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Ducatis and desmos


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#1 brands77

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Posted 08 December 2022 - 10:51

In both MotoGP and WSBK the Ducatis seem to be faster in a straight line than their competitors. I know they are fantastic engineers and very innovative, but I wonder could the desmodromic valve system that they use be one of the reasons for their speed advantage?

 

I think that they have a patent on it and is this the reason why no other team uses the system? I am not certain but the other teams I think use pneumatic valves.

 

Does their desmo system really give them a big advantage?

 

I also thought that some car engines have used desmo systems in the past, did the Cosworth DFV use a desmo system? So does Ducati have a patent for all desmos or only a specific version or have they licenced it for use in car engines?

 

It would be very interesting to find out.



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#2 Tim Murray

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Posted 08 December 2022 - 11:08

The Mercedes-Benz racing cars of the 1950s (W196 and 300SLR) had desmodromic valve operation, as did the F1 Scarabs. Although Cosworth did experiment with desmo, it never made it onto a race engine.

Here’s an earlier thread from the car forum:

Desmodromic valves

#3 brands77

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Posted 08 December 2022 - 15:11

Sorry about mirroring something already discussed. Not only is the discussion on the forum it is recent too! It has answered quite a few of my questions.

 

However, not being hugely technical myself, do you think Ducati have an advantage from using it? Their engines have always been more powerful and no other bike manufacturer use the system. It seems too me to be the main difference between their engines and the others.


Edited by brands77, 08 December 2022 - 15:11.


#4 Rodaknee

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Posted 09 December 2022 - 05:43

The Desmodromic valve train is much lighter than the usual coil spring setup.  This allows the engine to rev much higher.  I don't know the exact numbers but the WSV Ducati revs to over 16k, whereas the other engines rev out at 12/13k.  The Ducati also gets to max revs much quicker.

 

It's unlikely other manufacturers will use the desmodromic system as it is so closely related to Ducati, they'd be handing the Italians free publicity by copying them.  Every manufacturer seeks that USP to sell their wares.



#5 djr900

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Posted 23 December 2022 - 11:21

I suppose - less friction, and valve bounce being impossible would be the benefits,

Perhaps some extreme cam profiles would work with desmo, but not with other systems
( I don't know this, just speculating)

I think if the other manufacturers thought it was a must-have , they would come up with their own version with a Japanese name.

Having said all this , there have been plenty of championships won by non-desmo bikes, and as Ducati have made it a selling point of their bikes for decades, they have to stick with it or lose face if they do something more conventional

#6 tonyed

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Posted 24 December 2022 - 07:59

The most efficient way of controlling valves is, of course, to eliminate them altogether - I believe it's called a two stroke.



#7 Robin127

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Posted 24 December 2022 - 16:00

The most efficient way of controlling valves is, of course, to eliminate them altogether...

 

Unless it's a disc valve...


Edited by Robin127, 24 December 2022 - 16:00.


#8 Macca

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Posted 24 December 2022 - 16:54

Or a reed valve……..or an exhaust Powervalve

Paul M

#9 tonyed

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Posted 25 December 2022 - 05:49

Is this pedantry corner?

 

A disc valve rotates so does not need mechanical control, only attachment. A reed valve works on pressure difference only and a power valve is relatively slowly moving, all not quite in the league of poppets valves in  four stroke.   


Edited by tonyed, 25 December 2022 - 05:49.