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M2 Technical Topics > N55 Engine / Drivetrain / Exhaust / Bolt-ons / Tuning > Benefits of an M Performance exhaust...

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      08-13-2017, 04:11 PM   #89
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Originally Posted by DoggieHowser View Post
Has anyone ever done dyno tests with the MPE?

I find it odd that there isn't any Performance gain at all.

I'm wondering if the zero Performance claim has to do with not affecting emissions ratings and taxes. Or against warranty claims. For instance, a user who has modified his car to have the same Performance increase using other methods can claim it shouldn't affect the warranty of the car.
I dyno'd mine with MPE and got 337WHP. Well within margin of error from other dynos of stock cars.

SAE smoothing 5 on a dynojet.

I couldn't live with the drone so I replaced it with the Akra Evolution (similar tone, slightly smoother and quieter. Overall I like the noises better). Haven't been back to dyno yet. Might do it this fall when humidity drops because despite the best correction, humidity and heat inside a building will still wreck the results. Akra claims gains but I don't really believe it.
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      08-15-2017, 03:27 AM   #90
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BMW M2 M-Performance Exhaust Detail Review - Is it worth the money?


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      04-29-2018, 12:06 AM   #91
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Originally Posted by Artemis View Post
The loudest bass sound on the M2 during cold start lasts close to 40 seconds since firing up the engine. Subsequently the deep bass sound dies down and the normal bass sound remains while idling.

What happens AFAIK: the engine management arranges to quickly heat up the catalytic convertors through 'open loop' fueling (fueling control loop: fuel/air-fuel ratio feedback loop between the injector pulse and oxygen sensors). On cold start, some open loop algorithm pulses the injectors until the time that oxygen sensors are sufficiently warmed up to properly do their job. Oxygen sensors feature heater wires to help shorten this time and maintain operating temperature. Hence, the open loop fueling only happens during a brief time window after firing up the engine and won't be triggered that way if the engine was already warmed up to operating temperature (you'll notice that there won't be that hallmark cold start deep bass sound if you restart the engine briefly after a drive). Reason for all this: emissions requirements and getting the cold engine a little quicker up to temp.

With a manual gearbox, the loudness of an M2 cold start (with or without MPE) or 1M (with or without Akrapovič exhaust) can definitely be toned down by using the clutch and accelerator pedals in close harmony. Fire up the engine (if you got MPE: don't open the butterfly valve) and immediately climb a little higher in the revs (thus higher than the usual 1200-900rpm engine idle yo-yo cold start start-up sequence) with the accelerator pedal, whilst partially depressing the clutch pedal. Just a matter of subtle interaction between the left and right feet to slowly move forward/backward out of your parking space whilst gently subduing the deep bass sound. You'll notice that by doing so, you'll reduce that deep bass sound loudness. And as this pedal interaction only takes place at very slow speed and for a very brief period of time (just enough to move the car from its parking spot), it's best to operate when in a location where the deep bass sound could eventually bother other people nearby (especially from dusk till dawn). A lesser known fringe benefit of a 6MT compared to an M-DCT.

Technical explanation (general): "Internal combustion engine cold-start efficiency: A review of the problem, causes and potential solutions":
http://www.sciencedirect.com/science...96890414001939



Hear one in real life. Tastes may differ, but to many ears, the MPE takes the M2 to another sound level. And when under load with revs ranging between 5K and 7K, it can sound gloriously 'beast'.

Thanks Artemis!

My first mod will be to code out the annoying cold start procedure. My M3 sounded like a vacuum cleaner sucking up nails every time I started it. Ugh.

I test drove 7 used M2s this weekend. I'm almost ready to pick one. While the stock M2 exhaust sounds dramatically better than my recently sold 2016 M3, the MPE is simply glorious. It was standard in the M2 Performance Edition I test drove ( as part of the PE package). It was incredible! And the car feels like so much more than simply an exhaust and coilovers.

I would like to compare the MPE side by side to an M2 with a stock exhaust and a Fabspeed Catted Downpipe, which I've been told adds both power and sound!

Either way, I look forward to annoying my electric car driving neighbors, who frowned and looked away every time I drove up in the M3.



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      04-29-2018, 09:26 AM   #92
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Originally Posted by Mustangquadcam View Post
Thanks Artemis!

My first mod will be to code out the annoying cold start procedure. My M3 sounded like a vacuum cleaner sucking up nails every time I started it. Ugh.

I test drove 7 used M2s this weekend. I'm almost ready to pick one. While the stock M2 exhaust sounds dramatically better than my recently sold 2016 M3, the MPE is simply glorious. It was standard in the M2 Performance Edition I test drove ( as part of the PE package). It was incredible! And the car feels like so much more than simply an exhaust and coilovers.

I would like to compare the MPE side by side to an M2 with a stock exhaust and a Fabspeed Catted Downpipe, which I've been told adds both power and sound!

Either way, I look forward to annoying my electric car driving neighbors, who frowned and looked away every time I drove up in the M3.



I am surprised that you could find so many used M2s in Portland. There is only one in Seattle. The M2 PE is rare and you should scope that one up.

By the way, I do love my MPE.
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      04-29-2018, 11:36 AM   #93
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I love my MPE although I'm fighting the cold start vibration/rattle. It really is awesome.
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      04-29-2018, 10:14 PM   #94
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Quote:
Originally Posted by DanG View Post
I am surprised that you could find so many used M2s in Portland. There is only one in Seattle. The M2 PE is rare and you should scope that one up.

By the way, I do love my MPE.
I didn't. I flew to Long Beach, and looked at cars in Newport Beach, Laguna Beach, San Diego, etc. It was a fun weekend!
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