Green G30 Sleeve Valve Engine

[Stuart]

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

[lohring]

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

[dieselpilot]

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.

[Laurentic]

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

[Vixen]

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

[Jo]

The cylinder liner is CI. The cylinder sleeve is EN24

Jo

[Vixen]

Thanks Jo 

[Laurentic]

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

[Vixen]

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

[steamer]

As near as I can tell A311 is the same as 1144SP  stress proof

[Admiral_dk]

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 
Do you think that they keept the secret to themselves ?

Per

[Vixen]

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 
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

[steamer]

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

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

[Vixen]

"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 

Mike