[219R]

Chk out the cranks. Guess which one is the 1199 and the SL.....

 

[W17]

The standard 1199 crank can be modified to replicate the SL crank . I can possibly see a disadvantage of the SL crank and lightened flywheel on a high speed track .
Possibly fitting a standard flywheel to suit a particular track might be the answer ?

 

[rubbish]

what would be the disadvantage on a high speed track??

 

[W17]

Lack of inertia .

 

[rubbish]

Lack of inertia .

How's that a disadvantage though?? Less inertia means easier to flick side to side, better acceleration, etc. I would think those are advantages on any type of track.

 

[W17]

How's that a disadvantage though?? Less inertia means easier to flick side to side, better acceleration, etc. I would think those are advantages on any type of track.

Top end speed on long straights . I agree on a more technical track it's a advantage .

 

[lostpckt]

I'll claim ignorance here, aren't there 3 cranks in this picture? I assume the far left is the SL, what are the other 2? 1199 and 1199R?

 

[W17]

I'll claim ignorance here, aren't there 3 cranks in this picture? I assume the far left is the SL, what are the other 2? 1199 and 1199R?

Correct .

 

[DucatiJ2012]

Top end speed on long straights . I agree on a more technical track it's a advantage .

Wouldn't that be made up by the shear lightweight factor of the bike as a whole? Yes mainly acceleration but you'll still have a high top speed with that lightened bike

 

[W17]

Wouldn't that be made up by the shear lightweight factor of the bike as a whole? Yes mainly acceleration but you'll still have a high top speed with that lightened bike

I was more thinking of the lines of rotating mass of the crankshaft not the entire bike . Keep in mind it is a question not a statement .
The fact inertia will be lost but can be added with a different flywheel .

 

[DucatiJ2012]

I was more thinking of the lines of rotating mass of the crankshaft not the entire bike . Keep in mind it is a question not a statement .
The fact inertia will be lost but can be added with a different flywheel .

You're referring to the fact that a higher mass will want to rotate faster once going hence making the bike go faster top end?

 

[W17]

You're referring to the fact that a higher mass will want to rotate faster once going hence making the bike go faster top end?

That's it .

 

[DucatiJ2012]

That's it .

Yeah, I know what you're getting at and if it was only the crank that was the difference in weight savings then it would help, but when the whole bike is so light...it's probably gonna make much more of a difference than the extra bit of inertia. I think the bike is something 30-40lbs lighter than most bikes with fluids...that'll make more of an impact than the rotating mass

 

[W17]

Yeah, I know what you're getting at and if it was only the crank that was the difference in weight savings then it would help, but when the whole bike is so light...it's probably gonna make much more of a difference than the extra bit of inertia. I think the bike is something 30-40lbs lighter than most bikes with fluids...that'll make more of an impact than the rotating mass

The questions are really only based around my own development with my bike .
I am bringing the motor up to SL spec but have decided to leave the crank .

 

[rubbish]

Ha! So you mean your R wasn't powerful enough?

 

[219R]

The inserts (plugs) in the crank cheeks are kinda interesting, as well as the machined removal of material. We used to bore holes in my Norton crank cheeks and replace the bore with Mallory inserts. Mallory being a lot heavier than the OEM crank cheek material. The reason being, we could remove more material from the areas of the crank furthest away from the rotating CL of the crank, thus reducing a bunch of crank flex under maximum loading. Less crank flexing, of course keeps everything moving in the proper direction reducing wear and tear, as well as drag. If I were going to the expense of replicating the SL motor, blue printing, balancing, etc. I would take a long look @ not only the lighter crank shaft, but also the way Ducati has moved the material around on the crankshaft. Just sayin, pretty impressive piece of work that SL assembly!!!

 

[tye1138]

Ducati used a very similar crank on the 999F series and they found it would destroy bearings due to vibration. They wound up going with plain bearings like the Superleggera. But then, the energy went into the cases and it was quite common to find cracked bearing races on those motors.

Theoretically a heavier crank doesn't rob the engine of too much power, the advantage is so minimal, it doesn't even show up on a dyno. It is much lighter and does allow the motor to spin up and slow down much quicker and that feeling is what they're after. It helps with corner entry and spooling up the motor on exit. When your trying to build the lightest ever, you gotta reduce weight everywhere.

 

[219R]

Been informed by higher powers that the inserts are Tungsten, and that all the R and RS motors were like this,

 

[plain vanilla]

The inserts (plugs) in the crank cheeks are kinda interesting, as well as the machined removal of material. We used to bore holes in my Norton crank cheeks and replace the bore with Mallory inserts. Mallory being a lot heavier than the OEM crank cheek material. The reason being, we could remove more material from the areas of the crank furthest away from the rotating CL of the crank, thus reducing a bunch of crank flex under maximum loading. Less crank flexing, of course keeps everything moving in the proper direction reducing wear and tear, as well as drag. If I were going to the expense of replicating the SL motor, blue printing, balancing, etc. I would take a long look @ not only the lighter crank shaft, but also the way Ducati has moved the material around on the crankshaft. Just sayin, pretty impressive piece of work that SL assembly!!!

Actually that was what I was planning on referring to in my next question...

Is the crank actually lighter or did they reduce it's drag through the case by machining it to a smaller surface area and profiling the edges, while retaining the weight due to the inserts.

The counterweight mass is dependent upon the mass of the entire assembly including the rods and pistons, so it would seem it could only be reduced in accordance with reductions in the connecting rods and pistons.

 

[Zootcadillac]

I was about to write, after only reading the first page, that you are missing the balancing weights that are inserted. But then I got here and see you have it covered. The reduction in size is compensated for y the addition of precise weight in well modelled and tested positions.

The team of engineers and specialists under the guidance of new Chief Project Engineer Andrea Forni revised every single element of the machine, starting at the heart of its already extreme 1198cc V-twin. The crankshaft was significantly reduced in mass and size by completely reworking the large counterweights that now look like slim tomahawk blades decorated by small cylinders of tungsten (which is much heavier than steel) inserted at the sides to achieve the appropriate balancing mass. In this way, the crankshaft is reduced also in terms of cross section, thus decreasing the drag caused by pumping the oil vapors in the crankcase.​