Was just doing some reading on bio-diesel and found this write-up.
http://biodiesel.infopop.cc/eve/forums/a/tpc/f/419605551/m/2721003282/p/1
Summary is that many 2007+ Diesel motors will inject a small amount of fuel after the combustion process just to be vaporized and flushed out to the DPF..
First question I have is do our diesels do this?
Second is, does anyone else think this is odd? Wouldn't the bio diesel showing up in the crank case (sump) suggest a large amount of cylinder blow-by? Also, why don't we see a large amount of dino diesel showing up now if this is the case? We are supposed to believe that dino diesel atomizes substantially better and thus is exhausted more efficiently, but bio-diesel is plenty adequate for combustion?
EDIT: Answer to question #2
Post-injection of fuel into the cylinders is intended to vaporize in the cylinder but not combust, exiting then through the exhaust valves and traveling downstream where the introduction of the unburned fuel to the catalyst creates an exothermic reaction incinerating the collected soot. Inevitably the heavier fractions of fuel will not vaporize during post-injection and in liquid form can adhere to the cylinder walls. Through the slapping motion of the pistons and oil rings, the unburned fuel from post-injection can make its way through the tight, hot quarters between the piston, rings and cylinder walls. The fuel accumulates in the crankcase and dilutes the oil, which is a major concern regarding engine wear and longevity.
"Using post-injection you will generally see elevated levels of fuel dilution regardless of what fuel you're using," Sappok says. Because biodiesel has a higher distillation temperature and boiling point, when it's present in the post-injected fuel it tends to dilute the oil on a level disproportionate to its blend ratio in the fuel. Fang says this is just now becoming understood.
from here:
http://www.biodieselmagazine.com/articles/2290/understanding-the-post-injection-problem/
http://biodiesel.infopop.cc/eve/forums/a/tpc/f/419605551/m/2721003282/p/1
Summary is that many 2007+ Diesel motors will inject a small amount of fuel after the combustion process just to be vaporized and flushed out to the DPF..
First question I have is do our diesels do this?
Second is, does anyone else think this is odd? Wouldn't the bio diesel showing up in the crank case (sump) suggest a large amount of cylinder blow-by? Also, why don't we see a large amount of dino diesel showing up now if this is the case? We are supposed to believe that dino diesel atomizes substantially better and thus is exhausted more efficiently, but bio-diesel is plenty adequate for combustion?
EDIT: Answer to question #2
Post-injection of fuel into the cylinders is intended to vaporize in the cylinder but not combust, exiting then through the exhaust valves and traveling downstream where the introduction of the unburned fuel to the catalyst creates an exothermic reaction incinerating the collected soot. Inevitably the heavier fractions of fuel will not vaporize during post-injection and in liquid form can adhere to the cylinder walls. Through the slapping motion of the pistons and oil rings, the unburned fuel from post-injection can make its way through the tight, hot quarters between the piston, rings and cylinder walls. The fuel accumulates in the crankcase and dilutes the oil, which is a major concern regarding engine wear and longevity.
"Using post-injection you will generally see elevated levels of fuel dilution regardless of what fuel you're using," Sappok says. Because biodiesel has a higher distillation temperature and boiling point, when it's present in the post-injected fuel it tends to dilute the oil on a level disproportionate to its blend ratio in the fuel. Fang says this is just now becoming understood.
from here:
http://www.biodieselmagazine.com/articles/2290/understanding-the-post-injection-problem/
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