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Stratified charge in the W222 engines? Facelifted models?
TLDR summary for everyone:
Direct injected engines in N. America have not been able to run a very lean burn mode/high compression ratio "stage" called "stratified injection". The reason for this (TLDR flavour) is that our fuel has had too much sulfur in it. I learned today that in the US (and I believe in Canada), that as of early 2017, the sulphur content has actually dropped significantly, to I believe 10ppm, and that by 2020 that this will drop even further.
Does anyone know for sure? This is a big deal for DI haters like me (I suffered through the Audi 2.0 TFSI debacle), because this now means these engines can run in a lean burn mode under partial throttle application. Historically these DI engines have burned richer than they needed to (and consumed more fuel then they needed to), due to the sulphur content in our fuel. I would really like to know if these DI engines now FINALLY can enter lean burn mode.
Thank you.
before anyone asks, my research has been on the S450 MY18/MY19 M276 DELA engine. I have no idea how things work on the 550 as I am not in the market for one.
^^Reason I care above is because of the decreased concern of fuel dilution due to stratified mode injection*
Last edited by superangrypenguin; 09-02-2018 at 08:40 AM.
I don't know if it's just the sulfur, lean burn creates NOx emissions that are above our regulations, an issue other places don't have. Maybe that is because of the sulfur content of the fuels, I don't know. I have seen, even in GM PCM's the logic for lean burn cruise and it's always disabled here in the states for that reason. Not even on DI motors, but DI makes it far more efficient.
I don't know if it's just the sulfur, lean burn creates NOx emissions that are above our regulations, an issue other places don't have. Maybe that is because of the sulfur content of the fuels, I don't know. I have seen, even in GM PCM's the logic for lean burn cruise and it's always disabled here in the states for that reason. Not even on DI motors, but DI makes it far more efficient.
I know automakers have disabled lean burn mode in the US for several years, most notably VAG explicitly has referred to FSI as "fuel straight injection" vs "fuel stratified injection" in the US vs Europe. This was back around 2007-2010. Our fuel standards and sulphur content is neck and neck vs Europe now (from what I have researched). Do you know if GM's PCM logic is still disabled these days as I seem to recall GM has had DI engines for a while, and Ford has as well with their EcoBoost line.
I know automakers have disabled lean burn mode in the US for several years, most notably VAG explicitly has referred to FSI as "fuel straight injection" vs "fuel stratified injection" in the US vs Europe. This was back around 2007-2010. Our fuel standards and sulphur content is neck and neck vs Europe now (from what I have researched). Do you know if GM's PCM logic is still disabled these days as I seem to recall GM has had DI engines for a while, and Ford has as well with their EcoBoost line.
I'll look through some new tunes, but on the 2016 Camaro I tuned recently, the lean cruise is disabled and from what I know it always will be in the USA market due to emissions restrictions.
This maybe why USA designated gasoline engine is not using stratified combustion, USA allowable Nox and Particulate Matter is much lower than Europe, but Europe CO and CO2 allowable limit is lower than USA. https://longtailpipe.com/2015/10/02/...of-dieselgate/
So its kinda ironic if USA did not reduce its sulfur level as fast as Europe but demand less Nox and PM.
I spoke to an oil engineer working with Shell just few days ago. It was casual conversation about fuel.
He said refineries are designed around what crude oil is the source. So its kinda custom production.
It is not easy, not fast and not cheap to produce X when the refinery is designed for Y.
I read removing sulfur is not that cheap too.
I believe EPA ruling has at the least, partially to do with USA oil reserve concern.
This is probably a political decision where a country must be able to stay independent of foreign oil import for as long as they could, and use their own oil reserve, if war ever happens.
I do not know what kind of crude oil USA owns, but one thing for certain their refineries are designed for that.
Also money talks, I am sure the oil company try to spend less or delay as long as they can on any major expenses and can sleep well with high sulfur in their gasoline https://www.ogj.com/articles/print/v...ine-costs.html
I am sure if car manufacturers see the current low sulfur fuel of Tier 3 readily available nation wide , and improve NOX cat converter technology,
in a few years they will introduce to US market the stratified combustion version for the gasoline engine.
This maybe why USA designated gasoline engine is not using stratified combustion, USA allowable Nox and Particulate Matter is much lower than Europe, but Europe CO and CO2 allowable limit is lower than USA. https://longtailpipe.com/2015/10/02/...of-dieselgate/
Happy reading....
Thank you and for the post below. I did read this actually, as I read that PDF from cover to cover late last night after learning about the sulphur content changes in US fuels. That is why the official news release from Mercedes Benz in my original post got me going..."YAY!!!!!!!!!"
My understanding of this topic is that as the sulphur content drops, the NOx emissions drops too from stratified charge/lean combustion. Just trying to see if it's finally being rolled out in the new S450 The document you are referring to is also old, almost 8 years old and was released when the M276 was first released, and does not contain info about the M276 DELA 30 as an example. I've been trying desperately to find the latest technical document on it but alas, I cannot find it.
So its kinda ironic if USA did not reduce its sulfur level as fast as Europe but demand less Nox and PM.
I spoke to an oil engineer working with Shell just few days ago. It was casual conversation about fuel.
He said refineries are designed around what crude oil is the source. So its kinda custom production.
It is not easy, not fast and not cheap to produce X when the refinery is designed for Y.
I read removing sulfur is not that cheap too.
.
The main reason USA has not gone with low sulphur gasoline is that it would add cost to the product.
If you remember in the pre "ultra-low-sulphur" diesel days, diesel was less expensive than gasoline, now it is more expensive.
The same adder would be imposed to produce desulphurized gasoline ($0.20-$0.30 per gallon)
09-01-2018, 05:18 PM
