4.7 Bi-Turbo: Laughingly under rated...
I definitely notice a difference between the E550 and the C63, though I have described the E550 acceleration as "like the C63 without the drama".
When you step on it in the C63 you get noise and a nice rumbling sensation as you zoom away. In the E550 you get almost the same acceleration, but without all the noise and vibration. You have to look at the speedo to realize how fast you just accelerated.
It's a great car.
See RENNtech's info: http://www.renntechmercedes.com/www/node/702
(scroll through pictures)
Their graph compares the stock M278 engine to their tune. Stock is considerably more than 402..... or 429.
Read the results a '12 CLS 550 (on their forum) had at the strip after the RT tune: best of 12.3/ 1/4 mile: stock (including tires) except tune. Wheelspin was an issue.
Last edited by Dueclaws; Jun 1, 2012 at 10:36 AM.

I came from a revvy Japanese V6 and thought I was still adjusting to all that torque from the E550 starting at 1900 rpm.
I do like the subtle whine from the turbos with all the windows down pulling away from city stop lights
Does anyone really believe the MB dyno doesn't work?
BTW chassis dyno's are notoriously error prone especially when trying to apply some correction factor to get the crank horsepower. In particular they have no method to accurately control the intake temperature or the airflow over a turbo engine inter-cooler system be it air to air or air to water. Usually they attempt to blow air with a big squirrel cage fan.
Be very suspicious of any HP results that don't make a correction to SAE or whatever the european standard conditions are.
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Does anyone really believe the MB dyno doesn't work?
BTW chassis dyno's are notoriously error prone especially when trying to apply some correction factor to get the crank horsepower. In particular they have no method to accurately control the intake temperature or the airflow over a turbo engine inter-cooler system be it air to air or air to water. Usually they attempt to blow air with a big squirrel cage fan.
Be very suspicious of any HP results that don't make a correction to SAE or whatever the european standard conditions are.
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I think this is one of those car myth's passed on through the ages started when in fact it was done for insurance reasons as in my previous post. Those days are long gone.
In what universe would understating the horsepower result in more sales which is after all the main objective of any business.
BTW increasing the ignition lead does not always increase engine performance. At some point it results in a horsepower loss since the initiation of combustion tries to drive the piston back down into the bore.
I think this is one of those car myth's passed on through the ages started when in fact it was done for insurance reasons as in my previous post. Those days are long gone.
In what universe would understating the horsepower result in more sales which is after all the main objective of any business.
A lot of companies do it to avoid eating into another cars sales. i.e many have claimed the 1M to be VASTLY underrated because they didn't want it to encroach on the E92 M3's power.
BTW increasing the ignition lead does not always increase engine performance. At some point it results in a horsepower loss since the initiation of combustion tries to drive the piston back down into the bore.
The OEM's don't understate the HP, they actually state the correct HP using prudent engineering design parameters in both the hardware and software.
I think anyone who chooses to violate these margins in a street car is foolish. That is why you in essence throw away any factory warranty when you change the tune. The auto industry is littered with denied warranty claims form people who used "tuner" upgrades".
I have no problem with people doing this. I do have a problem with people who blow something up doing this and then whine about the car being poorly designed and/or the OEM not standing behind their product.
BTW increasing the ignition lead does not always increase engine performance. At some point it results in a horsepower loss since the initiation of combustion tries to drive the piston back down into the bore.
My boat has 2- 1,000 hp engines and we gained 25 hp going from 30* to 32*. These engines are built for endurance and power; there are so many variables involved that it's difficult to make comparisons to other engines.
Regardless, I'm very impressed with the power of our '12 E550C.
My boat has 2- 1,000 hp engines and we gained 25 hp going from 30* to 32*. These engines are built for endurance and power; there are so many variables involved that it's difficult to make comparisons to other engines.
Regardless, I'm very impressed with the power of our '12 E550C.
I have no idea how the MB engines are designed but I'd be really surprised of they were not very fast flame front designs since this in general produces more efficient and cleaner use of fuel input which these engines seem to do a very good job of given their excellent fuel economy.
If anyone knows what is the lead at full throttle at higher rpms of these engines?
I have no idea how the MB engines are designed but I'd be really surprised of they were not very fast flame front designs since this in general produces more efficient and cleaner use of fuel input which these engines seem to do a very good job of given their excellent fuel economy.
If anyone knows what is the lead at full throttle at higher rpms of these engines?
Direct injection does allow a little better volumetric efficiency by allowing the intake port/valve design to be a dry air design. This tends to flatten out the torque curve some but max power is at an rpm value above the peak torque point.
I wonder how direct injection engines will do in long term reliability since the injector nozzles are right in the combustion chamber. I guess we will find out down the road.
It would be interesting to compare part numbers in these M278's. Maybe the only difference, if any, is a tune.
Anyone have access to the 2012 M278 engine part numbers?
Last edited by Dueclaws; Jun 4, 2012 at 10:21 PM.
I say speculation because he also let me watch while he updated my ECU - he has no real part in it. The computer communicates with Stuttgart and uploads the correct software. He can't really see any information regarding engine tuning.






