The next-lower rung on a BMW horsepower ladder would be a single-cam 3.5-liter version of the six. These represent a step down performance-wise, from the 280-to 330-hp versions that power the M-cars, but they are available, cheap, and can be made to produce 250 hp with excellent reliability. So my second choice is to hack the heart out of a European-spec BMW 535is for installation in the Greyhound.
But there are a few problems here also. Number one is getting the wiring harness installed so that the engine management functions and the Bosch injection system operate correctly. Keep in mind that I have a healthy distrust of electronic appliances relying on epoxy blobs for their continuing function. Those damn little electrons keep getting lost or forgetting what they're supposed to do or, worst of all, ganging up at a minor restriction and blowing up the component.
Then there are the physical factors to deal with to install this motor. There are motor mounts to fabricate, there's the driveshaft to shorten, there's the interference fit between the injection plenum and the brake booster, and on, and on. Hey, I don't have all year here! I'm already behind by many months on this project, so I need a good, cheap, bolt-in solution.
That brings us to Option 3, a hot-rodded, low-mileage version of the 3-liter inline six, as it originally appeared in my coupe. This is a desirable option from several standpoints: 1). It's an authentic motor from a historical standpoint, which will warm the cockles of a vintage scrutineer's heart; 2.) They are simple mechanically, as they run an actual distributor for spark and those antique devices referred to as "carburetors" to supply gas. Quaint but effective; and 3.) They will bolt right in without any messy structural modifications. For a weld-grinding misanthrope, like me this is downright necessary. So what I really need is a cheap, low-mileage, Stage II prepared, 3-liter BMW inline six.
Impossible, you say? Well, the planets have to be in alignment, you have to have done something really worthy so that Fortuna's wheel is topping out, and you have to be holding your mouth right. . . then just look on eBay. eBay? I know. The usual response is, "I'd sooner buy a used snake than a motor on eBay." But that's not my experience. I bought my race-car hauler, a dandy Suburban, on eBay. And I bought a really neat BMW 2002tii on eBay. So I found myself surfing around in the "BMW-other models" section of eBay's automotive listings with race-car parts on my want list. It was there I spied the 1972 Bavaria for sale.
The Bavaria was a sedan version of the Greyhound, therefore many of the mechanical parts, including the driveline, are interchangeable. And this was not just any old Bavaria. No siree. This one had "triple carburetors." Very interesting. And the motor had done only 35,000 miles since being rebuilt by a "performance rebuilder in Virginia." Very, very interesting.