The inline 6-cylinder engine in the E320 CDI is no slouch, but, the common-rail motor can do much more.  

Benefits of Chip Tuning

The most obvious benefit of chip tuning is POWER.  All chip tunes increase power output my different amounts, and often the power upgrade is offered in “Stages” – Stage 1, Stage 2 etc.

Secondly, lots of chip tunes for the newest generation diesels offer fuel economy improvements.  Depending on the platform, these can be significant or mild improvements.

Lastly, reconfiguring the EGR system can limit soot build up in components like EGR valves & intake manifolds.

E320 CDI Stock Power

208 horsepower & 369 lb-ft of torque.

E320 CDI Chip Tuning Options

There are a few vendors that offer chip tunes:

• Rocketchip – offers Stage 1 & 2 tunes without any hardware modifications.  Stage 1 nets an advertised extra 50 horsepower and 52 lb-ft of torque, while stage 2 bumps that to 60 horsepower & 90 lb-ft.  Cost: $400
• Green Diesel Engineering – Advertised 30 hp increase plus 3-5 mpg economy improvement.  Cost: $695

What We Used

We have used Rocketchip for TDI tuning for over a decade, so, when Jeff from Rocketchip was in our area we took our 2006 E320 CDI to him for the Stage 2 treatment.  Importantly, Mercedes common-rail diesels benefit from an injector calibration before and after tuning.  Jeff reports much better power, fuel economy and smokiness if the calibrations are done correctly vs. not at all.

Overall the car is noticeably quicker, but the 90 additional lb-ft of torque is really the part you feel.  The 2,000-3,000 RPM range, where power used to build slowly as RPMs increased, is now the real bread-and-butter power range.  The improved torque number also results in the improvement in MPG as the engine needs to turn less in order to make the same amount of overall power.  The light smokiness when punching the accelerator is totally gone, too, which was very nice improvement as well.

This Stage 2 tune is the highest power increase that Rocketchip feels comfortable asking from the stock turbocharger.  The OM648 block can handle much more, however.  OM648 turbos are frustratingly hard to find, so, an upgrade might be in the future.  Stay “tuned”.