Bomber209 said:
I only meant a small dribble into the cylinder, and if that got passed the 'Rings' there wouldn't be enough left to cause the destructive problem you meant.
That was kinda my point, that it's such a small amount of fuel that it couldn't cause hydrolock, but also couldn't result in the amount of fuel dilution people are experiencing, even assuming your theory of how it works is correct.
Lets throw some numbers at it and see what comes out?
A VERY rough calculation of the fuel involved in one post injection can be made.
Fuel consumption 5.3 litres per 100km at a speed of 100 km/h (my actual figures)
1 hr = 5.3 litres
1 minute = 0.08833 litres
1500 engine revolutions per minute, and two injections per revolution (four cylinders) = 3000 injections per minute
0.8833/3000 = 0.00002944 litres of fuel per injection
Post injections are about 30% the volume of main injections (purely my observations), so...
0.00002944 x 30% = 0.0000088333 litres of fuel per post injection.
So, if you turn the engine off during a regen then 0.0000088333 x 2 (assuming two of the four cylinders are in the exhaust stroke at that moment) = 0.000017666 litres of fuel could potentially remain in the cylinders to make its way into the sump.
The oil capacity of the DS is 6.5 litres and some have reported 6% fuel dilution, which is 0.39L.
0.39/0.000017666 = 22083
So, so you'd need to have more than 22,000 interrupted regens to potentially get that amount of fuel dilution, and that's assuming the whole post injection remains in the cylinder AND finds its way into the sump. To put that in perspective, if you have one interrupted regen every day, then that's sixty years of motoring!
So, I think something else is going on. And if you apply the same numbers (which I won't bore you with) to an active regen, you find about half a litre of unburnt fuel washes through the engine on EACH regen! It's well documented that an unfortunate side effect of post injection is that some of this fuel makes its way past the piston rings and into the sump during the regeneration - in any car, not just the DS. Then you add in the fact that LR themselves have stated that because of the "architecture" of the Ingenium in the DS it needs more regens, of longer duration, and injecting more fuel, and you begin to see where the fuel in the oil is coming from....
As for the fuel getting passed during the 'exhaust' stroke, the next stroke being 'inlet' should negate that effect surely
Sorry, don't know what you're getting at there, but if you could explain a bit more fully I can try and reply.