• May 1, 2009
2009 BMW 750i – Click above for high-res image gallery

Somehow, we doubt that dyno numbers are quite as important to individuals who are in the market for a new BMW 7 Series as they are to someone shopping for a new Camaro, GT-R or Corvette. As casual observers, though, we'll always be interested to see what happens when a twin-turbo V8 from Bavaria's finest gets a chance to stretch its legs a bit. Fortunately, we're not disappointed with the results.

BMW rates the 4.4-liter twin-turbo V8 at 400 horsepower at 5,500 rpm and 450 pound-feet of torque at 1,800 rpm as it leaves the factory. According to the lucky crew over at Inside Line, BMW's brand-new 750i managed to put down an impressive 391 horsepower at around 5,500 RPM and 434 lb-ft of torque at about 3,500 RPM. Those numbers are at the rear wheels, so drivetrain losses of around 15% must be factored in to find the true power output of the engine itself.

In other words, this engine puts out considerably more ponies than BMW claims. Interestingly, the same is true of BMW's 3.0-liter twin-turbo inline six-cylinder engine. We don't know about you, but this is an error we can forgive.



[Source: Inside Line]


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  • 26 Comments
      • 5 Years Ago
      BTW, where did Inside Line get that BMW? Was it one someone else bought off the dealer lot, or was it a ringer supplied by the manufacturer for testing?
        • 5 Years Ago
        Wow. "provided the car to them".
        • 5 Years Ago
        BMW provided the car to them. Sometimes they buy them, but more recently manufacturers have been providing cars for them.
      • 5 Years Ago
      Based on 15%, this car is making 460hp, 510lb-ft torque. Which, based on performance numbers, looks about right.

      HOwever, we can't say for sure, for obvious reasons (only test I've seen, we don't know if the losses are exactly 15%).
      • 5 Years Ago
      My friend was shopping for BMWs lately and the salesman told him that their cars are actually rated at the wheels. I have no idea if this is true or not, of course.
      • 5 Years Ago
      I think Consumer Reports is the only mag who buy cars off the lot. Inside Line,MR,RT generally are loaned cars by the manufacturers for road tests and long term tests.
        • 5 Years Ago
        Inside Line used to buy their cars... in fact some like their Challenger now is bought retail. But lately the manufacturers are sending them all the cars since they figured that it's very beneficial for them to have a blog post on their cars all the time time. But dang they got an R8 for 20k miles. So jealous. :P
      • 5 Years Ago
      Holly, good news for me.
      • 5 Years Ago
      didn't you know? bmw horses are more efficient than other horses, so they actually make more power per horse. the same can be said of the old VW 1.8t that made 150 hp... (sarcasm anyone?)

      not sure if this is actualyl done to give the perception that the motor somehow is actualyl better than it is, or if this is just to avoid those frequent 'monday' motors. by stating the car makes 400hp when it actually makes more, could be re-expressed as the peak power of the car will be no less than 400hp at the fly.
      • 5 Years Ago
      I don't care if the car had more power than a Veyron, the 7-Series is still one of the ugliest cars on the road....even the owners of these cars think they are ugly.
      • 5 Years Ago
      This was probably done for marketing purposes., advertising 400hp looks impressive but if they put a number like 461hp people will start comparing it to cars with 500hp.
      • 5 Years Ago
      Is it just me or was there a typo? According to the article, the numbers that Inside Line came up with are lower than the BMW figures. What's so impressive about that?
        • 5 Years Ago
        Thanks for the info Rob and Seminole.
        • 5 Years Ago
        Read the entire post -- the dyno numbers are at the rear wheels, which incurs a drag penalty, which means the numbers at the flywheel are x% higher, where x is anywhere between 10 and 20, depending on specifics.
        That being said, it seems quite a few new cars coming out have higher numbers at the wheels than expected given their ratings. Perhaps the engineers have gotten really good at minimizing frictional losses in the drivetrain over the past few years? Maybe the "standard" 10-15% loss for a RWD is too high these days?
        • 5 Years Ago
        I should also clarify that I meant a chassis dyno that measures power through the wheels. You can hook the engine itself up to an engine dyno that will give you the numbers with no drivetrain loss.

        For more info, http://en.wikipedia.org/wiki/Dynamometer
      • 5 Years Ago
      I thought that the practice of advertising brake hp in lieu of effective hp had been banished years ago? Is there any sort of standardized rating system?
        • 5 Years Ago
        You're thinking of the differences between Gross HP (measured at flywheel with no accessories and no exhaust system) and SAE Net (Measured at flywheel with standard accessories and full exhaust system. There is a standard, although it varies slightly between Europe (DIN) and the US (SAE) but they're within 1% of each other typically. It's not practical for manufacturers to advertise wheel-horsepower since different transmissions, final drives, and even the weight of tires and wheels will change these numbers slightly.
      • 5 Years Ago
      Just to make sure: is everyone applying the same standards? Metric vs. mechanical horsepower? It's only about 1.5% but it would explain part of the difference.
      • 5 Years Ago
      Twin turbo V8 only making 400HP? Wut?
        • 5 Years Ago
        BMW's twin turbo 4.4 that was used in the '99 Bentley Arnage was only 350hp, but that had a larger cylinder bore & less boost.
        • 5 Years Ago
        With 450 lb-ft of torque at 1,800 rpm.
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