speedracerntrixie

My Feedback: (29)

Its now a case of " it ain't broke " so I have no real need to go looking for a fix. I have roughly 20 flights on it since going to the teflon tube and the engine runs very well.

jim woodward

arnstein

I have measured the fuel pressure on the YS ZERO and at idle I read 0.8 bar. YS recommended to lean the pump 1/4-1/2 turn, will that drop the pressure from 1.1/1.2 to 0.8?
Anybody measured the fuel pressure on the YS ZERO?

Arnstein

drac1

My Feedback: (4)

I don't have a zero, but on my 185cdi 1/8th turn on the reg is around 70 - 80 kpa difference in pressure.

arnstein

Are you sure it is not 7-8 kPa per 1/8 turn? If that is the case everything makes sense.
YS 185 nitro: 1.1-1.2 bar @ idle.
For YS 185 Zero, YS suggest leaning the pump på 1/4-1/2 turn:
1/4 turn gives 14-16 kPa ( 0.14 – 0.16 bar ) pressure reduction
1/2 turn gives 28-32 kPa (0.28 – 0.32 bar)
YS 185 Zero: 0.78 bar (1.1 -0.32) – 1.06 (1.2-0.14) bar
I am at 0.8, at the lower end of the range.
Would be interesting to hear if anybody else has any experience, I guess there will be some variation.

drac1

My Feedback: (4)

Yes, I am sure!!

14 - 16 kpa is NOT 0.14 - 0.16 bar. It is 0.014 - 0.016 bar.

You say 1/4 turn is 0.14 - 0.16 bar, (which is 140 - 160 kpa ). I said 1/8 turn is 70 - 80 kpa, so that's exactly the same as my readings.

Have you flown the engine at that 0.8 bar setting?

arnstein

Yes, I have flown it several times with 0.8 bar setting. Still fine tuning due to ambient temperature change for like 10C to 24C.
Wrt unit conversions have you tried e.g.: https://www.convertunits.com/from/kPa/to/bar

Arnstein

drac1

My Feedback: (4)

Knowing what the actual pressure is, isn't really necessary. Flying is the only way to set the reg and needle properly. I start with the reg rich and lean it 1/8 a turn at a time until the transition is smooth.
Does the Zero need the reg adjusting due to temperature change?

arnstein

I claim that the Zero is not more sensitive to temperature changes than the nitro version wrt pump adjustment. The pump adjustment and needle adjustment I have made is very minor and probably a mix of temperature and not being in properly tuned in the first place.

The pressure measurement “papaone” presented under the 200-thread is very interesting. And I agree it is not required for tuning a YS engine. However, if things does not turn out as planned, a very hypothetical situation though, I think it is nice if a pressure recording at idle and WOT can determine whether the pump is OK or not.

Arnstein

drac1

My Feedback: (4)

My 185cdi - 30% nitro, is 1.1 bar at idle. I haven't checked my 200.

Once the reg is set, I suppose having to keep richening the reg is an indication that the pump is worn.

apereira

I will try this week the pressure gauge for the first time, I think it will save some time to get to the close point where the final adjustment is in the air. I do my final adjustments in the air, I mostly adjust by sound and response.

arnstein

Having used the YS-Zero this season here is my findings / thoughts:

· The engine produces max power on a very narrow needle range setting, compared with using fuel containing 20-30% nitro. Having said that, the power produced is enough for both P19 and F19. A get around 7000 rpm on APC 20x10.5 PNC, slight less on the APC 20.5x10 PNC.

· I use 10% oil (Molsyn 80K), the rest is methanol. For temperature mid 20s C and above, I find the best method to have a reliable engine is the cool down the fuel. As the attached graph shows the vapour pressure of pure methanol increase very rapidly, the 10% oil in the methanol will raise this curve somewhat.
The problem is in verticals like a stall turn, due to gravity the fuel pressure at the pump inlet drops, assume the distance between the tank and engine is 0.5 m, the pressure drop (approx.) is rho*g*h = 800*9.81*0.5 = 4 kPa = 0.04 bar. In addition the pressure drop across the clunk and the friction. In this flight condition (stall turn) it easy to get a vapour lock.
In this respect going back to the days with crankcase pressure in the tank would be a good idea.

· Measuring the pump pressure at idle I ended up at slightly less than 1 bar (0.96 +/- 0.04). It is possible to get the engine to run at a wide range of different pump pressure settings, but in this case it will not run properly at all throttle settings. Initially I had it at 0.8 bar, however, much less power at midrange.

· To obtain a good idle and transition the cam bearing need to be in a very good condition, more critical than running with a lot of nitro. Personally I would prefer cam bearings with a higher load capacity / stiffness. Compared with the non-DZ engine the load on these bearings have increased.

· Running cost very low, compared to any other power source.

On my engines only the piston is changed for the standard nitro version. For a “genuine” Zero, Yamada may have introduced additional changes, e.g. the carburettor body with throttle has a different part number compared with the non-Zero version.

MCFLY-RCU

My Feedback: (9)

arnstein

The manual for the zero you may download from: dz185cdizero.pdf

Anything on the outside of engine to confirm you know of?
I converted to the zero-version myself, replacing the piston only. So I do not know if there is any marking on the outside of the engine. To be absolutely sure you have to compare the pistons (nitro vs. zero).

Running nitro in a zero engine would not be good, right?

Some has used 5% nitro with success:

https://www.brueckner-aviation.com/e.../carf-valiant/

The manual for the zero only states 0% nitro.

If it is a zero, does Klotz oil have any blends of oil that are good for a fai blend?
Sorry not familiar with the Klotz oil.

Good luck!

Arnstein

apereira

Yes, Klotz has the full synthetic oil, do not use the blended as it has Castor in it 4%, use the Techniplate for helicopters or the full sinthetic one.

MCFLY-RCU

My Feedback: (9)

John F3A Junkie

Hello Gents,

does the 185 Zero runs hotter than the 185 CDI due to the lack of Nitro in fuel? And therefore the engine is not the best option for high temperature enviroments?
From reading the all the above, I understand that vibration is increased compared to regular 185 or CDI and the YS damper should be used even with the Hyde soft mount?

Thank you,
john

drac1

My Feedback: (4)

There's no provision on the Hyde Mount to use the YS damper. It's not needed with the Hyde Mount.

arnstein

Does the 185 Zero runs hotter than the 185 CDI due to the lack of Nitro in fuel?

My experience says yes, more attention needed to ensure high speed air past the engine.

And therefore the engine is not the best option for high temperature environments?

No, not due to temperature up to 30C, no experience running it at higher ambient temperatures. The reason I ran into problems was due to the fuel temperature. With an oil content of 10% the vapor pressure of the fuel is low. I got problems in maneuvers like the stall turn, vapor lock in the fuel pump. My workaround was to cool down the fuel (to 5C), see previously posted graph. Have not tried to pressurize the fuel tank.


From reading the all the above, I understand that vibration is increased compared to regular 185 or CDI and the YS damper should be used even with the Hyde soft mount?

I have no measured data confirming your statement, however, the mass/spring system comprising the steel piston in the fuel pump and the valve spring, is affect by the dynamic behavior of the engine itself. The less vibration the engine has at idle, a steady idle can be obtained at decreasingly lower rpm. Hence the need for a viscous damper. I have tested successfully two mounts:

1. YS mount.

2. CK Aero: YS Hyde Soft Mount

Both of these mounts have the same interface, and uses the same viscous damper.
Arnstein

bjr_93tz

Way back when I was having the first round of issues with my DZ170cdi, I stretched the springs in the pump so the valves would seat with more pressure.

While it worked fine in my hand with a large piston stroke, it turned out the vacuum required to open the valve on the suction side couldn't be achieved if/when a bubble got into the pump by the much shorter piston stroke that the intake pushrod imparts . Imagine trying to draw water up into a syringe that has a bubble in it, the piston displacement needed to overcome the volume change in the air bubble just wan't enough.

Just another one of those interesting nuggets of discovery..

arnstein

I have now done some mods to my installation, improved the cooling of the engine. Previously I had only foam around the cylinder/head down to the mounting lugs to get high air speed around the cylinder/head. I forgot the area below (i.e. lower part of crankcase), I have now added foam here.

The change in engine temperature and fuel pump temperature was significant. I am now able to run the engine at 26-27C without needing to cool the fuel. Apparently previously the air took the easiest way out, that was unfortunately not past the cooling fins of the cylinder/head. By restricting the flow at the lower part of the crankcase by adding foam, more air passes the cooling fins.

Replaced my old YS engine mount with a new one, this also improved the throttling characteristics. And made the engine easier to tune, runs more consistent from idle to WOT.

If you are happy with “YS175CDI” power the Zero is certainly and alternative. The running cost is also attractive.

Arnstein