OM606 Turbo Selection for Truck application
OM606 Turbo Selection for Truck application
As to VE- you might have a point but I can't imagine VE to be so different at 2500 vs 3500 RPM given the same boost? I would understand a 5% reduction in efficiency but I don't "think" it would be more than that on a boosted 4 valve engine?? I'm seeing 20% + increases in EGT.
My fuel map is like yours, fuel request at 50% throttle is 58.7 (table value) and it's the same from 2000 -4500 RPM. I'm not sure how to correlate the table values of delivered fuel (in ul) but- this is what confused me and caused me to really think about what might be happening at the thermocouple. This lead me to suspect the turbo exhaust restriction as possibly contributing to the higher EGT?
In my mind- going a constant speed with the same load- IF - 50% throttle @ 2500 RPM & 3500 RPM produces:
- the exact same fuel delivery per the fuel request table at both RPM points,
AND - the same exact boost request per the Boost target table at both RPM points,
then the a couple things logically follow:
1: The engine must be under "less" load (less torque demanded) at higher RPM by virtue of being in a lower gear-
2: There must be more exhaust flow across the EGT due to the higher RPM.
So why then is the EGT significantly higher at the same fuel and boost?
a: It could be the intake air spends less time in the intercooler (due to the higher flow) and thus "cools" off less.
b: I could be the higher exhaust flow across the thermocouple is backing up due to the smallish turbo exhaust section and saturating the probe (increasing the time (duty cycle) the probe sits in the hot pulsed exhaust gases versus the cooling pulses that occur between combustion events) ?
I've read a lot people see significant reduction in EGT by going to a free flowing exhaust and I think that's because the exhaust velocity and the cooling pulses help "cool" the probe. I know my exhaust is very free flowing so this leads me to suspect the turbo?
How did you get to 100% fueling = 83ul of fuel? I do still have the stock (6mm) pump.
BTW- I've not made any plans for the turbo and I may be willing to part with it once I install the 2359 but I don't know when I'll have time to do it OR if I will like it better than the 2056.
Since EMAP pressures are related to boost pressures, I've intentionally set my max boost to about 26 psi (2750 mbar max boost request) to try to keep EMAP away from the valve float pressures.
As to VE- you might have a point but I can't imagine VE to be so different at 2500 vs 3500 RPM given the same boost? I would understand a 5% reduction in efficiency but I don't "think" it would be more than that on a boosted 4 valve engine?? I'm seeing 20% + increases in EGT.
My fuel map is like yours, fuel request at 50% throttle is 58.7 (table value) and it's the same from 2000 -4500 RPM. I'm not sure how to correlate the table values of delivered fuel (in ul) but- this is what confused me and caused me to really think about what might be happening at the thermocouple. This lead me to suspect the turbo exhaust restriction as possibly contributing to the higher EGT?
In my mind- going a constant speed with the same load- IF - 50% throttle @ 2500 RPM & 3500 RPM produces:
- the exact same fuel delivery per the fuel request table at both RPM points,
AND - the same exact boost request per the Boost target table at both RPM points,
then the a couple things logically follow:
1: The engine must be under "less" load (less torque demanded) at higher RPM by virtue of being in a lower gear-
2: There must be more exhaust flow across the EGT due to the higher RPM.
So why then is the EGT significantly higher at the same fuel and boost?
a: It could be the intake air spends less time in the intercooler (due to the higher flow) and thus "cools" off less.
b: I could be the higher exhaust flow across the thermocouple is backing up due to the smallish turbo exhaust section and saturating the probe (increasing the time (duty cycle) the probe sits in the hot pulsed exhaust gases versus the cooling pulses that occur between combustion events) ?
I've read a lot people see significant reduction in EGT by going to a free flowing exhaust and I think that's because the exhaust velocity and the cooling pulses help "cool" the probe. I know my exhaust is very free flowing so this leads me to suspect the turbo?
How did you get to 100% fueling = 83ul of fuel? I do still have the stock (6mm) pump.
BTW- I've not made any plans for the turbo and I may be willing to part with it once I install the 2359 but I don't know when I'll have time to do it OR if I will like it better than the 2056.
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