The Kneeslider

Doers Builders and Positive People

Ducati Elenore 868cc V8

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Ducati Elenore 868cc V8
Ducati Elenore 868cc V8

Dieter Hartmann-Wirthwein, who we saw some time back with his 4 cylinder 125cc Monkey Bike, was working on a Ducati V8 project. It looks like the engine project is finished and he’s even got a patent for the connecting rod arrangement using the original 900SS crankshaft. Think about that, this is a V8 engine using the original 2 cylinder 900SS crankshaft! From the drawing, you can see the outer pistons connected by a pivoting rod, but what is hard to see is how the connecting rod is connected to the inner pistons so as not to interfere with the pivot rod. It would be really helpful to see some other perspective drawings, but it looks ingenious. I’ll post more drawings or photos as I get them.

Ducati V8 patent drawing
Ducati V8 patent drawing

The cylinders have a 56mm bore and 44mm stroke for a displacement of 868cc. Using the original 900SS crank, the engine fits in the 900SS frame. This guy is good, excellent work!

Thanks, Hugo, for the heads up!

Link: Wirthwein Motoren

Be sure to see the Ducati V8 Update

Ducati V8 in 900SS frame
Ducati V8 in 900SS frame
Ducati V8
Ducati V8
Ducati V8 cylinders
Ducati V8 cylinders

Posted on Filed Under: Engines, Motorcycle Builders

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Comments

  1. Does it use desmo cams? This a wonderful exercise in complexity and ingenuity. I’d love to hear it run — but will it run any better than a Ducati twin? The 900SS is already highly developed by the factory boys. Still, whatever turns your crank, so the speak.

  2. Not desmo. Comparing this to a 900SS is not the point in any way, this is a pure engineering project of the “let’s see if we could do this” variety. Anyone that can do this and get it running is OK in my book.

  3. That is absolutely fantastic! To fit a V8 into the same space as a V-twin is extremely impressive, regardless of the fact that both engines have roughly the same displacement. That rocker arm conrod design is brilliant, it reminds me of the old Commer Knocker truck engines which had opposing pistons with rocker-actuated conrods.

  4. Fantastic! It’s a quad-V-pivoting-twingle! Rube Goldberg would be proud. Let’s hope this guy doesn’t turn his genius toward evil, the world would be doomed.

  5. Cheers for his innovation. Let’s not forget that some other odd ideas from our past came out of some unusual creative minds – Mr. Tesla and his urge to transform AC, I could go on . . . . still a great work of engineering art, whether I ever own one or not

  6. It looks from the one drawing that you can see the small end connecting rod pivot bearings edge-on. Based on this one drawing, I can’t see any way that the y-shaped connecting rod is not offset from the piston centers. This must introduce uneven wear in the pistons and cylinders, but it’s probably not an issue for this prototype.

  7. I can see how that could provide some pretty interesting power characteristics, since the outer cylinders are providing force while the con-rod is on the upward stroke. It will be interesting to see how it ends up performing.

  11. @scritch I think the force from the outer piston’s connecting rod applies force to counter the inner Y-rod’s force. Very cool.

  12. Very impressive. I’d also like to know how it performs. Seems like a long distance from the outboard cylinders to the crank, but maybe it’s made up for with the single connecting rod with four cylinders behind it. I’m no engineer. Are all four cylinders in one half of the bank at a different stage while running?

  13. Thats gotta be some pretty complex pistons, the two pistons in the middle needs two pivot axis. One for the “regular” rod and on a 90 degree plane another pivot for the rocker rod. It might have been easier to make it consist of two square fours set in a V…..
    Thure

  14. Very interesting concept, with a lot of potential.
    But I wonder why, in order to avoid the complications with the middle pistons, that “Y” shaped connecting rod doesn’t connect to the medial pivoting rods, instead of the middle pistons?

    Why didn’t he went this way…?

  16. It’s amazing what our brains are capable of……if it keeps up we’ll hit on a solar turbine before too much longer. Maybe there’s a place for ball jointed connecting rods next…..remember the little cox engines and all (.049 cid) ?

  17. Wow – this guy has got serious talent – just checked out his website and while looking at his R50 project (with his own 4 valve heads no less!) I noticed a miniature radial engine in the background!

    Respect!

  19. Very interesting. The outer pistons will fire and “pull” the inner pistons up. Then reverse.

  20. I like it, complexity, weirdness and all. I suspect we’ll be hearing about Dieter for years to come.

  22. While it has a great “gee whiz” factor and the guy has tremendous machining talent, it’s overly complex and I believe it will have much LESS power than the original twin configuration. This is thinking too far outside the box. Just because it can be done doesn’t mean it’s a good idea that it should be done.

  23. Yeti B; You’re right, but look on the good side, he’s off the streets and out of the bars, which his wife is probably happy about.

  24. This is some serious archemy, and I’d love to hear the noise this makes. To push everything through one rod it must be made of Scrith! How are those rocker arms lubricated? Dropping a con rod would be extremely brutal.

  25. The biggest advantage is spreading the peak loads throughout the rotation of the engine. This would result in less peak force on the crank and transmission. It could well make the engine a candidate for supercharging. Wish I’d thought of this truly outside the box wonderful example of creativity.

  26. “To push everything through one rod it must be made of Scrith!”
    Not really so, matt. Those “lateral” pistons, “pull and push” directly on the pistons near to them. It might be a more balanced solution then the traditional way.
    And let’s [b]imagine[/b] this engine makes 200hp/liter, that would mean less power then a 1200cc superbike (same connecting rods as the street version) Ducati V2, but with considerable less torque.

    Hope someone finds some drawings/photos of how those middle pistons are connected to both connecting an pivoting rod.

  27. Nice looking engine and hope it runs ok.,Love all the finning on air cooled engines, they make water cooled engines look bland in comparison.

  28. I’m extremely impressed! What an amazing concept. I’ve never seen anything quite like this, so I wonder what the naysayers have seen. Most of us would be well served to reserve judgement regarding the value of the idea to power it makes ratio until dyno charts are posted.

  29. So, the only way i can envision the attachment is through 4 smaller bolts in a cross “+” profile. The connecting rod(4) attached to the pivoting part, should look like a fork with a very short stem and longer arms. While the main connecting rod(2), attached to the crank, should look like a “Y” with a long stem.
    That’s how it is? I’m asking because that double profile on the main connecting rod would suggest the opposite of what i described. But that’s impossible.
    Anyway, it’s dizzying to imagine all this moving.

  30. there are likely two pairs of outer rocker-rods. The center pistons would require three rods each, including the middle Y-rod and two link-rods. In total, on eight cylinders, this would have 22 “rods” (2 “Y rods, 8 link-rods, 8 rockers, and 4 outer rods). I’ll draw a picture if you need.

    -todd

  31. As a concept – thinking outside the proverbial box for sure. The two outer pistons actually pulling the main con-rod up during the matching inner cylinder compression/exhaust stroke. And the other bank offset by 90* – PERFECT!… except for all that extra reciprocating weight. The design is clearly not intended for practical mass production. If anything, it is a piece of art, and if Dieter can actually make this thing perform “as intended”, it becomes an EXTRAORDINARY piece of art.
    Now, where does the second conrod bearing go (on the 900SS crank?) Do let me know please.!

    @Phled 10.01.10 at 3:54 pm
    “The middle pistons do not require skirts”? thing.
    Mid pistons have skirts, they are turned 90*.
    @kneeslider, 44mm bore and 56mm stroke ads up to 682 cc, not 868

  32. Fantastic piece of work. I’d love to see (and hear!) a vid of that thing running. I suspect it’ll be pretty noisy!

  33. I think there are two of the short connecting rods (#4) for each piston. That way there would be a gap in the middle for the y-rod in the piston. 16 total for the v-8.

  34. Bob, 682 vs 868. Bore and stroke numbers were reversed, a little dyslexic engineering. I did a quick Saturday morning calculation and get 867.091. Good catch. Thanks.

  35. todd and w, yeah you’re right.
    Looking at the drawing and seeing that his doesn’t make a difference between the outer and inner pistons short connecting rods…
    …2 short connecting rods and one long Y connecting rod for each of the inner pistons, makes sense.
    I still want to see some scale drawings or photos, to see how the 2 parallel short rods(on the inner pistons) offer enough clearance for the movement of the main Y connecting rod.
    Must be a beauty 😛 seeing in in motion.

  39. It does look beautiful. But I’m wondering about the harmonics of vibration induced by the angular momentum of the little conrods (not the y-shaped one, but all the four other ones per bank). The way the drawing looks, they will be oscillating through an arc of about 90 degrees, back and forth. In a normal engine, most of the mass can conserve angular momentum by continuing its motion in a circular rotation, and you can balance the harmonics by distributing mass in specific places along that rotating assembly. I don’t see, just looking at this, how the angular momentum loads are balanced. But then,I’m no mechanical engineer. Can somebody help me out here? This thing looks like it would shake itself apart.

  40. Simply beautiful to see! Truly amazing connecting rod layout. Can’t wait to hear what it sounds like!

  41. @DoctorNine, I’m no mechanical engineer either (one year doesn’t count :P), but those short conrods moving in an arch, come in pairs. When one moves down there is an opposite one moving up. They’re not quite identical but the movement looks somehow balanced?

    There are not 4 short conrods per bank, there are 6. Each inner piston seems to have 2 of them ( plus the main Y conrod).

  43. Yeah, I figured that they were supposed to have primary balance by making each little conrod the same. But even if they try to make them exactly the same size and weight, they won’t be. This will lead to harmonic vibration. As I understand it, the slight imbalance produces precedence in the angular momentum, but again, I’m not an engineer. In regular V engines in the US, we have those harmonic balancers on the front end of the crank for that. But I can’t see how you would fix the problem in this design. that’s what I’m curious about.

  45. Phled could be right, the middle pistons would not require skirts. The rockers will keep the pistons from…rocking with the crank and the connecting rod (the “Y” one) will keep them from rocking with the rockers.

    I think “Monkey Motion” is the correct term for this.

    -todd

  47. There must be more pictures of the piston pin arrangement, since there is a section cut line, A, on the drawing, cutting right through the two axis pivot point in the piston. Could be interesting to see the design in that cut plane.

  49. I may believe this if and when I see it at Intermot in Cologne this week.

    The design and patent application raise some fundamental questions regarding a lot of things. From the choice of engine as a starting point to the design of those inlets. There are even those around me thinking the whole thing could be a hoax…

  52. “The design and patent application raise some fundamental questions regarding a lot of things. From the choice of engine as a starting point to the design of those inlets.”

    The choice of engine as the starting point and those inlets, just like the valvetrain or cooling options, have absolutely nothing to do with the design/patent, and are completely irrelevant.

  56. Another interesting tidbit; he can use any standard inline-4 camshaft as long as the valve spacing is the same. They would need to be modified to have the drive sprocket between the outer right pistons instead the center.

    Considering all the extra valve area he will have and the fact that they are individually smaller this thing should have quite a bit more torque than the original motor.

    -todd

  57. I can only see one provided spark plug space in only one of the heads (on the outside bottom bank of cylinders). How do we explane for the existance of the other seven spark plugs? I also notice that the bottom bank of cylinders have a different fin pattern than the top bank, for better air flow.

  58. OK, possibily there is a spark plug located on both outside heads, left and right, of the bottom bank of four cylinders. I do not see a spark plug on the top bank of cylinders. If there are hidden spark plugs, does this mean that the heads
    will need to be removed, for servicing the plugs?

  59. @ David,
    I’m gonna go out on a limb here and say that, considering this guy appears to be a creature of habit judging from his other projects, that the “missing” spark plugs are all located on the outboard side of each cylinder common to both banks of cylinders. For example, if you take a look at the fifth picture of the 125 Four engine he has on his page, you can see the rear side of the inboard cylinder and the “missing” sparkplug.

  61. i seen this a week before kneeslider posted it and was very leery of it and its outright overall look. it would amaze me to stand in front of this( not beside it at all) and witness it actually starting and running. sorry if it in fact does. i dont think so.

  62. The image looks like a cross-section of one bank. The forked center rod will pivot on a wrist pin to follow the motion of the crank journal. This means the inside links from the rocker arms going to the outer pistons – are also forked to straddle the wrist pins carrying the forked rod. The forked inner link may have the only wrist pin that goes all the way through.
    That is what I am seeing.

  63. It’s mad and glorious at the same time. Engineering like this doesn’t come along often. Perhaps it’d need refinement to make it durable and reliable in a road bike but it shows a lot of original thought. I bet it sounds good too.

  64. @ursus. That’s how i imagined it also. But since on the drawing, both the short conrods, that connect the outer and inner pistons to the rocker arms (piece number 3) are described as identical…
    …it seems that the inner pistons are connected to the pivoting part(5) by 2 short conrods, so there is space between them for the movement of the main Y conrod.

  66. I guess this is one of those things that if you have to ask why, you will never understand.

    It’s a beautiful engine!