i've heard this and seen it when looking through magazines, but can it really be done? Can an engine this small really handle forced induction or is this a completely different type of supercharging?

The YS engines use the pumping action of the under side of the piston to pump more than one intake strokes worth of air and fuel into one intake stroke. A form of super charging, yes, and it works very well, they also pressurize the fuel tank with this same pumping action and the result is excellent throttle response, transition and idle. Maybe LadyFlyer will give me a passing grade for this.

OS has a 120 supercharged engine that uses a real "roots" type blower on the back of the engine. I think they quit making this engine, but one can still find them around.
Suptter

Most YS and one OS engine is supercharger. They develop more power that their counterparts.

Here's a pic of the O.S. 1.20 Supercharged....

Here's a pic of the YS 1.40 supercharged....

AMAZING!
I've never seen such a small supercharger before!! HAHA this is totally cool!!
Thanks for the pics!
IF this thing had a turbo.. what would it be? a T.05? spinning at like 120k rpm? lol
-ram

Sorry to throw a damper on, but the YS engine pictured above is not a "Supercharged" version, it is "Fuel Injected". That is the DZ 140 from YS. The unit on the front is a pump for the fuel injection. Fuel is direct injected just before the intake valve.

That OS indeed uses a real supercharger, however, it is so heavy that the extra power generated is largely neutralized by the weight...
But still, it is a fine piece of machinery.

The YS 140 is indeed supercharged, it may not have an external device attached to it called a supercharger but as I mentioned in my post above it uses the pumping action occuring in the crankcase to overfill the cylinder therefore it is supercharged and sort of fuel injected except at idle.

....how about this one....

Sorry to burst your bubble, but you are incorrect on both counts. The 140 DZ is in fact "supercharged" in that the crank case is used to increase the intake pressure to a level above that of the ambient atmosphere. While the unit on the front of the engine is in fact the pump and regulator, it does not inject fuel just before the intake valve. Follow the blue lines in the picture and you will see that they both go to the carb. Fuel is "injected" into the carb to mix with the intake air which then passes into the crank case where it 1) lubes the bottom end of the engine and 2) is pressurized by the piston. As the induction disk, which is keyed to the crank shaft, rotates to the correct position, the pressurized air/fuel mixture is released into the second half of the carb which then directs it up the runner and finally to the intake valve in the head. The picture above is a bit misleading because it shows the fuel inlet on the pump attached to the lube line on the back side of the carb. The lube line should be routed to the head where it provides a small amount of fuel to the rocker assembly for lubrication of the rockers and the valve stems. The excess fuel will travel down the push rod tubes and lube the cam and lifters.

John

....Yep....

Daver, I have a question about the unit on the front of the 140DZ, the unit at the bottom front in post 11 is purely a regulator, is the one on the upper front of the 140 actually a pump or just a regulator and still needs the checkvalve to trap crankcase pressure in the tank. Thanks

The tap off of the crank on the 140 DZ is just a pressure port which is timed by a passage in the crank. The regulator is actually mounted to the pump which is located on the pushrod tube. Refering to the plumbing diagram on YSPerformance.com http://www.ysperformance.com/prod140DZ.htm
there is no need, or place to install, a check valve on this engine. This appears to be a first for YS!

John

I don't really know anything about the 1.40, Hobs.

Except they cost a bundle. I snagged the 1.20 from
Central Hobbies at $369. when they were on sale.
( going in the DP Ultimate )

Thanks Dave and John, of course when I went to check it out one of those mysteries in hobby jumped out at me.
Rated rpm 2,000 to 11,000 but use a prop that will keep it in the low to mid 8,000s.

...if you follow my post's, you know that I prop my
engines down more than most. I'll be crankin' that
1.20 for all it's worth when I go full throttle. If I wanted
to chug around at 8K....I would put a 1.20 two stroke in
it....(with too much prop) Ha Ha Ha...

The 1.20 says "Practical rpm....2,000-12,500....If it wont
turn 12....I'll be unhappy.

Too bad they dropped the 1.20. What's up with that !

YSers, I went to the Yamada site in Japan downloaded the operators manual for the DZ140. It's setup and adjustment is quite different from what we're used to on Ys's. The lowspeed or idle adjustmenat is accomplished by adjusting the regulator, clockwise is rich ccw is lean, it does not appear to have a low speed screw on the carb which may not be a carb at all since it controls airflow and meters fuel flow to the fuel injector. Also it comes with a venturi restrictor that limits rpm by 3 to 400 to promote fuel economy, I wonder how many of those will stay in. They recommend not trying to hand start it only use a starter. It comes with a special clunk that when any part of the clunk is exposed, the engine stops. It will not empty the tank. There is also a 140L that appears to have the old style regulator.

This is pretty standard in the model engine biz. They list the practical RPM you should keep the engine within to avoid damage from over revving it. 8K is listed as the "happy" RPM as that appears to be the area where the engine makes the most torque, but not lug the engine which can lead to over heating and detonation (prop throwing).

Dave, I don't know if that 1.20 will be happy spinning 12K for very long. I've always propped them for mid to high 9's. I've never seen one propped to spin up as high as you're talking about, but I guess there's always a first. Let us know how well it's doing after the first case of fuel OK?

John

Ok, John....but that's not to mean I'll be reving the
snot out of it all day long.....Just means when I want
full power....I want FULL POWER...

I have a couple planes "in front" of the Ultimate, but I
should have it up by summer....unless I go with the 1/3
Pitts....

Dave.

Sounds a bit like the 60 short stroke and 61 long stroke airplane engines of old, except that the regulator adjustment is backwards. The more I read about the 1.40 DZ, the weirder it gets

I seriously doubt the restrictor will stay in many engines. Why would you buy an engine of this type only to restrict the rev's?

You could argue that the carb is now more of a throttle body than a carb, but then, so were the older YS engines as well as the current YS 45. There is no spray bar per say that you would associate with an engine of another manuf. The butterfly, on the older engines, has a tapered slot which allows more fuel to squirt into the intake as the throttle is opened. It doesn't rely on any venturi vacuum whatsoever. Very good design even if they are a bit different from what we cut our teeth on. I would love to get my hands on a 1.40 DZ that I could tear down to see exactly what's going on inside.

John

That's fair. Just make sure you are standing behind it the first time you open'er up

John

He He...that's right...I have an O.S.,and a Magnum .90
as well as a Magnum and YS 1.20's....I didn't buy the
YS for a Cub....

I hope not, unless that's a 1/3 scale Cub you're talking about

John