Four stroke rotary valve engine

[radfordc]

I've been working on the plans for this engine.

I'm concerned about lubrication to the lower end. All the fuel/oil mixture is in the head and cylinder and none in the crankcase. The old Webra T4 engine also deal with this problem. But, I've seen two different versions of the Webra.

One engine inducts fuel through the crankcase and one doesn't. I can only assume that the change was made because Webra determined that enough oil was blowing past the rings to adequately lube the crank.

 

[mu38&Bg#]

FYI, the Webra in these photos has an Aspin valve.

All model four stroke RC engines use blow by lubrication. Use a typical model fuel and it will be OK. If you intend to run spark ignition and gasoline it can be tricky and you may have to run as much as 12:1 oil. I noticed there are no ball bearings on the crankshaft, so I'm not sure what the case will be for lubrication needs.

Greg

 

[blighty]

i have an sc91 fs and the engine has a bit of fuel pipe coming from the underneath of the carb that goes to the crank case. idea being some of the air/fuel mix get diverted to lubricate the crank.

if it helps i'll post a pic of it.

 

[agmachado]

I liked this idea... I think that this would help in very small engine models... type with cylinders of 10 or 12mm...

Cheers,

Alexandre

 

[blighty]

sorry for the delay.

 

[mu38&Bg#]

i have an sc91 fs and the engine has a bit of fuel pipe coming from the underneath of the carb that goes to the crank case. idea being some of the air/fuel mix get diverted to lubricate the crank.

Actually, the system pulls spent gasses and oil from the crankcase back to the intake like your car, positive crankcase ventilation. OS was the first to use this design.

If you use but one ring it will leak plenty of oil into the crankcase.

 

[blighty]

come to think of it you might be right there, but wouldn't it suck and blow? if you get my meaning.

 

[mu38&Bg#]

Yes, but while running, blow by will create a slow flow out of the crankcase.

 

[radfordc]

Well, I made the first parts today...and made the first booboo! I made the cylinder head and it turned out good. Then I made the rotary valve and it fits the hole in the cylinder head perfectly....but I cut the ports wrong. I get to do it right the next time.

 

[cfellows]

Here's some inspiration for you...

[ame=http://www.youtube.com/watch?v=eJlE-1dmEak]http://www.youtube.com/watch?v=eJlE-1dmEak[/ame]

And a much older rotary valve engine...

[ame=http://www.youtube.com/watch?v=-dgbGNbi8wk]http://www.youtube.com/watch?v=-dgbGNbi8wk[/ame]

Chuck

 

[radfordc]

Very nice. That one on top is alot like what I've got in mind. Is the valve in that one just plain steel turning in aluminum?

 

[radfordc]

Finally got the head and rotary valve complete.