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BHP from MAF reading

AndrewW Jul 1, 2019

  1. AndrewW

    AndrewW Registered User


    I've had my 2010 S4 since October last year (love it - best all round car I've ever had) and I've always had a sneaking suspicion that it wasn't standard.

    Short of paying for a Dyno run (which I may still have to do...) I've been reading about ways to calculate the power from logging the MAF readings in VCDS, so I started logging the RPM and MAF and did a 1200-redline run in third gear, the peak (in kg/hr) came through as 1236.18 (@ 6613 rpm), which translated to 343.38 g/s, which (apparently) should be divided by 0.8 to give the BHP, which came out as 429bhp.

    These are the only two runs I've tried so they may not be the best but 429bhp still seems extremely high.

    What do you think to my logic above? I'm sceptical but I've also read from people who swear by it.

    Any other tips on how to figure out what it's running?

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  3. MuPPeT_ON_TouR

    MuPPeT_ON_TouR Well-Known Member Silver Supporter

    If it's a 3.0 supercharged that figure isn't completely mad for just a stage one map.

    I'm sure there should be a code that can be read to see if it has been mapped.
    V6_Man likes this.
  4. V6_Man

    V6_Man Moderator Staff Member Moderator VCDS Map User

    I agree with @MuPPeT_ON_TouR , it sounds like the S4 is running a stage 1 map. The easiest way would be to read the ECU and find the time stamps as it should show when the changes were made. However, it might not be as simple as some tuners do lock the ECU for any readings, e.g. MRC.

    You than have the option of draggy / Vbox runs and see the traps etc on WOT in 3rd-4th (between 2k-3k rpms to the redline). It might not be accurate but will give you an indication.

    And last but not the least, the easiest option would be to pay £45 and just have a couple of runs (usually 3) on a dyno. However, your numbers will vary depending on the dyno you are using, tyre pressure & tread, ambient temperature, humidity, the correction factor used by the operator and a million other factors. For example, I am MRC stage 2. I have ran 490PS on MRC dyno (Cartec Dyno), 405bhp on Unicorn's (Dyno Dynamics Dyno, which is also called as a heartbreaker dyno :)) and 523ps on ARC Dyno in Gloucestershire (which is also a Cartec Dyno and same as MRC).

    Just like Doctors will prescribe you with different medicine for same health issues, there are hardly two Dynos that will give you identical numbers.

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