Though diesel motorcycles have sometimes been referred to laughingly, the Neander turbo 1400 offers some real benefits. Photography by Kyoichi Nakamura.
Let's face it—we motorcyclists have a pretty dismal opinion of diesel engines, usually derived from the painful consequences of encountering a road surface coated with oil carelessly dropped by a truck or even one of the increasing numbers of cars powered by Rudolf Diesel's compression-ignition motor invented back in the 1890s. Since then, the diesel engine has become a mainstay of marine, locomotive, urban transport, road haulage and stationary use—indeed, any application where its inherent benefits of 30 percent lower fuel consumption, cleaner emissions and longer life, as compared to an equivalent internal combustion petrol engine employing the Otto principle (i.e., using a spark plug to light the fire), can sufficiently offset its disadvantages of increased noise, vibration, higher manufacturing costs, and greater weight and bulk. While permitting the use of cheaper, non-fossil fuels (Rudi ran his early engines on peanut oil!), diesel engines require a heavier, more robust construction, until now making them unsuitable for certain applications such as aircraft and motorcycles.
Germany's Neander Motors plans to change all that, thanks to a unique new 1430cc turbocharged parallel-twin diesel engine that's been developed for them by Rupert Baindl. The twin-crank 750cc BMR Supermono single, which actually got built and produced an amazing 115 bhp at 12,000 rpm, according to Rupi, then morphed into a projected 990cc four-con-rod parallel-twin MotoGP racer that never got past the CAD stage, and thence to the prototype of what promises to be the world's first turbo-diesel production motorcycle. Indeed, the incredible diesel device I found waiting for me to ride in the Bavarian countryside south of Munich, masquerading at a swift glance as an American-style cruiser with a big parallel-twin motor that could easily resemble Triumph's forthcoming 1500cc custom, is a bike literally unlike any other, and not only because of its choice of fuel. That's because the hefty 1430cc air/oil-cooled parallel-twin motor with 108 x 78.2 mm cylinders and 360-degree crank throws, employs twin crossways-mounted contrarotating crankshafts, coupled together by gears, and each carrying two steel con-rods (so, a total of four, two for each cylinder). Each pair of these jointly supports a lightweight three-ring steel piston with ultra-short skirts via twin staggered gudgeon pins, resulting in minimal piston side-thrust as on a conventional motor. This, in turn, reduces potential friction and wear, in spite of the high 16:1 compression ratio. The plain-bearing big end on each con-rod pivots on a bolted-on external outrigger sleeve attached to each geared crank, and the con-rods are internally drilled for extra lubrication, much like a Ducati superbike's.
With a 68-inch wheelbase, the Neander 1400 Turbo Diesel has very cruiser-like dimensions.
Atop this very robust but innovative bottom-end layout sits an equally unique eight-valve DOHC cylinder head, with four radial valves per cylinder (35mm inlets, and 30mm exhausts) operated via bucket and shims by twin overhead camshafts. The central chain drive to these is taken directly off the forward crank to spin its companion camshaft, which is directly geared across the top of the motor to the other, rear, camshaft. However, unlike on the MV Agusta F4, which also boasts a radial-valve layout, the Neander motor employs the cylinder head format patented by Austrian engineer Ludwig Apfelbeck, and most notably used by BMW on its 1960s Formula 2 racing cars. Instead of inlet valves on one side and exhausts on the other, as on a conventional pent-roof head, the valves are paired diagonally—so, exhaust, inlet, exhaust, inlet, driven by conical cams. "Apfelbeck suffered many problems with his radial-valve layout," says Baindl. "It's very similar to Honda's RVFC system, and as soon as high revs were used, the rockers would fail. The problems got even worse when they short-stroked the BMW F2 engine for 1600cc, so I decided to use the Rotax conical-valve system, which does not use rockers."
The Neander's inlet tract is channeled vertically down the center of the head, between the two camshafts, while the four exhaust valves each feed into separate dedicated header pipes (two at the front of the engine and two at the rear), which give the illusion of the quite wide motor being a four-cylinder. They're jointly routed into a single Garrett turbocharger with intercooler, delivering 1.4 bar boost pressure to the airbox containing the 31mm throttle body, and thence into a three-way catalyst mounted down in front of the engine, before finally exiting via twin lowslung pipes either side of the motor. The direct-injection Bosch common-rail EFI employs a single six-hole top injector, but a fuel cooler located in front of the steering head is required to prevent the incoming charge from cooking owing to heat transfer from the combustion chamber.
Thoughtfully integrated gauges monitor all the drivetrain's vitals.
Fitted with a unit-construction six-speed gearbox employing Aprilia RSV1000R ratios with multiplate dry clutch, gear primary and Gates toothed belt final drive, this unique powerplant weighing 238 lbs. dry, delivers a claimed 94 bhp at 4200 rpm at the crank, matched to a thoroughly tractor-like 175 Nm of torque at just 2600 rpm. But the Neander Turbodiesel's cycle parts are surprisingly conventional, with the parallel-twin motor slotted into a conventional chrome-moly tubular-steel spine frame designed by German custom specialist Gunther Zellner, with the engine underslung beneath. The frame's fully adjustable Ohlins cantilever monoshock rear end is quite radical by cruiser standards, however, matched to 43mm upside-down Paioli forks up front which are set at a kicked-out 31-degree head angle, with 109mm of trail, resulting in a rangy 1740mm wheelbase. Neander executive Lutz Lester says the company is looking at offering a 1950mm version when production of a first limited edition of 50 bikes is scheduled to start in March 2007, with a target price of $85,000 or euro 68,500, including tax.
OK, that's what the Neander is, but, why is it so? Even before the established theoretical advantages of burning diesel over gasoline, what are the purported benefits of a radical engine design quite unlike anything anyone has ever done before? Bottom end first, and here the twin contrarotating-crank layout, with appropriate counterbalancing, can obviously eliminate the gyroscopic effects of crank rotation on the handling, as well as cancel out both primary and secondary vibration is that offset cranks can allow a twin-crank motor to lengthen the inlet and power strokes, in terms of crankshaft rotation, compared to the compression and exhaust strokes. Lengthening the inlet stroke gives more time to draw in mixture and cool the piston crown, while a longer power stroke allows more time for the expanding gas to push on the piston. Shortening the compression stroke gives less time for heat to transfer, while reducing the exhaust stroke results in higher exhaust gas speeds and better scavenging. The bottom line of all this is more power, delivered more efficiently.
Moving up the engine, the twin-crank layout not only eliminates piston side-thrust, thus substantially reducing friction and wear, and allowing use of a shorter-skirted, lighter piston which reduces reciprocating weight and allows higher revs (Baindl's twin-crank BMR revved to an amazing 12,000 rpm quite safely, an incredible piston speed for a 750cc single, but promotes greater mixture turbulence via increased piston speeds. And thanks to the unique design of the Apfelbeck head, whose vertical inlet ports curve as they approach the valve, the mixture is presented for optimum combustion effect, offering ideal burn characteristics which not only aid power delivery, but also help reduce emissions, says Baindl (who's had the help of leading Swiss tuner Willi Rufenacht in developing all his twin-crank engines, as well as electronics wizard Ewald Mayer in de-bugging the diesel version, and Dr. Werner Bauer at Munich's University of Applied Sciences in refining the design). But, that begs the question: Why a diesel? Lutz Lester explains.
High-quality chassis components include a chome-moly frame. The exhaust includes a catalyst.
"Phillip Hitzbleck of Neander had the copyright for a very famous German comic figure called Werner," explains Lester. "Werner is a free-living biker who's always in trouble with police, drinks beer and likes playing with motorbikes and engines. He's a cult figure in Germany. There were a couple of hit movies about him in the 1990s, and there've been Werner party events with up to 250,000 people attending. But in '99 Phillip Hitzbleck wanted to lead the brand name of Werner to another level—for example, making a TV series, or holding a new bike event in the north part of Germany over three days with music, drag racing, dyno shootouts, things like this. Anyway, to promote this we had the plan to take the Werner theme to MotoGP with our own bike, but we decided, if we go racing, we must do it with something completely new, and then we heard about Rupert Baindl's twin-crankshaft MotoGP twin-cylinder engine. This sounded perfect, but we couldn't find enough partners for the GP racing program, so then Rupert said, 'Why don't we bring this engine to the street as a diesel engine? This could be the first turbodiesel engine worldwide to come in a motorbike.' So in 2002 Phillip decided to leave the Werner company, put in his own money to restart Neander, and bring all the people together in order to create a production turbodiesel motorcycle anyone can buy. Now you're about to ride the result!"
Slinging a leg over the Neander Turbodiesel's low 25.5-inch seat, which is relatively plush even if the passenger pad on the back mudguard is little more than a token perch, gives no hint of the surprise in store when you press the starter button on the right handlebar.Reach behind your right leg for the ignition key, turn on the fuel tap as the pump starts buzzing, thumb the starter button (no need to preheat as on old-generation diesels), and get ready for a shock. For this is a powercruiser Not Like the Others—it's not just ready to rumble the moment it hits the highway, it does so from the moment the beefy starter motor combats the 16:1 compression to crank those massive 108mm-bore pistons, persuading the twin-crank four-con-rod parallel-twin turbodiesel motor to light up. The Neander is uncannily still, both at idle and on the go, however hard you rev it. As in, no vibes!
Select bottom gear and feed the light-action clutch out slowly to move away, and though the Neander picks up pace perfectly smoothly, there also isn't a huge amount of surge until the tach reading on the MoTeC dash shows 2000 rpm or so and the turbocharger starts to do its stuff as the boost pressure builds. There's a delicious surge of liquid power from then on up, with the torque curve peaking at just 2600 rpm, but then staying practically horizontal until the 4200-rpm power ceiling, when power and especially torque tail off quite steeply (though Baindl says they've revved the motor out to 7000 rpm safely). But what you musn't do is let the diesel engine's deceptive clatter con you into thinking that you should just rumble around everywhere at low rpm. You can do so, of course, and this is a perfectly aimiable bike to plonk around city streets on, but then you'll be sacrificing the "sport" part of the sport-cruiser package, because the turbo'll be off boost. When you persuade yourself to crank 'er up, the Neander comes alive to the sound of a faint whistle from the Garrett turbo, which you can just make out above the engine's subdued but still unmistakeable diesel clatter, delivering fast, forceful acceleration in spite of the bike's hefty 595-lb. dry weight of the kind which makes you glad you have that meaty rear tire—at least for straight-line work.
You don't normally associate a diesel engine with this sort of motorcycle performance.
But maybe the biggest surprise once you've adjusted your mindset to accepting you're riding an oil-burning powerbike, is how fast this diesel motor gains revs. Coupled with the relatively short span of power and especially torque, this means you'll find yourself using the six-speed Aprilia gearbox much harder than you might have expected with a supposedly humble diesel, if you ride the Neander like the sport-cruiser it undoubtedly is. I regularly saw 100 mph/160 kph at just 2820 rpm during my afternoon road rumble around Bavaria, and thanks to a reasonably rational riding stance I wasn't blown off the back in achieving it, so figure this is a genuine 240 kph/150 mph turbodiesel mile eater in real-world riding. That's to be expected from something Made in Germany, the land of autobahns—but in both that country and everywhere else, the Neander would make a very suitable basis for a long-distance tourer, with its frugal fuel economy, awesome torque, and zero vibration. The Turbodiesel is not tiring to ride at any distance, and the dry-sump engine's relatively low C of G means it's also quite a relaxing handler, that takes fast sweeping turns or tight hillside hairpins in its stride, though you can't forget that rangy wheelbase in a hurry.
Really, the only downside to this thoroughly avant-garde diesel engine package is the noise it makes, which frankly isn't very pleasant—especially under full load, when the level of clatter rises quite significantly. This is not a bike you're going to want to bring home late at night if your next-door neighbor has even remotely good hearing, though I suppose you can say the same thing about a Harley with a Screamin' Eagle pipe. Anyway, the issue isn't so much about the engine itself being mechanically noisy, more that the turbodiesel tune simply isn't one that sounds at all melodic or even very sophisticated when you're actually riding it, especially compared to conventional bikes costing one-tenth of the Neander's heady sticker price.
Diesel technology has advanced so much in the past 10 years, not only thanks to turbocharging, but also due to variable nozzle geometry, and especially the evolution of the common rail system, such as found on the Neander. By any standards, this bike is a surprise—not only for its unique mechanical format, but also for the effective manner in which it applies the benefits of diesel development to a motorcycle.
SPECIFICATIONS
Neander 1400 TurboDiesel
Engine: Air/oil-cooled turbocharged parallel-twin diesel with twin 360-degree geared crankshafts, dual con-rods per cylinder
Valve arrangement: Apfelbeck eight-valve cylinder head with gear-driven double overhead camshafts, and radial valves with opposed inlet and exhaust tracts
Bore x stroke, displacement: 108 x 78.2 mm, 1430cc
Compression ratio: 16:1
Carburetion: Garrett turbocharger with intercooler, Bosch electronic direct fuel injection, single top injector, 31mm throttle body
Transmission: 6-speed Aprilia RSV1000R gearbox, multiplate dry clutch
Final drive: Belt
Weight: 595 lbs. dry
Rake/trail: 31 degrees / 109 mm
Wheelbase: 68.5 in.
Seat height:25.5 in.
Front suspension: 43mm Paioli inverted fork
Rear suspension: Single cantilever Ohlins damper
Wheels: Spun-aluminum, 18x3.5 front, 18x5.5 rear
Front brake: 2, 4-piston Performance Machine calipers, 11.8-in. discs
Rear brake: 4-piston Performance Machine caliper, 11.8-in. disc
Front tire: 130/60-18 Metzeler Marathon
Rear tire: 240/40-18 Metzeler Marathon
Claimed top speed: Over 140 mphClaimed power & torque (at crankshaft): 94 bhp @ 4200 rpm, 129 ft/lb @ 2600 rpm
Resource
Neander Motors, Kiel, Germany
www.neander-motors.com