Solenoid Operated Valves...
04-01-2005, 01:36 PM
#21
No. No way a conventional coil spring can control the vavle properly when you're talking about 19,000 (not a misprint) RPMs. Do the math on the valve train and you'd find that it would far exceed that number (wouldn't it or would it be 1/4?). At anyrate, I would imagine electromag. vavles with springs in passanger cars would be ok but the harmonics of springs @ those extremes of an F1 car would simply not work.
Richard
04-01-2005, 02:06 PM
#22
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Originally Posted by Richard@WCCH
Back in the 80's, Honda was involved with developing a 500cc four stroke motorcycle engine to try and compete with the 2 strokes. The engine designation was NR500. It had 2 connecting rods per piston, oval and pistons and cylinders, and 8 valves per bore. It had a powerband from 19000-21000 rpm and used valve springs to actuate the valves. I have no idea how they pulled it off, but it was an incredible engine from a mechanical engineeering point of view. Honda dropped the program because they were still too far from the 2 strokes to be competitive.
Richard
Richard
Impressive. Doubt those valve springs lasted that long though. Also I wasn't elluding to the need for 19~20k RPMs on a street vehicle. LOL
I'm not that much of an armchair engineer.
04-01-2005, 03:23 PM
#23
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Originally Posted by Dave_62
A picture is worth......http://www.bmwworld.com/technology/valvetronic.htm
I was wrong about the infinitely variable timing bit. It only has 60 degrees variation in the cam timing. The lift is fully variable though.
I was wrong about the infinitely variable timing bit. It only has 60 degrees variation in the cam timing. The lift is fully variable though.
04-01-2005, 04:04 PM
#24
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Originally Posted by Richard@WCCH
Back in the 80's, Honda was involved with developing a 500cc four stroke motorcycle engine to try and compete with the 2 strokes. The engine designation was NR500. It had 2 connecting rods per piston, oval and pistons and cylinders, and 8 valves per bore. It had a powerband from 19000-21000 rpm and used valve springs to actuate the valves. I have no idea how they pulled it off, but it was an incredible engine from a mechanical engineeering point of view. Honda dropped the program because they were still too far from the 2 strokes to be competitive.
Richard
Richard
They used a oval piston because it had less frictional surfaces than two standard round pistons. The engine was awesome but, after I saw it that one time I really never heard anything else about it.
04-01-2005, 10:38 PM
#25
Originally Posted by XLR8NSS
I remember that engine....it was way back in the 80's?
They used a oval piston because it had less frictional surfaces than two standard round pistons. The engine was awesome but, after I saw it that one time I really never heard anything else about it.
They used a oval piston because it had less frictional surfaces than two standard round pistons. The engine was awesome but, after I saw it that one time I really never heard anything else about it.
Boring and honing an oval bore must have been just slightly less difficult than making oval piston rings
Not sure what the crank stroke was, but it must have been short to rpm so much. The other advantage the engineers were counting on was the fact that with four intake and four exhaust valves per cylinder, the center valves had no cylinder wall shrouding which permitted big airflow enabling the ultra high rpm capabilities. Engine idle speed was something around 4-5 thousand rpm 
Richard
04-02-2005, 12:19 AM
#26
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Infinetly variable timing is great, except wouldn't we still be limited by fixed intake runners/geometry? Would some sort of variable size/volume runner system in conjunction with the infinetly variable valve timing be even better? Thinking about this stuff makes my head hurt.
04-02-2005, 01:19 AM
#27
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caterpillar is currently using solenoids and oil psi to actuate intake valves there is still a cam and rockers and valvsprings but the duration is virtualy unlimited. Also talk of future camless and crankles engines, has pistons but uses oil , hydraulic psi I dont know my head is starting to hurt too
