# How Much Power is Lost by the Drivetrain?



## Quacker (Feb 5, 2011)

I have a 2012 535ix that I suspect is not making full power. Does anyone know how much power is lost between the motor and the wheels? With this info and a good dyno run, I should be able to confirm or disprove my suspicion that the motor is not putting out. 

The reason that I suspect this is that I had the same car in a 2011 model, and I swear it was faster.

TIA,
Q


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## matt540 (May 22, 2009)

In-between 10-20%


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## Quacker (Feb 5, 2011)

Thanks Matt. Is there any particular experience that this comes from?


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## damnboy37 (Mar 29, 2013)

AWD cars lose a min of 25%


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## 435iBlkMamba (Jan 29, 2014)

Is there a different number for hp and tq? I saw a video on the 435i being dyno'd with the mppk and the guy was saying the tq loss is less?


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## oldman12 (Apr 13, 2011)

OMG a MINIMUM of 25% drive train loss because its 4WD??? 

LMFAO! Where do you guys come up with such nonsense?

First off, you need to take the car to someone who has a dyno that supports "4 wd" but better yet, since you have ALL WHEEL DRIVE, let me be more specific. You need to take it to someone who knows how to dyno your car properly ie. what gear to put your 8 speed transmission in to test it and also, do not floor the throttle if in Sport mode and so on. 

The old e60 535ix I have seen put down 253 hp and a tiny bit more tq. in stock form, so since BMW claims 300hp at the crankshaft, that's a whopping 16% drive train loss from my calculation.

SMH....:tsk::tsk::tsk: minimum 25% loss....


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## damnboy37 (Mar 29, 2013)

oldman12 said:


> OMG a MINIMUM of 25% drive train loss because its 4WD???
> 
> LMFAO! Where do you guys come up with such nonsense?
> 
> ...


So, you have less drive terrain loss than most RWD cars & are closer to what the average FWD, and you are the one shaking your head.

Mind=Blown


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## oldman12 (Apr 13, 2011)

Wow! ignorance is bliss....

First off, tell me, what is "drive terrain loss"? Since you don't even know, its "drivetrain" loss!!!!!

And, what FWD BMW are you referring to?

Finally, instead of posting ***** you know nothing of and cannot support what you are saying, how about shutting the hell up and learn something? I have an 08 535i (as in, RWD) and since I put down 266 whp and 271 ft lb of torque on a dynoject dyno on 93 octane, I am pretty qualified to state 'stuff' on here unlike yourself.

So, as proof to Quackert that I know what I'm talking about and you are just "talking", take a look here:





Yep, still smh at you and now even your response....


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## damnboy37 (Mar 29, 2013)

Your piece of **** dyno videos have yet to show me this magical 16% power loss you think it has. You have no proof on how much crank hp the N54/55? has other than what BMW says. 

There was a time JDM cars had "276 crank hp", while they dyno'd more to the wheels. By your logic, JDM cars gained power to the wheels. Does that make sense, stupid?

BTW, I never once specified BMWs Mind=Still Blown

Edit

I'll shut up once I get proof that engine does, in fact, have 300 crank up. I know engineers find more efficient ways to reduce this type of loss, but 16% is just too little.


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## oldman12 (Apr 13, 2011)

Your claims were obviously demystified and now you are changing what your words around. You didnt answer my question as to what "drive terrain" means? You didnt answer my FWD question. Now you are on a BMW message board where the original poster is asking about his all wheel drive BMW and you are talking what other cars exactly? I PROVE my point with a dyno run but because you have been embarrassed you f ing moron, now you want to be an internet thug. The proof is in the video and if that is a POS video to you, then you are just upset because you were proven wrong. Whatever! You have a LOT to learn from what I can tell.

Have fun in being wrong.


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## [email protected] (Mar 14, 2014)

335 usually make 265 on dyno (depending on the Dyno and weather)
thats about 22%


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## oldman12 (Apr 13, 2011)

22% drivetrain loss on 300 hp is 66. thus 300 minus 66 equals 234.

But, since two stock 335's I have dynoed myself made 262 and 267 whp *before* modding them with a few bolt ons and software, that would be in line with your statement Mike of 265 whp. Further proving my point for accuracy. Those numbers show a 12% drivetrain loss which is about right.


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## [email protected] (Mar 14, 2014)

Lol my bad 

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## jpradun (Feb 13, 2013)

I'm not interested in joining the flame war, but I'm an engineer who enjoys these kinds of discussions, so I will post what I know and don't know.

Most RWD cars have power loss closer to 15% (+/- 5%) and AWD is another 7%, on average. Drivetrain losses also increase as more power is added, due to an increase in heat (friction, RPM). I don't know anyone who has put a stock N54/N55 motor on an engine dyno. It's pretty well known, however, that BMW underrates the 300 crank hp number. 335i dynos about 275-285hp and 335ix dynos about 20-30hp less. That means approximately 7-10% more losses through BMW's AWD.

We cannot come up with an exact amount without first putting the motor on an engine dyno, but we can reasonably guess that BMW's system has 12-28% drivetrain losses, where 12% is the best-of a manual RWD model and 28% is the worst of an AWD automatic. I'd venture the RWD is closer to 14-15% and AWD is closer to 22-23% losses, on average. This would imply the stock engine crank power should be closer to 335hp +/- 10hp.

335hp? Well, what do you know...


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## rdkind62 (Jan 11, 2008)

Well, I'm no engineer (actually I am, but not a mechanical one) but I did sleep at a Holiday Inn last night. And I do know that showing a dyno run has nothing to do with how much loss there is in a drivetrain. I personally dyno'ed my car last Friday and had 305.8 HP and 341.3 in tq at the wheels but it still doesn't tell you how much drivetrain loss there is. I'm going to go with jpradun and suggest there is in the neighborhood of 15% - 18% loss on RWD and 7% - 9% more loss on AWD. Only real way to know is take the engine out and put it on an engine dyno and then put it back in the car and get wheel HP.


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## booyaazaa (May 23, 2012)

:rofl::rofl::rofl::rofl: Maybe I should try a Holiday Inn too. :thumbup:


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