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      02-27-2018, 10:29 PM   #182
SflBimmer8484
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Quote:
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.
First, lets keep in mind these cars are on a dyno.. The efficiency of dyno fans cannot be compared to a real world 100+ mph 4th gear run. While we do have a really nice fan setup its no where near the flow you would get on the street in this scenario.


I do agree the turbo is running out of efficiency at these power levels given the 93 octane and stock turbo. However in this situation the high boost and lack of oversized intercooler really hurt on this run. We saw temps of 188f deg at the manifold with a ambient temp of 76F deg. These are some of of the highest I have seen on the dyno. So will a intercooler keep making power? Most likely not but it will reduce the the power being lost up top and give you a smoother curve overall.

Unfortunately we were not able to get the car back on the dyno after we installed our Step core intercooler on this car but, we have logged our M2 before and after with a 40 deg drop in temp compared to the stock intercooler. Install takes roughly 30 min which makes it a no brainer.

Last edited by SflBimmer8484; 02-28-2018 at 12:01 PM..
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