Lister cast piston

[HobbyNutParticipant @hobbynut]

I was sent a casting for a Lister piston by Ennech. He also emailed me the machining details.

I set it in the lathe and made the internal bore to size, so that I could set it on a mandrel.

I then took a piece of Alum bar and machined a mandrel

[HobbyNutParticipant @hobbynut]

[HobbyNutParticipant @hobbynut]

The piston was then locktited onto the mandrel

Then a cut was taken, and machined down to 28mm dia.

[HobbyNutParticipant @hobbynut]

The ring grooves were then machined, and the OD polished with some 240 W&D.

[HobbyNutParticipant @hobbynut]

Unfortunately this did not end well. When I heated the skirt with my pencil torch to break it free, the piston and skirt parted ways at the lower ring groove. On inspection, I had gone 1 mm too deep on the id from the base of the piston, making that area too thin.

The casting was not at fault, I was, and the piston was a joy to machine, with only a few very small pinhole air pockets in the casting.

Oh well, I tried.

[HobbyNutParticipant @hobbynut]

The final pics.

[MichaelRParticipant @michaelr]

After all that good work on the piston, why not have the only Lister fitted with a Slipper Piston.

Stick.

[Ian S CParticipant @iansc]

Been there, done that, with the labyrinth grooves on a hot air engine piston, made the grooves .020" deep, instead of .010", I make the skirts of my pistons usually no thicker than .040", and if possible a little thinner. Just part of the job! Ian S C

[HobbyNutParticipant @hobbynut]

I am sure that the piston would work still being shorter and all. it is still long enough that it wont turn over in the bore, the only thing missing is the oil ring. I am going to try it "one of these days".

I have seen plenty of Ford and Chevy V8 racing pistons that are very short for the bore size.

[Sub MandrelParticipant @submandrel]

You must be a biker! – Piston broke!

Neil

[HobbyNutParticipant @hobbynut]

Posted by Stub Mandrel on 31/08/2013 16:47:49:

You must be a biker! – Piston broke!

Neil

Thats true….I am all of that!!!

[Sub MandrelParticipant @submandrel]

Bear in mind the phrase may have a somewhat different meaning in your side of the Atlantic – p****d means drunk, not angry, in the UK!

Neil

[Gordon WassParticipant @gordonwass]

If it helps I've run a real full size lister with a piston like that, a bit of slap and a bit of oil burning but otherwise ok.

[HobbyNutParticipant @hobbynut]

Neil, I am an Aussie….

Gordon, I have the Lister all apart at the moment, and I intend to fit that piston, just to see what happens.

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Lots of aero-engines had pistons which were very short compared with their diameter .

A piston of any length / diameter ratio can be made more or less stable by altering the height of the little end pin within the total height of the piston .

Pivot pin very near the top solid surface is most stable arrangement .

Pivot pin near lower end of skirt is least stable arrangement and is usually positively unstable .

Rolls- Royce had an array of single cylinder test and development engines at Derby .

Some were single cylinder segments of actual engines like Merlins and some were pure research engines .

Any new design or modification was developed on these engines and new actual parts were tested for endurance and ultimately to destruction .

One series of test was as regards piston length/ diameter ratio . They showed that given proportions and detail design were ok extremely short pistons could be made to work successfully .

MikeW

[Sub MandrelParticipant @submandrel]

> Neil, I am an Aussie….

Well that explains anything!

Neil

[HobbyNutParticipant @hobbynut]

That piston is in the engine. It seems like it is working OK, there is lots of compression now. Still wont run

[EnnechParticipant @ennech]

If there is more compression you may have to increase the injector pressure as this must always be greater than the cylinder pressure at injection point.

[HobbyNutParticipant @hobbynut]

Well, I am in the process of building a new head from steel, and a new injector, ala DUX. It does not have a moveable plunger. The pump needs a seal, and I will build a new piston for it also. I will then hook everything up, before fitting the head to check if/what the spray pattern looks like.

[JasonBModerator @jasonb]

How are you seeing what the spray pattern is like as you need to see whats comming out at the pressure inside the combustion chamber. Pumping into open air will not show how the injector works inside the engine.

J

[EnnechParticipant @ennech]

Picture from Gardner LW Instruction Manual (don't do this at home)

[JasonBModerator @jasonb]

That really only shows that there is no blockage in the lines.

Without testing the injector under pressure you won't know if the pump is producing more pressure than the engine compression or what the spray pattern is like.

J

[Gordon WassParticipant @gordonwass]

Testing the injector spray pattern outside the engine is standard full size practice ,in my house anyway. True it will not be the same under pressure but it's a good start. I don't know what sort of pump / injector you have made, can't imagine it even, but the relative bore sizes should give a good idea of press. differences, similar to a steam injector ?

[EnnechParticipant @ennech]

You could easily rig up a test rig by using a brake master cylinder and pressure gauge you will get away with it for a short time before the seals swell.

[EnnechParticipant @ennech]

The Gardner LW injector (sprayer) operates at between 1935 1md 1960 psi when new.

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