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      02-28-2018, 08:54 AM   #185
BimmerPost Supporting Vendor

Drives: M2
Join Date: Jan 2016
Location: Miami, FL

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Originally Posted by XutvJet View Post
Everything I've read says the drop in power in beyond ~5500rpms with a stock turbo N55 with a tune is merely the result of the turbo exceeding it's efficiency and blowing has hard as it can.

BMW goes to great lengths to artificially deliver a naturally aspirated powerband. With the standard issue N55, power drops after about 5800rpms (a bit less with PWG cars). With the MPPK and M2 N55s power drops after around 6200rpms. When you tune these cars, you wreck that OEM power delivery and greatly increase low and midrange power. When you do this, you reveal the efficiency range of the N55 turbo which peaks at around 5500-5700rpms just like we're seeing with this AA dyno.

I don't disagree that heat soak can affect stock intercooler BMWs and there are plenty of dynos out there showing this, but IMO, this is not what we're seeing with these dynos. From what I'm seeing, this is tune that is pushing the turbo to it's maximum, if not slightly beyond. Perhaps a lack of fuel as well.

We'll have to see what others see with their own independent dynos. This is a Mustang dyno afterall. It's a great way to really develop a solid tune. It's a great tool to influence your results if you so choose. I'm not in anyway saying AA is doing this, but you can easily manipulate data with a Mustang to show gains that aren't there or underscore the base dyno, etc. A Dynojet? Not really. There's some BSing you can do, but it's really easy to see.
I have fuel logs that will show an appropriate AFR throughout the pull, but realistically there is no excuse to release a tune with incorrect AFR seeing as these cars use widebands to target a ratio anyways.

I agree with you on the dyno comments, it is 100% possible to skew numbers with a Mustang, but that's something we simply don't do. If I wanted to mess with the readings, I would have done a 3rd or 4th gear pull to get lower IATs and more ignition timing (which would keep the power from falling as much up top) and then adjusted the weather parameters in the software to get the peak number I wanted in order to have a very pretty dyno to post. We dyno all of the cars here in higher gears with added load to try and match actual driving conditions. The same car with our flash on a Dynojet will never produce lower numbers than on our Mustang. Hopefully we'll see some independent results posted here soon.

We're engineers before we're programmers, so we have more R&D invested on the dyno modifying the core of the actual tune as opposed to the protocols and tools used to implement it. The tune you receive from us is guaranteed not to be the same as any other tuner. We aren't selling the same OTS maps that many companies are purchasing and selling as their own.