Author Topic: Liney RV-1 valve port size  (Read 3716 times)

Offline sshire

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Liney RV-1 valve port size
« on: October 21, 2013, 06:22:50 PM »
I'm about to begin the Liney RV-1 at double scale.
I've doubled all dimensions.
The valve ports are .055 in diameter. If I double these to .110, the area of the opening is 4 times the original. Will this work or should I calculate the port diameter to give 2X the area?
Best,
Stan

Offline Admiral_dk

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Re: Liney RV-1 valve port size
« Reply #1 on: October 21, 2013, 09:23:14 PM »
Interesting question and the answer is maybe  ;)

Since you're doubling the bore that gives a four times + double stroke = 8 times swept volume  :noidea:

Apparently not enough .... Ah but you're doubling the lift of the valves too, so now we're getting there .... Maybe ...!

There's a good chance that it is just right, but only an experiment will comfirm. I would personally try it just doubled up as you already done the drawings.

Let's hear from those who done builds in double or half scale - what's the result ?

Offline smfr

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Re: Liney RV-1 valve port size
« Reply #2 on: October 21, 2013, 09:47:52 PM »
I would think that the valve timing is most important, which is controlled by when the inside and outside edges of the valve intersect the port openings. If you need more volume, you can make the ports and the valve cavity wider.

Simon

Offline b.lindsey

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Re: Liney RV-1 valve port size
« Reply #3 on: October 22, 2013, 12:42:33 AM »
Stan, i would drill it for two times the area. Any error will be on the small side. As Simon said, the timing is more critical than the passage diameters. You can always enlarge them if need be.

Bill

Offline sshire

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Re: Liney RV-1 valve port size
« Reply #4 on: October 22, 2013, 02:11:32 AM »
Thanks guys. Erring on the small side seems more reasonable than having to remake the part because the hole was too big. I'm thinking about 50% larger there and doubling all other dimensions.  You know I can't leave well enough alone with any of my builds, so I'm also redesigning the bearing blocks to accept the "no-lube" acetal bearings with stainless steel balls. Actually, I couldn't leave my kitchen alone when all I needed to do was replace the cabinet hardware. Then there was the bathroom........
Best,
Stan

Offline smfr

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Re: Liney RV-1 valve port size
« Reply #5 on: October 22, 2013, 02:47:02 AM »
I just now looked at pictures of the Liney RV-1 and realize that it doesn't have slide valves, so take my advice with a large pinch of salt!

Does it have a standard wobbler-type valve arrangement? If so, I think doubling the hole size should keep the timing the same, right?

Simon

Offline sshire

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Re: Liney RV-1 valve port size
« Reply #6 on: October 22, 2013, 04:53:11 AM »
Simon
Salt taken.
It's a rotary valve. The cylinders are located at each end with a longitudinal air passage and inlet and exhaust passages intersecting it.
Best,
Stan

Offline b.lindsey

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Re: Liney RV-1 valve port size
« Reply #7 on: October 22, 2013, 12:03:16 PM »
Stan, Liney also recommends drilling the port holes in place at the time of assembly. It can be done otherwise as they also point out, but I followed their advice and the timing worked perfectly. This will be a sizeable little engine ar 2X scale!! Keep us posted as you progress please.

Bill

Offline sshire

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Re: Liney RV-1 valve port size
« Reply #8 on: October 22, 2013, 12:48:55 PM »
Bill
I've studied the plans for the last month and have certain areas highlighted. The valve drilling in place is one. As you've found out, it's a good idea re: valve timing.
This should be an adventure.
A big tube appeared on the front porch yesterday from Online Metals! I could have saved time by just ordering 10 pounds of chips from them. I'm going to tram the BP, give the one- shot oiler a push,spread some way oil on the lathe and begin.
Also going to email Doug at Liney to get his thoughts on the 2X RV-1. I can't be the first one to try this.
Best,
Stan

Offline b.lindsey

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Re: Liney RV-1 valve port size
« Reply #9 on: October 22, 2013, 03:16:41 PM »
Stan, what did you mean re: Online Metals? Were the items packed badly? damaged in shipment?  Could be something other members may want to know.

Bill

Offline sshire

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Re: Liney RV-1 valve port size
« Reply #10 on: October 22, 2013, 06:30:47 PM »
Bad attempt at humor. I meant I get a piece of metal,  and after machining, have almost as much weight in chips as the part weighs. Sorry for the confusion. Online Metals has always been great. Their packing is first rate. Never a problem.
Best,
Stan

Offline b.lindsey

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Re: Liney RV-1 valve port size
« Reply #11 on: October 22, 2013, 09:38:31 PM »
OK, thanks for the clarification...alfter half a semester of teaching freshman the introduction to engineering course, my sense of humor is often at it's wits end too!!!

Bill

Offline sshire

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Re: Liney RV-1 valve port size
« Reply #12 on: October 22, 2013, 09:52:28 PM »
That's exactly why I retired. Different academic discipline. Same students.
Best,
Stan

Offline b.lindsey

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Re: Liney RV-1 valve port size
« Reply #13 on: October 23, 2013, 12:47:02 AM »
Stan, as I may have said somewhere in my build  log of the RV-1, we are considering this model as a platform for a Junior design project. Part of the current thinking on that is to make it at something over 1X scale but probably under 2X scale...mainly to keep material costs reasonable. For that reason (partly) i am interested in your 2X version. Of course I enjoy your build logs regardless. We were talking about this today in fact, and would have the students do all the calculations, likely make drawings in Solidworks, and ultimately be able to test the output on some sort of small dyno.  So ...I'm here for the duration :)

Bill

Offline sshire

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Re: Liney RV-1 valve port size
« Reply #14 on: October 23, 2013, 11:40:08 AM »
I have begun.
Cut and squared the base. A bottom- up build. I've emailed Doug at Liney to get his suggestion on port size.  Stay tuned.
Best,
Stan