evo III. It bolted up to my gm oil cooler bracket some how so I just kept it on there...
(08-01-2021, 06:25 AM)jav1 is your 606 basically stock? If I tried to rum close to 30psi of boost, I got valve float around 4700 rpm. DId you have any issues with valve float?
BTW- i gte no black smoke at all under boost. But I can easliy hit 1400-1500f egt under high rpm with a heavy foot.
I have a dieselmeken 7.5mm injection pump. Running my in tank fuel pump regulated to 15 psi. The stock turbo is compounded with an he351cw. I am only running that little boost as my transmission controller detects slip at around 100 mph when it is making full boost. My intercooler is also under sized. It is from an Evo III. It bolted up to my gm oil cooler bracket some how so I just kept it on there...
(08-01-2021, 04:40 PM)vica153 What turbo? Sounds like the turbo isn't as efficient at that higher RPM resulting in higher compressor outlet temp. Plus higher RPM and higher pressure both mean more mass for the intercooler to cool, so higher intercooler outlets temps. All of that is going to result in higher EGTs.
Do you have an exhaust pressure gauge? That would be a good way to see the turbo working too hard at 3500rpm/25psi.
Why not try 3500rpm and ~ 15psi? Jumping up to 25psi and 3500rpm should be a ~75% increase in HP, which seems excessive if you only want a little more to maintain speed uphill.
My turbo is the GT2256. It is a little smaller than the traditional GT2359 normally found on 606 but it is widely used on the new 3.0 v6 diesels and I've read has more modern vane geometry which is supposed to make it more efficient? I do think your right that Higher RPM exhaust flow is likely too much for the hot side of the turbo though.
I do have an Exhaust back pressure sensor but it's been a struggle to keep it working. I've gone though 4 and have a brand new 5 bar that I haven't installed yet. They keep failing despite my having a wound steel cooling loop transitioning to rubber line. The rubber line isn't melting but the sensors fail very quickly for reasons I can't figure out. I have made some logs of boost vs exhaust back pressure and it was reasonably close to 1:1.5 relative... a little worse absolute. For example- at 25psi boost :which is around 40psi absolute, exhaust PB was around 65psi absolute. Baldur reasoned that the 50 psi relative in the exhaust may be contributing to valve float.
I'm not sure I understand this statement- "Why not try 3500rpm and ~ 15psi? Jumping up to 25psi and 3500rpm should be a ~75% increase in HP" . I think you were referring to my example of climbing a hill in 3rd gear then downshifting? But - in my example I was at 2500 RPM@ 22psi boost and when I downshifted, RPM went up to 3500 @ 25 psi boost? BUT- I don't follow the increase in HP thing?? HP would be related to fuel- not boost. An increase in boost without added fuel wouldn't increase HP or am I missing the point?
(08-01-2021, 04:40 PM)vica153 What turbo? Sounds like the turbo isn't as efficient at that higher RPM resulting in higher compressor outlet temp. Plus higher RPM and higher pressure both mean more mass for the intercooler to cool, so higher intercooler outlets temps. All of that is going to result in higher EGTs.
Do you have an exhaust pressure gauge? That would be a good way to see the turbo working too hard at 3500rpm/25psi.
Why not try 3500rpm and ~ 15psi? Jumping up to 25psi and 3500rpm should be a ~75% increase in HP, which seems excessive if you only want a little more to maintain speed uphill.
My turbo is the GT2256. It is a little smaller than the traditional GT2359 normally found on 606 but it is widely used on the new 3.0 v6 diesels and I've read has more modern vane geometry which is supposed to make it more efficient? I do think your right that Higher RPM exhaust flow is likely too much for the hot side of the turbo though.
I do have an Exhaust back pressure sensor but it's been a struggle to keep it working. I've gone though 4 and have a brand new 5 bar that I haven't installed yet. They keep failing despite my having a wound steel cooling loop transitioning to rubber line. The rubber line isn't melting but the sensors fail very quickly for reasons I can't figure out. I have made some logs of boost vs exhaust back pressure and it was reasonably close to 1:1.5 relative... a little worse absolute. For example- at 25psi boost :which is around 40psi absolute, exhaust PB was around 65psi absolute. Baldur reasoned that the 50 psi relative in the exhaust may be contributing to valve float.
I'm not sure I understand this statement- "Why not try 3500rpm and ~ 15psi? Jumping up to 25psi and 3500rpm should be a ~75% increase in HP" . I think you were referring to my example of climbing a hill in 3rd gear then downshifting? But - in my example I was at 2500 RPM@ 22psi boost and when I downshifted, RPM went up to 3500 @ 25 psi boost? BUT- I don't follow the increase in HP thing?? HP would be related to fuel- not boost. An increase in boost without added fuel wouldn't increase HP or am I missing the point?
Exhaust pressure 50% higher than intake pressure seems excessive. Maybe for short bursts to build boost after transitions like shifting, but for steady state I would hope for much lower exhaust pressure. If you need that much drive pressure to maintain target boost, then I think your target boost is a bit too high.
Also, how much intake pressure do you need to have enough air to max out a 6mm pump?
With the same amount of fuel and presumably torque, a 40% increase in RPM would result in a 40% increase in HP. If you only need a little ~15% more HP to maintain speed, then you should be able to let off the accel pedal a little .....reduce the boost & fuel after shifting to 2nd. That would give you enough power to maintain speed and reduce EGTs.
Exhaust pressure 50% higher than intake pressure seems excessive. Maybe for short bursts to build boost after transitions like shifting, but for steady state I would hope for much lower exhaust pressure. If you need that much drive pressure to maintain target boost, then I think your target boost is a bit too high.
Also, how much intake pressure do you need to have enough air to max out a 6mm pump?
it seems like a wideband would be really helpful, that way you could get your afr set for each condition. I ended up getting my gtd2060vz on my 606 and have been doing a little bit of guess work to choose what boost request for what fuel.
keep us posted!
X Double Dot
08-03-2021, 11:39 AM #8Hey Jav, what is your fuel at the 2500 and 3500rpm conditions? I would think you would want your boost request table to roughly be equivalent to your fuel request, but it sounds like at 3500 you have higher boost with lower fuel request? maybe there is significant unnecessary? backpressure at this point. does lowering the boost request at the 3500 point help or hurt egt? I assume a lower boost makes egt go up, but it might be worth confirming that incase the backpressure is just that high.
it seems like a wideband would be really helpful, that way you could get your afr set for each condition. I ended up getting my gtd2060vz on my 606 and have been doing a little bit of guess work to choose what boost request for what fuel.
keep us posted!
(08-03-2021, 11:39 AM)X Double Dot Hey Jav, what is your fuel at the 2500 and 3500rpm conditions? I would think you would want your boost request table to roughly be equivalent to your fuel request, but it sounds like at 3500 you have higher boost with lower fuel request? maybe there is significant unnecessary? backpressure at this point. does lowering the boost request at the 3500 point help or hurt egt? I assume a lower boost makes egt go up, but it might be worth confirming that incase the backpressure is just that high.
it seems like a wideband would be really helpful, that way you could get your afr set for each condition. I ended up getting my gtd2060vz on my 606 and have been doing a little bit of guess work to choose what boost request for what fuel.
keep us posted!
Fuel request, and boost request tables are each based on 2 inputs- RPM on the horizontal axis and Throttle position on the vertical axis for the fuel table. For boost request, it's Fuel amount on the vertical axis.
So on the fuel table, the fuel request is the same for 2500 RPM and 3500 RPM IF the throttle is at the same position. And, the boost request is also the same at both RPM conditions as the throttle doesn't change... so this is what adds to my confusion? If I keep the throttle at the exact same setting and down shift (automatic by they way so it's pretty easy to downshift while maintaining throttle position)- the only thing that changes should be RPM. SO I should have the same fuel flow. I do get a bit more boost I think driven by the higher RPM but would think higher boost same fuel, lower torque demand "SHOULD" mean lower EGT??? Not so.
I've been doing a lot of reading and it appears lambda and AFR aren't great indicators in a diesel application. At least not in comparison to gasoline engines. There's often excess oxygen in diesel combustion and AFR values must be adjusted based on fuel composition including meth and perhaps winter/summer blends.
(08-03-2021, 11:39 AM)X Double Dot Hey Jav, what is your fuel at the 2500 and 3500rpm conditions? I would think you would want your boost request table to roughly be equivalent to your fuel request, but it sounds like at 3500 you have higher boost with lower fuel request? maybe there is significant unnecessary? backpressure at this point. does lowering the boost request at the 3500 point help or hurt egt? I assume a lower boost makes egt go up, but it might be worth confirming that incase the backpressure is just that high.
it seems like a wideband would be really helpful, that way you could get your afr set for each condition. I ended up getting my gtd2060vz on my 606 and have been doing a little bit of guess work to choose what boost request for what fuel.
keep us posted!
Fuel request, and boost request tables are each based on 2 inputs- RPM on the horizontal axis and Throttle position on the vertical axis for the fuel table. For boost request, it's Fuel amount on the vertical axis.
So on the fuel table, the fuel request is the same for 2500 RPM and 3500 RPM IF the throttle is at the same position. And, the boost request is also the same at both RPM conditions as the throttle doesn't change... so this is what adds to my confusion? If I keep the throttle at the exact same setting and down shift (automatic by they way so it's pretty easy to downshift while maintaining throttle position)- the only thing that changes should be RPM. SO I should have the same fuel flow. I do get a bit more boost I think driven by the higher RPM but would think higher boost same fuel, lower torque demand "SHOULD" mean lower EGT??? Not so.
I've been doing a lot of reading and it appears lambda and AFR aren't great indicators in a diesel application. At least not in comparison to gasoline engines. There's often excess oxygen in diesel combustion and AFR values must be adjusted based on fuel composition including meth and perhaps winter/summer blends.
Anyway, the higher RPM with same or higher boost is pushing the limits of your compressor, which means the compressor outlet temp is going to be much higher. The higher RPM also means more exhaust bottlenecked at your turbine, which is going mean higher exhaust pressure. Both of those are going to increase exhaust temp.
I would reduce your boost targets until steady state EGTs are in a comfortable range. I assume you correlate your fuel table with the boost table such that the resulting AFR is acceptable.
With a relatively small turbo, you're likely going to need to taper off your max boost target as RPM increases. I am curious how much boost it takes to max out a 6mm pump. If you only need 20psi to burn clean, then there isn't any benefit to running higher.
Can you log the boost target vs actual boost? ....Man all this cool stuff is making me wish I didn't switch you a mechanical pump.
Anyway, the higher RPM with same or higher boost is pushing the limits of your compressor, which means the compressor outlet temp is going to be much higher. The higher RPM also means more exhaust bottlenecked at your turbine, which is going mean higher exhaust pressure. Both of those are going to increase exhaust temp.
I would reduce your boost targets until steady state EGTs are in a comfortable range. I assume you correlate your fuel table with the boost table such that the resulting AFR is acceptable.
With a relatively small turbo, you're likely going to need to taper off your max boost target as RPM increases. I am curious how much boost it takes to max out a 6mm pump. If you only need 20psi to burn clean, then there isn't any benefit to running higher.
(08-03-2021, 02:14 PM)jav1(08-03-2021, 11:39 AM)X Double Dot Hey Jav, what is your fuel at the 2500 and 3500rpm conditions? I would think you would want your boost request table to roughly be equivalent to your fuel request, but it sounds like at 3500 you have higher boost with lower fuel request? maybe there is significant unnecessary? backpressure at this point. does lowering the boost request at the 3500 point help or hurt egt? I assume a lower boost makes egt go up, but it might be worth confirming that incase the backpressure is just that high.
it seems like a wideband would be really helpful, that way you could get your afr set for each condition. I ended up getting my gtd2060vz on my 606 and have been doing a little bit of guess work to choose what boost request for what fuel.
keep us posted!
Fuel request, and boost request tables are each based on 2 inputs- RPM on the horizontal axis and Throttle position on the vertical axis for the fuel table. For boost request, it's Fuel amount on the vertical axis.
So on the fuel table, the fuel request is the same for 2500 RPM and 3500 RPM IF the throttle is at the same position. And, the boost request is also the same at both RPM conditions as the throttle doesn't change... so this is what adds to my confusion? If I keep the throttle at the exact same setting and down shift (automatic by they way so it's pretty easy to downshift while maintaining throttle position)- the only thing that changes should be RPM. SO I should have the same fuel flow. I do get a bit more boost I think driven by the higher RPM but would think higher boost same fuel, lower torque demand "SHOULD" mean lower EGT??? Not so.
I've been doing a lot of reading and it appears lambda and AFR aren't great indicators in a diesel application. At least not in comparison to gasoline engines. There's often excess oxygen in diesel combustion and AFR values must be adjusted based on fuel composition including meth and perhaps winter/summer blends.
Lambda is a great indication of how much airflow you have in relation to the fuel flow. There's no clearer data to show you how much excess oxygen you have.
Baldur Gislason
(08-03-2021, 02:14 PM)jav1(08-03-2021, 11:39 AM)X Double Dot Hey Jav, what is your fuel at the 2500 and 3500rpm conditions? I would think you would want your boost request table to roughly be equivalent to your fuel request, but it sounds like at 3500 you have higher boost with lower fuel request? maybe there is significant unnecessary? backpressure at this point. does lowering the boost request at the 3500 point help or hurt egt? I assume a lower boost makes egt go up, but it might be worth confirming that incase the backpressure is just that high.
it seems like a wideband would be really helpful, that way you could get your afr set for each condition. I ended up getting my gtd2060vz on my 606 and have been doing a little bit of guess work to choose what boost request for what fuel.
keep us posted!
Fuel request, and boost request tables are each based on 2 inputs- RPM on the horizontal axis and Throttle position on the vertical axis for the fuel table. For boost request, it's Fuel amount on the vertical axis.
So on the fuel table, the fuel request is the same for 2500 RPM and 3500 RPM IF the throttle is at the same position. And, the boost request is also the same at both RPM conditions as the throttle doesn't change... so this is what adds to my confusion? If I keep the throttle at the exact same setting and down shift (automatic by they way so it's pretty easy to downshift while maintaining throttle position)- the only thing that changes should be RPM. SO I should have the same fuel flow. I do get a bit more boost I think driven by the higher RPM but would think higher boost same fuel, lower torque demand "SHOULD" mean lower EGT??? Not so.
I've been doing a lot of reading and it appears lambda and AFR aren't great indicators in a diesel application. At least not in comparison to gasoline engines. There's often excess oxygen in diesel combustion and AFR values must be adjusted based on fuel composition including meth and perhaps winter/summer blends.
Lambda is a great indication of how much airflow you have in relation to the fuel flow. There's no clearer data to show you how much excess oxygen you have.
Baldur Gislason
My reading suggests that tuning a diesel via emphasis on AFR may be less effective than via EGT. I'm sure there are other opinions but my understadnig is that unlike gasoline where a stoichiometric mixture is key to cumbustion, in a diesel there are instances where having an excess of fuel, and/or an excess of air can be very beneficial. For example, I've read an of excess boost can be very beneficial in cylinder purging and reduciing EGT... so I'm not sure targetting only enough boost for injected fuel is correct... but it may be?
Also- on the VGT control, I'm finding it more complex than I thought and many of the strategies also rope in EGR fuction, which is not my primary concern. And- the way the VGT itself works is a bit counter intuitive. IE. vanes closed increases back pressure to increase exhaust velocity BUT there.s a delicate balance as to where exactly the vanes need to be where the gains from boost offset the losses from back pressure at low RPM (EGR indpendant) AND- the compressors efficency isn't very good unless the vanes are at about 60% open. I've even read that the postion of the vanes don't produce linear results to boost based on position in different flow conditions, For example- its not as simple as closeing vanes increases boost and opennig vnaes decreases boost becuase in certain flow conditions closing the vanes will decrease and not increase boost and visa versa.
I do plan on running some tests once I install my new exhaust BP sensor but it is a learning experience.
We must be really geeky to find this stuff interesting but i do also. I'm learning and sadly there isn't a alot out there for how to tune a VNT turbo. To address your point that there isn't any benefot to having more boost than required to burn clean- thats an intersting point that I'm not sure about?
My reading suggests that tuning a diesel via emphasis on AFR may be less effective than via EGT. I'm sure there are other opinions but my understadnig is that unlike gasoline where a stoichiometric mixture is key to cumbustion, in a diesel there are instances where having an excess of fuel, and/or an excess of air can be very beneficial. For example, I've read an of excess boost can be very beneficial in cylinder purging and reduciing EGT... so I'm not sure targetting only enough boost for injected fuel is correct... but it may be?
Also- on the VGT control, I'm finding it more complex than I thought and many of the strategies also rope in EGR fuction, which is not my primary concern. And- the way the VGT itself works is a bit counter intuitive. IE. vanes closed increases back pressure to increase exhaust velocity BUT there.s a delicate balance as to where exactly the vanes need to be where the gains from boost offset the losses from back pressure at low RPM (EGR indpendant) AND- the compressors efficency isn't very good unless the vanes are at about 60% open. I've even read that the postion of the vanes don't produce linear results to boost based on position in different flow conditions, For example- its not as simple as closeing vanes increases boost and opennig vnaes decreases boost becuase in certain flow conditions closing the vanes will decrease and not increase boost and visa versa.
I do plan on running some tests once I install my new exhaust BP sensor but it is a learning experience.
Baldur Gislason
You need a certain amount of excess air, but trying to run leaner than that will only overwork the turbo and cause excessive back pressure. I find a lambda of 1.5 or so is great for cruising, and part throttle heavy load I like to be in the 1.2-1.3 region. Full throttle I may run as rich as 1.0 for short durations but that will result in high EGT and visible but not thick smoke, 1.1-1.2 is where it is mostly clean and not excessively hot.
Baldur Gislason
Baldur Gislason
I like the AEM X series 30-0300 gauge or 30-0310 inline controller. They each have CAN bus output for accurate logging and while the gauge displays up to 2.0 lambda it outputs values up to 6.5 lambda via CAN. Most other wide band options in the aftermarket don't read any leaner than 1.36 or 1.5 so the AEM X series is a really good option for a diesel due to its wide range in the lean region.
Baldur Gislason
I'll look into it... So I presume there is some compensation/ processing performed in the gauge that prevent the sensors direct hook up to the DSL-1? I'll likely need some guidance on how to facilitate the CAN communication with the DSL to facilitate logging... but that will be down the line.
Looking now but my specs say: "CANBUS OUTPUT LAMBDA VALUES OF .55 - 2.0" PART # 30-0310
I learn something new every day!
I'll look into it... So I presume there is some compensation/ processing performed in the gauge that prevent the sensors direct hook up to the DSL-1? I'll likely need some guidance on how to facilitate the CAN communication with the DSL to facilitate logging... but that will be down the line.
Looking now but my specs say: "CANBUS OUTPUT LAMBDA VALUES OF .55 - 2.0" PART # 30-0310
Yes the sensor itself does not output a lambda signal, it needs an active controller to generate the lambda signal. I have developed my own technology on that front which is present in the current generation LPC8 ECU, I may introduce other hardware that includes this at a later date.
Baldur Gislason
Those specs are inaccurate, the actual range is up to 6.55 lambda. However 2.0 is still better than most, and really sufficient. Only time you will see really leaner than 2.0 is idle and coasting.
Yes the sensor itself does not output a lambda signal, it needs an active controller to generate the lambda signal. I have developed my own technology on that front which is present in the current generation LPC8 ECU, I may introduce other hardware that includes this at a later date.
Baldur Gislason
I had a PLX devices wideband and it doesn't read near lean enough. The giant module boxes are annoying and take up way too much space. I switched to the X series AEM and never looked back. I have the whole PLX multi-gauge suite in my silvia and the DM-6 gauges are buggier than hell. Save yourself the space and headaches and go for the AEM. PLX has excellent customer service, but their products are in my opinion, inferior to the AEM.
(08-07-2021, 01:58 PM)TE27Levin I had a PLX devices wideband and it doesn't read near lean enough. The giant module boxes are annoying and take up way too much space. I switched to the X series AEM and never looked back. I have the whole PLX multi-gauge suite in my silvia and the DM-6 gauges are buggier than hell. Save yourself the space and headaches and go for the AEM. PLX has excellent customer service, but their products are in my opinion, inferior to the AEM.
Yes unfortunately PLX quality has gone to shit. Their early wide band controllers for the LSU4.2 were good, I had one for years in my mobile kit, mapped hundreds of cars with it, but they didn't have any nice gauges at the time so I built my own display for it.
The latest version which has a plastic case is basically trash, I measured the analog output impedance and it was 10 kilo ohms meaning you can't really connect anything to it without skewing the signal.
And the touch screen multi gauges are glitchy as hell, I fitted one in my buddy's RS6 and sometimes it decides to not display any numbers, only the lights, but the logo is always displayed on start up so it's not a hardware fault.
AEM don't have a great history in the instrumentation market, their earlier gauges were terribly inaccurate and the analog output voltage is nowhere close to what is specified in the manual. However the X series changes all of this, it has a dead accurate analog output and even better it has CAN bus.
Baldur Gislason
(08-07-2021, 01:58 PM)TE27Levin I had a PLX devices wideband and it doesn't read near lean enough. The giant module boxes are annoying and take up way too much space. I switched to the X series AEM and never looked back. I have the whole PLX multi-gauge suite in my silvia and the DM-6 gauges are buggier than hell. Save yourself the space and headaches and go for the AEM. PLX has excellent customer service, but their products are in my opinion, inferior to the AEM.
Yes unfortunately PLX quality has gone to shit. Their early wide band controllers for the LSU4.2 were good, I had one for years in my mobile kit, mapped hundreds of cars with it, but they didn't have any nice gauges at the time so I built my own display for it.
The latest version which has a plastic case is basically trash, I measured the analog output impedance and it was 10 kilo ohms meaning you can't really connect anything to it without skewing the signal.
And the touch screen multi gauges are glitchy as hell, I fitted one in my buddy's RS6 and sometimes it decides to not display any numbers, only the lights, but the logo is always displayed on start up so it's not a hardware fault.
AEM don't have a great history in the instrumentation market, their earlier gauges were terribly inaccurate and the analog output voltage is nowhere close to what is specified in the manual. However the X series changes all of this, it has a dead accurate analog output and even better it has CAN bus.
Baldur Gislason
EGT and Exhaust pressure are going to be more useful for you to optimize your VNT turbo. Finding exact specs on those VNT Garrett turbos is a pain. Its on the small side though. I think you might end up tapering to 20psi @ 3500rpm and 15psi @ 4000.
I feel like I derailed the thread by bringing up AFR. I only mentioned AFR in the broad sense that you're running lean enough to burn clean. Precisely monitoring AFR would be nice to have, but luckily with diesels you can just add fuel until it gets smokey and then pull back a little.
EGT and Exhaust pressure are going to be more useful for you to optimize your VNT turbo. Finding exact specs on those VNT Garrett turbos is a pain. Its on the small side though. I think you might end up tapering to 20psi @ 3500rpm and 15psi @ 4000.
Anyway- I spent the better part of an afternoon doing various types of runs to figure out how to best setup the VNT control, I confess I didn't make a lot of progress. For example- one area I wanted to improve was initial take off from a standing start. Right now if I jab the throttle at a stop sign, I get good puff of black smoke. I wanted to tune the VNT to provide the most boost to back pressure ratio without using the smoke limiting fuel table to try and curtail that. I adjusted the boost control duty cycle min/max tables to have no effect and created base duty cycle tables with a single value. The intent being to see what duty cycle produced the best boost to EBP ratio during a normal start from a stop sign.
In my setup, 100% duty cycle closes the VNT vanes, 0% =vanes are wide open. I ran several tests starting at 90% duty cycle and going down to 30% in 10% increments doing a 50% throttle start from a stop up to 25MPH on the same stretch of road- while logging boost duty cycle, map and EBP pressures and monitoring smoke and EGT. What i found was a bit confusing. There was very little difference between the 90% duty cycle run and the 30% run. I questioned weather the VNT mechanism was even working but at idle, I could make changes to the base duty cycle table and can tell the vanes are working due to an audible change in exhaust note and, I can see a small change in EBP consistent with duty cycle change. i just expected a more noticeable difference with such major vane position differences on acceleration runs -all other things being equal?
The 90% duty cycle did bring boost up a tiny bit quicker and it did have slightly more EBP not nothing note worthy. In fact- I used a block of wood under the pedal to have a consistent hard stop for the 50% throttle and the block wasn't perfect. Some runs are at 48% some are 52% throttle. The 4% difference in throttle position had a bigger impact on EBP than 20% duty cycle jumps in vane position differences??
I also ran 1 WOT run in 2nd gear from a stop to 5000 RPM. The truck pulled fine but EGT got to 1600F! EBP got about 45 psi- boost 27.
I was not making progress and at one point the EBP sensor log would climb- then go flat (as if pressure vanished ) then spiked back up.... i quit for the day and while the truck is running well, I feel my tuning efforts aren't producing the expected results. I needed to clear my head and I'll go back at it fresh but I'm struggling a bit
I will end up adding the Lambda sensor but this weekend I did fit up and program a new exhaust back pressure sensor (ford 6.0 power stroke). It is working but not as well as I'd like. It seems to completely cut out at times.
Anyway- I spent the better part of an afternoon doing various types of runs to figure out how to best setup the VNT control, I confess I didn't make a lot of progress. For example- one area I wanted to improve was initial take off from a standing start. Right now if I jab the throttle at a stop sign, I get good puff of black smoke. I wanted to tune the VNT to provide the most boost to back pressure ratio without using the smoke limiting fuel table to try and curtail that. I adjusted the boost control duty cycle min/max tables to have no effect and created base duty cycle tables with a single value. The intent being to see what duty cycle produced the best boost to EBP ratio during a normal start from a stop sign.
In my setup, 100% duty cycle closes the VNT vanes, 0% =vanes are wide open. I ran several tests starting at 90% duty cycle and going down to 30% in 10% increments doing a 50% throttle start from a stop up to 25MPH on the same stretch of road- while logging boost duty cycle, map and EBP pressures and monitoring smoke and EGT. What i found was a bit confusing. There was very little difference between the 90% duty cycle run and the 30% run. I questioned weather the VNT mechanism was even working but at idle, I could make changes to the base duty cycle table and can tell the vanes are working due to an audible change in exhaust note and, I can see a small change in EBP consistent with duty cycle change. i just expected a more noticeable difference with such major vane position differences on acceleration runs -all other things being equal?
The 90% duty cycle did bring boost up a tiny bit quicker and it did have slightly more EBP not nothing note worthy. In fact- I used a block of wood under the pedal to have a consistent hard stop for the 50% throttle and the block wasn't perfect. Some runs are at 48% some are 52% throttle. The 4% difference in throttle position had a bigger impact on EBP than 20% duty cycle jumps in vane position differences??
I also ran 1 WOT run in 2nd gear from a stop to 5000 RPM. The truck pulled fine but EGT got to 1600F! EBP got about 45 psi- boost 27.
I was not making progress and at one point the EBP sensor log would climb- then go flat (as if pressure vanished ) then spiked back up.... i quit for the day and while the truck is running well, I feel my tuning efforts aren't producing the expected results. I needed to clear my head and I'll go back at it fresh but I'm struggling a bit
What was the vane position for the 5000rpm 27psi run? Again, do need more than 20psi to burn all the fuel? I think step 1 should be getting WOT boost to hit the correct target. That is usually easier than controlling boost in all the variable situations. I would think your vane DC% would be near zero by 4000rpm.
As far as jabbing the throttle from a stop, fixing that depends on exactly what you have available for tuning parameters relative to vane&boost control. For starters you could set the vane DC% to max and then reduce fuel until the level of smoke is more acceptable. After that it's just a matter of making the normal boost control have a high vane DC% when you need it.
Assuming you 0-25mph tests were not hitting higher RPM, I think one thing they showed was that at lower rpm your vane DC% can quickly max out as TPS% increases without having to worry about excessive exhaust pressure.
At lower RPMs and lower fuel levels, it looks like the exhaust flow is low enough to not drastically increase pressure with vane position. Assuming the actuator is functioning properly thru its full range of motion. How much is that 4% change in throttle changing fuel? 48 to 52 is an 8% increase in TPS%, so if your fuel increased by 8% that would be a significant change in exhaust flow.
What was the vane position for the 5000rpm 27psi run? Again, do need more than 20psi to burn all the fuel? I think step 1 should be getting WOT boost to hit the correct target. That is usually easier than controlling boost in all the variable situations. I would think your vane DC% would be near zero by 4000rpm.
As far as jabbing the throttle from a stop, fixing that depends on exactly what you have available for tuning parameters relative to vane&boost control. For starters you could set the vane DC% to max and then reduce fuel until the level of smoke is more acceptable. After that it's just a matter of making the normal boost control have a high vane DC% when you need it.
Assuming you 0-25mph tests were not hitting higher RPM, I think one thing they showed was that at lower rpm your vane DC% can quickly max out as TPS% increases without having to worry about excessive exhaust pressure.
a few things in response.
From a dead stop to 25 MPH @ 50% throttle is a 1st gear pull. RPM never gets above 2500. 48-52% throttle is only 4% difference and while the fuel table does go from 46.7-58.7 in this test- the changes in fuel are as much a function of RPM change than the 4% throttle position difference.
Vane duty cycle at 5000 rpm 27 PSI is around 30% which is essentially vanes wide open. This might be hard to understand but I "Characterized" vane position vs duty cycle on the bench because the vacuum actuator motion isn't "linear". I know I only expressed full open/duty cycle and full close/duty cycle but at 30% duty cycle the vanes aren't 30% from being open they are more like 95% open.
Jabbing the throttle- My intent here wasn't really to reduce smoke. My intent was to understand how the turbo would "react" to large changes in VNT duty cycle (and its resulting VNT vane position) during a normal standing start. I expected to see differences or at least trends in map and EBP based on such a wide range of fixed vane positions. But I did NOT see that. The differences were rather minimal going from 90% all the way to 30% in this basic test. What differences there were seemed as impacted by very small variations in throttle input (4%) versus the very large differences in duty cycle (60%).
I expected the fixed 90% duty cycle to produce quicker spool up and higher EBP at the end of log. AND I expected the 30% duty cycle to produce slower spool up and lower EBP at the end of the Log. This didn't happen to any significant degree. Both spool up and EBP were very similar regardless of duty cycle and very minimal differences in pedal position.
It's not making sense to me.
Vica153-
a few things in response.
From a dead stop to 25 MPH @ 50% throttle is a 1st gear pull. RPM never gets above 2500. 48-52% throttle is only 4% difference and while the fuel table does go from 46.7-58.7 in this test- the changes in fuel are as much a function of RPM change than the 4% throttle position difference.
Vane duty cycle at 5000 rpm 27 PSI is around 30% which is essentially vanes wide open. This might be hard to understand but I "Characterized" vane position vs duty cycle on the bench because the vacuum actuator motion isn't "linear". I know I only expressed full open/duty cycle and full close/duty cycle but at 30% duty cycle the vanes aren't 30% from being open they are more like 95% open.
Jabbing the throttle- My intent here wasn't really to reduce smoke. My intent was to understand how the turbo would "react" to large changes in VNT duty cycle (and its resulting VNT vane position) during a normal standing start. I expected to see differences or at least trends in map and EBP based on such a wide range of fixed vane positions. But I did NOT see that. The differences were rather minimal going from 90% all the way to 30% in this basic test. What differences there were seemed as impacted by very small variations in throttle input (4%) versus the very large differences in duty cycle (60%).
I expected the fixed 90% duty cycle to produce quicker spool up and higher EBP at the end of log. AND I expected the 30% duty cycle to produce slower spool up and lower EBP at the end of the Log. This didn't happen to any significant degree. Both spool up and EBP were very similar regardless of duty cycle and very minimal differences in pedal position.
It's not making sense to me.
If the vanes are all the way open, that means the turbo can't reduce the boost below 27psi. The OM648 ran the same turbo and has no problem limiting boost to 15-20psi @ WOT and I'd be willing to bet the vanes weren't fully open at that point.
My 2056 is a slightly smaller turbo, but with the vanes fixed in the open position boost struggles to get much above 10psi. I think something isn't functioning correctly if "fully open" vanes still results in 22-27psi.
Yeah that really doesn't make sense. Doesn't the VNT actuator have a position output so you can monitor the actual position while driving? If the actuator works by itself, are the vanes sticking? Especially the 5000rpm 27psi with the vanes "fully open". That is quite odd. Unless you're talking absolute pressure, so only ~13psi of boost above atmospheric.
If the vanes are all the way open, that means the turbo can't reduce the boost below 27psi. The OM648 ran the same turbo and has no problem limiting boost to 15-20psi @ WOT and I'd be willing to bet the vanes weren't fully open at that point.
My 2056 is a slightly smaller turbo, but with the vanes fixed in the open position boost struggles to get much above 10psi. I think something isn't functioning correctly if "fully open" vanes still results in 22-27psi.
NO- no feedback on the vacuum actuator. Newer VNT turbos (like the latest VW tdi) had feedback on the vacuum actuator and the newer motor driven actuators have feedback but mine is old school with no feed back. I believe the vanes are working and when I look and test it in the garage- the actuator is moving to the expected positions.... does something happen on the road that doesn't in the shop? Maybe -but I doubt it.
Well herein lies some of my problem. AS best as I can tell, and I've done a lot of reading... the vanes and their control strategy isn't as simple as closing them raises boost and opening them lowers boost. I wish it was that simple but I'm finding that its not.... which is why I'm trying to "learn" how vane position effects boost at varying load conditions.
Here's what my reading suggests. The vanes can be closed to raise exhaust velocity, at the expense of restricting flow BUT in the closed or nearly closed position it does not direct the exhaust flow towards the turbine. In fact some vane positions, at certain flow values, do direct flow towards the turbine and produce more spooling than more "closed" positions. Suggesting that vectoring flow may be more advantageous than higher velocity in certain conditions. Turbine efficiencies vary and are outside of peak efficiencies' at most locations other than an Ideal position which is somewhere around 60% open.
I struggling to understand control but as I said- the truck runs really well, and pulls hard. My biggest complaint is high-ish EGT. I do have a VNT 2359 but I was hoping to nail down the control strategy on what I have before introducing a new variable.
Nope not absolute pressure- my numbers are relative to 1 atmosphere.
NO- no feedback on the vacuum actuator. Newer VNT turbos (like the latest VW tdi) had feedback on the vacuum actuator and the newer motor driven actuators have feedback but mine is old school with no feed back. I believe the vanes are working and when I look and test it in the garage- the actuator is moving to the expected positions.... does something happen on the road that doesn't in the shop? Maybe -but I doubt it.
Well herein lies some of my problem. AS best as I can tell, and I've done a lot of reading... the vanes and their control strategy isn't as simple as closing them raises boost and opening them lowers boost. I wish it was that simple but I'm finding that its not.... which is why I'm trying to "learn" how vane position effects boost at varying load conditions.
Here's what my reading suggests. The vanes can be closed to raise exhaust velocity, at the expense of restricting flow BUT in the closed or nearly closed position it does not direct the exhaust flow towards the turbine. In fact some vane positions, at certain flow values, do direct flow towards the turbine and produce more spooling than more "closed" positions. Suggesting that vectoring flow may be more advantageous than higher velocity in certain conditions. Turbine efficiencies vary and are outside of peak efficiencies' at most locations other than an Ideal position which is somewhere around 60% open.
I struggling to understand control but as I said- the truck runs really well, and pulls hard. My biggest complaint is high-ish EGT. I do have a VNT 2359 but I was hoping to nail down the control strategy on what I have before introducing a new variable.
2256 is roughly a ~30lb/min compressor at best. 3L running 27psi @ 5000rpm is roughly 50lb/min. Thats enough air to make over 400hp, but only if you have a big intercooler and were actually on the compressor map. Yours is going to be a bit less since you're WAY off the map, but still probably ~40lb/min. Pretty amazing the turbo can actually do that, but it comes at the cost of way overspeeding your turbo which is unlikely to last long. The 400F increase in EGT is likely due to the compressor outlet temp increasing by 400F. I think its almost impossible that your compressor outlet temps are less than 400F and more likely they're closer to 500F.
A good boost limit for a 30lb/min compressor would be 25psi @ 3000rpm, 20psi @ 3500rpm, 15psi @ 4000rpm, 10psi @ 5000rpm. That would be pushing the limits of the compressor and should keep your turbo happy while still pushing enough air to make 250+hp. If you're running a stock 606 injection pump, then I still think 20psi is plenty to cleanly max it out. So you should really have a max target of 20psi until 3500rpm and then taper off.
I would also still argue that something must not be working correctly with the VNT. I have worked on custom VNT setups on a 617 and 606. Even with crude mechanical attempts at vane control (that do a poor job taking advantage of the VNT), we never had any issue with the turbo wanting to run high boost levels even with the vanes open. I have also found examples of other people tuning electronic VNT turbos using basic mapping without having issues with out of control boost limits.
I would try removing the actuator, checking the range of motion of the vanes, locking the vanes at full open and see what your boost does then. If it still wants to hit 20+ psi at 5000rpm then either something else isn't working and/or you're going to want an external wastegate to get boost under control.
Closing the vanes at high rpm to restrict flow and lower boost would be very tricky and even if it worked it would counterproductive in terms of power & efficiency.
I would definitely get your peak boost under control ASAP. I finally got around to doing the math on that. It's so bad I almost don't believe you lol.
2256 is roughly a ~30lb/min compressor at best. 3L running 27psi @ 5000rpm is roughly 50lb/min. Thats enough air to make over 400hp, but only if you have a big intercooler and were actually on the compressor map. Yours is going to be a bit less since you're WAY off the map, but still probably ~40lb/min. Pretty amazing the turbo can actually do that, but it comes at the cost of way overspeeding your turbo which is unlikely to last long. The 400F increase in EGT is likely due to the compressor outlet temp increasing by 400F. I think its almost impossible that your compressor outlet temps are less than 400F and more likely they're closer to 500F.
A good boost limit for a 30lb/min compressor would be 25psi @ 3000rpm, 20psi @ 3500rpm, 15psi @ 4000rpm, 10psi @ 5000rpm. That would be pushing the limits of the compressor and should keep your turbo happy while still pushing enough air to make 250+hp. If you're running a stock 606 injection pump, then I still think 20psi is plenty to cleanly max it out. So you should really have a max target of 20psi until 3500rpm and then taper off.
I would also still argue that something must not be working correctly with the VNT. I have worked on custom VNT setups on a 617 and 606. Even with crude mechanical attempts at vane control (that do a poor job taking advantage of the VNT), we never had any issue with the turbo wanting to run high boost levels even with the vanes open. I have also found examples of other people tuning electronic VNT turbos using basic mapping without having issues with out of control boost limits.
I would try removing the actuator, checking the range of motion of the vanes, locking the vanes at full open and see what your boost does then. If it still wants to hit 20+ psi at 5000rpm then either something else isn't working and/or you're going to want an external wastegate to get boost under control.
Closing the vanes at high rpm to restrict flow and lower boost would be very tricky and even if it worked it would counterproductive in terms of power & efficiency.
Hey John, FWIW, Mine responds to backing off on the tougher climbs both by backing off the throttle and downshifting. I need to keep the boost up to around 20 psi. Egt drops from 1400 to 1200. Takes a little longer to finish the climb but who cares? Most of the truckers follow the same strategy. It's a diesel baby! I can't go 20 miles on the Interstate without hitting 5% grades in WV, so I don't have a choice.
50harleyrider
10-25-2021, 11:10 AM #27Hey John, FWIW, Mine responds to backing off on the tougher climbs both by backing off the throttle and downshifting. I need to keep the boost up to around 20 psi. Egt drops from 1400 to 1200. Takes a little longer to finish the climb but who cares? Most of the truckers follow the same strategy. It's a diesel baby! I can't go 20 miles on the Interstate without hitting 5% grades in WV, so I don't have a choice.
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