Myth: xi v i drivetrain loss

ChuckBimmer · 06-21-2008, 07:29 AM

I keep seeing posters state that the xi has great drivetrain loss compared to the i. In generally, greater drivetrain loss does occurs in a 4wd vs 2wd due to greater friction/heat loss. However, the BMW x-drive is a very efficient system with more RWD bias at higher speeds minimizing the drivetrain loss. If you believe the following dyno results: http://www.e90post.com/forums/showth...ghlight=xdrive. The whp loss is only 2% which is insignificant so I can say that there is NO significant drivetrain loss compared to the i. The greater drivetrain loss should occur at lower speeds with all 4 wheels engaged. However, the xi is faster 0-60 (only 0.1sec) and yes it is probably do to greater traction but if there was significant drivetrain loss it should nullify the traction. Again, I believe the xi is very efficient minimizing drivetrain loss.

GMWNashville · 06-21-2008, 07:42 AM

isnt that just kind of common sense? all drivetrain loss is more evident at lower speeds depending on gearing...be it awd or 2wd...

ChuckBimmer · 06-21-2008, 07:46 AM

Quote:

Originally Posted by volkswackin

isnt that just kind of common sense? all drivetrain loss is more evident at lower speeds depending on gearing...be it awd or 2wd...

Some are stating the myth that the xi has greater drivetrain loss vs i. I am trying to state that there is insignificant drivetrain loss compared to the i. At high and low speeds.

StarrDlux · 06-21-2008, 08:12 AM

yup if you want to check it compare the mpg sticker ratings. you will see. those tests are far more stringent than ours. if the car gets 17/21 on XI and the rwd get 18/22 you got your answer.

imo having equal (25%) to all wheels leads to best wear. you have equal wear on each tire, each driveshaft. but only 25% (audi a4) to each component therefor less wear than focusing the energy to 1 wheel (non-lsd 335i)

thats just my theory.

grkmec · 06-21-2008, 08:38 AM

Quote:

Originally Posted by StarrDlux

yup if you want to check it compare the mpg sticker ratings. you will see. those tests are far more stringent than ours. if the car gets 17/21 on XI and the rwd get 18/22 you got your answer.

imo having equal (25%) to all wheels leads to best wear. you have equal wear on each tire, each driveshaft. but only 25% (audi a4) to each component therefor less wear than focusing the energy to 1 wheel (non-lsd 335i)

thats just my theory.

Can't you attribute the slight mpg differences to exta weight of xdrive and aerodynamics since the xi rides a little higher than the i

sleepdoc · 06-21-2008, 08:39 AM

Dubbedoutbimmer · 06-21-2008, 08:51 AM

Quote:

Originally Posted by ChuckBimmer

I keep seeing posters state that the xi has great drivetrain loss compared to the i. In generally, greater drivetrain loss does occurs in a 4wd vs 2wd due to greater friction/heat loss. However, the BMW x-drive is a very efficient system with more RWD bias at higher speeds minimizing the drivetrain loss. If you believe the following dyno results: http://www.e90post.com/forums/showth...ghlight=xdrive. The whp loss is only 2% which is insignificant so I can say that there is NO significant drivetrain loss compared to the i. The greater drivetrain loss should occur at lower speeds with all 4 wheels engaged. However, the xi is faster 0-60 (only 0.1sec) and yes it is probably do to greater traction but if there was significant drivetrain loss it should nullify the traction. Again, I believe the xi is very efficient minimizing drivetrain loss.

true story

hotrod182 · 06-21-2008, 08:57 AM

Quote:

Originally Posted by volkswackin

isnt that just kind of common sense? all drivetrain loss is more evident at lower speeds depending on gearing...be it awd or 2wd...

In most performance tests, high speeds, and 1/4 mile traps, are where the all wheel drive cars pale in comparison to 2 wheel drive.

sleepdoc · 06-21-2008, 09:10 AM

Quote:

Originally Posted by hotrod182

In most performance tests, high speeds, and 1/4 mile traps, are where the all wheel drive cars pale in comparison to 2 wheel drive.

Where were you when I made this same point awhile back?....... Surprisingly, many members seem to think the xi is as fast or faster....

ChuckBimmer · 06-21-2008, 09:17 AM

Quote:

Originally Posted by hotrod182

In most performance tests, high speeds, and 1/4 mile traps, are where the all wheel drive cars pale in comparison to 2 wheel drive.

Can you post the STOCK numbers.

arter · 06-21-2008, 11:14 AM

The Xi will gain 0.1- 0.2 seconds on the launch due to it's greater traction.
After than it loses about 0.2 seconds in the 1/4 due to the weight increase (100 lb = 0.1 seconds I believe) and also due to it's higher height ( about 1 inch) it has greater air drag. Overall stock, it should be about .1 to .2 seconds slower in the 1/4 mile.

The drivetrain loss is only about 1% more over all so that is like losing 4 Hp, not a big issue. With a coil job, you can drop the Xi to match or be lower than the i's height to match air drag. Weight, well that will always be more ( you can hire Danica Patrick at 92 lb's to drive your car to halve the difference).

So the xi will be slower than the i other than at launch.

How about drag racing on ice

oCyrus55 · 06-21-2008, 12:36 PM

Quote:

Originally Posted by arter

The Xi will gain 0.1- 0.2 seconds on the launch due to it's greater traction.
After than it loses about 0.2 seconds in the 1/4 due to the weight increase (100 lb = 0.1 seconds I believe) and also due to it's higher height ( about 1 inch) it has greater air drag. Overall stock, it should be about .1 to .2 seconds slower in the 1/4 mile.

The drivetrain loss is only about 1% more over all so that is like losing 4 Hp, not a big issue. With a coil job, you can drop the Xi to match or be lower than the i's height to match air drag. Weight, well that will always be more ( you can hire Danica Patrick at 92 lb's to drive your car to halve the difference).

So the xi will be slower than the i other than at launch.

How about drag racing on ice

Agreed, xi's are way faster in the snow, and, up here in Ohio, we get snow for the majority of the year.

I also have to drive up some pretty big hills in the snow, I don't think the i could handle them.

thekurgan · 06-21-2008, 05:14 PM

Quote:

Originally Posted by StarrDlux

imo having equal (25%) to all wheels leads to best wear. you have equal wear on each tire, each driveshaft. but only 25% (audi a4) to each component therefor less wear than focusing the energy to 1 wheel (non-lsd 335i)

thats just my theory.

Wouldn't the front tires have more wear since the steering occurs there? Just a thought.

lauer87 · 06-21-2008, 05:22 PM

Quote:

Originally Posted by oCyrus55

Agreed, xi's are way faster in the snow, and, up here in Ohio, we get snow for the majority of the year.

I also have to drive up some pretty big hills in the snow, I don't think the i could handle them.

So you it snows for 6 months out of the year in Ohio? Interesting......

OpenFlash · 06-21-2008, 05:26 PM

Quote:

Originally Posted by ChuckBimmer

I keep seeing posters state that the xi has great drivetrain loss compared to the i. In generally, greater drivetrain loss does occurs in a 4wd vs 2wd due to greater friction/heat loss. However, the BMW x-drive is a very efficient system with more RWD bias at higher speeds minimizing the drivetrain loss. If you believe the following dyno results: http://www.e90post.com/forums/showth...ghlight=xdrive. The whp loss is only 2% which is insignificant so I can say that there is NO significant drivetrain loss compared to the i. The greater drivetrain loss should occur at lower speeds with all 4 wheels engaged. However, the xi is faster 0-60 (only 0.1sec) and yes it is probably do to greater traction but if there was significant drivetrain loss it should nullify the traction. Again, I believe the xi is very efficient minimizing drivetrain loss.

I have reason to believe that Dynojets artificially inflate awd numbers to be more equivalent to their 2wd numbers. In other words, I don't believe they just add the front and rear roller power together and come up with a number.

Shiv

oCyrus55 · 06-21-2008, 06:41 PM

Quote:

Originally Posted by lauer87

So you it snows for 6 months out of the year in Ohio? Interesting......

Actually, yeh. I've had snow days in May before... Plus, this car has great torque for plowing....

arter · 06-21-2008, 07:55 PM

So if we lower it and put on carbon lips or splitters on the front we have snow plows. I knew this car would pay off. I can do peoples driveways now......

oCyrus55 · 06-21-2008, 09:36 PM

Quote:

Originally Posted by arter

So if we lower it and put on carbon lips or splitters on the front we have snow plows. I knew this car would pay off. I can do peoples driveways now......

Oh, for sure. I'm planning on starting my business this winter.

SteelTorque · 06-22-2008, 10:49 AM

Quote:

Originally Posted by hotrod182

In most performance tests, high speeds, and 1/4 mile traps, are where the all wheel drive cars pale in comparison to 2 wheel drive.

Pale in comparison? Are you bench racing again?

I trapped 111mph with V2 only.

hotrod182 · 06-22-2008, 11:31 AM

Quote:

Originally Posted by SteelTorque

Pale in comparison? Are you bench racing again?

I trapped 111mph with V2 only.

Yeah, your right, I bench race more than anyone here. What world are you living in? Maybe if you didn't have an XI you would have done 113mph instead of 111mph.
And as far as running a 12.8, even a RWD 335i can achieve those times with the same tune.

06-21-2008, 07:29 AM	#1
ChuckBimmer Liv'n the Dream 8 Rep 181 Posts Drives: '08 335 Join Date: Apr 2008 Location: USA iTrader: (0)	Myth: xi v i drivetrain loss I keep seeing posters state that the xi has great drivetrain loss compared to the i. In generally, greater drivetrain loss does occurs in a 4wd vs 2wd due to greater friction/heat loss. However, the BMW x-drive is a very efficient system with more RWD bias at higher speeds minimizing the drivetrain loss. If you believe the following dyno results: http://www.e90post.com/forums/showth...ghlight=xdrive. The whp loss is only 2% which is insignificant so I can say that there is NO significant drivetrain loss compared to the i. The greater drivetrain loss should occur at lower speeds with all 4 wheels engaged. However, the xi is faster 0-60 (only 0.1sec) and yes it is probably do to greater traction but if there was significant drivetrain loss it should nullify the traction. Again, I believe the xi is very efficient minimizing drivetrain loss. __________________ '08 335xi Sparkling Graphite/ZPP/ZSP/Step/CA/iDrive/iPod Performance: Dinan Stage III Flash (OC, FMIC), Dinan Exhaust, KWV3, 19' BMW Performance Wheels Stealth: V1, NavAlert, Laser-Interceptor, HuberOptik Tint Future: CAI
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06-21-2008, 07:42 AM	#2
GMWNashville Colonel 173 Rep 2,373 Posts Drives: 19 G05, 16 F80, 10 E70x5D Join Date: Jan 2008 Location: Nashville, TN iTrader: (2)	isnt that just kind of common sense? all drivetrain loss is more evident at lower speeds depending on gearing...be it awd or 2wd...
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06-21-2008, 08:12 AM	#4
StarrDlux Pussycat's Meow 9 Rep 682 Posts Drives: '08 335i montego \| Stock Join Date: May 2008 Location: Midtown (Altanta) iTrader: (0)	yup if you want to check it compare the mpg sticker ratings. you will see. those tests are far more stringent than ours. if the car gets 17/21 on XI and the rwd get 18/22 you got your answer. imo having equal (25%) to all wheels leads to best wear. you have equal wear on each tire, each driveshaft. but only 25% (audi a4) to each component therefor less wear than focusing the energy to 1 wheel (non-lsd 335i) thats just my theory. __________________ 2008 335i montego \| stock 2002 A4 1.8TQS \| APR 1+ 1990 VW Corrado \| Stage 4 by SNS
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06-21-2008, 08:39 AM	#6
sleepdoc Lieutenant 260 Rep 475 Posts Drives: 2022 M3CX DG/Blk Join Date: Dec 2007 Location: South Florida iTrader: (1)	__________________ Sold 2018 F80 M3 Sold 2010 Nissan GTR Sold: 2008 335i
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06-21-2008, 11:14 AM	#11
arter cruising 42 Rep 815 Posts Drives: xdrive45e Join Date: May 2008 Location: San Clemente, Ca iTrader: (1)	Yes top end will be slower The Xi will gain 0.1- 0.2 seconds on the launch due to it's greater traction. After than it loses about 0.2 seconds in the 1/4 due to the weight increase (100 lb = 0.1 seconds I believe) and also due to it's higher height ( about 1 inch) it has greater air drag. Overall stock, it should be about .1 to .2 seconds slower in the 1/4 mile. The drivetrain loss is only about 1% more over all so that is like losing 4 Hp, not a big issue. With a coil job, you can drop the Xi to match or be lower than the i's height to match air drag. Weight, well that will always be more ( you can hire Danica Patrick at 92 lb's to drive your car to halve the difference). So the xi will be slower than the i other than at launch. How about drag racing on ice __________________ 2011 e92 M3 Monte Carlo Blue ESS 535 - gone but not forgotten 2018 porsche 991 GTS 2021 X5 xdrive45e
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06-21-2008, 07:55 PM	#17
arter cruising 42 Rep 815 Posts Drives: xdrive45e Join Date: May 2008 Location: San Clemente, Ca iTrader: (1)	So if we lower it and put on carbon lips or splitters on the front we have snow plows. I knew this car would pay off. I can do peoples driveways now...... __________________ 2011 e92 M3 Monte Carlo Blue ESS 535 - gone but not forgotten 2018 porsche 991 GTS 2021 X5 xdrive45e
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