Patxipt

Hi guys!

This forum has been busy with all the lil' diesels I've been having my share here too, bench running my PAW 09 RC almost everyday for 2 tanks of fuel. I'm a proud smelly dude!

I'll be receiving a used OS FS-26 shortly and began to think on how to dieselise it without having all the problems with valve clearance that arise on this little engine. On my past experiments with my other FS-26 (sold in the meantime to a fellow airboater from down under), the maximum compression ratio achieved was around 11~12:1. More than this and I had no valve clearance from the piston.
So, today I burned a few neurons and came up with the following idea (see attachment):
Instead of lowering the chamber, why not fill it up like we "do" on 2-stroke engines? This way valve clearance would be the same as from factory, and thus no valve binding on the piston problems!
Holes would be provided for the valves and the glow plug hole would still function as support for the Lanova cell (or another simple compression adjustment device).
The filling block could be cast and then machined to proper dimensions, with a couple of screws holding it to the inside of the cylinder head.

What do you engine gurus think of this approach?

erik58

My Feedback: (4)

I'm thinking of dieselizing an os four stroke making a longer rod to boost the compression. I think filling the head would take a lot of work. just a thought there's a thread in here some where about doing that. good luck Erik

lildiesel

How about filling the squish band instead of filling the dome area around the valve seats and plug hole? You could make several ring inserts and experiment with blending the radius to the dome.

Patxipt

Erik, making a longer rod will present the same valve binding problems as lowering the head [:@]
lildiesel, could you explain better? I don't get the idea[&:]

lildiesel

The squish band is essentially the area you don't cover in yellow in your illustration. Fill the squish band and not the combusition dome. Check out this illustration from a machinist's site about karting engines. [link=http://www.muller.net/mullermachine/docs/squish1.html]squish band explained[/link] The illustration is for a domed piston but the concept also applies to a flat topped piston.

Patxipt

but the area that is not in yellow is the head gasket, not a squish band...[sm=red_smile.gif] honest!

Motorboy

This is allready old news.. follow all history how to convert the 4 stroke engine to run as a diesel engine as here: http://www.rcuniverse.com/forum/fb.asp?m=900816

Patxipt

Oh, I remember that thread! It just wasn't showing up on the search facility for me[&:]
Any more Qs will be posted there.
But, Jens, what do you think of my approach above? (just for the sake of it )

Motorboy

You has 2 alternative to convert the 4 stroke engine as a diesel engine:

1. With adjustable compression ratio (as i showed the link in early post.)

2. Fixed compression ratio and will be adjusted with cylinder head gasket depent on fuelmix.

See the engine with fixed compression ratio in the Enya 41-4CD as here how to remove the material from cylinder head and check the compression with fluid and the 1 ml syringe with needle. Follow the history of the engine with too low compression ratio (fault production by Enya Mfg..) here: http://www.rcuniverse.com/forum/fb.asp?m=5493013

erik58

My Feedback: (4)

machine notches in the piston for valve clearence or home made piston. Erik

Motorboy

Ready made from factory, the valves in the enya engine are angled while the OS, Magnum,SC ... are not angled, also the valves are in same line as in the sleeve.

The piston in the Enya 4 stroke dieselengine are without pistonring. Lapped castiron piston and steel sleeve.