With the newest update of their Software Upgrade for the M278 – 4.7L V8 BiTurbo, RENNtech boosts the 550-Series to AMG Power Levels.

The RENNtech upgraded M278 now produces 540 HP and 705 LB-FT at crank. Compared to power numbers by Mercedes-Benz, the 550 gains up to 138 HP and 262 LB-FT. This Software update delivers up to 10 HP and 99 LB-FT more than the previous version.

The vast amount of increased torque across the entire RPM range gives the 550 an extra edge to compete with AMG powered vehicles. All this without sacrificing around town comfort and daily driver reliability.

The M278 – 550 engine is currently offered for the W222 – S Class, C217 – S Coupé/Cabriolet, C207 – E Coupé/Cabriolet, C218 – CLS Class, X166 – GLS SUV and R231 – SL Class.

The updated RENNtech software will also be shipped for the discontinued models, the W221 – S Class, W212 – E Class, C216 – CL Class, W166 – ML Class and X166 – GL Class.

In addition to the updated ECU Upgrade, RENNtech is releasing the all new ‘RENNtech 550 Sport Package’. Included in this all-around transformation package are ECU-Upgrade, Carbon-Fiber Decklid Spoiler and Stainless Steel Sport Mufflers. Optional are your choice of RENNtech Deep Monolite Wheels in Brushed Aluminum or Gunmetal. Currently available for select models.


550 – M278 | 4.7L V8 BiTurbo Stock Performance:
*W212-E, C207-E, C218-CLS
Rated by Mercedes-Benz: 402 HP @ 5,000-5,750 RPM | 443 LB-FT @ 1,600-4,750 RPM
Rated by RENNtech: 435 HP @ 4,900 RPM | 508 LB-FT @ 2,350-3,650 RPM

*W222-S, C217-S, R231-SL, C216-CL
Rated by Mercedes-Benz: 449 HP @ 5,250-5,550 RPM | 516 LB-FT @ 1,800-3,500 RPM
Rated by RENNtech: 469 HP @ 4,900 RPM | 563 LB-FT @ 2,350-3,650 RPM


550 – M278 | 4.7L V8 BiTurbo RENNtech Upgraded Performance:
*Applies to all Models, crank power calculation based on 17% Drivetrain loss on 4-MATIC models and 14% Drivetrain loss on RWD models
Rated by RENNtech: 540 HP @ 4,500 RPM | 705 LB-FT @ 2,850-3,450 RPM



Check our website for more information. Click here.

i need a TT engine now , after seeing this

Same price as the previous version? Any concerns with the transmission or other components (i.e. requires upgrade to maintain daily driveability)?

Yes, price will be the same.
And No concerns about daily driveabilty or maintenance. We have multiple cars tested extensively over the past months and had no issues with the updated software.
We always have the longlivety of the vehicles in mind while developing our products and won't sacrifice that for power.

First: Congratulation for this terrific results!

As I already commented at FACEBOOK, I have two questions.

Your stock graph shows a rev limiter around 6,700 rpm? I thought it would be a lot lower? Also: My cars (2014 CLS 550 / 2012 E 550 4matic) do an automated upshift even in "M"-mode well below 6.300 rpm. So how did you measure that?

Second question - the 550 4matic has the W7X700 transmission. A transmission that is rated to 700Nm (514 ft lb), which was the reason for Mercedes to limit the torque in the S 550 as far as Mercedes says. Your tune has 960 Nm - so you are 37% over the limit. Do you also do a tune / mechanical update to the transmission?

This was my main concern, with more words and spoken more goodly.

Thank you for noticing.

We forwarded the question regarding the transmission to our software and development department and will post a more detailed answer.

Wow....That is very impressive.

Very Nice

When you tune your car, this is at your own risk, don't expect your car to act like OEM, brand-new car from the dealership, this is not how the engine was intended to run, this is for performance and again at your own risk, whether it blows the transmission or not sooner is the question but no one is forcing you to do this upgrade.

+1 Peter.

If someone wants to go down this road, they just have to understand they have to accept any risks and trade-offs. Both in terms of reliability and longevity, as well as what that means financially, in terms of potential repair costs, going forward. I can't imagine with a boosted torque value that is 37 percent above the engineered max of the transmission, that the longevity of the transmission wouldn't be adversely impacted without some additional upgrading of the transmission to handle the extra stress.

Thank god you're here....without your firm grip of the obvious I'm not sure what we'd do...

sadly this is not obvious to many people, hence questions like that come up millions of time like:

"what's the safest tune?"
"will a tune hurt my warranty?"
"want to tune my car but don't want to ruin my warranty"
"why can't I have a 700hp car even though I paid for a 400hp car?"
"will the dealer detect my tune?"

For those who tuned your car or going to tune your car.
You need to realize 3 words... "Pay to play"
I would spend money to keep my car at optimal condition.

And...
I am also curious to find out how the transmission hold up under this amazing power.

As you might have noticed, renntech simply replaced the "dyno sheet" above after my question with the same "dyno sheet", however with a new scale on the x-axis.^^

I also got a PM by renntech, where they stated that they did not experience any problems with these torque figures in two 550ies (at least one being a rear wheel drive) and are not aware of any problems with transmissions on the 700 gearbox in general.

By the way: Mercedes uses the W7X700 transmission in a few 63 AMG as well - the GLE 63 for example. Usually the 63 4matic S has a torque of ~660 ft lb (900Nm), the GLE with the 700 transmission is limited to 558 ft lb (760Nm). So please keep that in mind, when modding your cars. Also, at least my transmission (Euro Specs) does not accept higher torque values (depending on gear), so if I would only do an ECU-tune, my gearbox would command a torque reduction to the ECU to safe the transmission, shafts and differentials. This can easily been reproduced when torque braking the 4matic...the engine torque will then be limited pretty strictly (torque management) for drivetrain safety, as tire slip cannot help to relieve it as in rwd-applications.

The only ways to get rid of that (that I know of) is an transmission tune (TCU) OR to send false torque date to the tcu. Instead of 700 ft lb (which the engine puts down in reality), the ECU sends a value of i.e. 510 ft lb to the TCU. So the TCU thinks, that everything is all right...but it then gets an 60% overload (compared to stock).

Disclaimer: I am not a tuner and I have no experience with engine tuning. This are a few thoughts based on data published by various sources such as Mercedes. So I might have a few misconceptions. Please feel free to correct my, where I am wrong!