Desmodromic?
11-07-2005, 09:10 PM
#22
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It takes all day for me to run the valves on my 916 ducati desmo.216 available shim sizes and you still have to face them off to get the clearance perfect.With a properly
set up desmodronic valve train you won't float the valves until you drive over the crankshaft.
set up desmodronic valve train you won't float the valves until you drive over the crankshaft.
11-08-2005, 05:23 PM
#23
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the moto GP machines are 4 cyl v 90deg 998cc and 269 HP!!!!!!
and the name is DESMOCEDICI (sixteen valve- desmo) FYI
all titanium, magnesium, carbon F, and a very efficient trellis frame CrMo steel...
yes, steel chasis in the age of superalloys.... Go figure....
now they are not as succesfull in the first moto gps, but now ducati corse (race dept) is selling a STREET desmocedici with "only" 220 Hp.
ANYBODY WANT ONE!!!!!!!
I DO !
and the name is DESMOCEDICI (sixteen valve- desmo) FYI
all titanium, magnesium, carbon F, and a very efficient trellis frame CrMo steel...
yes, steel chasis in the age of superalloys.... Go figure....
now they are not as succesfull in the first moto gps, but now ducati corse (race dept) is selling a STREET desmocedici with "only" 220 Hp.
ANYBODY WANT ONE!!!!!!!
I DO !
11-30-2005, 10:26 AM
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I brought up camless ideas using hydraulics or elecromechanical technology about a year ago and got shot down here pretty bad. I bet Lotus will do well with it. Imagine idling and fuel economy of a honda and screaming like a pro stock. Maybe a slight exageration, but you get the idea.
11-30-2005, 11:43 AM
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Originally Posted by BADSZ28
I brought up camless ideas using hydraulics or elecromechanical technology about a year ago and got shot down here pretty bad. I bet Lotus will do well with it. Imagine idling and fuel economy of a honda and screaming like a pro stock. Maybe a slight exageration, but you get the idea.
12-10-2005, 05:55 PM
#27
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I'm sure that diesel technology will trickle down to us soon enough. Take a look at the blower on the International pickup. It has technology the FI guys would love to have. It'll probably be the same thing with electronically actuated valves. They'll first appear on engines that are used hard and long enough to pay for themselves, and when the technology gets cheaper and people are more comfortable with them, they'll appear on regular street cars. Actually, I see BMW coming out with them on a street car first, but still...
12-12-2005, 11:15 AM
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Originally Posted by DanO
Yup, thats one of the projects i have worked on. works great but $$
Are you serious? If so, some details please. You can’t leave us hanging like that….
I’ve read and seen some hydraulic actuated VVT systems, but didn’t know an electronic one actually existed.
12-12-2005, 11:36 AM
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Originally Posted by DanO
No, it is the Hydralic actuated one also known as "Lotus AVT", here at eaton we developed all the hardware, lotus developed the software/controls (basically the PCM for the valves).
As far as details... i dont think i can divulge too much at this point. (as the saying goes, I could tell you but then I'd have to kill you)
As far as details... i dont think i can divulge too much at this point. (as the saying goes, I could tell you but then I'd have to kill you)
12-12-2005, 05:04 PM
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Gotcha DanO. You have one enviable job there….... must be fun playing with all those new toys and R&D. I’m famlier with what Lotus is/has been doing. Read it a while back in a newsletter I believe.
All this VVT talk makes me wish GM would have put more effort into the LT5.
All this VVT talk makes me wish GM would have put more effort into the LT5.
12-18-2005, 08:32 PM
#33
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The "Desmo"system was created back i believe in the 1930's by Mercedes and Norton and maybe some others at a time when valve springs were the limiting factor to engine performance.
Ducati developed its own design in the late fifties and sixties to a "production" level for much the same reason.
It then became a Ducati trademark so to speak and is still used on virtually all of its bikes including GP machines to this day.
Due to the advancement in spring technology and the wide application of 4 and 5 valve head designs the advantages with regard to the elimination of valve springs(excep light hairpin springs to help idle and starting)is all but null and void.
However the system still has advantages with regard to aggressive cam profiles.
A desmo engine can run much more aggressive profiles than a springer engine.
The disadvantages?Complexity,expensive to manufacture ,expensive to service.
They hold their adjustment fairly well these days but the advantage of less power to drive the system is minimal.Remember although in a springer system you have to use power to compress the valve springs you also get some(not all) back when the cam rotates to the closing flank and the spring gives you back some of the energy you put in to compress it.
Ciao
Ducati developed its own design in the late fifties and sixties to a "production" level for much the same reason.
It then became a Ducati trademark so to speak and is still used on virtually all of its bikes including GP machines to this day.
Due to the advancement in spring technology and the wide application of 4 and 5 valve head designs the advantages with regard to the elimination of valve springs(excep light hairpin springs to help idle and starting)is all but null and void.
However the system still has advantages with regard to aggressive cam profiles.
A desmo engine can run much more aggressive profiles than a springer engine.
The disadvantages?Complexity,expensive to manufacture ,expensive to service.
They hold their adjustment fairly well these days but the advantage of less power to drive the system is minimal.Remember although in a springer system you have to use power to compress the valve springs you also get some(not all) back when the cam rotates to the closing flank and the spring gives you back some of the energy you put in to compress it.
Ciao
12-18-2005, 08:43 PM
#34
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Yup... think about turning an engine over by hand (with the plugs out so you're not fighting compression). It's really not that tough, even with double springs.
12-18-2005, 09:15 PM
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Originally Posted by CamTom12
Yup... think about turning an engine over by hand (with the plugs out so you're not fighting compression). It's really not that tough, even with double springs.
Most of your loss comes from the pumping and frictional losses
there is a significant difference between WOT turning and closed throttle turning too. pumping losses are huge.
