Quote:
Originally Posted by XutvJet
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.
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I agree with you and this is definitely true in the n54 world. However once the turbos are upgraded they seem to hold power better. People say the n55 is a bit better about holding power but so far all the graphs I see power falls off hard. Real hard. I think this really robs the feel of the car actuslly. It makes it much less fun. It was a major gripe for me in my n54.
Concerning your points about dynos .. where do mainline dyno fit in the spectrum. I haven't heard much about them. They are known to read to real
Low. As in lower than mustang?