Comparing tune files.

[seagreen323i]

I got my hands on tune file from a former well known bmw tuner. Don't want to name names but all I really found was some throttle sensitivity remapping and about 1° - 1.5° of additional timing past 4k rpm at full load. Looked around for any vanos tweaks that they claimed and didn't find a single value or scaler changed....
Food for thought.

Something I also found interesting was the reduction in ignition timing at the same time the camshaft overlap increases due to vanos. Thought that was pretty interesting as well.




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[seagreen323i]

First one is the modified tune
2nd one is stock

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[BimmerBreaker]

You'd be surprised how many popular tuners don't do much of anything beneficial. I know someone in California who runs a very popular BMW shop and they have a dyno. Owner has an S54 so we had a bunch of people send their tunes to him. About 2/3 of them made a little more power than stock, like 2-5hp, 1/3 actually lost power over stock, one of the most popular tuners on the market now was the biggest loser - losing 18hp vs stock. We ran the dyno several times and on different days to verify the results. Many of them (probably 1/2 at least) also were also a little sketchy by ignoring knock values and ignoring other safety parameters.

We developed an optimal S54 tune by mixing and matching various values by comparing the kg/hr MAF readings from real world testing while logging values with Testo. Where one tune was optimized in one rpm range we used that tune's settings for that range and another tune's elsewhere. Dynoed that custom tune and it made the most power over the whole rpm range.

So in short, just because a lot of people buy tunes from a tuner doesn't make that tuner good. Dyno numbers are also easy to fudge by the tuner to market their product and it's also easy to make a tune feel good by adjusting the throttle map or even doing things like decreasing low RPM power so you feel a "gain" up top (where it hits stock power level)