Rotary valved engines

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Harold_V
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Re: Rotary valved engines

Post by Harold_V » Thu Dec 26, 2013 5:32 am

Do not assume that I am always right, for I am not. I'm very good about having things pointed out to me, especially when I'm not properly informed, and usually graciously thank those who offer the proper view. However, when it gets down to opinions, I'm not easily swayed. :-)

If, at any time, you find I am not correct in ANYTHING I have posted, please feel free to correct me. I welcome such corrections, as that's how I learn, and my ego isn't so large that I won't allow it to happen.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

wildun
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Location: Auckland, New Zealand.

Re: Rotary valved engines

Post by wildun » Thu Dec 26, 2013 6:11 am

Harold_V wrote: If, at any time, you find I am not correct in ANYTHING I have posted, please feel free to correct me. my ego isn't so large that I won't allow it to happen.

Harold
That's good Harold, we share the same views in most things!
I believe you have some experience in foundry work.
Over a short period during my working life, I had the opportunity to do some corebox/pattern design (and manufacture) often had to go to the local foundry to confer with the patternmakers there and sometimes had a good look at the casting processes in the foundry as well, but I never actually got to try any of this, so I may be asking some questions on that later.

There is just one more thing I want to say :- I believe that wisdom or foolishness, (like beauty) do not have a definition set in concrete and are often just the opinion the beholder.

Cheers,
Will.

Harold_V
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Joined: Fri Dec 20, 2002 11:02 pm
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Re: Rotary valved engines

Post by Harold_V » Thu Dec 26, 2013 3:45 pm

Ahhh!
Foundry work!
I expect you have as much experience in that arena as I have. The only possible exception may be in melting, as I routinely melted pure gold and silver, along with the alloys, all in the process of refining precious metals.

I have created a small handful of patterns for various projects, but have, of necessity, had to turn to foundries to have them cast. Assuming I live long enough, I expect I'll be able to address my own castings now, however. I have an induction furnace, which would allow for casting steel, stainless, ductile and gray iron, and have a crucible furnace planned for non-ferrous alloys. It's not a huge unit, but 100 pounds of these alloys will certainly allow for making modest castings. I've had a curiosity about foundry work since my youth, but never a strong enough desire to work in the industry. As a result, I have much to learn.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

wildun
Posts: 32
Joined: Fri Sep 13, 2013 7:13 pm
Location: Auckland, New Zealand.

Re: Rotary valved engines

Post by wildun » Thu Dec 26, 2013 8:45 pm

Harold_V wrote:Ahhh!
Foundry work!
I expect you have as much experience in that arena as I have.......... I have an induction furnace, which would allow for casting steel, stainless, ductile and gray iron, and have a crucible furnace planned for non-ferrous alloys. .............As a result, I have much to learn.

Harold
HAROLD,
No, I haven't got much real experience at all, but making wooden patterns and C.I. coreboxes was a very exciting period in my life (only lasted about 1 year, but I turned down working with CNC machinery because I was happy doing what I was doing) - I had no one to guide me, just books and a little intuition and inventiveness got me through!- never became a real expert!

Sorry to be getting away from the original subject of the thread!, so I think I'll start a new thread in the appropriate place.
Will.

magic9r
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Location: Sheffield, England

Re: Rotary valved engines

Post by magic9r » Sat Feb 08, 2014 10:41 am

Has anyone looked at Coates' stock price for the last 10 years -

http://investing.money.msn.com/investme ... ymbol=COTE

click the 10Y below the graph.

I wonder who bought Dollar shares :lol:

Now might be the time to buy $100 of their stock if you think they'll ever do anything but spend investor money on fat salaries and expensive toys to spuriously drop their engines into ;-)

- Nick

georgepapa
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Joined: Fri Jun 26, 2015 6:49 am

Re: Rotary valved engines

Post by georgepapa » Mon Jun 29, 2015 4:30 am

my perhaps naive question regarding the spring loaded valves is that while compressing the spring energy is needed but when the spring is returning the energy is given back, or am I terribly wrong?
george

JackF
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Location: Caldwell, Idaho

Re: Rotary valved engines

Post by JackF » Mon Jun 29, 2015 10:16 am

Just a wild guess here but I'm thinking that HP lost can't be regained by the spring closing the valve. And if there IS a possibility that some HP can be regained I suspect it will not equal that which is lost. Once again, just an uneducated WAG. :wink: :lol:. I'm sure those more knowledgable on the subject will correct any wrong thoughts. :D

Jack.

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steamin10
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Re: Rotary valved engines

Post by steamin10 » Tue Jun 30, 2015 11:30 am

Generally speaking, the valve train operations are wasted energy. Porting, and rotary designs are more efficient for waste, but have the problem of correct timing. Nearly all production engines use cam shaft and tappet designs, losing some energy loss by using roller tappets, that are not as bad at wasting energy.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
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dly31
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Re: Rotary valved engines

Post by dly31 » Wed Jul 01, 2015 5:01 pm

Of course there are frictional losses and the springs don't return 100 percent of energy but I have noticed that camshafts with many lobes tend to be pretty easy to rotate by hand. So the springs do seem to return energy as they extend.
Don Young

Magicniner
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Re: Rotary valved engines

Post by Magicniner » Wed Feb 17, 2016 6:58 pm

dly31 wrote:Of course there are frictional losses and the springs don't return 100 percent of energy but I have noticed that camshafts with many lobes tend to be pretty easy to rotate by hand. So the springs do seem to return energy as they extend.
At hand operated speeds this is true, if you investigate cam profile design you will find that an important part is that of the closing side of the cam lobe, ensuring that the valve/spring/collet etc. combination can follow at optimum RPM, otherwise valve bounce will ensue.
Given that at optimum RPM the valves will absorb 100% of the energy required to open them and that in closing the spring force/mass of the system will follow the cam but with little effective force it is reasonable to assume that valve opening energy will be close to s 100% loss,

- Nick

P.S. Coates shares are still in the crapper, rotary valves are good for minimal maintenance but crap for efficiency ;-)

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