2007 BMW Alpina B7 - Engine

Meet Alpina, a German company whose history with BMW goes back 46 years but is little known in the U.S., as the B7 is only the second model officially brought to our shores. The first, about four years ago, was the Alpina Roadster V-8, essentially a version of the Z8 roadster with an automatic transmission. All 450 bound for North America found owners.

Alpina’s partnership with BMW—B7s roll off the assembly line in Dingolfing, Germany, with standard 7s—separates it from other BMW tuners, and that is particularly helpful when tweaking hugely complex 7-series electronics to deal with a supercharger.

The B7 imported here is based on the short-wheelbase 750i, but since Alpina started development back when the 7-series—the 745i—was powered by a 325-hp, 4.4-liter V-8, that’s the basis for the B7. To handle the 11.6 psi of intercooled boost whipped up by the centrifugal ­supercharger, the engine gets lower-compression-ratio pistons as well as a ­stronger crankshaft and connecting rods. The result is a mighty 500 horsepower and 516 pound-feet of torque, making it the most powerful 7-series—wait, it’s the most ­potent BMW—on offer.

A centrifugal supercharger doesn’t make big boost at low rpm, and in fact, a half-throttle launch in the B7 feels much like the power delivery of a turbo, with a surge appearing around 2500 rpm. That means the B7’s sticky Michelins are never overwhelmed, which adds to the B7’s deceptively quick mystique. Sixty mph arrives in 4.4 seconds—a full second quicker than the 750i, and the gap widens from there—as the cabin fills with a subdued bellow from the V-8. Wind roar isn’t really noticeable until—Whoa! Does that say 100 mph? And the supercharger never makes a peep.