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Interesting post here. Yes, I get that are selling something:

https://blog.amsoil.com/what-is-cetane-and-why-does-it-matter

I have used the following since I bought the car almost 2 years ago. Absoluetly no smoke and my tail pipes are completely clean. No black soot or anything. They are just silver coloured the way they were made. It cleans and also increases Cetane levels. Don't OD since too much Ceatne is not good!

On my last MOT the guy (who I know) said that my emissions were very low for a diesel. Happy Days.

 

xcvzczv.jpg

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I'm not sure of European requirements for emissions, but if your car has a functioning DPF and SCR system and no mechanical failures the tips on your exhaust pipes should be incredibly clean no matter what you dump into the fuel tank.  I worked for a company with 300 diesel powered (80,000 pound GVWR) trucks, the only time the exhaust tips got dirty after SCR and DPF was introduced was if a turbo failed and overloaded the DPF.  We never put anything in the tanks other than #1 or #2 ULSD diesel fuel, depending on the weather.  We even had a Volvo rep come check the VN370 tractors with a machine to test emissions - the results were the exhaust was not only cleaner than the air going into the air intake, it contained enough oxygen that you could breathe it.  

 

Increased Cetane levels and cleaner injectors -  always good though

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On 4/14/2021 at 8:58 PM, p38fln said:

I'm not sure of European requirements for emissions, but if your car has a functioning DPF and SCR system and no mechanical failures the tips on your exhaust pipes should be incredibly clean no matter what you dump into the fuel tank.  I worked for a company with 300 diesel powered (80,000 pound GVWR) trucks, the only time the exhaust tips got dirty after SCR and DPF was introduced was if a turbo failed and overloaded the DPF.  We never put anything in the tanks other than #1 or #2 ULSD diesel fuel, depending on the weather.  We even had a Volvo rep come check the VN370 tractors with a machine to test emissions - the results were the exhaust was not only cleaner than the air going into the air intake, it contained enough oxygen that you could breathe it.  

 

Increased Cetane levels and cleaner injectors -  always good though

Interesting. I belong to a BMW meet and greet club here in the UK. I made a big point about this when we last met. Each and every diesel car had soot (in varying degrees) in their tail pipe.

PS Just noticed what you say re: DPF. Most I know have had them removed (£1,000 fine in UK). They are, for some reason, the one's that smoke. I believe mpg is better BUT performance is unaffected despite dealer claims.

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On 4/21/2021 at 2:53 PM, SuzukiBoy2 said:

Interesting. I belong to a BMW meet and greet club here in the UK. I made a big point about this when we last met. Each and every diesel car had soot (in varying degrees) in their tail pipe.

PS Just noticed what you say re: DPF. Most I know have had them removed (£1,000 fine in UK). They are, for some reason, the one's that smoke. I believe mpg is better BUT performance is unaffected despite dealer claims.

Yes if the car has a "deleted" DPF then it's going to smoke.  That's the whole reason for the DPF (diesel particulate filter): to eliminate smoke, soot and ash from the exhaust.  MPG will go up with the DPF removed because most cars don't run heavy enough loads to keep the catalyst in the DPF filter hot enough to burn the collected soot and ash off, so the engines go in to a regeneration cycle.  Regeneration raises the RPM of the engine high enough to keep exhaust temps hot and air flowing for the regen cycle.  The second part of the regen cycle is diesel fuel is pumped into the exhaust pipe through a fuel injector located in the DPF, and then a glow plug ignites the fuel.  The goal is to raise the exhaust temperature high enough to cause a chimney fire, which will burn all the ash and soot from the DPF filter.  The goal temperature is at least 600 C/1100 F, so the recommendation is to never allow a regeneration cycle while off road, in a garage, or somewhere else near anything that could ignite at 1100 F.  Dumping fuel straight into an exhaust pipe and then lighting it on fire makes the the overall fuel efficiency go down.  

Regeneration happens more frequently if the engine is allowed to idle, such as just idling for heat or AC or going through city traffic.  It happens less frequently under heavier loads, such as high speed driving or going through the mountains since the natural temperature of the exhaust and engine combustion itself is going to be higher and therefore produce less soot (and will also help burn off existing soot) under these conditions.  

Performance would go up with the DPF removed if the DPF was removed after it clogged up for whatever reason.  It is possible to clean a DPF off the vehicle by using an air wand at 150 PSI assuming nothing too terrible got into the DPF.  Turbo failures which typically dump large quantities of oil into a DPF can render it unsalvageable but even these can occasionally be saved by first baking them in an industrial kiln to boil the oil off (This has to be done carefully because oil vapors can damage kiln components).  

The other technology I mentioned, SCR, is Selective Catalytic Reduction.  This works by injecting what they politely call DEF or AdBlue into the tailpipe, after the DPF.  DEF or AdBlue is simply urea in liquid form in a specific concentration (32.5% urea to 67.5% water).  Urea is exactly what you think it is, but is produced in a laboratory rather than in a liver for this purpose.  I'm not sure why, it seems dairy farms would be able to produce quite large quantities of urea without any laboratory help.  The urea combines with the NOx molecules and then splits into nitrogen, water and carbon dioxide.  I'm not sure why the Volvo was pumping oxygen out too, I may have misunderstood what he was saying.  

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  • 3 weeks later...
On 4/23/2021 at 4:32 PM, p38fln said:

Yes if the car has a "deleted" DPF then it's going to smoke.  That's the whole reason for the DPF (diesel particulate filter): to eliminate smoke, soot and ash from the exhaust.  MPG will go up with the DPF removed because most cars don't run heavy enough loads to keep the catalyst in the DPF filter hot enough to burn the collected soot and ash off, so the engines go in to a regeneration cycle.  Regeneration raises the RPM of the engine high enough to keep exhaust temps hot and air flowing for the regen cycle.  The second part of the regen cycle is diesel fuel is pumped into the exhaust pipe through a fuel injector located in the DPF, and then a glow plug ignites the fuel.  The goal is to raise the exhaust temperature high enough to cause a chimney fire, which will burn all the ash and soot from the DPF filter.  The goal temperature is at least 600 C/1100 F, so the recommendation is to never allow a regeneration cycle while off road, in a garage, or somewhere else near anything that could ignite at 1100 F.  Dumping fuel straight into an exhaust pipe and then lighting it on fire makes the the overall fuel efficiency go down.  

Regeneration happens more frequently if the engine is allowed to idle, such as just idling for heat or AC or going through city traffic.  It happens less frequently under heavier loads, such as high speed driving or going through the mountains since the natural temperature of the exhaust and engine combustion itself is going to be higher and therefore produce less soot (and will also help burn off existing soot) under these conditions.  

Performance would go up with the DPF removed if the DPF was removed after it clogged up for whatever reason.  It is possible to clean a DPF off the vehicle by using an air wand at 150 PSI assuming nothing too terrible got into the DPF.  Turbo failures which typically dump large quantities of oil into a DPF can render it unsalvageable but even these can occasionally be saved by first baking them in an industrial kiln to boil the oil off (This has to be done carefully because oil vapors can damage kiln components).  

The other technology I mentioned, SCR, is Selective Catalytic Reduction.  This works by injecting what they politely call DEF or AdBlue into the tailpipe, after the DPF.  DEF or AdBlue is simply urea in liquid form in a specific concentration (32.5% urea to 67.5% water).  Urea is exactly what you think it is, but is produced in a laboratory rather than in a liver for this purpose.  I'm not sure why, it seems dairy farms would be able to produce quite large quantities of urea without any laboratory help.  The urea combines with the NOx molecules and then splits into nitrogen, water and carbon dioxide.  I'm not sure why the Volvo was pumping oxygen out too, I may have misunderstood what he was saying.  

Good write-up 👍

it’s worth pointing-out that not all engines have the injector-in-exhaust for regeneration. Such engines rely on squirting diesel fuel into the cylinders on the exhaust cycle; usually this burns on its way through the pre-catalyst and dpf........the downside is that some of this neat diesel finds its way into the sump to join your lube oil (and fuel isn’t a good thing).

The other thing is that the dpf isn’t a full-flow device like a catalyst (try looking through one) and the exhaust has to pass through the walls of the honeycombed structure. Soot builds-up there and the backpressure builds. At a set point this should trigger a regeneration. Sadly, due to driving style these cycles are interrupted and the cycle is not completed (you may not even notice your car is doing a regen unless you hear crackling from the exhaust pipe or chance to burn your fingers on the exhaust tip!

if your dpf is easy(ish) to remove, I have heard of good results from putting them in an ultrasonic bath.

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