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Top Speed Limiting

  1. Oct 18, 2011 #1
    Can anyone say me how the top speed in vehicles can be limited (changed). Is it possible to reprogram the top speed limit set by OEM?

  2. jcsd
  3. Oct 18, 2011 #2
    Not exactly sure how each manufacturer does it, but you can set a soft rev limit in top gear on the ECU, it'll do one of several power limiting things. A custom map can change these sorts of things.
    Last edited: Oct 18, 2011
  4. Oct 18, 2011 #3
    "but you can set a soft rev limit in top gear on the ECU, it'll do one of several power limiting things" didn't get ur point.

    But generally the Vehicle's ECU is non- programmable (I believe). This means how come a custom map can be added?

    Assume my vehicle's top speed limit is 180 kmph. I wanna give reset the limit to 90 kmph. Considering today's generation vehicles, can I reset the limit. May be I would change this value again later.
  5. Oct 18, 2011 #4
    ECU's aren't hardwired, they are essentially flash memory with look up tables. As such they can be pretty easily changed.

    In most cases setting a soft rev limit doesn't require a remap, you can plug in a laptop and some OEM (or OEM knock off) software and just type in a number. Not knowing the exact ECU, and how the ECU works means I can't give an exact answer.

    Getting the right kit is prohibitively expensive for one job. Seeing the dealer or a 3rd party mapping company is your best bet.

    Why on earth do you want to set the limit so low anyway? You'll likely have trouble in top gear with that on any sensibly geared car.
  6. Oct 18, 2011 #5
    Thnx. Well I just want to know whether such a change is possible. But is it legal to reset the OEM values flashed in vehicle's ECU atleast from Insurance point of view?
  7. Oct 18, 2011 #6
    It's perfectly legal to do, people get maps all the time. Setting a top speed lower than the car 'as sold' from the factory should (logically) make a premium go down if the limit is done officially, it probably won't though as car insurance people are all gits. Only way to find out for sure is to ring up and ask.

    Lots of company vans have it done (you see little stickers saying this van is limited to xx MPH).
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