Originally Posted by studavis' post='496877' date='Nov 20 2007, 10:09 AM

You still have to deal with the frontal cd of the car, mass, and horsepower. I'd bet my last two shrinking dollars, that the 550i at sea level, standard day of 70 degrees, with no engine limiter, full fuel, one 170 pound driver, and the cd player belting out AC/DC "Highway to Hell" the car will not go one mph faster than 172.

Originally Posted by studavis' post='496877' date='Nov 20 2007, 07:09 PM

...the car will not go one mph faster than 172.

Originally Posted by studavis' post='496877' date='Nov 20 2007, 01:09 PM

You still have to deal with the frontal cd of the car, mass, and horsepower. I'd bet my last two shrinking dollars, that the 550i at sea level, standard day of 70 degrees, with no engine limiter, full fuel, one 170 pound driver, and the cd player belting out AC/DC "Highway to Hell" the car will not go one mph faster than 172.

Originally Posted by 550isport' post='495956' date='Nov 18 2007, 01:05 PM

Steve Dinan says 175 for a Dinan 550 w/380 hp. My guess OEM is about 170. 2) look it up on Road & Track (they list maximum speed next to the ratio) and 3) I'm guesing that you're inquiring why redline isn't higher like the M5's V-10....It has to do with a number of factors. The 4.8 (N52 I believe) is a series production engine developed and made by BMW for use in more than one model. It is a jack of all trades. Decent consumption, smooth cold start and idle, very good longevity and reliability (we hope) and exceptional low, mid and top end power. The M5's V10 is a very costly purpose built engine designed by the gurus in the Motorsport division for use in essentially one platform and for use with the SMG exclusively. It has noticably less low end grunt than the 550 (below 4000 rpms) and it gets seriously low milege despite displacing only another 200cc. The V10 can rev higher because its stroke (the distance the piston travels) is shorter than a "regular" engine of its size. Like a Ferrari 2.8 litre V-8, it has large pistons that don't travel that far up and down. The result is less low end torque, but the reward is high end horsepower. You also need strong enough engine components to withstand the higher rpms and the ability to get enough air into the engine at those high rpms. If you take anything away from my amateur response here, let it be that the V10 is not a better version of the V8. They are different in design and construction and they are intended to meet very different goals. So a limit higher than 6500 or 7000 on a standard BMW V8 would probably come at a price you wouldn't want to pay....

DRP