Is the pressurized Y.S. intake system all that efficient?  
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Is the pressurized Y.S. intake system all that efficient? - 3/8/2002 7:06:41 PM   
ChuckN



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From: tucson, AZ, USA
Status: offline 		Does the Y.S. supercharging system realize a net gain in power? It takes quite a bit of power to push the piston down the cylinder and compress the air/fuel charge in the crankcase. Do you suppose that any benefits of the Y.S. supercharging system are negated by pumping losses? I suspect they might be, but the fuel injection style "carb" and the fact that the fuel gets thoroughly vaporized in the crankcase adds greatly to Y.S. performance. Could this be why they run so well on higher nitro? Part of the reason Top Fuel drag cars run so well on 95% nitromethane is the fact that their big superchargers do a tremendous job of homogenizing the fuel/air mixture.
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Re: Is the pressurized Y.S. intake system all that effi... - 3/8/2002 7:15:25 PM   
can773



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From: Calgary, AB, CANADA
Status: online 		[QUOTE]Originally posted by ChuckN
Does the Y.S. supercharging system realize a net gain in power? It takes quite a bit of power to push the piston down the cylinder and compress the air/fuel charge in the crankcase. Do you suppose that any benefits of the Y.S. supercharging system are negated by pumping losses? I suspect they might be, but the fuel injection style "carb" and the fact that the fuel gets thoroughly vaporized in the crankcase adds greatly to Y.S. performance. Could this be why they run so well on higher nitro? Part of the reason Top Fuel drag cars run so well on 95% nitromethane is the fact that their big superchargers do a tremendous job of homogenizing the fuel/air mixture. [/QUOTE]


Well considering that the 140L puts out more power than any other 4-stroke at the same displacement and similar power to others above its displacement makes me think that yes they do realize a net gain in power.

However the new DZ is as powerful as any of the 140 2-strokes, running an unpressurized system, apparently gaining the power from injecting the cooler fuel right behind the intake valve.


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YS 140 - 3/9/2002 12:33:09 AM   
Traxxas_Tech



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Status: offline 		I havent done any serious tests, but In my opinion, The YS 140L is as much or more powerful than the Saito 1.80. It swings the same prop (APC 16x8) at almost the same RPM! The Pressurized YS system pretty much guarantees you of fuel delivery, You'll never worry about sputtering/failing in High G manuevers. Basicly, if fuel is in the tank, the engine will drink it! Just my two cents worth.

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Is the pressurized Y.S. intake system all that efficient? - 3/10/2002 6:33:27 PM   
rexbirk


 

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Joined: 12/15/2001
From: Columbus, OH, USA
Status: offline 		Once you own and run a YS for a time and learn about handling it you can't help but be impressed. They are more powerful but I think more importantly the throttle response is incredible. It is immediate and linear. You can idle for 5 minites and hit the throttle and you have immediate power, no loading up.

Also the engine holds it settings. I get it out of the car and fuel, start up and fly. You don't have to constantly fiddle with the needles. All in all a very satisfying engine to own. I have 2 91AC's and will not hesitate to buy YS again when I need another engine.

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YS - 3/10/2002 6:46:26 PM   
Hobbsy



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From: Colonial Beach, VA, USA
Status: offline 		Thanks for all this info, I'm recieving a YS .91 FZ on the 15th of this month and am looking forward to bending the learning curve upward with something new and a little different.

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Is the pressurized Y.S. intake system all that efficient? - 3/10/2002 7:27:13 PM   
ChuckN



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From: tucson, AZ, USA
Status: offline 		A good friend of mine (an aerospace engineer to boot) has a Y.S. 91 he bought about a year ago and we still haven't been able to make it idle right. We've tuned it on the test stand and in the airplane, trying to isolate anything that might be going wrong. He's talked with Shadel and Verano on the phone but to no avail. I suspect he'll be sending that thing back before long. Any ideas on why this one just won't run reliably? Is it the weird airbleed style carb? It's not like the 1.20s I have had experience with.

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Case blending vs. direct injection - 3/10/2002 8:07:20 PM   
RossiRay


 

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From: Spring Valley, CA, USA
Status: offline 		Interesting fact that the new DZ is a port injection setup that yields more power than the FZ or L method. So the crank case blending of the fuel/air mixture is not a benefit.

I don't think the fuelies are runing the blowers as mixture blenders. Anybody know what kind of boost pressures are being run now on those things? Must be close to 4 bar. Imagine how much crank power it must take to spin the blower!

Pumping losses do occur, but they are overwhelmend by the increased charge density. As for the YS, Clarence Lee measured 8 psi at full bore on the original SF 1.20. Only other 1.20 to have any positive intake pressure was the OS SP, but who could make it run? And all other 1.20's do not have the power of the YS.

And though the DZ is not the high pressure system of old, it is a pumped system. With a fuel cooler to boot.

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Is the pressurized Y.S. intake system all that efficient? - 3/10/2002 9:15:17 PM   
Diablo-RCU


 

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From: Hammond, IN, USA
Status: offline 		Wierd running 91?

Most run very well, but if this one doesn't it could be:

Bad piston/ring/cylinder or valve cover air leak or regulator housing air leak. I believe there's also an O-ring on the crankshaft that could leak air.

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Re: Is the pressurized Y.S. intake system all that effi... - 3/10/2002 9:50:27 PM   
Sport_Pilot



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From: Acworth, GA, USA
Status: online 		[QUOTE]Originally posted by ChuckN
Part of the reason Top Fuel drag cars run so well on 95% nitromethane is the fact that their big superchargers do a tremendous job of homogenizing the fuel/air mixture. [/QUOTE]

How can that be? The fuel is injected either at the intake port or directly into the cylinder?

Modern day AA fuel dragsters have gone from 2000 HP to over 6000 HP in the last 20 years. The major reason are higher capacity ignition systems which can ignite a much richer charge of nitro!

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Is the pressurized Y.S. intake system all that efficient? - 3/11/2002 2:24:26 AM   
ChuckN



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From: tucson, AZ, USA
Status: offline 		Today's Top Fuelers have at least 3 injectors PER CYLINDER. Eight before the blower, eight after the blower, and at least one per each intake port, plumbed right into the head (called "down nozzles" . Even today's alcohol fueled sprint cars have at least 2 injectors per cylinder. One per each velocity stack and one "down nozzle" in each intake port.

What I was getting at with Top Fuelers was that with the incredibly rich fuel mixtures they run (roughly 2:1 air to fuel) they are able to light a fire and keep it going without having a hydraulic lock, which really does happen from time to time. The screw type blowers must have as much to do with mixing the fuel into the air as they do with boosting manifold pressure.

It has also been found that once a Top Fueler leaves the starting line the magnetos are no longer necessary. They run very much like glow engines at full throttle. After each run all 16 plugs (two per cylinder) are trashed.

The funny thing about Y.S. engines is that they don't have a combustion chamber shape traditionally associated with high-nitro percentages. They have a standard wedge type combustion chamber similar to small block Chevys and Mopars. Which is also the shape O.S. uses.

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Is the pressurized Y.S. intake system all that efficient? - 3/11/2002 5:53:04 AM   
ChuckN



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From: tucson, AZ, USA
Status: offline 		True! The only time you are running too rich with nitromethane is when you lock up a cylinder

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Is the pressurized Y.S. intake system all that efficient? - 3/11/2002 6:04:53 AM   
Sport_Pilot



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Status: online 		[QUOTE]Originally posted by ChuckN
Today's Top Fuelers have at least 3 injectors PER CYLINDER. Eight before the blower, eight after the blower, and at least one per each intake port, plumbed right into the head (called "down nozzles" . Even today's alcohol fueled sprint cars have at least 2 injectors per cylinder. One per each velocity stack and one "down nozzle" in each intake port.
[/QUOTE]

That they do, so is it the blower mixing the fuel or the incredible number of injectors? After all most of the injectors are after the blower

[QUOTE]Originally posted by ChuckN

What I was getting at with Top Fuelers was that with the incredibly rich fuel mixtures they run (roughly 2:1 air to fuel) they are able to light a fire and keep it going without having a hydraulic lock, which really does happen from time to time. The screw type blowers must have as much to do with mixing the fuel into the air as they do with boosting manifold pressure.

It has also been found that once a Top Fueler leaves the starting line the magnetos are no longer necessary. They run very much like glow engines at full throttle. After each run all 16 plugs (two per cylinder) are trashed.

[/QUOTE]

I don't think that is completely true, and even if it were true the starting line is the most important part. They sure don't look like they are running when the mags cut out, but that may just be in comparison. With such rich mixtures the ignition must be either very hot, or mutiple sparkplugs (I think some are running 3 plugs per cylinder now). I think with two plugs the timing had to be advanced to 60 degrees. I believe they are running mixtures richer than 2:1 now, infact I think it is close to 1:1, very close to hydralic lock for sure, but when that was happening I believe they went to lower compression ratios.

Of course with rich mixtures of gas the spark can be of a lower voltage, it may be true of nitro also to a certain point. But LadyFlyer the AA dragsters would run liquid nitro with no air if they could find a way. Nitro will explode and burn without mixing with air, but is extremely hard to ignite, without a blasting cap. So at some point a rich mixture of nitro needs much higher voltage. It may seem strange to say the electronic mag is what made AA fuel dragsters jump from 2000 to 6000 HP, for surely there is more going on, I could be wrong but I believe it to be true. Of course once you can ignite a richer mixture at the proper timing, then you stress the engine more, so redesign of engines, injectors, blowers, etc.

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LadyFlyer - 3/11/2002 7:14:17 AM   
Sport_Pilot



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Status: online 		I believe 2:1 two parts air to one part fuel is a rich mixture for Nitro. Shouldn't that be closer to 2.6 to one? I could be wrong I didn't look it up. But the point is that the 100% nitro fuel cars have been upping the mixture to richer and richer. Nitro doesn't need air to burn! A load of 100% nitro with no air (I would think) would be the ideal. Unless maybe LOX is used!

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Is the pressurized Y.S. intake system all that efficient? - 3/11/2002 10:31:25 AM   
Sport_Pilot



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Status: online 		When I said that I think it is close to 1:1, I should have said that I wouldn't be suprised if it is closer to 1:1!

Also when I think about it, maybe more credit should be given to tire, drive train, and traction. No need to increase horsepower if you can't get it to the ground!

We have gotten a bit off topic.

I think that maybe ChuckN has a point that if improves mixture. If only from the crank spinning around!

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