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Old Nov 22, 2012, 04:31 PM
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Ontario, Canada
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Quote:
Originally Posted by DarZeelon View Post
A comprehensive review for this engine appears in Christian Traders...

The RPM numbers they achieved dwarf the claimed HP numbers for this engine!

I calculated with the Reivers PropPower, Prop factor 1.23 for APC:

• 10 x 6 - 14,660 = 1.18 HP
• 11 x 6 - 12,987 = 1.39 HP (1.35 PF)
• 11 x 8 - 11,450 = 1.13 HP
• 12 x 4 - 12,615 = 1.16 HP
• 12 x 6 -10,893 = 1.08 HP
• 13 x 4 - 11,556 = 1.24 HP
• 13 x 6 - 10,128 = 1.19 HP
• 14 x 4 - 9,463 = 0.93 HP

What can I say!?
Phew! I hope mine works as well as the reviewer's. This engine will be my entry into gas power. Seems like I've been following this thread forever.
-
Well this engine is now discontinued at the the website where it was reviewed http://www.modelling.christiantrader...2_NGH_GT9.html
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Last edited by rmsingh; Nov 23, 2012 at 02:21 PM. Reason: New information
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Old Nov 24, 2012, 11:10 AM
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Quote:
Originally Posted by rmsingh View Post
christiantraders
Their engine runs on faith and puts out more rpm.
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Old Nov 24, 2012, 11:20 AM
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Israel, Ramat HaSharon
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Quote:
Originally Posted by rmsingh View Post
Well this engine is now discontinued at the the website where it was reviewed.
Maybe it does run on faith, but HobbyKing seem to have it in large numbers.

See here.
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Old Nov 24, 2012, 11:42 AM
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USA, TX, Grapevine
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Well my engine RPM numbers aren't too low in comparison. But at the time I hadn't run more than a few tanks through the engine on a test stand. It has been running real good in my large low wing plane though. It could be he adjusted the static timing a little where I just left it as is from the factory. Maybe their gasoline is different than ours here, or they have more oxygen in the air than we do too.

Being a bit paranoid about the oil percentage in the fuel, I am running a little more oil in my engines though and that can affect the power output too.

MA 11x6 11,700 RPMS
MA 11x7 11,500
MA 11x8 11,000
APC 11x8 10,700
MA 12x6 9,800
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Last edited by earlwb; Nov 24, 2012 at 11:46 AM. Reason: add more information, forgot something
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Old Nov 24, 2012, 12:29 PM
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Israel, Ramat HaSharon
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Earl,


Somehow, gas engines need much less oil percentage-wise, compared to glow engines; despite using about 40% as much fuel when running.

For this engine, which has a bushed con-rod, 4-5% is right, compared to 17-20% for glow engines. That is about one tenth of the oil; and had it been a needle-bearing con-rod, 1/20 the amount of oil would easily be sufficient.

I guess it is the way oil mixes with the different fuels. It actually dissolves in gasoline, while in methanol it is a suspension rather than a solution.

On the APC 11x8 you got 0.92 HP...
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Old Nov 24, 2012, 09:09 PM
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Maybe so, but as a engine gets more small in displacement, the oil needed is more and conversely a large engine needs less and less as it gets bigger and bigger. Mr Duke Fox originally came up with that and it seems to hold true even today. The big Supertigre glow engines are usually a good example in that the G3250 works fine with 12% and maybe 10% oil in the fuel. They actually sell special low oil content Supertigre glow fuel here in the USA too.

But I managed to spin the bushing out of a couple of rods on two of my NGH 9cc engines. I assume it was because the engines went lean in the air when the fuel pump had problems. Michael Chow thought it was a defective rod. But then maybe not. With the more lean air to fuel ratio in a gasoline engine, there is less oil as well and a more lean run can become bad really fast. Thus I tend to be more paranoid about it at this time. so far none of the engines have had a rod fail again, so maybe it works.
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Old Nov 24, 2012, 11:56 PM
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Earl,


I spoke in length regarding the issue with Pé Reivers.

There were two late model .40 size engines made by MVVS, the 'normal' #3066 and the Quickie #3068.
The differences are the obviously greater timing numbers and the larger carburettor, but the crankshaft differs in one more aspect...

...Its crank-pin is ground slightly smaller, to increase the oil clearance for the con-rod bottom-end.
Both engines use the same con-rod and drilling the hole in the bronze bushing larger is not the best practice.

The normal engine uses 0.03-0.04 mm of oil clearance, while for high RPM the Quickie needs 0.05 mm at least, increasing in applications that need really high RPM (up to 25K) to 0.07-0.08 mm, or the engine will spin the bottom-end bushing.

Perhaps your NGH engines spun the bushing because of insufficient oil clearance?

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Old Nov 25, 2012, 07:05 AM
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Yes I can agree that that is a strong possibility as to what happened.
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Old Nov 25, 2012, 07:25 AM
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Istanbul, Turkey
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I have measured 12100+ RPM s with 11-6 prop(Unfortunately I cant remember the brand) on bench.Mineral oil used generously.
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Old Nov 25, 2012, 09:21 PM
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The main difficulty with the ngh carb/pump was to understand it. The pump does not work unless there is a tiny bit of suction from the carb. My "dry tests" of the pump did all fail because i did not have the carb connected. But as soon there is a small vacum from the carb the pump works. Sounds logical now.

People wear gloves! I cut up my fingers with that prop while adjusting the carb screws. Blood everywhere.
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Old Nov 27, 2012, 02:21 PM
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Today did have a test on bench with my GT9.Changing LSN with an original one from a SK50 carb. LSN.
It seems worked but I only could have a quickie test.So I cant say it definitely worked.But during run,(11-7,7 prop.A Chinese one similiar with APC) It seems very reasonable idle speed(very little fuel spitting though),good WOT(some missing cant be eliminated by needle) , good transition and best,while nose up simulating still runs at WOT and still transits from low speeds to full speed.
I hope I can go on with some more serious reports.
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Old Nov 28, 2012, 08:47 PM
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Quote:
Originally Posted by Cesco View Post
The main difficulty with the ngh carb/pump was to understand it. The pump does not work unless there is a tiny bit of suction from the carb. My "dry tests" of the pump did all fail because i did not have the carb connected. But as soon there is a small vacum from the carb the pump works. Sounds logical now.

People wear gloves! I cut up my fingers with that prop while adjusting the carb screws. Blood everywhere.
Man that is a major bummer on the prop strike. I hope you heal up fast.

Well what happens is the pump pumps fuel into the regulator side of the engine and fills up the reservoir there. The regulator diaphragm expands out and allows the pivot arm for the fuel inlet valve to close off the fuel flow. So unless the engine's carb is drawing fuel out of the regulator reservoir, the fuel stops. So as the engine draws fuel from the reservoir, the fuel volume descreases and the the little nub in the center of the diaphragm touches the pivot arm and overcomes the spring tension and opens the fuel inlet valve allowing the pump to push more fuel into the reservoir. Then the process repeats of course.
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Old Dec 07, 2012, 07:52 PM
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What 3d planes are being flow with this motor? Would the 3dhs 58" edge be a good choice?
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Old Dec 08, 2012, 07:43 PM
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Originally Posted by tele1974 View Post
What 3d planes are being flow with this motor? Would the 3dhs 58" edge be a good choice?
It depends on your flying style. If you want hover capability and unlimited vertical capability, then this engine wouldn't work for you. But in a 3D plane with a 48 inch to 50 inch wing span, it may do pretty good though. Something like the Dazzler .40 or equivalent might give performance pretty close to that for hovering and vertical climb outs.
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Old Dec 09, 2012, 01:48 AM
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Yesterday I have more test runs on GT9.I could have good run on all of the throttle spectrum including good low idling but I couldnt have reliable WOT during nose up simulation on bench.
It seems pump have problem to raise fuel to carb while having some level, at WOT.Seems running good at WOT on nose up but giving any throttle play makes it an absolute stop.
Now I need to change pulse nipples but I dont know how and when I can find 2 of them.
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