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Buell Motorcycle Forum » Quick Board Archives » Archive through May 21, 2004 » Pneumatic valves « Previous Next »

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Shazam
Posted on Wednesday, May 12, 2004 - 04:43 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

How fast could one of these tractor motors spin with pneumatic valves instead of the pushrod set-up

The technology is proven in Formula one racing.

could be the next "First on a production bike" offering from Buell. Talk about lightening the powerplant......no cams, no pushrods, valvesprings, rockers.....just solenoids and compressor?

I know I am fantasizing, what do you all think?

Is it only me who envisions sitting on the side of the road telling the inline fours that stop to help......"I ran out of air"
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Reepicheep
Posted on Wednesday, May 12, 2004 - 05:00 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I think our relatively long stroke engines are pretty close to the limits with piston speed anyway, even if the valves could be helped. You could go to a much more oversquare stroke, but you would then loose all your low end torque, and would still be at a real disadvantage to the 4's.

Cool technology though.
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Shazam
Posted on Wednesday, May 12, 2004 - 05:31 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

damn, I forgot about piston speed.....

still thinking variable valve timing, better cylinder fill, lighter componentry.....

just daydreaming....................
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Rex
Posted on Wednesday, May 12, 2004 - 05:44 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

see motorcyclist magazine this month for the KTM gp bike////REX
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Blake
Posted on Wednesday, May 12, 2004 - 10:42 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Despite popular misconception (I too used to believe as you do), pneumatic valves do indeed utilize conventional cams. The "pneumatic" part only replaces the springs.
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Kenb
Posted on Thursday, May 13, 2004 - 08:00 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

and as I understand it the F1 cars use a total loss system. There is a nitrogen tank onboard that is topped off during pit stops. The pressures needed are pretty high, thus unpracticle for casual use. F1 engines have a life span of 200 miles or so they are pretty stressed at almost 20000 rpm
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Benm2
Posted on Thursday, May 13, 2004 - 08:23 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I think the new vette engine uses variable valve timing, on its pushrod two-valve motor. (05 model year) Its only got one cam to worry about, versus the Buell's four, so its a little easier mechanism-wise.
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Djkaplan
Posted on Thursday, May 13, 2004 - 11:49 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

It's only a matter of time before totally active valve timing and lift is feasible. Before internal combustion engines become a thing of the past, we'll eventually figure out how to squeeze the most amount of efficiency out of them.
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Jmartz
Posted on Thursday, May 13, 2004 - 02:34 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I read of a solenoid actuated valve motor with no throttle plate. Active control of lift and duration took the engine form idle to redline. Pretty cool if such technology would become feasable for street use. No cam on this one.
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Shazam
Posted on Thursday, May 13, 2004 - 03:18 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Blake, thanx for the heads up. I haven't been exposed to the technology in the least.

to bring up another ingenious device for feeding an engine....has anyone else ever seen the rotary valve design? I saw a program some time ago where some guy was testing a set-up on lawnmowers or some such small engine. It consisted of a gear driven (rpm following) disc atop the combustion chamber that had slots cut in it which were only exposed during the relevant portion of the cycle, the slots acted as the valve opening.

The whole thing (valve train) had one moving part(the disc)!
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Captainplanet
Posted on Thursday, May 13, 2004 - 04:17 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Shazam,

A lot of 2 stroke motors use that rotary valve design. As least they used to. I haven't been into one in while. Other 2 strokes use reed valves that get pulled open by the engine vacuum.
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Rocketman
Posted on Thursday, May 13, 2004 - 09:05 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

We've covered this rotary valve thing recently. Rotary valve on a two-stroke is nothing to do with rotary valves on a four stroke. Not even remotely similar.

Jose, I think you speak of Lotus. They have designed a motor that uses NO cam what so ever.

Rocket
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