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Hi All,
I originally had the car on dyno with the items below installed and the dyno reading was 380.50 kw (approximately 516.93hp).<?xml:namespace prefix = "o" ns = "urn:schemas-microsoft-com<img src=" /><o:p></o:p>
I originally installed the Hartge Tune which promises 642hp (472.19KW) at the flywheel, And also installed an Akrapovic Exhaust System plus BMC Air Filters on my car.<o:p></o:p>
<o:p></o:p>
I have now also installed Alpha AMS catted down pipes purchased from IND Distribution in the US.<o:p></o:p>
I have also installed GuppeM air intakes (removed old air boxes with BMC filters).<o:p></o:p>
Had the car tuned again.<o:p></o:p>
I put the Car on Dyno and it now has a reading of 414kw at the rear wheels (approximately 563.04hp). I used the formula 1kw=1.360hp.<o:p></o:p>
I still don’t know what my flywheel hp. is, as I have read some posts which say that the M5 loses around 6% at rear wheels, and others say around 15%, but by my calculations it’s around 20%. I stand to be corrected.<o:p></o:p>
Based on the above assumption regarding hp at flywheel: 6% = 598.98hp; 15%= 662.40hp; 20%=703.80hp.<o:p></o:p>
I would really like an answer to the above, and thanks.<o:p></o:p>
I state that I never did a stock run before modifications, so I do not know what the factory spec would be on the same dyno.<o:p></o:p>
I have attached a copy of my current Dyno report.
 

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Being RWD I'd expect transmission loss to be around 6-10%.
 
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Being RWD I'd expect transmission loss to be around 6-10%.
The SAE correction for BHP to WHP or vice versa is 15%.
414 KW = 555 HP (assuming that figure is WHP) 653 BHP or 487 KW
 

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Discussion Starter #4
Thanks for correcting the kw to hp details.
I'm just wondering if anyone has done a dyno run on a stock F10 M5. if so please post figures or a dyno report if possible just to clear the myth regarding power loss to wheels.
 

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Thanks for correcting the kw to hp details.
I'm just wondering if anyone has done a dyno run on a stock F10 M5. if so please post figures or a dyno report if possible just to clear the myth regarding power loss to wheels.
There is power loss between the engine and the road; this is no myth and 12-18% is a fairly accurate calculation.

The reality is that BMW lies. A friend's F10 competition package (allegedly 570 BHP) with back boxes only, measured 591 WHP.
 

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The SAE correction for BHP to WHP or vice versa is 15%.
414 KW = 555 HP (assuming that figure is WHP) 653 BHP or 487 KW
Is that for an F10 M5? A level of trans loss that high would be more akin on an AWD car, I'd be highly surprised if an F10 M5 with M-DCT had a trans loss %age into double figures so if the o/p got 517 at the wheels I'd reckon somewhere in the low 600's.
 

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Is that for an F10 M5? A level of trans loss that high would be more akin on an AWD car, I'd be highly surprised if an F10 M5 with M-DCT had a trans loss %age into double figures so if the o/p got 517 at the wheels I'd reckon somewhere in the low 600's.

The SAE correction for BHP to WHP or vice versa is 15%.
414 KW = 555 HP (assuming that figure is WHP) 653 BHP or 487 KW
I'll post the SAE Standard when I get home. But the losses are from the turning of the gear sets, pump, prop' shaft, pinion, differential, axles brakes and wheel assemblies. So, 15% is likely very accurate.
 

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I'll post the SAE Standard when I get home. But the losses are from the turning of the gear sets, pump, prop' shaft, pinion, differential, axles brakes and wheel assemblies. So, 15% is likely very accurate.
That would surprise me for the M-DCT.
 

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SAE J1349 r.08/04 Engine Power Test Code

8.1 Reporting Requirements
All reported engine test data shall carry the notation: “Performance obtained and corrected in accordance
with SAE J1349.Revised Jan04. Any deviation from this document, its procedures, or limits shall be
noted (e.g., Correction factors used exceed valid range defined in the SAE J1349 Procedure Revised
Dec03, Correction factors determined using assumed mechanical efficiency of 85% rather than actual
test data.) The following information is to be provided in the engine power rating report:

SAE J1349 rev.8/2004

View attachment SAE_J1349-Dyno Correction.pdf

 

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8.1 Reporting Requirements
All reported engine test data shall carry the notation: “Performance obtained and corrected in accordance
with SAE J1349.Revised Jan04. Any deviation from this document, its procedures, or limits shall be
noted (e.g., Correction factors used exceed valid range defined in the SAE J1349 Procedure Revised
Dec03, Correction factors determined using assumed mechanical efficiency of 85% rather than actual
test data.) The following information is to be provided in the engine power rating report:

SAE J1349 rev.8/2004

View attachment 453562

But isn't that notice from 2004 so relates to the E39 or possibly E60 which both have very different transmissions to the F10. The M-DCT is highly efficient, far more so than the SMGIII in the E60 so I'd expect far lower transmission losses.
 

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But isn't that notice from 2004 so relates to the E39 or possibly E60 which both have very different transmissions to the F10. The M-DCT is highly efficient, far more so than the SMGIII in the E60 so I'd expect far lower transmission losses.
In what way is the DCT more efficient? It has more moving parts and it still requires an hydraulic pump. To the best of my knowledge the SAE's mechanical efficiency assumption of 85% has not changed through the current rev. But if we want to know for sure, measure the WHP of the vehicle in question. Then remove the engine and measure the actual BHP of the engine alone. The delta will determine the mechanical efficiency of the transmission and driveline.
 

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In what way is the DCT more efficient? It has more moving parts and it still requires an hydraulic pump. To the best of my knowledge the SAE's mechanical efficiency assumption of 85% has not changed through the current rev. But if we want to know for sure, measure the WHP of the vehicle in question. Then remove the engine and measure the actual BHP of the engine alone. The delta will determine the mechanical efficiency of the transmission and driveline.
Me thinks the o/p wont do that but agree it's the only way to get an accurate measure. Also why wheel dyno's are at best an indication of outputs as the 'operator adjustments' can be anything you require.
 
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