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31 Aug 2003, 16:16 (Ref:704086) | #1 | ||
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Camshafts in F1?
In this article http://www.f1racing.net/news.php?ID=62059 Renault explains the direction of their motors development. In the last paragraph it was mentioned that some changes would be made to the camshafts. Can someone explain to me how camshafts work with a pneumatic system. I thought that was how the valves opened not with cams...
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31 Aug 2003, 18:42 (Ref:704158) | #2 | |
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F1 motors still use gear driven camshafts just like in the early 1990s. However, the metal wire coil springs have been replaced with pnuematic springs. The advantages are three fold. 1) The risk of catastrophic valvetrain failure due to material fatigue of the springs is nearly eliminated. 2) The inherent limitations due to coil spring harmonics is overcome. 3) Pnuematic springs have far more damping, or so I'm told.
That said, the top F1 motor was around 19k rpm last year. Meanwhile, the top CART engine(no pnuematic springs allowed) was around 17k in 2002. |
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31 Aug 2003, 19:18 (Ref:704186) | #3 | ||
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Ok thanks but now this raises more questions. If air is being used to open the valves what does the cam actually do? I mean the cams would open the valves and the springs would return them to the valve seat. Do the cams still open the valves while the pneumatic system closes them?
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31 Aug 2003, 21:32 (Ref:704285) | #4 | ||
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The valve is still opened by the cam physically. Only the closing is done pneumatically and not by springs.
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31 Aug 2003, 21:38 (Ref:704294) | #5 | ||
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After having read the article I really don't know where Dudot is hinting at. His first statement of "one or two tenths through modifications to the cylinder head" could be anything really, from better flowing heads, to better motor management characteristics when i.e. TC is applied.
His lats one though ("We are also studying some other details, notably on the camshafts.") may be a hint to their 'big' rumour, the engine without camshafts but with a different valve operation (electro-magnetically the rumour was). But that still remains to be seen and may just be a little P.R. move to give some fuel to press rumours about Renault. |
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31 Aug 2003, 21:59 (Ref:704306) | #6 | ||
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as has been said, the cam still does the opening and closing. The pneumatic "springs" simply control the closure just like normal valve springs. The other major plus is that the valve closure is much softer because the air spring provides a sort of controlled, softer closing because of the expansion as it closes softening. The move toelectromagnetic cams is still a long long way away. the only engine to race succesfully with such a system was a diesel truck that was campaigned up Pikes peak a few years ago (a very low rev application). It also used a one way actuator which still relied on springs for closure. The ultimate goal would be a two way system which would allow absolute control over all parts of the valve movement event.
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31 Aug 2003, 23:23 (Ref:704366) | #7 | ||
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Thanks for the clarification guys.
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1 Sep 2003, 08:15 (Ref:704567) | #8 | |
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I often wonder how many lost engines would be due to broken valve springs vs pnuematic leaks?
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1 Sep 2003, 12:02 (Ref:704742) | #9 | ||
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A fair number, as with any seal, there is some inherent leakage around the edge. The cars carry a reserve tank, but you can also see the mechanics top the tank off at pitstops sometimes
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1 Sep 2003, 22:46 (Ref:705173) | #10 | |||
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Quote:
The 'camshaft details' he alludes to are normal stuff-advanced profiles,configurations,materials,etc |
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3 Sep 2003, 15:40 (Ref:707067) | #11 | ||
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you can also pick up some efficiency by using thinner cam lobes. They are down on horespower already so if theyt could reduce friction as well it would only help and make any future change more effective
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