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Discussion Starter #1
Car and driver claims the new BMW X3 M with 473 hp can run 0-60 in 3.3 sec and the 1/4 in 11.6 at 119. How is this even possible? The X3 M weighs only 800 lbs less than the TH, yet is down 230 hp vs the TH.


Running the numbers.... a 4600 lb vehicle with 473 hp will run the 1/4 in 13 seconds and a 5400 lb vehicle with 700 hp will run it in 11.8 seconds, which is really close to the real world stock TH numbers.


Thoughts?
 

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2 things:

1) BMW is notorious for underrating their engine output
2) Power-to-weight and gearing all play a factor.

I just came out of an X5M, and it ran 11.9 in decent air, a bit better than the claimed 12.3-12.4

Does C&D correct their times to sea level?
 

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I remember there was lots of talk about all the car magazines use a certain method of measuring that makes the numbers slightly better. Thinking the term was rollout
 

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Considering that people have put the M5 competition on dynos and have seen over 600 hp at the wheels, it wouldn’t shock anyone if the x3m engine was close to 580+ hp at the crank.


Wife is checking out the X7’s but we may have to wait until the new X5m appears in April/May before making that decision



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Discussion Starter #5 (Edited)
2 things:

1) BMW is notorious for underrating their engine output
2) Power-to-weight and gearing all play a factor.

I just came out of an X5M, and it ran 11.9 in decent air, a bit better than the claimed 12.3-12.4

Does C&D correct their times to sea level?

Not sure how C&D came to their final numbers, but I was mistaken on the HP numbers for the X3 competition. It's actually 503 for the competition package. This would net that suv on paper at 12.8 in the 1/4. To get the X3 to a 11.6 quarter mile run, it would need to be making nearly 700 hp. Almost 200 hp more than claimed. No way BMW's numbers are that far off.


Hell, 503 whp in a 4600 lb vehicle won't even get you in the 11's on paper.


I know on paper isn't perfect, but it does get you close to the correct numbers and these aren't even close for the BMW X3 ZCP.
 

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M5 and the X3 basically weigh the same, about 4400lbs

M5 comp are trapping 125ish, and High 10’s/lowlow 11’s and by dyno numbers , 700 crank.

At about 580-600 crank hp for the x3, those numbers seem inline.


We are about 800 Lbs more and run 11.6’s with not much more then 700 crank.

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I’m not sure what calculator was used to estimate The ETs, but my personal experience has a 700hp, 4450# car with 2.43 rear gears running 10.70s at over 130.

That was with a slow 5-speed auto shifting.

Add better gearing and a trick ZF 8-speed, and mid-to-high 11s seems doable with about 550hp and same weight.

I would wager a soda pop that these are underrated by about 10%
 
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