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Carbon Build-Up on New Direct Injected Mercedes Engines
01-14-2012, 12:05 AM
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Nissan GT-R BE / '12 Ducati-1199 Panigale S / '12 C300-4M Loaded/GLK350-4M Loaded
Carbon Build-Up on New Direct Injected Mercedes Engines
For all those who have the 2012 C250 or C350 Coupes with Direct Injection, you all may wish to keep track of this thread over on the C-Class Sedan Forum.
Link: https://mbworld.org/forums/c-class-w...n-buildup.html
Link: https://mbworld.org/forums/c-class-w...n-buildup.html
Last edited by MBRedux; 01-14-2012 at 05:56 PM.
01-15-2012, 09:01 PM
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I'm sure there'll be 'cleaning' fixes on the way if not already available, as this has been a well known problem for some time 
02-14-2012, 04:24 PM
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Sadly it's starting to look as if MBenz dropped the ball with this one and are about to follow in the disastrous footsteps of their fellow German competitors. I don't wish to be the bringer of bad news, but I recently got off the phone with Mercedes Technical in NJ/USA. After speaking with several subordinates, I finally received a call back from a senior technical representative... this was his response to the questions and fears we all have with their latest Direct Injected engines and the infamous carbon issues which have plagued their competitors who converted to this technology much earlier than they did and now find themselves being hit with massive class-action lawsuits.
His Technical response:
"To date, we have no reports of carbon build-up on our direct injection engines. The use of high quality, high octane detergent gasolines will help assure that your Mercedes Engine will perform as designed with minimal carbon build up."
I nearly crapped in my pants I was laughing so hard. Clearly this generic response wasn't written by an engineer, or anyone who truly understood how this technology works! In fairness I asked if there was some integrated engineering that went into these new engines that would aid in the reduction of carbon build-up.... adding that they haven't had any reports of carbon build-up because these brand-new engines haven't been on the road long enough! He said he was "not aware of any additional technology" (such as Dual Injectors, EGR and PCV rerouting, oil separators, valve guide improvements, etc) in these new engines.
Well there you go.... I would have thought if they indeed had addressed this carbon issue during the design and engineering phase, it would have been front and center with a proper response for all those smart enough to ask.
It's not there, they have no answer and that scares me. They have NO satisfactory response to a simple question which makes me think they didn't do anything to address this HUGE problem and are hoping that it doesn't jump up and bite them! Yikes! That's sad Mercedes!
I would be very skeptical and cautious about buying these new DI engines from Mercedes... and I have two on order! We're rethinking it as I type.
Read more link: https://mbworld.org/forums/c-class-w...n-buildup.html
Last edited by MBRedux; 02-14-2012 at 04:27 PM.
02-14-2012, 04:57 PM
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Like the Audi forums for S5 and RS4s,
Carbon Build up is a known issue and Audi also won't address. However, they'll fix it under warranty if the car misfires (which happened to many people).
If you care about the performance of the car, you should either not buy the car or count it as a maintenance cost in the future.
Getting the valves clean can cost anywhere from $800-$1500. The RS4 guys are getting them clean on annual basis (some more often than others).
Carbon Build up is a known issue and Audi also won't address. However, they'll fix it under warranty if the car misfires (which happened to many people).
If you care about the performance of the car, you should either not buy the car or count it as a maintenance cost in the future.
Getting the valves clean can cost anywhere from $800-$1500. The RS4 guys are getting them clean on annual basis (some more often than others).
02-14-2012, 06:07 PM
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'12 C204 C250, '05 SLK350 (sold)
I'm coming up on 10k miles/Service A on my C250 Coupe, should I have them check this? I can try to complain of reduced throttle response/power and bad mpg?
02-14-2012, 06:23 PM
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Like the Audi forums for S5 and RS4s,
Carbon Build up is a known issue and Audi also won't address. However, they'll fix it under warranty if the car misfires (which happened to many people).
If you care about the performance of the car, you should either not buy the car or count it as a maintenance cost in the future.
Getting the valves clean can cost anywhere from $800-$1500. The RS4 guys are getting them clean on annual basis (some more often than others).
Carbon Build up is a known issue and Audi also won't address. However, they'll fix it under warranty if the car misfires (which happened to many people).
If you care about the performance of the car, you should either not buy the car or count it as a maintenance cost in the future.
Getting the valves clean can cost anywhere from $800-$1500. The RS4 guys are getting them clean on annual basis (some more often than others).
Actually VW/Audi/Porsche/Lambo have come up with a fix that will soon be integrated into all their new DI engines.
They simply kept the DI injector inside the cylinder and placed another injector back inside the port where it was originally so the detergent fuels can clean the intake system as you drive. They call it dual injection.... simple right? Yup! But Mercedes didn't care to look around before they jumped into Direct Injection... let's hope that this tech guy is wrong and that MB did address the problem in some way.
PS: My wife and I just cancelled our two orders tonight.
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02-14-2012, 06:34 PM
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This process is accelerated yes, but it still so gradual that most manufactures of DI engines are betting that the average daily driver won't even notice it until the warranty has expired.
Audi wasn't so lucky though and they along with their parent, VW, are in deep doodoo.
We cancelled our orders.
02-14-2012, 08:31 PM
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'12 C204 C250, '05 SLK350 (sold)
Might as well get a PowerChip and push the engine even harder before warranty (and my lease) expires!
The issue isn't about "blowing up" your engine. It's the opposite, the engine grows old real fast...slows down and gets sluggish. Over time, somewhere between 20K-50K miles, DI engines start feeling sluggish with severe hesitation, loss of power, etc. Then as the miles pile on the condition gradually worsens.
This process is accelerated yes, but it still so gradual that most manufactures of DI engines are betting that the average daily driver won't even notice it until the warranty has expired.
Audi wasn't so lucky though and they along with their parent, VW, are in deep doodoo.
We cancelled our orders.
This process is accelerated yes, but it still so gradual that most manufactures of DI engines are betting that the average daily driver won't even notice it until the warranty has expired.
Audi wasn't so lucky though and they along with their parent, VW, are in deep doodoo.
We cancelled our orders.
02-24-2012, 12:40 AM
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Okay here we go...... !!!!!!!!!!!!
I did a little poking around and found this... and it looks good... maybe! The new DI engines are designated M276 and M278, (V6 - V8). Both utilize the same head design although the V8 is turbocharged. But for our discussion, we are more interested in the set up of the injectors, which are piezo-electric direct petrol injection and the location of the intake valves relative to the injector. The new engine has a reduced V-angle between the cylinder banks, 60 now vs. 90, making the engine naturally balanced, enabling the designers to eliminate the friction hogging balancer shaft. The fuel efficiency numbers are truly astonishing for this engine, more than 24% more economical than the previous engine!
Let's look at the pix...
M276 V6
^ See where they placed the direct injected fuel injector?.... TDC! Now look at this picture...
M278 V8 but same head design.
^ You can better see in this picture that because of where the piezo electric injector is located, (not to the side but above the intake valves) Kevibk2 may have hit the nail on the head! The intake valves (the larger ones) are perfectly located to take full advantage of the injectors spray pattern cleansing properties.
__________________________________________________ ___________
The following is taken from Autoholics:
"In contrast to the V8, the new V6 engine is naturally aspirated, and has the potential for future use of a turbocharger thanks to the modular design concept.
A completely new intake and exhaust gas system with a variable-resonance intake manifold and optimised airflows was also developed for the new V6. This enabled the output of the 3499 cc engine to be increased to 225 kW (306 hp) (Previous engine of the same displacement in the S-Class: 200 kW/272 hp). Torque has increased from 350 Nm to 370 Nm, and is available between 3500 and 5250 rpm.
Key figures for the new V6 engine
No. of cylinders
V6
Displacement (cc)
3499
Bore (mm)
92.9
Stroke (mm)
86
Compression ratio:
12.2:1
Output (kW at rpm)
225 at 6500
Torque (Nm at rpm)
370 from 3500-5250
Both the new V6 and the new V8 from Mercedes-Benz have aluminium crankcases, pistons and cylinder heads. The crankshaft, connecting rods and valves are of special forged steel.
Mercedes-Benz has achieved this considerable leap in efficiency with the use of innovative technology – including newly developed, third-generation direct petrol injection with spray-guided combustion, multiple injection and multi-spark ignition. With this new generation of V-engines, Mercedes-Benz is clearly demonstrating that with concerted further development, internal combustion engines still have a great deal of potential, and that V6 and V8 engines with their great running refinement are fit for the future.
The technology package in the new engine generation includes a number of new developments that are unique in this combination:
• In combination with multi-spark ignition, a further developed, third generation direct fuel injection system with spray-guided combustion and piezo-electric injectors offers further possibilities for fuel savings – in the V8 by means of an improved, homogeneous combustion process, and in the V6 by a new, stratified combustion process with a considerably extended characteristic map and fuel-efficient lean-burn technology.
• In conjunction with start/stop technology, shift point adjustment and specific friction-reducing measures, improvements in day-to-day fuel consumption by more than 20 percent are possible.
• Power consumption by ancillary units has been reduced. These include an optimised water pump with second generation thermal management, a demand-controlled oil pump, a volume-controlled high-pressure fuel pump and an intelligent generator management system.
Lightweight construction techniques and detailed improvements have also reduced in-engine friction considerably compared to the previous engine.
Third generation direct petrol injection
Direct petrol injection with spray-guided combustion, which Mercedes-Benz was the first car manufacturer to introduce in series production, has been developed further as a third generation. The system pressure is up to 200 bar, the pressure being variably optimised according to the engine’s characteristic map. Completely newly developed piezo-electric injectors allow up to five injections per intake stroke for the best possible mixture formation.
The crystalline structure of the piezo-ceramic changes in microseconds under an electric voltage, and with a precision of just a few thousandths of a millimetre. The central component of a piezo-electric injector is the piezo-stack, which directly controls the metering needle. With a response time of just 0.1 milli-seconds, the fuel injection can be very sensitively and precisely adjusted to the current load and engine speed, with a beneficial effect on emissions, fuel consumption and combustion noise.
The multiple injections even in tiny quantities made possible with piezo-electric injection technology were used by Mercedes-Benz engineers to control a wider characteristic map with the efficient lean-burn process, and to provide the conditions for further functions:
• As the first new operating mode, Mercedes-Benz engineers have developed “Homogeneous stratified combustion” (HOS). As the name implies, HOS is a combination of homogeneous lean-burn and classic stratified combustion. The first injection is sprayed into the intake stroke, forming a homogeneous basic mixture. Actual “stratified” injection takes place during the compression stroke before ignition, and is a single or double injection depending on the characteristic map.
(Please Note: This may be the answer I've been looking for! HOS can be programmed to spray multiple times during the power stroke, and at any rpm! (Amazing but so does my GT-R) This means that Mercedes engineers quite possibly took advantage of this technology to spray off the intake valves during those milliseconds! See next point below.)
• Another new operating mode is known as “Homogeneous Split” (HSP). In this homogeneous combustion process, more than 95 percent of the fuel is singly or multiply injected, followed a very small “ignition” injection to stabilise combustion. This is used when combustion conditions are difficult.
The characteristic map of the new Mercedes-Benz V6 engine is therefore basically divided into up to four areas:
− idling range (homogeneous)
− low partial load up to 4 bar and 3800 rpm (stratified)
− medium partial load 4 to 8 bar and up to 4000 rpm (HOS)
− high load and entire engine speed range (homogeneous or HSP)
__________________________________________________ _____________________
Well there you have it! This is the best possible proof I can find to date that the boys over in the new sub-plant of the Untertürkheim engine werks, lies the new V-engine factory at Bad Cannstatt, knew what they were doing!
M276 V6
^ This picture doesn't help our discussion at all but I thought is was very cool so I included it.
I did a little poking around and found this... and it looks good... maybe! The new DI engines are designated M276 and M278, (V6 - V8). Both utilize the same head design although the V8 is turbocharged. But for our discussion, we are more interested in the set up of the injectors, which are piezo-electric direct petrol injection and the location of the intake valves relative to the injector. The new engine has a reduced V-angle between the cylinder banks, 60 now vs. 90, making the engine naturally balanced, enabling the designers to eliminate the friction hogging balancer shaft. The fuel efficiency numbers are truly astonishing for this engine, more than 24% more economical than the previous engine!
Let's look at the pix...
M276 V6^ See where they placed the direct injected fuel injector?.... TDC! Now look at this picture...
M278 V8 but same head design.
^ You can better see in this picture that because of where the piezo electric injector is located, (not to the side but above the intake valves) Kevibk2 may have hit the nail on the head! The intake valves (the larger ones) are perfectly located to take full advantage of the injectors spray pattern cleansing properties.
__________________________________________________ ___________
The following is taken from Autoholics:
"In contrast to the V8, the new V6 engine is naturally aspirated, and has the potential for future use of a turbocharger thanks to the modular design concept.
A completely new intake and exhaust gas system with a variable-resonance intake manifold and optimised airflows was also developed for the new V6. This enabled the output of the 3499 cc engine to be increased to 225 kW (306 hp) (Previous engine of the same displacement in the S-Class: 200 kW/272 hp). Torque has increased from 350 Nm to 370 Nm, and is available between 3500 and 5250 rpm.
Key figures for the new V6 engine
No. of cylinders
V6
Displacement (cc)
3499
Bore (mm)
92.9
Stroke (mm)
86
Compression ratio:
12.2:1
Output (kW at rpm)
225 at 6500
Torque (Nm at rpm)
370 from 3500-5250
Both the new V6 and the new V8 from Mercedes-Benz have aluminium crankcases, pistons and cylinder heads. The crankshaft, connecting rods and valves are of special forged steel.
Mercedes-Benz has achieved this considerable leap in efficiency with the use of innovative technology – including newly developed, third-generation direct petrol injection with spray-guided combustion, multiple injection and multi-spark ignition. With this new generation of V-engines, Mercedes-Benz is clearly demonstrating that with concerted further development, internal combustion engines still have a great deal of potential, and that V6 and V8 engines with their great running refinement are fit for the future.
The technology package in the new engine generation includes a number of new developments that are unique in this combination:
• In combination with multi-spark ignition, a further developed, third generation direct fuel injection system with spray-guided combustion and piezo-electric injectors offers further possibilities for fuel savings – in the V8 by means of an improved, homogeneous combustion process, and in the V6 by a new, stratified combustion process with a considerably extended characteristic map and fuel-efficient lean-burn technology.
• In conjunction with start/stop technology, shift point adjustment and specific friction-reducing measures, improvements in day-to-day fuel consumption by more than 20 percent are possible.
• Power consumption by ancillary units has been reduced. These include an optimised water pump with second generation thermal management, a demand-controlled oil pump, a volume-controlled high-pressure fuel pump and an intelligent generator management system.
Lightweight construction techniques and detailed improvements have also reduced in-engine friction considerably compared to the previous engine.
Third generation direct petrol injection
Direct petrol injection with spray-guided combustion, which Mercedes-Benz was the first car manufacturer to introduce in series production, has been developed further as a third generation. The system pressure is up to 200 bar, the pressure being variably optimised according to the engine’s characteristic map. Completely newly developed piezo-electric injectors allow up to five injections per intake stroke for the best possible mixture formation.
The crystalline structure of the piezo-ceramic changes in microseconds under an electric voltage, and with a precision of just a few thousandths of a millimetre. The central component of a piezo-electric injector is the piezo-stack, which directly controls the metering needle. With a response time of just 0.1 milli-seconds, the fuel injection can be very sensitively and precisely adjusted to the current load and engine speed, with a beneficial effect on emissions, fuel consumption and combustion noise.
The multiple injections even in tiny quantities made possible with piezo-electric injection technology were used by Mercedes-Benz engineers to control a wider characteristic map with the efficient lean-burn process, and to provide the conditions for further functions:
• As the first new operating mode, Mercedes-Benz engineers have developed “Homogeneous stratified combustion” (HOS). As the name implies, HOS is a combination of homogeneous lean-burn and classic stratified combustion. The first injection is sprayed into the intake stroke, forming a homogeneous basic mixture. Actual “stratified” injection takes place during the compression stroke before ignition, and is a single or double injection depending on the characteristic map.
(Please Note: This may be the answer I've been looking for! HOS can be programmed to spray multiple times during the power stroke, and at any rpm! (Amazing but so does my GT-R) This means that Mercedes engineers quite possibly took advantage of this technology to spray off the intake valves during those milliseconds! See next point below.)
• Another new operating mode is known as “Homogeneous Split” (HSP). In this homogeneous combustion process, more than 95 percent of the fuel is singly or multiply injected, followed a very small “ignition” injection to stabilise combustion. This is used when combustion conditions are difficult.
The characteristic map of the new Mercedes-Benz V6 engine is therefore basically divided into up to four areas:
− idling range (homogeneous)
− low partial load up to 4 bar and 3800 rpm (stratified)
− medium partial load 4 to 8 bar and up to 4000 rpm (HOS)
− high load and entire engine speed range (homogeneous or HSP)
__________________________________________________ _____________________
Well there you have it! This is the best possible proof I can find to date that the boys over in the new sub-plant of the Untertürkheim engine werks, lies the new V-engine factory at Bad Cannstatt, knew what they were doing!
M276 V6^ This picture doesn't help our discussion at all but I thought is was very cool so I included it.
02-24-2012, 12:06 PM
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2012 C250 Coupe
Yeah, to be honest, I have NO idea what all of that above nonsense means... If what I have gathered is correct, it simply talks about changes made to help increase efficiency, but how does this relate to the carbon build-up issue?
02-24-2012, 02:22 PM
#13
Good find, MBRedux. From what I read from your post, MB did resolve the carbon deposit issues in their future DI engines.
Why 3rd generation? Isn't the current DI engine their 1st generation? What happened to the 2nd generation?
I think people in this forum are more concerned if MB did resolve the carbon deposit issues in their MB current engine offerings. Do these engines need annual injector cleaning?
I love my old V6 (M112) and it was a well-proven technology. After 150K miles, it is still going strong. Maybe I should wait 1-2 years to replace
my car to aviod the current DI engines.
Why 3rd generation? Isn't the current DI engine their 1st generation? What happened to the 2nd generation?
I think people in this forum are more concerned if MB did resolve the carbon deposit issues in their MB current engine offerings. Do these engines need annual injector cleaning?
I love my old V6 (M112) and it was a well-proven technology. After 150K miles, it is still going strong. Maybe I should wait 1-2 years to replace
my car to aviod the current DI engines.
Last edited by mis3; 02-24-2012 at 02:24 PM.
02-26-2012, 02:20 PM
#14
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Nissan GT-R BE / '12 Ducati-1199 Panigale S / '12 C300-4M Loaded/GLK350-4M Loaded
Good find, MBRedux. From what I read from your post, MB did resolve the carbon deposit issues in their future DI engines.
Why 3rd generation? Isn't the current DI engine their 1st generation? What happened to the 2nd generation?
I think people in this forum are more concerned if MB did resolve the carbon deposit issues in their MB current engine offerings. Do these engines need annual injector cleaning?
I love my old V6 (M112) and it was a well-proven technology. After 150K miles, it is still going strong. Maybe I should wait 1-2 years to replace
my car to aviod the current DI engines.
Why 3rd generation? Isn't the current DI engine their 1st generation? What happened to the 2nd generation?
I think people in this forum are more concerned if MB did resolve the carbon deposit issues in their MB current engine offerings. Do these engines need annual injector cleaning?
I love my old V6 (M112) and it was a well-proven technology. After 150K miles, it is still going strong. Maybe I should wait 1-2 years to replace
my car to aviod the current DI engines.
02-26-2012, 03:52 PM
#15
Has it been confirmed that the current MB DI engines have the carbon deposit issues? Maybe MB did implement a solution in their current engine offerings to keep the intake system clean.
06-21-2018, 02:32 PM
#16
Junior Member
Response to DI post on M276 engine
Okay here we go...... !!!!!!!!!!!!
I did a little poking around and found this... and it looks good... maybe! The new DI engines are designated M276 and M278, (V6 - V8). Both utilize the same head design although the V8 is turbocharged. But for our discussion, we are more interested in the set up of the injectors, which are piezo-electric direct petrol injection and the location of the intake valves relative to the injector. The new engine has a reduced V-angle between the cylinder banks, 60 now vs. 90, making the engine naturally balanced, enabling the designers to eliminate the friction hogging balancer shaft. The fuel efficiency numbers are truly astonishing for this engine, more than 24% more economical than the previous engine!
Let's look at the pix...
M276 V6
^ See where they placed the direct injected fuel injector?.... TDC! Now look at this picture...
M278 V8 but same head design.
^ You can better see in this picture that because of where the piezo electric injector is located, (not to the side but above the intake valves) Kevibk2 may have hit the nail on the head! The intake valves (the larger ones) are perfectly located to take full advantage of the injectors spray pattern cleansing properties.
__________________________________________________ ___________
The following is taken from Autoholics:
"In contrast to the V8, the new V6 engine is naturally aspirated, and has the potential for future use of a turbocharger thanks to the modular design concept.
A completely new intake and exhaust gas system with a variable-resonance intake manifold and optimised airflows was also developed for the new V6. This enabled the output of the 3499 cc engine to be increased to 225 kW (306 hp) (Previous engine of the same displacement in the S-Class: 200 kW/272 hp). Torque has increased from 350 Nm to 370 Nm, and is available between 3500 and 5250 rpm.
Key figures for the new V6 engine
No. of cylinders
V6
Displacement (cc)
3499
Bore (mm)
92.9
Stroke (mm)
86
Compression ratio:
12.2:1
Output (kW at rpm)
225 at 6500
Torque (Nm at rpm)
370 from 3500-5250
Both the new V6 and the new V8 from Mercedes-Benz have aluminium crankcases, pistons and cylinder heads. The crankshaft, connecting rods and valves are of special forged steel.
Mercedes-Benz has achieved this considerable leap in efficiency with the use of innovative technology – including newly developed, third-generation direct petrol injection with spray-guided combustion, multiple injection and multi-spark ignition. With this new generation of V-engines, Mercedes-Benz is clearly demonstrating that with concerted further development, internal combustion engines still have a great deal of potential, and that V6 and V8 engines with their great running refinement are fit for the future.
The technology package in the new engine generation includes a number of new developments that are unique in this combination:
• In combination with multi-spark ignition, a further developed, third generation direct fuel injection system with spray-guided combustion and piezo-electric injectors offers further possibilities for fuel savings – in the V8 by means of an improved, homogeneous combustion process, and in the V6 by a new, stratified combustion process with a considerably extended characteristic map and fuel-efficient lean-burn technology.
• In conjunction with start/stop technology, shift point adjustment and specific friction-reducing measures, improvements in day-to-day fuel consumption by more than 20 percent are possible.
• Power consumption by ancillary units has been reduced. These include an optimised water pump with second generation thermal management, a demand-controlled oil pump, a volume-controlled high-pressure fuel pump and an intelligent generator management system.
Lightweight construction techniques and detailed improvements have also reduced in-engine friction considerably compared to the previous engine.
Third generation direct petrol injection
Direct petrol injection with spray-guided combustion, which Mercedes-Benz was the first car manufacturer to introduce in series production, has been developed further as a third generation. The system pressure is up to 200 bar, the pressure being variably optimised according to the engine’s characteristic map. Completely newly developed piezo-electric injectors allow up to five injections per intake stroke for the best possible mixture formation.
The crystalline structure of the piezo-ceramic changes in microseconds under an electric voltage, and with a precision of just a few thousandths of a millimetre. The central component of a piezo-electric injector is the piezo-stack, which directly controls the metering needle. With a response time of just 0.1 milli-seconds, the fuel injection can be very sensitively and precisely adjusted to the current load and engine speed, with a beneficial effect on emissions, fuel consumption and combustion noise.
The multiple injections even in tiny quantities made possible with piezo-electric injection technology were used by Mercedes-Benz engineers to control a wider characteristic map with the efficient lean-burn process, and to provide the conditions for further functions:
• As the first new operating mode, Mercedes-Benz engineers have developed “Homogeneous stratified combustion” (HOS). As the name implies, HOS is a combination of homogeneous lean-burn and classic stratified combustion. The first injection is sprayed into the intake stroke, forming a homogeneous basic mixture. Actual “stratified” injection takes place during the compression stroke before ignition, and is a single or double injection depending on the characteristic map.
(Please Note: This may be the answer I've been looking for! HOS can be programmed to spray multiple times during the power stroke, and at any rpm! (Amazing but so does my GT-R) This means that Mercedes engineers quite possibly took advantage of this technology to spray off the intake valves during those milliseconds! See next point below.)
• Another new operating mode is known as “Homogeneous Split” (HSP). In this homogeneous combustion process, more than 95 percent of the fuel is singly or multiply injected, followed a very small “ignition” injection to stabilise combustion. This is used when combustion conditions are difficult.
The characteristic map of the new Mercedes-Benz V6 engine is therefore basically divided into up to four areas:
− idling range (homogeneous)
− low partial load up to 4 bar and 3800 rpm (stratified)
− medium partial load 4 to 8 bar and up to 4000 rpm (HOS)
− high load and entire engine speed range (homogeneous or HSP)
__________________________________________________ _____________________
Well there you have it! This is the best possible proof I can find to date that the boys over in the new sub-plant of the Untertürkheim engine werks, lies the new V-engine factory at Bad Cannstatt, knew what they were doing!
M276 V6
^ This picture doesn't help our discussion at all but I thought is was very cool so I included it.
I did a little poking around and found this... and it looks good... maybe! The new DI engines are designated M276 and M278, (V6 - V8). Both utilize the same head design although the V8 is turbocharged. But for our discussion, we are more interested in the set up of the injectors, which are piezo-electric direct petrol injection and the location of the intake valves relative to the injector. The new engine has a reduced V-angle between the cylinder banks, 60 now vs. 90, making the engine naturally balanced, enabling the designers to eliminate the friction hogging balancer shaft. The fuel efficiency numbers are truly astonishing for this engine, more than 24% more economical than the previous engine!
Let's look at the pix...
M276 V6^ See where they placed the direct injected fuel injector?.... TDC! Now look at this picture...
M278 V8 but same head design.
^ You can better see in this picture that because of where the piezo electric injector is located, (not to the side but above the intake valves) Kevibk2 may have hit the nail on the head! The intake valves (the larger ones) are perfectly located to take full advantage of the injectors spray pattern cleansing properties.
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The following is taken from Autoholics:
"In contrast to the V8, the new V6 engine is naturally aspirated, and has the potential for future use of a turbocharger thanks to the modular design concept.
A completely new intake and exhaust gas system with a variable-resonance intake manifold and optimised airflows was also developed for the new V6. This enabled the output of the 3499 cc engine to be increased to 225 kW (306 hp) (Previous engine of the same displacement in the S-Class: 200 kW/272 hp). Torque has increased from 350 Nm to 370 Nm, and is available between 3500 and 5250 rpm.
Key figures for the new V6 engine
No. of cylinders
V6
Displacement (cc)
3499
Bore (mm)
92.9
Stroke (mm)
86
Compression ratio:
12.2:1
Output (kW at rpm)
225 at 6500
Torque (Nm at rpm)
370 from 3500-5250
Both the new V6 and the new V8 from Mercedes-Benz have aluminium crankcases, pistons and cylinder heads. The crankshaft, connecting rods and valves are of special forged steel.
Mercedes-Benz has achieved this considerable leap in efficiency with the use of innovative technology – including newly developed, third-generation direct petrol injection with spray-guided combustion, multiple injection and multi-spark ignition. With this new generation of V-engines, Mercedes-Benz is clearly demonstrating that with concerted further development, internal combustion engines still have a great deal of potential, and that V6 and V8 engines with their great running refinement are fit for the future.
The technology package in the new engine generation includes a number of new developments that are unique in this combination:
• In combination with multi-spark ignition, a further developed, third generation direct fuel injection system with spray-guided combustion and piezo-electric injectors offers further possibilities for fuel savings – in the V8 by means of an improved, homogeneous combustion process, and in the V6 by a new, stratified combustion process with a considerably extended characteristic map and fuel-efficient lean-burn technology.
• In conjunction with start/stop technology, shift point adjustment and specific friction-reducing measures, improvements in day-to-day fuel consumption by more than 20 percent are possible.
• Power consumption by ancillary units has been reduced. These include an optimised water pump with second generation thermal management, a demand-controlled oil pump, a volume-controlled high-pressure fuel pump and an intelligent generator management system.
Lightweight construction techniques and detailed improvements have also reduced in-engine friction considerably compared to the previous engine.
Third generation direct petrol injection
Direct petrol injection with spray-guided combustion, which Mercedes-Benz was the first car manufacturer to introduce in series production, has been developed further as a third generation. The system pressure is up to 200 bar, the pressure being variably optimised according to the engine’s characteristic map. Completely newly developed piezo-electric injectors allow up to five injections per intake stroke for the best possible mixture formation.
The crystalline structure of the piezo-ceramic changes in microseconds under an electric voltage, and with a precision of just a few thousandths of a millimetre. The central component of a piezo-electric injector is the piezo-stack, which directly controls the metering needle. With a response time of just 0.1 milli-seconds, the fuel injection can be very sensitively and precisely adjusted to the current load and engine speed, with a beneficial effect on emissions, fuel consumption and combustion noise.
The multiple injections even in tiny quantities made possible with piezo-electric injection technology were used by Mercedes-Benz engineers to control a wider characteristic map with the efficient lean-burn process, and to provide the conditions for further functions:
• As the first new operating mode, Mercedes-Benz engineers have developed “Homogeneous stratified combustion” (HOS). As the name implies, HOS is a combination of homogeneous lean-burn and classic stratified combustion. The first injection is sprayed into the intake stroke, forming a homogeneous basic mixture. Actual “stratified” injection takes place during the compression stroke before ignition, and is a single or double injection depending on the characteristic map.
(Please Note: This may be the answer I've been looking for! HOS can be programmed to spray multiple times during the power stroke, and at any rpm! (Amazing but so does my GT-R) This means that Mercedes engineers quite possibly took advantage of this technology to spray off the intake valves during those milliseconds! See next point below.)
• Another new operating mode is known as “Homogeneous Split” (HSP). In this homogeneous combustion process, more than 95 percent of the fuel is singly or multiply injected, followed a very small “ignition” injection to stabilise combustion. This is used when combustion conditions are difficult.
The characteristic map of the new Mercedes-Benz V6 engine is therefore basically divided into up to four areas:
− idling range (homogeneous)
− low partial load up to 4 bar and 3800 rpm (stratified)
− medium partial load 4 to 8 bar and up to 4000 rpm (HOS)
− high load and entire engine speed range (homogeneous or HSP)
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Well there you have it! This is the best possible proof I can find to date that the boys over in the new sub-plant of the Untertürkheim engine werks, lies the new V-engine factory at Bad Cannstatt, knew what they were doing!
M276 V6^ This picture doesn't help our discussion at all but I thought is was very cool so I included it.
11-14-2021, 02:42 PM
#18
Any updates on the issue of Carbon buildup?
These issues take time/mileage to rear their ugly heads (posts that state; I've got 40k miles and all is well are meaningless). I'm assuming by now, these cars have over 100k miles and IF carbon buildup is an issue it would have presented by now.
FYI; I'm considering purchasing a S550 and they come in 2 different flavors; the 273 Naturally aspirated or the 278 Direct injected (lots more power - who doesn't want more power?).
Having read through Consumer reports and a few other sites, I've concluded that DI engines are problematic but not in ALL cases.
These issues take time/mileage to rear their ugly heads (posts that state; I've got 40k miles and all is well are meaningless). I'm assuming by now, these cars have over 100k miles and IF carbon buildup is an issue it would have presented by now.
FYI; I'm considering purchasing a S550 and they come in 2 different flavors; the 273 Naturally aspirated or the 278 Direct injected (lots more power - who doesn't want more power?).
Having read through Consumer reports and a few other sites, I've concluded that DI engines are problematic but not in ALL cases.
