A two stroke supercharger can work

[Error401]

To an extent Bill. These are the 4 Stroke YS engines I refered to before, this one is a 1.10 ci.
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXEMJ6&P=0

The box on the back is the air chamber. The crank case is not ventilated like a normal 4 stroke, and is used as the air pump. The carb is on the back and is double throated and has a rotary valve on the back plate to time the intake of air. the nippples on the front of the case are for the tank pressure and fuel feed likes. The crank actually times an injection of fuel at a given time and a given ammount. The tank is pressurized to around 20 psi and has a 1 way valve on the pressure line.

On the off rotation (non power) the system sucks in a shot of air and fuel, then compresses it into the air chamber and then takes another shot of FA and shoves both (or nearly so) into the cylinder when the intake valve opens. then pow, and starts over. I flew the .91 AC in a pattern plane for a couple years and it was the most powerful 4 stroke in it's size range. It was also the most reliable engine I have ever owned. The down side of all this is the crazy ammount of gaskets it had. I also had to keep a watch on all the gaskets because of the pressures involved with the system.

So, the key difference between the engines is that the one I linked (and it's bretheren) and the setup discussed here is that the YS AC engines are 4 stroke. More importantly, they have a very high effeciency in the pump design (namely the engine itself being the pump). The other thing to note is the price of the engine listed (about $400) as opposed to about half that for a comporable sized OS 4 stroke.

This might be off topic, but I think the YS engines are freakin cool. Wish they made a car version.

 

[Sublime]

Bill,
On a VTwin motor, like a harley there are times when no intake valves are open... superchargers exist on these.
Relative to the engine displacement, the "intake manifold" on an RC engine is equivalent if not larger.

As for the piston compressing the air in the crank, I know how it works... I know that its a fact. Whats also a fact is that even NA the air is precompressed my mother nature before it enters the crank.

cramey88,
I agree the RB SC is garbage, but its really the only starting point for this. For this discussion though, I think it needs to be seperated from the feesiblity of a true 2 stroke SC. Maybe a wankel design would be better for the compressor. There must be some use for a tiny air compressor... someone must make one. How do fish tank air pump work?

 

[cramey88]

Sublime,
The math just won't work if there was a product already in production serving another purpose other than force feeding a nitro rc engine it would not take the rpm needed to boost air into an engine capable of turning nearly 40,000 rpm.A centrifigul supercharger on a car such as vortech,paxton,ati procharger etc..,will turn aprrox. 45,000 rpm on a engine turning only 6500 rpm. the materials used to achieve these speeds are very precision and of the upmost in tensile strength.Again i would experiment with nitrous oxide its proven no moving parts and does not rob horespower from the engine making it a 100% efficient.........However I would like to see a supercharger work on a scale engine.......

 

[Sublime]

cramey88,
You have a point, but relative to the engine displacement, the fan is huge for the RB. But, I guess centrifugal isn't the way to go.

Maybe a wankel style compressor... weren't those first intended to be used as SCs anyway?

NOS just feels like cheating... 1:1 or scale... but thats a seperate discussion altogether... I regret even posting my stance

 

[El Pirata]

Originally posted by Error401
To an extent Bill. These are the 4 Stroke YS engines I refered to before, this one is a 1.10 ci.
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXEMJ6&P=0

Imagine what that baby would do on my t-maxx...

 

[Error401]

Originally posted by cramey88
However I would like to see a supercharger work on a scale engine.......

Check this out:
http://www.conleyprecision.com/

Originally posted by El Pirata
Imagine what that baby would do on my t-maxx...

It would probably twist it into a pretzle.

 

[El Pirata]

Originally posted by Error401

Check this out:
http://www.conleyprecision.com/

Already seen that one.

Originally posted by Error401
It would probably twist it into a pretzle.

But it would look cool doing it...

 

[Error401]

Especially in midair.

 

[El Pirata]

Now that would be cool beans! I wanna try it. :idea: