Close

    • Mercedes-Benz R172 SLK55 M152 5.5 liter V8 dyno resutls - 362 wheel horsepower stock

      The new R172 generation SLK55 features a naturally aspirated M156 5.5 liter V8. It is basically the M157 twin turbo unit sharing the same bore and stroke as well as direct injection but without the turbos and having a higher compression ratio at 12.6:1 versus 10.0:1 for the twin turbo M157 motor.

      The SLK55 AMG hits a respectable 362 wheel horsepower stock on a dynojet. That is a peak figure and the majority of the runs were in the ~350 range. For a rated horsepower output of 415 the SLK55 puts out good power to the wheels and may be just slightly overrated. Another way to look at it is that the motor dyno's on average a few horses higher than a stock E92 M3 despite being rated only one horse higher and having an automatic transmission.

      With this motor only being utilized in one car currently it is unknown if it will get good aftermarket support with such a comparatively small market. There is potential it looks like for over 400 wheel horsepower with bolt on's. Not anywhere near as potent as an M156, but respectable.

      This article was originally published in forum thread: Mercedes-Benz R172 SLK55 M152 5.5 liter V8 dyno resutls - 362 wheel horsepower stock started by Sticky View original post
      Comments 2 Comments
      1. Dueclaws's Avatar
        Dueclaws -
        We previously owned a SLK55; the biggest problem is getting power to the ground (wheelspin). But the new 5.5 engine is a plus.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Dueclaws Click here to enlarge
        We previously owned a SLK55; the biggest problem is getting power to the ground (wheelspin). But the new 5.5 engine is a plus.
        I like the new engine but it has cast pistons on purpose to hold it back. Don't like that and I wish it had the M156.

        Doesn't make sense to me that Mercedes developed 1 motor for 1 car but since it is basically a naturally aspirated M157 I guess it didn't cost them much to do.