Originally Posted by Cuda340
...If Chrysler was going to use the old designation, it would have been this year with the introduction of the retro 6.1 (392 cu. inch) SRT Challenger.
I assume you meant "6.4". There are a couple of reasons that Chrysler didn't launch the Challenger SRT with the 6.4. One, the 6.1 was planned from the beginning to run a minimum of 5 model years, to recoup R&D, and a gen II 6.1 is not out of the question. Two, marketing-wise there was no need to bring out the 6.4 for the 2008 or 2009 model year.
Originally Posted by Cuda340
Chrysler is trying to develop a high hp engine that will be able to hold it own with the 400+ hp Camaro and the Shellby Mustang and not hurt it with future CAFE standards. Remember that Chrysler would prefer to sell its top-of-the-line engine in the SRT and not in some limited production model like the SS Challenger (quantity=profits).
SRT has already developed, and is currently testing their next production engine, the 6.4. While CAFE is always a consideration, the low-volume production of SRT8 models does not put much of a dent in the CAFE averages. Typically, SRT8 production has been on average only around 3% of the model lineup.
Originally Posted by Cuda340
The 6.5 must be significantly different from the 6.4 for it to be more acceptable of the MDS system.
But as mentioned, there is no "6.5" currently under consideration or development. MDS has been around a long time, before development of the 6.1 and 6.4 even started. It wasn't that they "just" discovered that MDS wouldn't work properly in the 6.1/6.4 and now have to build a new "6.5" engine. There is no reason at all, nor is there a need for a "6.5". Beyond the 6.4, think something like "7.0".
Note that MDS is more of a marketing ploy than a significant "fuel saving" feature. The real world gains are far less than the "+20%" that they were quoting when MDS was first introduced. Most SRT owners are not worried about gaining another mpg or two, and would certainly not want it if it came with any performance related drawbacks.