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Registered 2015 SLK55 AMG
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102 Posts
Discussion Starter #1
If the SLK55 has a naturally aspirated 5.5-liter V-8 engine (M152), which I thought meant no blower, no supercharger, and no electronic fuel injection (EFI), what device does the engine have that determines which cylinders get gas how much gas each cylinder gets?
 

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Registered 2018 SLC43
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166 Posts
Ahead of it's time!

I don't think there has been a similar engine produced since that does this for production cars?

I do understand why the move to the 3l V6 biturbo in the last AMG was necessary for fuel economy, and emissions, with some supplementary benefits to handling from the decreased weight up front, but nothing is as smooth or as great sounding as a V8!
 

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Premium Member 2012 SLK55 AMG
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3,878 Posts
If the SLK55 has a naturally aspirated 5.5-liter V-8 engine (M152), which I thought meant no blower, no supercharger, and no electronic fuel injection (EFI), what device does the engine have that determines which cylinders get gas how much gas each cylinder gets?
Naturally aspirated = No forced induction ie turbo, supercharger.
The 55s do have EFI and just about everything on the car is controlled by some sort of ECU :wink::grin:
 

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Registered 2015 SLK55 AMG
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102 Posts
Discussion Starter #5
I believe what I was looking for is called Direct Fuel Injection (DFI), which appears to be a method of injection that is more advanced than Electronic Fuel Injection (EFI).

According to Porsche:

Porsche made the move to direct fuel injection (DFI), the first major revision to the sports cars injection technology in 40 years. DFI, as the name suggest, injects the petrol straight into the combustion chamber, leaving pure air to be fed through the intake manifold.

From https://www.greencarcongress.com/2011/07/m152-20110721.html

Mercedes-AMG has developed a new high-revving, naturally aspirated 5.5-liter V8 engine (M152) featuring the AMG Cylinder Management cylinder shut-off system. Although peak output in the new engine increased by 60 hp to 415 hp (309 kW) and torque increased from 376 lb-ft to 398 lb-ft (540 N·m) compared to the existing AMG 5.5L V8, fuel consumption is about 30% less.

The AMG 5.5-liter V8 engine with AMG Cylinder Management and direct fuel injection will be applied exclusively in the 2012 SLK55 AMG, which will debut at the International Motor Show (IAA) in Frankfurt/Main in September. The SLK55 AMG will remain the only roadster in its segment with an eight-cylinder engine, Mercedes said.

The new M152 engine is based on the AMG M157 5.5-liter V8 biturbo engine which first debuted on the 2011MY CL63 AMG and S63 AMG. Numerous components and systems are basically identical, e.g. the displacement, bore/stroke, distance between cylinders, ECO stop/start system and direct injection technology. Distinguishing features versus the M157 include new intake air ducting, new cylinder heads, the modified valve drive, an adapted oil supply system and an optimized crankcase.
 

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Super Moderator CA 2012 SLK55 AMG w/P30
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13,271 Posts
Gets me pretty good gas milage when I tried to see what she could do :wink:

 

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Premium Member 2001 SLK320/2000 SLK230
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Diesels have used direct injection forever, automakers just this decade however when you couple DI with boost you can develop A Lot of HP, over 125 bhp/liter on pump gas and with a warranty. Right now it is used by Renault, Hyundai, Ford, Audi, and GM (ATS-V 3.6 DI turbo: 464 hp).

And just to tootle a bit.
 

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Premium Member 2012 SLK55 AMG
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6,208 Posts
I believe what I was looking for is called Direct Fuel Injection (DFI), which appears to be a method of injection that is more advanced than Electronic Fuel Injection (EFI).

According to Porsche:

Porsche made the move to direct fuel injection (DFI), the first major revision to the sports cars injection technology in 40 years. DFI, as the name suggest, injects the petrol straight into the combustion chamber, leaving pure air to be fed through the intake manifold.

From https://www.greencarcongress.com/2011/07/m152-20110721.html

Mercedes-AMG has developed a new high-revving, naturally aspirated 5.5-liter V8 engine (M152) featuring the AMG Cylinder Management cylinder shut-off system. Although peak output in the new engine increased by 60 hp to 415 hp (309 kW) and torque increased from 376 lb-ft to 398 lb-ft (540 N·m) compared to the existing AMG 5.5L V8, fuel consumption is about 30% less.

The AMG 5.5-liter V8 engine with AMG Cylinder Management and direct fuel injection will be applied exclusively in the 2012 SLK55 AMG, which will debut at the International Motor Show (IAA) in Frankfurt/Main in September. The SLK55 AMG will remain the only roadster in its segment with an eight-cylinder engine, Mercedes said.

The new M152 engine is based on the AMG M157 5.5-liter V8 biturbo engine which first debuted on the 2011MY CL63 AMG and S63 AMG. Numerous components and systems are basically identical, e.g. the displacement, bore/stroke, distance between cylinders, ECO stop/start system and direct injection technology. Distinguishing features versus the M157 include new intake air ducting, new cylinder heads, the modified valve drive, an adapted oil supply system and an optimized crankcase.
If you read down the document I posted our engines do have DFI. Here is the paragraph.


Efficiency

Exclusive combination of advanced technologies

The high-tech M152 powerpack not only enthralls with its extraordinary power delivery and torque, but
also thanks to a combination of advanced technologies which is unequaled anywhere in the world. No
other petrol engine features direct injection at a pressure of 200 bar, spray-guided combustion and piezoinjectors
in conjunction with map-controlled cylinder shut-off, an all-aluminium crankcase with
"spectacle" honing, four-valve technology with continuous camshaft adjustment, a high compression ratio
of 12.6 : 1, a stop/start system and generator management – while revving to a maximum of over 6800
rpm. All these design features lead to high thermodynamic efficiency, which is in turn the precondition for
high fuel efficiency and low exhaust emissions. Moreover, deciding in favor of a large-displacement,
naturally aspirated eight-cylinder unit with cylinder shut-off resolves the conflict of aims between high
output/torque delivery and decidedly low fuel consumption figures.


 

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Registered 2005 SLK55 AMG
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924 Posts
The A45s in fact has direct and indirect. The latter apparently can 'dump' more fuel into cylinders under heavy loads than the DFI. Apologies for my previous comments on multipoint.

Maya ~ Tapatalk
 

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Registered 2015 SLK55 AMG
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102 Posts
Discussion Starter #10
MartinatMersea

Thank you for the excellent article. I did more checking to make certain that “direct petrol injection” and “direct fuel injection” were the same thing. Your article referred to “direct petrol injection.” In the US, petrol and gasoline usually mean the same thing, but fuel can apply to gasoline or diesel fuel. As Padgett pointed out, direct fuel injection has also been used in diesel engines. I started this thread become someone asked me if my SLK55 had electronic fuel injection, and I wanted to do some checking before I answered the question.

From the M152 PDF posted by MartinatMersea:

The distinctive AMG 5.5-liter V8 engine with AMG Cylinder Management and direct petrol injection will find exclusive use in the new SLK 55 AMG, which will celebrate its world premiere at the International Motor Show (IAA) in Frankfurt/Main in September. This means that the latest version of the SLK 55 AMG will remain the only roadster in its segment with an eight-cylinder engine.

Since I have the attention of people who know a lot more about engines than I do, I have another question. Is it possible to add a blower or supercharger to an SLK55 M152 engine and improve the engine’s performance?
 

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Premium Member 2005 SLK55 AMG
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621 Posts
MartinatMersea

Thank you for the excellent article. I did more checking to make certain that “direct petrol injection” and “direct fuel injection” were the same thing. Your article referred to “direct petrol injection.” In the US, petrol and gasoline usually mean the same thing, but fuel can apply to gasoline or diesel fuel. As Padgett pointed out, direct fuel injection has also been used in diesel engines. I started this thread become someone asked me if my SLK55 had electronic fuel injection, and I wanted to do some checking before I answered the question.

From the M152 PDF posted by MartinatMersea:

The distinctive AMG 5.5-liter V8 engine with AMG Cylinder Management and direct petrol injection will find exclusive use in the new SLK 55 AMG, which will celebrate its world premiere at the International Motor Show (IAA) in Frankfurt/Main in September. This means that the latest version of the SLK 55 AMG will remain the only roadster in its segment with an eight-cylinder engine.

Since I have the attention of people who know a lot more about engines than I do, I have another question. Is it possible to add a blower or supercharger to an SLK55 M152 engine and improve the engine’s performance?

Pretty shure The Sarge will fill in here:D But AFAIK there are no compressors or turbos avaliable for that engine. You need a R171 55 AMG to do that. Time for you to upgrade>:D
 

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Premium Member 2012 SLK55 AMG
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6,208 Posts
MartinatMersea

Thank you for the excellent article. I did more checking to make certain that “direct petrol injection” and “direct fuel injection” were the same thing. Your article referred to “direct petrol injection.” In the US, petrol and gasoline usually mean the same thing, but fuel can apply to gasoline or diesel fuel. As Padgett pointed out, direct fuel injection has also been used in diesel engines. I started this thread become someone asked me if my SLK55 had electronic fuel injection, and I wanted to do some checking before I answered the question.

From the M152 PDF posted by MartinatMersea:

The distinctive AMG 5.5-liter V8 engine with AMG Cylinder Management and direct petrol injection will find exclusive use in the new SLK 55 AMG, which will celebrate its world premiere at the International Motor Show (IAA) in Frankfurt/Main in September. This means that the latest version of the SLK 55 AMG will remain the only roadster in its segment with an eight-cylinder engine.

Since I have the attention of people who know a lot more about engines than I do, I have another question. Is it possible to add a blower or supercharger to an SLK55 M152 engine and improve the engine’s performance?
In short the answer to your questions is no. The high compression of the engine is the limiting factor.
 

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Premium Member 2001 SLK320/2000 SLK230
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2,719 Posts
The M152 was first available in 2012 and the specs were ideal for a gasoline engine but the 12.5:1 compression mandated DI to be able to run on pump gas.. Here in 2019, 3-4 liter blown V6s with DI are the new standard.

That said I *suspect* a blown M152 would require a new computer, injectors, high pressure fuel pump, and MAF. It's not just a bolt on.

Probably better to just find a M157.
 

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Registered 2005 SLK55 AMG & 2006 Kleemann 55K S8
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919 Posts
Just a bit about DFI and why some cars have EFI also... The one big downside of DFI is that there is no fuel washing over the intake valves as the fuel is sprayed directly in to the cylinder. This will cause buildup of burnt oil on the valves and hurt performance in time. That is the main reason many companies have now switched back to some EFI. You need a VERY good PCV system if you don't do that.

Other than that, DFI is by far the way to go. The fuel is sprayed directly in to the cylinder at the perfect time and it also helps to cool the cylinder.
 

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Registered 2006 SLK280
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7 Posts
It surely is an impressive engine but I had to stop and giggle at the phrase: "a perfect synthesis of perceptible dynamism"

Thanks for the PDF link.
 

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Premium Member 2012 SLK55 AMG
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2,510 Posts
Probably better to just find a M157.
I agree with you that M157 engine is the way to go if it can be made to fit. Not only would it give over 100 extra bhp in standard form it’s also highly tuneable if you want to chase bigger numbers.

Getting a donor engine and ancillaries from a wreck currently wouldn’t cost much more than what Kleemann were charging for their R171 supercharger kit for.

As the M157 and M152 are so closely related and from the same era, integration of the various electronic systems should be fairly straightforward too!

Heaven forbid if my engine ever went pop, it may well be easier to source an M157 than a M152.
 

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Registered 2012 SLK55 AMG w/P30
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3,471 Posts
I agree with you that M157 engine is the way to go if it can be made to fit. Not only would it give over 100 extra bhp in standard form it’s also highly tuneable if you want to chase bigger numbers.

Getting a donor engine and ancillaries from a wreck currently wouldn’t cost much more than what Kleemann were charging for their R171 supercharger kit for.

As the M157 and M152 are so closely related and from the same era, integration of the various electronic systems should be fairly straightforward too!

Heaven forbid if my engine ever went pop, it may well be easier to source an M157 than a M152.
If my experience is any indication, I believe you’re actually correct that a M157 is easier to source than M152. Still waiting a month later for a $.25 O-ring. Only made for the M152.
 
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