MotoGP RPM limits

<div class='quotetop'>QUOTE (gsfan @ Mar 20 2008, 04:38 PM) <{POST_SNAPBACK}><div class='quotemain'>This article has good info: <a href="http://www.sportrider.com/fetures/146_0704_suzuki_gsv_r990/index.html" target="_blank
http://www.sportrider.com/fetures/146_0704...r990/index.html</a>

Could you get us a link that work.
Edit:
Seems like the link is right but still doesn't work.
A bit down thier features page the article "Suzuki GSV-R990 - MotoGP Suzuki -Testing The Waters " have the same link

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see previous post for working link

<div class='quotetop'>QUOTE (Babelfish @ Mar 20 2008, 12:27 PM) <{POST_SNAPBACK}><div class='quotemain'>Could you get us a link that work.
just fix the spelling.

http://www.sportrider.com/features/...990/index.html

<div class='quotetop'>QUOTE (gsfan @ Mar 21 2008, 02:38 AM) <{POST_SNAPBACK}><div class='quotemain'>I suspect that same force preload is not present in a pneumatic valve train.

I was wondering that .... but I think its just a stronger spring they are making .... so its got to be worse for valve train force .. .. Originally I thought they were getting clever and timing Nitrogen pulses when needed to open and shut valves but I can't find any reference to that?? So it just looks to me that they have just made stronger springs from a pneumatic system??

Am I wrong?? anyone seen anythng on this? ...... I fully understand that we may not ( all hush hush and all that ) but gee whether its that classic case of poor interpretation we get when a journo "gets technical" or is it the case?

<div class='quotetop'>QUOTE (BarryMachine @ Mar 21 2008, 03:06 AM) <{POST_SNAPBACK}><div class='quotemain'>I was wondering that .... but I think its just a stronger spring they are making .... so its got to be worse for valve train force .. .. Originally I thought they were getting clever and timing Nitrogen pulses when needed to open and shut valves but I can't find any reference to that?? So it just looks to me that they have just made stronger springs from a pneumatic system??

Am I wrong?? anyone seen anythng on this? ...... I fully understand that we may not ( all hush hush and all that ) but gee whether its that classic case of poor interpretation we get when a journo "gets technical" or is it the case?

I suspect you are right, they "only" made a stronger and harder spring, but the clue is that is also have a lot less losses in friction and fattigue. Besides, the spring is not all loss. While the valve train must compress the air when opening the valve, some of those forces are returned when closing. With less losses in the "spring" I suspect that the net result is less losses and higher rpm. Something the somewhat surprising improved gas consuption should support.

<div class='quotetop'>QUOTE (Babelfish @ Mar 21 2008, 08:45 AM) <{POST_SNAPBACK}><div class='quotemain'>I suspect you are right, they "only" made a stronger and harder spring, but the clue is that is also have a lot less losses in friction and fattigue. Besides, the spring is not all loss. While the valve train must compress the air when opening the valve, some of those forces are returned when closing. With less losses in the "spring" I suspect that the net result is less losses and higher rpm. Something the somewhat surprising improved gas consuption should support.

No the forces are far lower and they are lower where it matters, at the lowest part of the power band. The upper end of the power band are helped because nitrogen oscillates at around 100 000hz so will never cause the valve bounce even the hardest spring will.

<div class='quotetop'>QUOTE (gsfan @ Mar 23 2008, 02:10 PM) <{POST_SNAPBACK}><div class='quotemain'>No the forces are far lower and they are lower where it matters, at the lowest part of the power band. The upper end of the power band are helped because nitrogen oscillates at around 100 000hz so will never cause the valve bounce even the hardest spring will.

100000Hz corresponds to 6million "events" per minute. even for a screamer engine the no. of accumulated valve events would equate to perhaps 40,000 events per minute ( counting exhaust and inlet and assuming parallel multivalve openings/closings ) so I don't think such things as resonant freq. of N are used. As it seems .... its just a feature to ensure that any peaks or troughs in pressure waves ( resonated/reflected ) are not high enough to cause a failure of the role of the pneumo-spring?


I originally thought they where using such "techo" stuff, but now I don't think they are. ie. The constructive use of pressure waves in nitrogen .... eg timed high pressure pulse to hit valve at just the right time .... I thought they were getting superclever .... but all I read makes it sound like they are just using a fixed pressure in place of a spring. The benefit is that the regulated pressure keeps the force acting againts the cam ( a loss ) and is lower than the peak pressures a spring achieves.

<div class='quotetop'>QUOTE (BarryMachine @ Mar 24 2008, 02:54 AM) <{POST_SNAPBACK}><div class='quotemain'>I originally thought they where using such "techo" stuff, but now I don't think they are. ie. The constructive use of pressure waves in nitrogen .... eg timed high pressure pulse to hit valve at just the right time .... I thought they were getting superclever .... but all I read makes it sound like they are just using a fixed pressure in place of a spring. The benefit is that the regulated pressure keeps the force acting againts the cam ( a loss ) and is lower than the peak pressures a spring achieves.

The Nitrogen is like a valve actuated spring, working like a gas shock in a sense. The big gain is that there is less weight involved in the mechanical movement department, unlike coil springs that compress and open. The gas is what moves, not steel componentry, hence is much lighter and can move more readily without being coil bound or subject to harmonic balance effects. This allows for a somewhat lighter valve train that high rev coil springs at the expense of relatively little extra complication in terms of componentry. However it is impossible to get past the friction effect that any sort of spring presses against the cam follower which is required to keep the valve from floating. The higher the rpm, the higher the pressure required, resulting in higher friction loadings.

Hyper

JUst found an interesting snippet or two that made me think that maybe Honda wanted to limit RPM as they have done it internally ( within Honda ) in the past to limit problems they had with reliablity ..... maybe they are still having them??


Also interestingly ... apparently Honda have tried Desmo valves but saw no real benefit in them..

from here:

http://books.google.com.au/books?id=fpoF0P...l=en#PPA1977,M1

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