[jclaib7]

Simple question. I've read a lot of reviews, looked at dyno results, and seen lots of different results. The dyno, elevation, temp etc... can drastically change results.

So what HP at the crank and wheel and how much torque does the M2 actually make stock at sea level? My thoughts on what i've gleaned from researching.

Rated HP(BMW) @ Crank 370hp
Actual HP @ Crank 410hp
Actual HP @ Wheel 380hp

Torque close to 400tq

[///cbrash]

Stock m2's don't get to 380 wheel hp as far as I know.

[BOhio]

Forgive me for spending your time and money, but here's what I hope you'll do, and post back, and then the rest of us -- and YOU -- will know.

https://www.sixsigmatuning.com/pages/dyno-rental

$100.00, plus the round-trip there (from your town). Google maps says it's an hour each way. And the place gets good reviews.

I hope you're right (not sure why, it just seems cool) that BMW under-reports the HP.

[akkando]

m2 is something like like 335 at the wheel. Barely under rated. I think it makes like 10 more than a m240 in the real world.

[BOhio]

[Artemis]

Originally Posted by Artemis

As we know, some official base M2 figures:

• max output: 272 kW = 370 hp (metric) or 365 hp (USA) @ 6500 rpm
• max torque: 500 (465+35) Nm = 369 (343+26) lb-ft @ 1400-5560 rpm

Akrapovič tested a stock M2 (2016) (i.e. before fitting their exhaust). Their test results (see here):

• max output: 284.3 kW = 386.5 hp (metric) or 381.2 hp (USA) @ 5500 rpm
  = 272 kW + 4.5221%
• max torque: 558.8 Nm = 412.1 lb-ft @ 2500 rpm
  = 500 Nm + 11.76%

M2 Competition:

• max output: 302 kW = 410.6 hp (metric) or 405 hp (USA)

Purely hypothetical exercise: if exactly the same factor as measured by Akrapovič for the base M2 would apply for the M2 Competition, you get the following results:

• max output: 302 kW + 4.5221% = 315.66 kW = 429.2 hp (metric) or 423.3 hp (USA).

Note: true that we got no info regarding Akra's protocol in measuring hp & Nm values, but we can reasonably assume that, if they quote a stock hp figure, that they got no interest in inflating that value (given the delta 'stock vs their exhaust'). Furthermore, it is in the interest of their reputation to quote genuine figures of their test sessions. By the way, the M2 hp figure with their exhaust mounted is rather 'modest'.


(source: see here)

[jclaib7]

Originally Posted by Artemis

Note: true that we got no info regarding Akra's protocol in measuring hp & Nm values, but we can reasonably assume that, if they quote a stock hp figure, that they got no interest in inflating that value (given the delta 'stock vs their exhaust'). Furthermore, it is in the interest of their reputation to quote genuine figures of their test sessions. By the way, the M2 hp figure with their exhaust mounted is rather 'modest'.

Attachment 1887721
(source: see here)

Patience i'm not an expert on these things but clarify please?

Official BMW Base: "365 hp (USA) @ 6500 rpm" This is power at the crank correct, no transmission losses?

Akropovic Test: "381.2 hp (USA) @ 5500 rpm" This is done on a dyno so power to the wheels correct? And if wheel then it should translate to +400 to the crank?

I know at the end of the day it doesn't really matter, just curious.

2:45 Min Nick Murray Review:

Claiming 380hp to the wheel. No back up data but he is a trusted reviewer.

[M-Pilot]

Originally Posted by jclaib7

Patience i'm not an expert on these things but clarify please?

Official BMW Base: "365 hp (USA) @ 6500 rpm" This is power at the crank correct, no transmission losses?

Akropovic Test: "381.2 hp (USA) @ 5500 rpm" This is done on a dyno so power to the wheels correct? And if wheel then it should translate to +400 to the crank?

I know at the end of the day it doesn't really matter, just curious.

2:45 Min Nick Murray Review:

Claiming 380hp to the wheel. No back up data but he is a trusted reviewer.

Those BMW and Akrapovic figures both represent crank HP. N55 M2 makes around 300-330whp depending on the fuel, dyno, etc. Here are some links to couple dyno results:

330whp (93oct)
——————————
https://f87.bimmerpost.com/forums/sh....php?t=1247410

303whp (92oct) and 309whp (94oct) measured on DynoDynamics
—————————————————
https://f87.bimmerpost.com/forums/sh...7#post20688842

287whp (91oct) DynoDynamics (This is probably the lowest I have seen. There may not be sufficient cooling)
———————————————-

[AndrewC1989]

Originally Posted by jclaib7

My thoughts on what i've gleaned from researching.

Rated HP(BMW) @ Crank 370hp
Actual HP @ Crank 410hp
Actual HP @ Wheel 380hp

Torque close to 400tq

No that's not right

The formula for finding wheel horse power (whp) = Crank horse power (bhp) - 15%

(For 4 wheel drive cars it's 18-20%)

So advertised, they make 365 at the crank (bhp)

Subtract 15% rear wheel drivetrain loss (~55hp) = 310 hypothesized whp

They dyno at ~335whp so this means they're a bit underrated, but not by much

You could say then that at the crank they should make 380-390 but at the wheel they're still making 335 regardless

So in reality the numbers are:

Rated HP(BMW) @ Crank 365hp
Actual HP @ Crank 385hp
Actual HP @ Wheel 335hp

[tranck]

All I know is that the car is fast as hell and w/ my Dinan Stage1 tune - faster.
And after 8K miles on the tune, no check engine light - happy guy here.

[XutvJet]

A stock 6mt M2 tends to make around 330hp to the wheels on a Dynojet. Assuming a 12-15% drivetrain loss (depending on who you ask), the N55 M2 makes around 375hp to 390hp stock.

[delhang]

Originally Posted by tranck

All I know is that the car is fast as hell and w/ my Dinan Stage1 tune - faster.
And after 8K miles on the tune, no check engine light - happy guy here.

I'm really interested in this setup. Do you have the Stage 1 with the Dinan Exhaust and Dinan Cold air intake? or just the piggy back?

How big of a difference from stock do you feel? more ooompphh on low and high?

Thanks

[tranck]

Originally Posted by delhang

I'm really interested in this setup. Do you have the Stage 1 with the Dinan Exhaust and Dinan Cold air intake? or just the piggy back?

How big of a difference from stock do you feel? more ooompphh on low and high?

Thanks

Just the Stage 1 - nothing else done to the car - stock exhaust and intake.

I wanted to be very cognizant re: the placebo effect but there's zero question that the car is faster especially mid-high range.

I highly recommend this tune and as said no CEL.

[UltraMagneticAL]

the first run is with only akra exhaust. i forget what each run was for, but you can search my posts and find it somewhere. my car is back to stock, so maybe I'll Dyno it one more time before selling it just to have the baseline for reference.

[jclaib7]

Originally Posted by andrewc89

No that's not right

The formula for finding wheel horse power (whp) = Crank horse power (bhp) - 15%

(For 4 wheel drive cars it's 18-20%)

So advertised, they make 365 at the crank (bhp)

Subtract 15% rear wheel drivetrain loss (~55hp) = 310 hypothesized whp

They dyno at ~335whp so this means they're a bit underrated, but not by much

You could say then that at the crank they should make 380-390 but at the wheel they're still making 335 regardless

So in reality the numbers are:

Rated HP(BMW) @ Crank 365hp
Actual HP @ Crank 385hp
Actual HP @ Wheel 335hp

Out of curiosity I followed up with Akropovic. It took them a week to get back to me, but for what it is worth, their numbers are to the wheel, not crank or BHP.


"Thank you for the email and the number are all to the wheels."
--
Alex Compton
Akrapovic Sales Specialist, European

[PackPride85]

Originally Posted by jclaib7

Out of curiosity I followed up with Akropovic. It took them a week to get back to me, but for what it is worth, their numbers are to the wheel, not crank or BHP.


"Thank you for the email and the number are all to the wheels."
--
Alex Compton
Akrapovic Sales Specialist, European

Correction factor, environmental conditions, cooling, gear, etc.....so many different factors come into play on a dyno. Even more if you're on a load based dyno.