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      01-08-2010, 03:24 PM   #1
JimD
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Why BMW will increase hp, may not change weight

Cost is probably a big reason but is not the point I want to make.

I googled for 1/4 mile calculators and 0-60 calculators. These are simple formulas that are empiracally derived (meaning they look at data from actual cars and develop a formula that matches the data). They are not extremely accurate but give you an idea. For both quarter mile times and 0-60, adding 50 hp to a 135i has almost exactly the same impact as dropping 500 lbs. For instance, the calculator predicts a 0-60 of 5.13 for a stock 135i and it drops to 4.57 with 350hp (with 3373 lbs) and 4.55 at 2873 lbs (with 300 hp).

Especially with a turbo motor you can reprogram, it seems to me a lot more feasible to add 50hp than drop 500 lbs. If you could achieve a similar effect dropping 200 lbs, I'd be more optomistic the M1 would be substantially lighter. The fact that you need 500 lbs to equal 50 hp make me think we may see a token weight change - an aluminum hood and/or carbon fiber roof - but the real change in performance will come from engine mods. An even simpler weight reduction we will hopefully see is lighter wheels and possibly tires.

Less weight would still be very desirable for handling benefits but it seems like the reasonably achievable weight loss will not affect acceleration a lot.

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      01-08-2010, 03:36 PM   #2
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Interesting write-up, JimD. I'm really not concerned about how much the advertised hp is. A lot of us understand the 135i does not have 300hp at the crank. It's much closer to 330hp. I can promise you this 135i wont have 350hp. It will likely be closer to 380hp. These babies will be Clydesdales.

On another note its not always that cut and dry in terms of using the formulas in regards to weight. There is a lot of tech now-a-days that make cars act the way they do. The devil is always in the details. For example, I would not expect a 2800lb 400hp boosted S2000 to beat a 3200 400hp C6 in most situations. So many things like displacement, tuning, traction, etc. comes into play. I really want to see what the Z4 "si" dynos at.



EDIT: I just went over to BMWUSA to look at the manufacturer weights for the X6 50i and X6M. 60 pounds separates these vehicles. You might be onto something.
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