Valvetrain
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Valvetrain
Whatever happened to the Desmodromic type of valvetrain?
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Re: Valvetrain
Probably, COST ...
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Re: Valvetrain
The fact that honda revved 4 strokes with valve springs to 21,000rpm in the 60s should be a clue to their usefulness.
Re: Valvetrain
Improved camshaft lobe design
Improved valve spring materials
Lighter, better quality valves
Four and five valve heads.
Improved valve spring materials
Lighter, better quality valves
Four and five valve heads.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
Studebaker-Packard V8 Limited
Obsolete Engineering
Re: Valvetrain
Ducati still uses it with success.
The MotoGP bikes are consistently at the top of the top speed charts.
The advantage over pneumatic springs appears to be small but with greater complexity. Ducati is invested the other manufacturers are able get similar to same power without it
Having worked on them for years the frictional losses are negligible. Not sure how they compare at 16000+ rpm.
The early Desmo valvetrains came about when valve springs were not very reliable at high RPM. (Mercedes as I recall)
The MotoGP bikes are consistently at the top of the top speed charts.
The advantage over pneumatic springs appears to be small but with greater complexity. Ducati is invested the other manufacturers are able get similar to same power without it
Having worked on them for years the frictional losses are negligible. Not sure how they compare at 16000+ rpm.
The early Desmo valvetrains came about when valve springs were not very reliable at high RPM. (Mercedes as I recall)
Re: Valvetrain
The biggest issue was material expansion from heat.
On a normal valvetrain, as the engine gets hot, the lash opens up, so we design a lash ramp to deal with it.
Think about what it does on a desmo system.
On a normal valvetrain, as the engine gets hot, the lash opens up, so we design a lash ramp to deal with it.
Think about what it does on a desmo system.
Mike Jones
Jones Cam Designs
Denver, NC
jonescams@bellsouth.net
http://www.jonescams.com
Jones Cam Designs' HotPass Vendors Forum: viewforum.php?f=44
(704)489-2449
Jones Cam Designs
Denver, NC
jonescams@bellsouth.net
http://www.jonescams.com
Jones Cam Designs' HotPass Vendors Forum: viewforum.php?f=44
(704)489-2449