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  • #31
    It ain't broke, don't f' with it...
    My dad always said.

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    • #32
      Originally posted by Eric View Post
      I thought by now we'd be using solnoids to open/close valves .
      no need for cam/timing gears/chain/belt/pushrods/lifters/cam followers/rockers/ bla bla bla.
      Imagine, a knob in the interior, that changed the "cam" timing events, grand touring/sport/ low speed power/high rpm power/ race/ and profile'n cruise'n lope.
      It be epic.
      Been done and it didn't work out well. Evidently there's an advantage to (relatively) slowly opening the valves so that the flow stream has time to accelerate to it's max port velocity (either intake or exhaust). IIRC, that was tried in Formula One engines and they went back to a mechanical valve train. As control techniques improve it might be worthwhile to revisit this when the tech exists to slowly lift the valve(s) and slowly close them (again, speed here is relative). Solenoids may not be the tech of choice as they snap on and off but there may be a linear actuator that can do the job.

      Dan

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      • #33
        Isn't Koenigsegg already producing an engine with no cam in their supercars??

        https://www.youtube.com/watch?v=OZWeNPi2XkE

        https://www.motortrend.com/news/is-the-era-of-the-camless-valvetrain-finally-upon-us-technologue/


        What's the latest on the revolutionary Freevalve camless engine? Get the latest from Christian Von Koenigsegg. The goal is independent control over each valv...


        Freevalve uses electro-hydraulic-pneumatic actuators combined with advanced sensor techniques. We overcome all of the typical cam-less techniques challenges.

        Last edited by Tubbed Pacecar; December 2, 2018, 03:31 PM.

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        • #34
          I thought F1, Ducati and MVs all had pneumatic valve trains. I guess weak suck low RPM stuff (sail boat motors) might benefit from slow valve events.

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          • #35
            Originally posted by cstmwgn View Post
            I thought F1, Ducati and MVs all had pneumatic valve trains. I guess weak suck low RPM stuff (sail boat motors) might benefit from slow valve events.
            Ducati has used desmodronic valvetrains for years (last I knew they still were). The cam both opens and closes the valves with a mechanical linkage - no valve springs. They have made it work but there's a lot of question as to whether it's worth the price of admission - but zero valve float or broken valve springs.

            Dan

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            • #36
              Partially F1 moved away from pneumatic valves because they no longer needed to keep increasing RPM--the engines got limited a few years ago.

              Desmodronic valve actuation is really neat! But it's comparably kinda heavy, and getting the lash set is a bit of a pain in the ass. Hell, setting lash on a shim under bucket is nasty enough.

              When engines use small valves, you can get away with an awful lot of RPM and keep the valvetrain alive. The best example I can think of was the RC166 (Honda racebike). 250cc class engine, inline 6, 24 valves. Max engine speed of 18,000rpm... not bad for the 1960's! Of course today, I think we all want rather bigger cylinders than those little 41mm pistons were running in (yep! 1.61" pistons!)....

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              • #37
                Originally posted by Deaf Bob View Post
                It ain't broke, don't f' with it...
                My dad always said.
                Did he say it when he was fixing something?

                My Dad always said stuff like that about "new" tech he couldn't afford . .. Then when it got cheap enough for him to buy, he'd go on about it like it was the greatest thing ever. That used to crack me up.

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                • #38
                  Originally posted by AndyB View Post
                  I think we all want rather bigger cylinders than those little 41mm pistons were running in (yep! 1.61" pistons!)....
                  Sometimes. But if the choice is between three trash-can-size slugs or eight little 41mm pistons, I'm picking the eight little poppers . . . One of the absolutely worst things about the current government-regulated vehicles is the trend toward awful-sounding engines of less than eight cylinders.


                  That being said, I certainly wish there were lots of affordable 32-valve non-diesel V8s in excess of 7.0 liters . . . . One of my biggest hot rodding disappointments is still having to chose between cubic inches and multi-valves. Total market failure, IMO.

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                  • #39
                    Well, your prayes were answered......before you were born

                    The Ford GAA engine was used in WWII Sherman tanks, 18L (~1100 CI), DOHC 4 valve, and IIRC, all aluminum

                    Your only problem will be fitting it into anything, although a few years back on the H.A.M.B., there were threads showing one in a late sixties Mustang, and another in a ford pickup

                    THE FORD GAA We take a look at the development history and features of an engine that powered the M4 Sherman and other vehicles. Starting life before




                    James

                    ================================================== ================================================== ============

                    Originally posted by Gateclyve Photographic View Post

                    Sometimes. But if the choice is between three trash-can-size slugs or eight little 41mm pistons, I'm picking the eight little poppers . . . One of the absolutely worst things about the current government-regulated vehicles is the trend toward awful-sounding engines of less than eight cylinders.


                    That being said, I certainly wish there were lots of affordable 32-valve non-diesel V8s in excess of 7.0 liters . . . . One of my biggest hot rodding disappointments is still having to chose between cubic inches and multi-valves. Total market failure, IMO.

                    Comment

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