[The Automotive Enthusiast]

Fresh details have surfaced concerning Mercedes-Benz' long-rumored inline six-cylinder, an engine type the automaker last produced in the late 1990s.
According to a Motoring report, Mercedes is developing a new straight-six engine family that will consist of both naturally aspirated and turbocharged units ranging from 2.2- to 3.5-liter of displacement.

While Mercedes had switched to V6 motors in the past due in part to their packaging advantages, the shift back to straight-sixes is said to be motivated by a desire to maintain or increase refinement as the brand continues to downsize its engines in the interests of efficiency.
The new mills are believed to share components with Mercedes' latest four-cylinders. Previous rumors have suggested they could also spawn a new range of three-cylinders.
Interestingly, no AMG derivatives of the six-cylinder are said to be under development, although that could certainly change in the future.
Should Motoring's report prove accurate, expect to see inline-sixes in the next-generation E-Class and SL-Class models. The current C-Class could also adopt the engines at its mid-cycle refresh, industry whisperings have hinted.

Read more: http://www.leftlanenews.com/details-...#ixzz36S83C6bm

[mkoesel]

Color me skeptical about the natural aspiration and the smaller side of the displacement range. Well, unless they are planning to take on BMW with an I6 motorcycle of their own (I kid of course, the engine will be way too big for that).

I am just as curious right now about what will happen with the non-AMG V8. Obviously they don't need 4.7L of displacement to get <= ~500hp when the new 4.0L AMG mill will blow way past that. We may see the V8 disappear from non-AMG vehicles entirely, since the I6 should be able to go to 500hp itself. If this happens, starting with the new E Class for example, then I'd expect BMW to follow suit soon after, perhaps even with the G30. If you think about it, the S55 could theoretically replace the N63 today. Not that they would do that, but a high output B58 using S55 tech is certainly possible.

[BMW269]

I too am sceptical about the 2.2l I6. But if true, that is best news ever. Small displacement but six cylinders.

[Soorena]

Originally Posted by Levi

I too am sceptical about the 2.2l I6. But if true, that is best news ever. Small displacement but six cylinders.

If the 2.2L version share the same block dimensions with 3.5L version, then it's not that great. You get 2.2L of displacement but you have to carry 3.5L engine's weight around. Reminds me of the E21 320. You could get them in two versions, 320i and 320/6. The 320/6 was a dog compared to the 320i.

[mkoesel]

Originally Posted by Soorena

If the 2.2L version share the same block dimensions with 3.5L version, then it's not that great. You get 2.2L of displacement but you have to carry 3.5L engine's weight around. Reminds me of the E21 320. You could get them in two versions, 320i and 320/6. The 320/6 was a dog compared to the 320i.

That's why I am skeptical. It doesn't really make sense to design a single engine block that has such a huge displacement range. I think someone is just throwing out a guess and casting a wide net so they can't be called out as being wrong later on.

I strongly suspect that this engine will have a 90mm bore center just like the M133 (and the M274 on which it is based) as well as the new M177/M178 V8s. I also think it will be limited to at most two displacements, the primary one being 3L (with perhaps a smaller 2.5-ish liter version). Creating an I6 engine long enough to accommodate even 3.5L would most likely lead to packaging difficulties. And they don't need it; they can just apply the M133 formula to the I6 and be over 500hp easily. In the next ten years, 200hp/L will be the new target for the higher end of the spectrum of turbocharged engines, and 150hp/L will be pretty standard in everything from small economy cars to 6000 lb. SUVs.

[BMW269]

Originally Posted by mkoesel

That's why I am skeptical. It doesn't really make sense to design a single engine block that has such a huge displacement range. I think someone is just throwing out a guess and casting a wide net so they can't be called out as being wrong later on.

I strongly suspect that this engine will have a 90mm bore center just like the M133 (and the M274 on which it is based) as well as the new M177/M178 V8s. I also think it will be limited to at most two displacements, the primary one being 3L (with perhaps a smaller 2.5-ish liter version). Creating an I6 engine long enough to accommodate even 3.5L would most likely lead to packaging difficulties. And they don't need it; they can just apply the M133 formula to the I6 and be over 500hp easily. In the next ten years, 200hp/L will be the new target for the higher end of the spectrum of turbocharged engines, and 150hp/L will be pretty standard in everything from small economy cars to 6000 lb. SUVs.

Well, Mercedes' purpose of going I6 is to reduce costs, so a 2.2l I6 makes no sense. I3 are to replace 4 cylinders in terms of power, I4 6 cylinders, I6 8 cylinder, and 8 are range topping engines beating V12 in terms of power. V12 stays as status.