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      08-29-2009, 06:04 AM   #41
BPMSport
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Drives: Harrop M3 / F10 M5 / F82 M4
Join Date: Apr 2008
Location: SoCal

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2000 BMW M5  [0.00]
1990 BMW 735i Turbo  [0.00]
2008 BMW M3  [7.50]
2015 BMW M3  [0.00]
2015 BMW M5  [0.00]
Quote:
Originally Posted by PencilGeek View Post
I think your assumptions of what work is performed during this so-called "custom tune" isn't entirely correct. Yes you get custom AFR -- but that's about as much actual custom work that you get. The rest is almost entirely boiler-plate and doesn't require your car to be on a dyno.
  • Opening throttle bodies earlier and all the way: check.
  • Modifying spark curve: check.
  • Change the RPM limiter: check.
  • Cat delete: check.
  • Launch control: check.
  • 91 octane tune: check.
  • Air filter: check.
If we really want to get technical about it, your custom tune is really only "custom" on the day you get it. After that, it might as well be a shelf tune. On any other day, the air density is different; density altitude is different, dew point is different; fuel may contain slightly different oxigenation; tempuratures are certainly different. All of these things affect the dyno results and the AFR of your motor. Your custom tune may have been custom on the day you got it, but it's not so custom a week later.

Even with that said, I'd still recommend a custom dyno-tuned ECU by AA or PowerChip if one can afford it.
I'm going to have to disagree with you here Robert. The custom tune is a worlds difference from a quick screen tune. These variables that you speak of are irregardless of the optimizations made to the mapping. It's not as easy as you make it out to be with your check list. It seems as if you are saying that we are tuning solely based on the temperatures/barometric pressure/ and altitude, and that in a different environment, the tune would not suit the car. If the car makes more power at X RPM under Y load with a custom tune, it will certainly make less at those points with an "off the shelf" tune under any conditions. I wouldn't call any of our tunes off the shelf, per se, as they are all dyno tested. We do not make blanket optimizations to the files that go in customers ECU's. In powertrips car we made a number of changes that require a dyno to fine tune to extract all of the hp possible. We can call in forensics here but lets not get ahead of our selves.
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Last edited by BPMSport; 08-29-2009 at 01:27 PM..
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