Author Topic: Green G30 Sleeve Valve Engine  (Read 3591 times)

Offline Laurentic

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Green G30 Sleeve Valve Engine
« on: May 21, 2018, 09:47:48 PM »
Has anyone out there built the Green G30 Sleeve Valve engine?  The plans date from 1988.  Casting kits were available - one was offered for sale not long ago so presumably some were built.  Would be interested to hear if anyone did build one how they got the thing to run and what compression pressure was achieved.

Chris

Offline dieselpilot

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Re: Green G30 Sleeve Valve Engine
« Reply #1 on: May 22, 2018, 02:17:03 PM »
Did you build one? Are you having trouble with it? I have a plan set.

Offline Laurentic

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Re: Green G30 Sleeve Valve Engine
« Reply #2 on: May 22, 2018, 02:52:32 PM »
Hi - yes I built one, won't start but as it has very low compression I'm not surprised.  I have a set of imperial plans from 1988 from which I built the engine.  A friend 'Down Under" built one before me and he couldn'y start his either.  Did you build one yourself?  Did it run?
Chris

Offline Jo

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Re: Green G30 Sleeve Valve Engine
« Reply #3 on: May 22, 2018, 03:17:58 PM »
They run very well. All they need is a good fit between the lapped piston/cylinder and a slightly wider fit with just enough space for some oil between the Liner and the Cylinder  ;)

Jo
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Offline kvom

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Offline Laurentic

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Re: Green G30 Sleeve Valve Engine
« Reply #5 on: May 22, 2018, 04:12:10 PM »
Jo - glad to hear they run very well, only wish mine did.  The sleeve bore was lapped so as the piston just slid in.  I fitted 2 piston rings to mine.  The drawing calls for a sliding fit for the sleeve liner interface, and that's what it is, a close sliding fit.  Have oiled sleeve to liner interface and piston to sleeve interface.  Still getting very low compression.  Suspect that the compression air is leaking by through the sleeve port before it seals against the junk head ring and out via inlet and exhaust ports, when I test it on low pressure air this is the impression I am getting.  Were the ones that run built as per the drawings or were their any mods, does anybody know? 
Chris

Offline Roger B

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Re: Green G30 Sleeve Valve Engine
« Reply #6 on: May 22, 2018, 06:48:00 PM »
I think that I can picture this but can you post a drawing of the cylinder/sleeve/piston layout?
Best regards

Roger

Offline dieselpilot

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Re: Green G30 Sleeve Valve Engine
« Reply #7 on: May 22, 2018, 06:59:50 PM »
How many degrees after BDC does intake close?

Offline Jo

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Re: Green G30 Sleeve Valve Engine
« Reply #8 on: May 22, 2018, 07:08:39 PM »
« Last Edit: May 22, 2018, 07:14:13 PM by Jo »
Enjoyment is more important than achievement.

Offline Roger B

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Re: Green G30 Sleeve Valve Engine
« Reply #9 on: May 22, 2018, 08:35:20 PM »
This looks to me that the top (junk head) piston ring is critical. I will read the rest of the German description tomorrow and comment on that.
Best regards

Roger

Offline Laurentic

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Re: Green G30 Sleeve Valve Engine
« Reply #10 on: May 22, 2018, 09:42:00 PM »
dieselpilot - inlet closes 64 degrees after BDC .

Jo - nice engine, quite sophisticated, have looked at that one before, but it's not the Green G30 sleeve valve engine.  Have you seen one (a G30) running?  If so, am envious!!

Roger - I agree that the junk head ring is critical.  I feel on my engine that the junk head ring only just closes off the sleeve port as the sleeve gets to TDC.  I think it should shut off earlier.  That's why I feel compression pressure is being lost via the sleeve port on the compression stroke.  To try and minimise this loos I am thinking that sleeve/liner interface should be lapped (I feel a new liner coming on here)- and hope that the heat doesn't seize things up.  Always assuming the damn thing runs of course.

Chris
« Last Edit: May 22, 2018, 10:07:20 PM by Laurentic »

Offline Laurentic

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Re: Green G30 Sleeve Valve Engine
« Reply #11 on: May 22, 2018, 09:46:49 PM »
Roger - to answer your first question, I will try and post a photo of the GA tomorrow. 

Chris

Offline Art K

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Re: Green G30 Sleeve Valve Engine
« Reply #12 on: May 23, 2018, 02:36:27 AM »
Chris,
I have always been fascinated by the sleeve valve engine. Can't say I've every heard of the Green G30 before today though. I recognize the difficulty with the timing cant just bump the cam forward or back to fix the timing. Looks great.
Art
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Offline Roger B

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Re: Green G30 Sleeve Valve Engine
« Reply #13 on: May 23, 2018, 02:11:33 PM »
I have had a quick look through the metallmodellbau build. I know its a different engine but there are a few points that may help:

-He states that the sleeve is made from a special steel, ETG100, that doesn't distort much with temperature.

-The sleeve is lapped inside and out to +/- 0.005mm of the nominal size.

-The shape and position of the ports is critical to the timing. He made a second sleeve to correct the timing errors after he carried out a timing check with the engine assembled.

I also wonder how important the sealing of the space in the junk piston above the sleeve is? When the ports pass by the junk piston ring there will be some leakage into this space. If it is sealed it should reach some form of equilibrium  :headscratch:
« Last Edit: May 23, 2018, 02:20:50 PM by Roger B »
Best regards

Roger

Offline dieselpilot

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Re: Green G30 Sleeve Valve Engine
« Reply #14 on: May 23, 2018, 02:39:22 PM »
64° is about what my CAD model shows. It isn't excessive, many production RC engines are ~60°ABDC. The port sealing by the ring only really matters for static compression. At running speed, face of the junk head will determine timing. It's no different than porting in a two stroke engine. The sleeve port passes the junk head ring at ~90°BTDC. Geometric compression ratio as designed is quite high. I considered fitting a dyke's ring in the junk head when I build mine, but don't feel it should be necessary.

There was a collector who had several Green engines on one of the RC forums. These were built by Green and sold complete. Very few were supplied complete, I've only ever seen a few for sale. He said he ran all of them and that they ran well.

Most glow engines don't need very good compression sealing to run, but often engines in this condition will be difficult to start and by hand sometimes impossible.

Offline Stuart

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Re: Green G30 Sleeve Valve Engine
« Reply #15 on: May 23, 2018, 03:16:03 PM »
Many moons ago I used to race 1/8 scale cars 3 1/2 cc veco cross flow nitro engines ( this was before the scnurl /sp engines were common) normally 90% nit to

I used to make a lot of bits for these engines including flat slide throttle bodies,the bores were honed and lapped

Now to the point I used dykes rings one the piston as you can imagine with all the nitro ring life was about 1 hour run time , but when the engine ran the best it had nil compression when tuned over by hand . To comment on starting I used a motor cycle starter motor and held the flywheel on that to start them up .as you say impossible with out a starter , but that’s how I understand how the dykes rings work as they are exposed to the combustion chamber due to there position and L shaped cross section
My aim is for a accurate part with a good finish

Offline lohring

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Re: Green G30 Sleeve Valve Engine
« Reply #16 on: May 23, 2018, 03:17:53 PM »
The cold sealing will be different from the hot sealing.  Two stroke sleeve valve engines were built with no junk rings in the head.  As the exhaust flowed over the top of the sleeve, the sleeve expanded.  Since the heat transfer improved with the lower clearance, an equilibrium was reached that resulted in good sealing.

Lohring Miller

Offline dieselpilot

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Re: Green G30 Sleeve Valve Engine
« Reply #17 on: May 23, 2018, 07:54:09 PM »
The two stroke sleeve valve functions a bit differently in that they use the top edge of the sleeve for valve action and is in fact sealing against the cylinder housing. Four stroke designs require junk head rings or they would have eliminated them. I don't think any of that matters here though, this engine has rings and they should be effective. I suspect the rings just aren't sealing well, but that could be any number of things.

Offline Laurentic

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Re: Green G30 Sleeve Valve Engine
« Reply #18 on: May 23, 2018, 10:01:31 PM »
Well, I was going to show a photo of the GA, not that the drawing is very clear, but seem to be unable to load the photo.  I suspect the photo is too big at 3.4mb but I seem to be unable to work out how to reduce the size.  It must be easy, I've done it before on here.  Must be having a very Senior Moment!

Thanks for all the replies/. Roger, I had noted that the sleeve had been lapped into the liner on the German engine, was thinking of making a new liner to try this.  I am also wondering about timing even though 64 degrees ABDC for inlet closing is reasonably normal.
dieselpilot - too right they are hard to start!  I am using a battery drill in fast speed mode without any joy.  Good to hear that someone has got them to run!  I am going to try and draw out the positions of the sleeve port at a few critical positions when I can, as I think my junk ring seals much later than 90 degrees BTDC and that may be part of the problem.  I rigged up a pressure gauge into the glow plug hole and turned it over on the drill and got about 20 psi compression pressure which seem far too low, notwithstanding the comments about glow engines running on low compression.  I thought glow engines needed 9:1 compression ratio and above.  By calculation I reckon my engine has about 11:1 compression ratio, so I am expecting a higher compression pressure than I am getting.

Chris
« Last Edit: May 23, 2018, 10:04:53 PM by Laurentic »

Online Vixen

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Re: Green G30 Sleeve Valve Engine
« Reply #19 on: January 12, 2022, 06:59:38 PM »
Has anyone out there built the Green G30 Sleeve Valve engine?  The plans date from 1988.  Casting kits were available - one was offered for sale not long ago so presumably some were built.  Would be interested to hear if anyone did build one how they got the thing to run and what compression pressure was achieved.

Chris


I know this is an ancient thread. I sold my Green G30 kit some time ago and regret it.

I have one question. What material was used to make the thin wall sleeve. My memory fails me yet again

Mike
« Last Edit: January 12, 2022, 07:47:46 PM by Vixen »
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Offline Jo

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Re: Green G30 Sleeve Valve Engine
« Reply #20 on: January 12, 2022, 07:47:03 PM »
The cylinder liner is CI. The cylinder sleeve is EN24

Jo
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Re: Green G30 Sleeve Valve Engine
« Reply #21 on: January 12, 2022, 08:11:31 PM »
Thanks Jo  :ThumbsUp: :ThumbsUp:
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Offline Laurentic

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Re: Green G30 Sleeve Valve Engine
« Reply #22 on: January 12, 2022, 10:06:00 PM »
Mike - I confirm Jo's answer,  CI for the liner and EN24 for the sleeve, which from bitter memory was a bitch to machine!  The OD was fine, the ID so difficult (for me anyway) to bore parallel.

I  was wondering why you were asking, are you making one yourself?

I gave up on this engine, could not get it to fire as distinct lack of compression but have been unable to determine why, so acute lack of interest kicked in.  If you are building it and have success in running it would be delighted to hear about it - it still niggles me, unfinished business!!

Chris

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Re: Green G30 Sleeve Valve Engine
« Reply #23 on: January 13, 2022, 12:24:52 AM »
Mike - I confirm Jo's answer,  CI for the liner and EN24 for the sleeve, which from bitter memory was a bitch to machine!  The OD was fine, the ID so difficult (for me anyway) to bore parallel.

I  was wondering why you were asking, are you making one yourself?..............

Chris

Chris.

Why am I interested?

I've been reading again Roy Feddons biography, during these long winter nights and have reached the part where Bristol's are developing their sleeve valve engines. The early engines, the Aqilla and the Preseus were all hand crafted in small numbers. When it came to mass producing the Herculese and later the Centurus, something better was required. Bristols spent a fortune (almost bankrupting the company) investigating hundreds of different materials and heat treatments. They eventualy developed a high silicon, low expansing aluminium alloy for the cylinder and a high expansion, nitrided, nickel chrome steel for the sleeve. That solved the temperature differential problem. The other problem was the thin wall sleeve ovality, due to stress relief, heat treatment  etc.. They solved that by running a dull, non cutting hone down the bore which manipulated the oval sleeves untill they became truely round. Must have worked a bit like a boilermakers roller tube expander.

I was trying to compare what materials model engineers were using by way of comparison. The Green G30 uses cast iron cylinder liner and a En24 sleeve as you say. while Pierter Descker's Bar and Stroud uses cast iron (or an unspecified steel) sleeve rubbing directly against the aluminium cylinder wall. Lee Hodgson uses A-311 (stress proof?) directly against  the aluminium cylinder wasll. I have not yet heard that many reports of sucessful model sleeve valve engine. Just curious as to why?

Cheers

Mike
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Offline steamer

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Re: Green G30 Sleeve Valve Engine
« Reply #24 on: January 13, 2022, 01:45:07 AM »
As near as I can tell A311 is the same as 1144SP  stress proof

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Offline Admiral_dk

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Re: Green G30 Sleeve Valve Engine
« Reply #25 on: January 13, 2022, 12:17:32 PM »
Very interesting story Mike - so you are saying the Bristol are the ones we can thank for 'modern High percentage Silicon Aluminium for Pistons' ...?
In that case, it took decades before it ended up in modern engine types  :thinking:
Do you think that they keept the secret to themselves ?

Per

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Re: Green G30 Sleeve Valve Engine
« Reply #26 on: January 13, 2022, 01:55:40 PM »
As near as I can tell A311 is the same as 1144SP  stress proof

Dave, thats also how I understand it. Neither material is readily available here in the UK.


Very interesting story Mike - so you are saying the Bristol are the ones we can thank for 'modern High percentage Silicon Aluminium for Pistons' ...?
In that case, it took decades before it ended up in modern engine types  :thinking:
Do you think that they keept the secret to themselves ?

Per

Per, The high silicon (12%) alloy for the cylinders (and pistons?) was developed by 'High Duty Alloys Ltd'; who developed high performance aluminium based alloys for both RR and Bristols.
The nickel chrome steel for the sleeves was KE 965 developed by Kayser Ellingham specifically for high performance aircraft exhaust valves.

Bristols were very carefull to keep the secrets of sleeve manufacture (how to make them round) to themselves. In fact all the 'Napier Sabre' sleeve valves were subcontracted to Bristols, as they found they could not do it themselves.

Interesting engine history

Mike
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Offline steamer

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Re: Green G30 Sleeve Valve Engine
« Reply #27 on: January 13, 2022, 02:48:26 PM »

"Dave, thats also how I understand it. Neither material is readily available here in the UK."

See    I know this guy in the states....
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Online Vixen

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Re: Green G30 Sleeve Valve Engine
« Reply #28 on: January 13, 2022, 02:59:43 PM »

"Dave, thats also how I understand it. Neither material is readily available here in the UK."

See    I know this guy in the states....

Ha ha, so do I  :lolb:

Mike
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