ECU Tune - differences between vendors

[Fen335i]

So, there have been numerous threads about ECU tunes for our cars...this may have been discussed before, but what is the main difference between these aftermarket tuning companies and how they set up their ECU tunes? How can one tuner claim they are getting 15-20hp from their tune and another only claims 6-8? Is there truely that big of a difference in tunes?

For example Dinan claims a relatively modest increase of 9hp @ 6000 rpm's with it's tune. However Powerchip seems to claim a lot more than that. I know there is a lot of variation in what type of Dyno equipment you use. Is that the explanation?

However, when you read reviews after guys have had these various tunes done, some say it's a huge improvement and others say it's just marginal (like leaving the car in "sport mode" all the time).

IF these dyno claims are true, what is a company like Powerchip doing that achieves the extra hp/torque that Dinan is not?

I'm not trying to point out particular tuners here (just using PC and Dinan as examples), just trying to understand why all the variation in ECU tunes that are available. Are some companies taking more risk than others? I know we've talked about how some companies are very conservative with their tunes. . . so maybe that's it. Are the more agressive tunes going too far and putting too much strain on the motor?

I'm all for extracting as much hp/tq that I can out of my motor, but don't want to do something dumb and put too much strain on it at the same time...


Any knowledgable folks out there that want to take a crack at this question?