M256 Engine Questions
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Joined: Jul 2022
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GLS 450 (2022), EQE SUV 350 (2025). GLS 450 (2007)
M256 Engine Questions
Hi Folks-
Apologies for the technical nature of this question, but I'm trying to understand the M256 engine and 48V electric motor in my GLS 450.
I'm assuming that the GLS has a normal torque converter like most other gasoline engines/transmissions. The engine also has a 48V kicker motor which I understand is used for both additional horsepower off the line and also for braking energy recuperation.
My question is: Is this electric motor on the engine or transmission side of the torque converter? Since any fluid coupling will introduce energy losses, it would seem that the 48V motor should be on the transmission side of the torque converter in order to avoid these losses both when accelerating and when braking. However, most of the images I've seen of the M256 engine appear to show the motor attached directly to the engine, which I would then assume would be upstream of the TQ.
Sorry for being pedantic, but I'm a retired engineer who's simply trying to understand how my new $100K car functions. Thanks!
Apologies for the technical nature of this question, but I'm trying to understand the M256 engine and 48V electric motor in my GLS 450.
I'm assuming that the GLS has a normal torque converter like most other gasoline engines/transmissions. The engine also has a 48V kicker motor which I understand is used for both additional horsepower off the line and also for braking energy recuperation.
My question is: Is this electric motor on the engine or transmission side of the torque converter? Since any fluid coupling will introduce energy losses, it would seem that the 48V motor should be on the transmission side of the torque converter in order to avoid these losses both when accelerating and when braking. However, most of the images I've seen of the M256 engine appear to show the motor attached directly to the engine, which I would then assume would be upstream of the TQ.
Sorry for being pedantic, but I'm a retired engineer who's simply trying to understand how my new $100K car functions. Thanks!
Member
Joined: Sep 2022
Posts: 151
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From: Houston
2021 GLS 450 & 23 GLS 450. Have a Holden Commodore, Jeep, truck, and more
Hi Folks-
Apologies for the technical nature of this question, but I'm trying to understand the M256 engine and 48V electric motor in my GLS 450.
I'm assuming that the GLS has a normal torque converter like most other gasoline engines/transmissions. The engine also has a 48V kicker motor which I understand is used for both additional horsepower off the line and also for braking energy recuperation.
My question is: Is this electric motor on the engine or transmission side of the torque converter? Since any fluid coupling will introduce energy losses, it would seem that the 48V motor should be on the transmission side of the torque converter in order to avoid these losses both when accelerating and when braking. However, most of the images I've seen of the M256 engine appear to show the motor attached directly to the engine, which I would then assume would be upstream of the TQ.
Sorry for being pedantic, but I'm a retired engineer who's simply trying to understand how my new $100K car functions. Thanks!
Apologies for the technical nature of this question, but I'm trying to understand the M256 engine and 48V electric motor in my GLS 450.
I'm assuming that the GLS has a normal torque converter like most other gasoline engines/transmissions. The engine also has a 48V kicker motor which I understand is used for both additional horsepower off the line and also for braking energy recuperation.
My question is: Is this electric motor on the engine or transmission side of the torque converter? Since any fluid coupling will introduce energy losses, it would seem that the 48V motor should be on the transmission side of the torque converter in order to avoid these losses both when accelerating and when braking. However, most of the images I've seen of the M256 engine appear to show the motor attached directly to the engine, which I would then assume would be upstream of the TQ.
Sorry for being pedantic, but I'm a retired engineer who's simply trying to understand how my new $100K car functions. Thanks!
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Joined: Sep 2018
Posts: 14,714
Likes: 4,606
From: unbegrenzt
2017 GLE350 4MATIC
Hi Folks-
Apologies for the technical nature of this question, but I'm trying to understand the M256 engine and 48V electric motor in my GLS 450.
I'm assuming that the GLS has a normal torque converter like most other gasoline engines/transmissions. The engine also has a 48V kicker motor which I understand is used for both additional horsepower off the line and also for braking energy recuperation.
My question is: Is this electric motor on the engine or transmission side of the torque converter? Since any fluid coupling will introduce energy losses, it would seem that the 48V motor should be on the transmission side of the torque converter in order to avoid these losses both when accelerating and when braking. However, most of the images I've seen of the M256 engine appear to show the motor attached directly to the engine, which I would then assume would be upstream of the TQ.
Sorry for being pedantic, but I'm a retired engineer who's simply trying to understand how my new $100K car functions. Thanks!
Apologies for the technical nature of this question, but I'm trying to understand the M256 engine and 48V electric motor in my GLS 450.
I'm assuming that the GLS has a normal torque converter like most other gasoline engines/transmissions. The engine also has a 48V kicker motor which I understand is used for both additional horsepower off the line and also for braking energy recuperation.
My question is: Is this electric motor on the engine or transmission side of the torque converter? Since any fluid coupling will introduce energy losses, it would seem that the 48V motor should be on the transmission side of the torque converter in order to avoid these losses both when accelerating and when braking. However, most of the images I've seen of the M256 engine appear to show the motor attached directly to the engine, which I would then assume would be upstream of the TQ.
Sorry for being pedantic, but I'm a retired engineer who's simply trying to understand how my new $100K car functions. Thanks!
Last edited by chassis; Aug 19, 2023 at 10:52 PM.
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Member
Joined: Jul 2022
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GLS 450 (2022), EQE SUV 350 (2025). GLS 450 (2007)
Pretty sure that if you have the M256 you have two turbos - one normal one, and a second electric one. The electric one has a faster response (i.e. less turbo lag) and the response is very quick. There's also a heat exchanger to cool the turbo discharge before sending the air to the cylinders.
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2020 GLS450 (wife) / 2024 Ford Bronco (mine) / 2014 VW Tiquan (son)
It has a single twin-scroll turbo, plus and electric supercharger that runs off the 48v system (hence the lack of turbo lag). Only thing missing is the nuclear reactor, but willing to bet will cost as much when it comes time to repair any of this stuff!
https://en.wikipedia.org/wiki/Mercedes-Benz_M256_engine
https://en.wikipedia.org/wiki/Mercedes-Benz_M256_engine
Out Of Control!!
Joined: Sep 2018
Posts: 14,714
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From: unbegrenzt
2017 GLE350 4MATIC
Garret 48V boost motor on the turbo. Garrett (formerly Honeywell) calls it an e-turbo.
https://www.carexpert.com.au/car-new...c-turbocharger
https://www.garrettmotion.com/news/m...-mercedes-amg/
https://www.carexpert.com.au/car-new...c-turbocharger
https://www.garrettmotion.com/news/m...-mercedes-amg/
Last edited by chassis; Aug 20, 2023 at 10:29 AM.
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2020 GLS450 (wife) / 2024 Ford Bronco (mine) / 2014 VW Tiquan (son)
How many mounts are there on this engine? Just two plus the transmission?
Out Of Control!!
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From: unbegrenzt
2017 GLE350 4MATIC
I noticed that too. I guess they can get away with it on a straight 6, not having to battle as much vibration as found in the V engines? I don't know, we'll see when we get to the point of needing to replace them. I'm over 60k and 3 years now and not really noticing too much issue in that department. Maybe a little extra looseness feeling when shutting down the car, a little tiny shimmy feel which is definitely mount related, but certainly not to the point of needing attention.
How many mounts are there on this engine? Just two plus the transmission?
How many mounts are there on this engine? Just two plus the transmission?
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I noticed that too. I guess they can get away with it on a straight 6, not having to battle as much vibration as found in the V engines? I don't know, we'll see when we get to the point of needing to replace them. I'm over 60k and 3 years now and not really noticing too much issue in that department. Maybe a little extra looseness feeling when shutting down the car, a little tiny shimmy feel which is definitely mount related, but certainly not to the point of needing attention.
How many mounts are there on this engine? Just two plus the transmission?
How many mounts are there on this engine? Just two plus the transmission?
Out Of Control!!
Joined: Sep 2018
Posts: 14,714
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From: unbegrenzt
2017 GLE350 4MATIC
What do you want to see? The ebay photo of the engine on the wood pallet (you saw that, right?) shows one black plastic engine mount bracket. Same on the other side. Transmission is a garden variety 9G. What else haven't you seen?
