Mercedes introduces new 4.0 liter M176 twin turbo V8 to replace the M278 4.6 liter V8 - 476 horsepower

[Sticky]

The M278 being replaced was inevitable but it is interesting that Mercedes is taking their AMG M177/M178 architecture and essentially putting it into cars throughout the lineup. In a way, you can think of this M176 as a budget AMG V8.

The bore and stroke is the exact same as the M177 and M178 at 83.0 x 92.0mm. Horsepower is 476 which you will note is just ahead of the W205 AMG C63 at 469 horsepower and the C190 AMG GT at 456 horsepower.

So what exactly is the M176 lacking compared to the M177 and M178 if it is making more horsepower than the base versions of either? Nothing. Figuring out why Mercedes is using a new engine code is the real question and perhaps they are just doing it to pretend this isn't an AMG engine architecture that is replacing the M278.

Engine		M 176	M 278
No. of cylinders/arrangement		8/V	8/V
Displacement per cylinder	cc	498	583
Displacement	cc	3982	4663
Cylinder spacing	mm	90	106
Bore	mm	83	92.9
Stroke	mm	92	86
Bore/stroke		1.1	0.92
Rated output	kW/hp	over 350/476	335/455
Peak torque	Nm	approx. 700	700
Compression ratio	1:	10.5	10.5
Emissions standard		EU 6	EU 6

We do not know if the turbos are different compared to the M177 and M178. Mercedes also does not comment on the engine internals but the 10.5:1 compression ratio is the exact same.

If BenzBoost were to guess we would say the internals are the exact same and perhaps the turbos are different. The tuning definitely is. The M176 offers 516 lb-ft of torque. This is equivalent to the AMG GT S and W205 C63 AMG S.

Equal torque at less horsepower implies the M176 is tuned for the low end. This makes sense considering it will debut in the heavy W222 S-Class.

The real takeaway from all of this is that Mercedes V8 tuning will expand with the volume of M176 V8 powered cars entering the market. A good thing for BenzBoost.

Dynamic power delivery combined with high efficiency: the new biturbo is one of the most economical V8 petrol engines in the world. The special features of the V8 (internal code: M 176) include cylinder shutoff at part load. The M 176 will launch with this technology next year in the new S-Class.

Developed by AMG for Mercedes-Benz, the hallmarks of the new V8 biturbo are exemplary efficiency and environmental compatibility as well as superlative performance. From its 3982 cc displacement, the new V8 biturbo produces over 350 kW (476 hp) with a maximum torque of around 700 Nm from 2000 rpm. The new engine will consume over 10 percent less fuel than its predecessor, which is rated at 335 kW (455 hp).

For even lower fuel consumption, when operated at part load the new M 176 shuts off four cylinders simultaneously by means of CAMTRONIC valve timing. This reduces the pumping losses while improving the overall efficiency of the remaining four cylinders by shifting the operating point towards higher loads.

The cylinders are turned on and off by the interplay between engine control and actuators on the cylinder head. The switchover to four-cylinder operation is accomplished by eight actuators that act on the axially movable cam parts of the intake and exhaust camshafts via a selector. These cam parts are held on the carrier shaft by gears and are locked in the respective end positions by means of a locking mechanism. The intake and exhaust valves of cylinders 2, 3, 5 and 8 do not open due to the zero-lift cams of the cam parts. At the same time, the fuel supply and ignition are deactivated, so that no unburned mixture is left in the deactivated combustion chamber.

Cylinder shutoff is active in the engine-speed range between 900 and 3250 rpm, provided the driver has selected mode C or E with the DYNAMIC SELECT switch. Cylinder shutoff is inactive in all other transmission modes. As soon as the driver requests higher engine power via the position of the accelerator or as soon as the engine speed goes above 3250 rpm, cylinders 2, 3, 5 and 8 are reinstated within a matter of milliseconds. The transition between the two operating modes is seamless and with no loss of comfort for the occupants. The main menu in the instrument cluster shows whether the engine is currently in four- or eight-cylinder mode.

The new V8 biturbo employs a centrifugal pendulum to reduce both the fourth-order vibrations in eight-cylinder mode as well as the second-order vibrations in four-cylinder mode.

A combination of biturbocharging and direct petrol injection with spray-guided combustion increases the thermodynamic efficiency, thereby reducing the fuel consumption and exhaust emissions. Particularly fast and precise piezo injectors spray the fuel at high pressure into the eight combustion chambers. Multiple injection occurs on-demand, ensuring a homogeneous fuel/air mixture. The delivery of fuel is electronically controlled and fully variable for a fuel pressure between 100 and 200 bar.

The engine is of closed-deck construction, which means that the engine block cover plate is extensively closed in the area around the cylinders. The engine block is of an aluminium alloy and produced by permanent mould casting. This ensures extreme strength while keeping the weight as low as possible, and allows high injection pressures of up to 140 bar. The further-improved NANOSLIDE® coating of the cylinder liners reduces the friction loss while contributing to excellent efficiency. The cylinder head uses an aluminium-zirconium alloy, which is a better conductor of heat than the standard aluminium alloy.

"Spectacle honing" is another measure for reducing the friction and therefore consumption: in this complex process, the cylinder liners receive their mechanical surface treatment when already bolted in place. A jig resembling spectacles is bolted to the engine block in place of the cylinder head, which is mounted later. The honing of the engine block already produces the same state of stress as when the cylinder heads are mounted. For this reason, the tension of the piston rings can be reduced, which leads to a further reduction in friction loss and lower oil consumption.

For an exceptional engine response and low exhaust emissions, the two turbochargers are positioned not on the outside of the cylinder banks, but between them in the "V" – experts call this the "hot inside V". In the interests of thermal protection for the engine components, the manifolds and exhaust turbochargers are specially insulated.

The efficiency-raising measures include the low-friction drive of alternator and refrigerant compressor by means of two short four-groove belts. The water pump is chain-driven by the timing assembly. A two-stage feedback-controlled oil pump circulates the engine oil. It varies the flow rate depending on the required load and engine speed, thereby helping to save fuel.

The M 176 has exhaust aftertreatment with two catalysts directly mounted on the engine and on the underfloor. The as-standard particulate filter is part of the exhaust system under the floor.

The M 176 is produced at the Untertürkheim plant in Stuttgart.

[leveraged sellout]

Now for the love of god can we get a new V12? At this point it's sort of ridiculous that they haven't developed a new one from this engine. 1.5 M178s would be truly astounding, nothing would touch it. And it would be easily modified into a true monster. Once the new S63 comes out with a tweaked M178 making nearly the power of the V12 and not a lot less torque (with a lot less weight and a better gearbox) - the 65 will seem useless. Really hope that's the next big announcement. Also they really need to figure out how to get their hydraulic suspension (Magic Body Control) to work with 4Matic, seeing as most S-Classes are sold with 4Matic which means you can't have the truly astounding MBC suspension. If the next V12 gets AWD - this needs to happen.

[Sticky]

At this point it's sort of ridiculous that they haven't developed a new one from this engine.

They really got their mileage out of that architecture. I'm not surprised. The V12 isn't really their focus. They just do it as a matter of prestige.

Once the new S63 comes out with a tweaked M178 making nearly the power of the V12 and not a lot less torque (with a lot less weight and a better gearbox) - the 65 will seem useless.

It's been this way since the M157 hit the scene.

[AMGAffalterbach]

Love that this is a closed-deck block, not uncommon for V8s though.

Forgive me if I've posted this previously, can't remember, but it's definitely interesting to note that the M177 in the E63 S 4Matic+ uses new twin-scroll turbos, whereas the version in the C63/S and AMG GT/s use single-scroll turbos. So much for those supposed patent conflicts with BMW and Audi. My guess is the same as yours on this, that they just have a different turbo setup. The single-scroll units on the C63 S are BorgWarner B04, can't imagine the rest differ much in size but probably have different compressor/turbine specs in similar housings.

[Sticky]

but it's definitely interesting to note that the M177 in the E63 S 4Matic+ uses new twin-scroll turbos, whereas the version in the C63/S and AMG GT/s use single-scroll turbos.

Agreed. They did this on purpose of course. The C63 and AMG GT S are less powerful as the E63 needs the power to go up against Audi's 4.0 TFSI and its twin scroll turbos. The E63 will likely gain more with a tune only as well.

If someone can figure out the manifold and turbo swap onto the AMG GT and C63 though...

[AMGAffalterbach]

If someone can figure out the manifold and turbo swap onto the AMG GT and C63 though...

Exactly what I'm thinking . I mean the M177 with twin-scrolls is at 603hp/627tq, the Audi Perforrmance 4.0 TFSI is at 605hp/553tq, and the BMW S63TU is at 575hp/500tq at 4.4 liters... (I guess the very limited M6 Competition is at 600hp/515tq, but still). BMW is really lacking in this department, not that they're known for their V8s, more specifically not in modern times.

BMW needs to come out with a new V8 soon to be competitive whether it is on the N63TU or S63TU front, moreso with this M176 announcement. To be fair, which makes complete sense, the most impressive specs from the list above appear in order of which engine architecture was released most recently. Doubt any of the german 3 would release a new engine without explicitly beating the competitors.

But to tie it back to the article, the Mercedes-Benz/Mercedes-AMG has the best engine development of the three I've seen recently, especially with the M256 inline-6 you wrote about, using the supplementary electronic turbine and all. Audi being a close second with that badass new 3.0 TFSI single twin-scroll in the V.

[Sticky]

BMW is really lacking in this department

Why do you say that? They really aren't. Their motor makes the most power tuned on the factory turbos.

BMW needs to come out with a new V8 soon to be competitive whether it is on the N63TU or S63TU front,

I strongly disagree.

But to tie it back to the article, the Mercedes-Benz/Mercedes-AMG has the best engine development of the three

Well let's see what the E63 does with the new manifold/turbos. The Audi 4.0 TFSI and BMW S63TU are both much stronger than the M177 and M178 in the C63/AMG GT.

[AMGAffalterbach]

My opinion is just based around specific output and my predictions for how the M5 will stack up head-to-head versus the RS7 Performance and E63 S 4Matic+ in real world performance. Yet, most of that I guess can be attributed to all-wheel-drive, which I'm sure BMW has on the roadmap. Still, based on anecdotal evidence from a few local friends that own repair shops here and specialize in the German three, they always send me pictures of the BMW biturbo V8s having issues with valve guides, oil pumps (as the recall addressed), and head work in general.

I wasn't aware that full bolt on numbers were highest for the S63TU, especially considering the factory car runs, what, 22 psi already? But tune-only numbers, my impression was that the BMW motor really lacks in torque compared to the other two. Having recently driven an RS7 with APR Tune + Exhaust, the Audi felt other wordly fast compared to a JB4 M5. Apples and oranges when it comes to the tune, I know. Sad we only have 91 here, and sit over a mile above sea level, so their full potential is lost anyway.

You're right on the new manifold/turbos. It really does come down to the efficiency and benefit of the twin-scroll design which the AMG motor was the last holdout to use. I stand corrected, though, I hope you're right that BMW remains competitive with the S63TU for a few years to come.

[Sticky]

My opinion is just based around specific output and my predictions for how the M5 will stack up head-to-head versus the RS7 Performance and E63 S 4Matic+ in real world performance. Yet, most of that I guess can be attributed to all-wheel-drive, which I'm sure BMW has on the roadmap. Still, based on anecdotal evidence from a few local friends that own repair shops here and specialize in the German three, they always send me pictures of the BMW biturbo V8s having issues with valve guides, oil pumps (as the recall addressed), and head work in general.

I understand. I'm basing my opinion on what I've seen in the aftermarket so far. I mean, BMW started the whole top mount twin scroll thing. Audi's engine is based on that and conversely Mercedes now.

They are going to AWD but obviously in the real world a stoplight it's hard to beat the AWD cars.

I wasn't aware that full bolt on numbers were highest for the S63TU, especially considering the factory car runs, what, 22 psi already?

You can check out the S63TU section but basically the motor got its flashing ability after the other two so it had ground to make it up. It has and makes more power with just a tune.

I stand corrected, though, I hope you're right that BMW remains competitive with the S63TU for a few years to come.

Honestly, if it's a variant of the S63TU going into the new M5 BMW will have the displacement and power advantage right off the bat.

[AMGAffalterbach]

Interesting notes Sticky, yeah. I love learning about these things, I'll look into S63TU tuning a bit more on here then.

Wonder what the next generation of hot V twin turbo V8s will bring. Maybe VGT combined with twin scroll, if the materials allow for the higher EGTs than diesel? Electronic assisted turbos or drivetrain? Even more downsizing? Exciting times.... Despite the fact they now all have the same general engine layout lol.

[Sticky]

Wonder what the next generation of hot V twin turbo V8s will bring. Maybe VGT combined with twin scroll, if the materials allow for the higher EGTs than diesel? Electronic assisted turbos or drivetrain? Even more downsizing? Exciting times.... Despite the fact they now all have the same general engine layout lol.

I hope they don't go any smaller. If displacement drops further we won't have a V8 any longer.

Electric motors are coming. Let's hope things like the AMG GT Concept are what they do. Combine the V8 with electric motors for an insanely fast platform.

[Nasser]

you can't wipe out the smile off your face once you hit the paddle and the boost kicks-in.... its a super fast sedan
very fast acceleration to 220kmh... can't wait to see modifiers release down pipe , air box , and a proper tune ...
I don't think there will be any sedan that can compete with it in the near future !!