Quote:
Originally Posted by ZM2
To be fair, no custom tune is going to beat the latest BM3 OTS maps since they already max out the stock HPFP.
And now that the Stg 2+ maps are out, no custom tune is going to beat the 2+ OTS unless you have a very specific situation like a Stage 3 turbo or are tuning with meth.
But the custom tuners will gladly take your money saying they can do better, not offer any refunds when they don’t, and some of them may blow your motor trying and then blame it somehow on you.
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Well this is a bit inaccurate imo, and here's why:
1) Just because the hpfp is maxed out doesn't mean there isn't more on the table, there are many other tuning factors besides fuel such as ignition timing for instance, and conditions that said car will experience. So no OTS map will ever be able to perfectly push each car to the potential, there will always be room for a custom tune to make the best possible fit for each car. But I do have to say bm3 makes the best ots maps I have ever seen, and I've seen alot in the bmw world and jdm world (subaru, mistubishi etc).
2) let's talk about ignition timing first: an ots map will never be able to fully max out the ignition timing curve on a car because of the variation in fuel quality around the world. Also it depends on how hot the climate is, what kind of intercooler you have and how it's able to deal with iats. So if an ots map were to push one car to the limit it may cause another car to knock so there must always be some conservation in this area in order to be a safe for all tune. So a custom tune would be able to tailor the ignition timing curve to perfectly match your fuel, climate, mods and have the car run 10/10 and never knock while an ots map can never get close.
3) altitude: from what I know the excellent tuners at bootmod3 halim (denmark)and ptf (Toronto) are both located at or very close to sea level. But bmw owners can be at any altitude from sea level all the way up to Denver colorado, and there is no way for a denver car to ever hit the boost targets of a sea level car. So the ots maps again have to take this into account when setting the boost targets, or maybe they don't and you have to run a lower stage map. Either way a one size fits all tune will never be able to accommodate atmospheric density and peak boost targets while staying in the effencency range of your turbo like a custom tune can. This is even further complicated by what kind of diverter valve and turbo inlet and downpipe (catless or high flow catted) you have as it will change wgdc allowing you to push more or less. Again a custom tune will be able to fully match your car to your altitude.
4) fuel quality: this is huge as there are acn maps for a reason. Europe tends to have higher octane fuels than NA, while even within a country fuel quality can vary vastly. For example in Canada the best fuel quality is in Alberta with husky 94, while BC' chevron 94 absolutely sucks imo (based on data logs observed with a tuner on an sti). So if you run an acn map it will be extremely conservative but you might have a bit more left on the table, if you run a normal map it might be too agressive.
5) ambient temps: in cold climates the air is more dense so you will need more fuel so the ots maps might not function properly. If it does function fine then there might be more on the table for hotter climates. Same goes for ignition timing.
So with a custom tune your car will be perfectly adapted to your environment, fuel quality, mods etc and it will absolutely better than any ots map. You can even vary your custom tunes to be adapted for your mods but leave room for climate variations, or adapted to favor timing over boost for track cars. Or max everything out for max power builds etc.
As you can see there can be more to gain with a custom tune. But that being said with quality ots maps like bm3 ones it might not be worth it.