since im still a beginner i am going to post this here. please dont move it.

i was thinking.

what if they made miniature turbochargers for RC engines.
is there anything like this out there ?
would it just be too expensive?

what do you guys think ?

-Felix

I had that thought myself. I believe Yamada do a turbocharged 4 stroke around 120 size. I think that there is performance to be gained by onther easier ways so that there are few turbos around. If you start your engine and blow gently in to the carb down a long tube you should hear it lean out. Maybe you could try to make one.
Tom

YS engines use a system that pressurizes the air to the carb I believe (or is it to boost fuel flow?).
Dennis-

I'm not sure if this helps because it is for off road and on road rc cars, but it is here at [link=http://www.rbinnovations.com/index.htm]RB Innovations[/link] I don't think they offer any kind of supercharger on an airplane other than that of what DBCherry described.

HOPE THIS HELPS!!!!

Joe

YS Engines makes all of the larger 4 strokes they offer both turbocharged and fuel injected. At or below 2000 rpm the fuel is drawn from the tank as any normal engine. Above 2000 rpm the fuel is then injected directly to the engine.

The big box on the back of the engine is the "Air Chamber" which pressurizes the air charge to the carb.

All of this works using crankcase pressure so the engine must be turned over at least 10 revolutions before it will start so that pressure can be built in the system.

I have had a YS91AC installed on a CG Ultimate and it had gobs of power [X(]. I have since replaced it with the YS110FZ and what an increase in power.

I also have a Saito 120 that does not put out this amount of power. YS does this while turning large props in the 8800 to 9500 rpm range which is the recommended operating range for these engines.

As far as aftermarket turbo/supercharges. I have never seen anything on them, sorry

if all you want to do is get more air into the carb, Could you secure a bent peice of tubing to the carb and have the opening facing the prop? That way, it gets more air the faster the prop is turning.

The YS engines are not "turbocharged" but they are "supercharged" from the crankcase by the pumping action of the underside of the piston. ( similar to the current two strokes).

I have heard that just pumping air into the carb doesn't work, and it is necessary to mount a supercharger between the carb and the cylinder.

I think OS may have tried an external rootes type supercharger in the eighties, successfully, but it was too costly.

(If anyone thinks I'm wrong, - please say so, but also explain why you think so! )

Sorry...mis-spoke...guess I should proof read

Carb needs vacuum to draw fuel through the venturi. If you pressurize the carb, you'll get little fuel draw.

OS used to make an actual roots-blower type supercharger equiped 120 4-stroke. They apparently don't make it any more. It looked like a rather big box where the carb would be. When I say big, I mean it was about as tall as the cylinder, almost as thick, rather wide. It really increased the size of the engine.

In the small sizes of our engines, it would appear that the approach taken by YS produces more power for less weight increase than a full up blower arrangement. Other companies also use pump systems to shove more fuel and air in to the engine.

A ram air venturi really wouldn't be that effective by itself, but you can get more power from an engine by makeing some modifications that smooth out the airflow in and out of the engine. Putting a "stack" above the carb is one way. There are various tricks you can do to the crankshaft, ports, and other parts of the engine to get more power as well.

On two-strokes, you can install a tuned pipe. It pretty much does the same thing as a supercharger, though in a different way. But the end effect is more fuel/air mixture getting in to the engine and more power.

The weight added by a super/turbocharger is nearly offset by displacement. If you look at the saito 120/150/180 4-strokes you will see that they weigh about the same as the YS110 and the YS is roughly equal to the 150 so for the same weight you could buy the saito 180 and get MORE power for that given weight. Know the idea of running a velocity stack up behind the prop, the problem is that you do not get any sort of constant flow. It is too turbulent to make work properly. The idea of a TURBOcharger I feel is the best way to go if you are looking for huge power gains because they like high RPM's. Turbos spin up around 100,000 RPM's and need high pressure from the exhaust to get enough energy to rev them up and make boost. In reality it is just WAY easier to up size the engine. You also get rid of all the related tuning hasels that go with a pressurized intake.

I would love to see a 4hp .46 2-stroke though.

Dave