Smoky slow diesels
Discussion
300bhp/ton said:
that is the B5.9 Cummins. I had one in a tractor for 8 years/6500+ hrs at a much lower power rating than the 500 hp they thought that pickup might have.The smoke is when the turbo spools up. Really, to get that amount of power reliably he needs the 15litre in it.
When those heavy duty diesels are set up properly there should be a haze coming from the stack when they are under full load, not a nuclear winter.
It also sounds like it is screaming its head off. I doubt that it running at 2200 rpm
Like a gasoline engine, a diesel engine makes best torque when the air to fuel ratio is significantly richer than stoichometric (ideal mass of fuel to use all the air in the cylinder) In a gasoline, the unburnt but vapourised and hot gasoline just burns off cleanly in the exhaust (sometimes as flames at the tailpipe when it's really rich ;-) But in a diesel, with exhaust temps being so much lower, and the fuel much less volatile, the unburnt hydocarbons tend to not fully oxidise, and form soot, which it the hazy clud you see being chucked out the tailpipe.
Modern CR diesel run at a minimium AFR of approx 16:1, whereas peak torque will be down at approx 12:1. Hence, especially when chipped etc, when making peak torque is important (usually at low rpm, below the boost threshold) the engine will be run as rich as possible (within the smoke limits set by the OEM if std) to make the most na torque, in an effort to smooth the transition into boost and the much high torque that the increased airflow can now support, even at a much leander AFR.
The "smoke limit" maps, are usually the first to be culled by the aftermarket chippers, in an effort to maximise torque, but at the expense of smoke production.
Modern CR diesel run at a minimium AFR of approx 16:1, whereas peak torque will be down at approx 12:1. Hence, especially when chipped etc, when making peak torque is important (usually at low rpm, below the boost threshold) the engine will be run as rich as possible (within the smoke limits set by the OEM if std) to make the most na torque, in an effort to smooth the transition into boost and the much high torque that the increased airflow can now support, even at a much leander AFR.
The "smoke limit" maps, are usually the first to be culled by the aftermarket chippers, in an effort to maximise torque, but at the expense of smoke production.
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