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Thunder Tiger 120 Pro Amazing forgotten motor

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Thunder Tiger 120 Pro Amazing forgotten motor

Old 03-09-2015, 11:04 AM
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nitrometan
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Default Thunder Tiger 120 Pro Amazing forgotten motor

Hi everybody!Someone just said is totally dead here and nobody says nothing.Well I thought it may be the right time to share you my experience .I wanted to buy a DLE 20 because 3 club members here do own one but a new one here is around 185 euro .I said then myself why not try the old good realible and powerful friend,the TT 120 Pro.With the prices gone down today for ignition,a conversion will be much better than spending the money for a new DLE.Because I converted in the past few Super Tigre and one of them after 25 liter of gas through still shows no signs of wear,just a little carbon deposit at exhaust port and very little on the piston I decided to give it a try.After verifying if works with glow-spark ignition,just switched to gasoline mix .The most challenging task was the idle setup.The needle must to be in a very precise position and the adjusting range is only 1/16 turn.1/16 too much and it is too lean,in the other direction and is too rich.With muffler pressure has a tendency to run a little rich in midrange.Without pressure does not work at all.
WoW!! I can tell tell you that this engine exceeded ALL my expectation AS GASSER!
I know very well:walbro and stuff.I just wanted to keep it simple and cheap and it works very good(actually VERY GOOD ).Even much better as DLE 20 (which seems to be for everyone the reference) at least at idle .Nobody in our club has 1600rpm steady at their DLE 20-s.And no one can do 8950 rpm with a 17X6 MenzS propeller.
Well,as somebody once said a video says more as 1569 words,you can see the first video here:
https://www.youtube.com/watch?v=gOCYGW3EB08
Old 03-09-2015, 11:17 AM
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That sounds like it runs quite well. Hopefully it will not prove to be too finicky on the carb adjustments when flying and the fuel level varies. If you really want to stay with a glow carb, you might try a Perry carb that has a midrange adjustment. I would just make an adapter and use a Walbro carb myself. Better adjustability for gasoline, and I like the fact that it is a pumped carb that will maintain its mixture throughout the flight. You are probably borderline on lubrication for that bushing type rod, and you wouldn't want a lean run to occur....

Here is a guy that converts engines that might have a carb adapter that would fit your engine. www.morrisminimotors.com He's on your side of "the pond". I just bought an adapter from him for a Magnum 180 that I am working on as I was in a hurry and didn't want to make one myself in this case. His adapter is well made.

AV8TOR

Last edited by av8tor1977; 03-09-2015 at 11:23 AM.
Old 03-09-2015, 11:57 AM
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nitrometan
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Well as I said,wanted to keep it simple and cheap.I can easily put a 9mm walbro carb at the backplate using original DLE setup(Flatters and filling the crank with a enligted teflon rod) but I just dont want to DLEising it.And belive me,after I tuned the engine I put it nose up,down,at various gas settings and still working perfectly.Motul800 Is an Double-esther based oil wich has MUCH better proprieties as other oils.My Big Cat,ST 3000 conversion has seen more than 25 liters gas and has not even the slightest wear sign at the rod or journal.That is why I use EXCLUSIVELY Motul 800 Road Racing.If I will have any reason to use some form of fuel pressure regulating pump,i will build one from an old Walbro carb,or buy one from NGH engines ,the one for 9cc engine.But as I said,it works at any attitude and I wish I had a GOPRO camera or something to be held in head to make a video to prove this.The conversion cost is under 50 usd,which is more than ok.I plan to put the engine in my Maxair Velox.For a 4,5kg AUW is not a bad idea.
Old 03-10-2015, 01:00 PM
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Nitrometan,

The following website: http://tech.flygsw.org/ has a lot of good information, including a gas conversion of the TT120.
The guy who wrote the article was as impressed with the TT 120 conversion as you are.
Old 03-10-2015, 03:18 PM
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nitrometan
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Well,I know the site very well from a long time and I followed what the gentleman there did ,but by me it works just with muffler pressure and no walbro,only with the original carburettor.Also I will not increase the compression as the gentleman there did because I do not want a vibrator.The engine runs very smooth like this and has more power like DLE 20,also a better idle.What I should expect more from an old alcoholic?
Old 03-10-2015, 04:59 PM
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Originally Posted by nitrometan
Well,I know the site very well from a long time and I followed what the gentleman there did ,but by me it works just with muffler pressure and no walbro,only with the original carburettor.Also I will not increase the compression as the gentleman there did because I do not want a vibrator.The engine runs very smooth like this and has more power like DLE 20,also a better idle.What I should expect more from an old alcoholic?
I saw that site some time ago, and always wondered why he felt the need to raise the compression. If anything, when switching from a design built engine for methanol, and changing to gasoline, one might LOWER the compression because methanol has a much higher octane, and cooling effect, than gasoline and can tolerate a higher compression ratio. (The obvious exception to this being an engine designed for high nitro, which doesn't apply here.) Another reason to keep the compression somewhat low, would be that gasoline engines run hotter than glow engines, and glow engines cooling fins are designed to run on glow fuel, so you wouldn't want to raise the compression and increase the heat load.

AV8TOR
Old 03-11-2015, 04:40 AM
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nitrometan
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Actually the engine runs almost with the same temperature because it has really nice cooling fins,much more effective as lets say Evolution 20cc.About the compresion ratio,it can be raised but again,i dont want a shaker for gaining a couple of hundreds rpm.I can remember after inserting a 0.35 mm shim to the Super Tigre 3000 I lost 200 rpm but whoaaaa,what a smooth running engine...I wish only the Thunder Tiger 120 pro had the same shape as the Super Tigre.
I am convinced that if I raise the compression ratio I will obtain a very powerful engine but with not a so smooth idle.
Old 03-11-2015, 05:01 PM
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Originally Posted by nitrometan
Well,I know the site very well from a long time and I followed what the gentleman there did ,but by me it works just with muffler pressure and no walbro,only with the original carburettor.Also I will not increase the compression as the gentleman there did because I do not want a vibrator.The engine runs very smooth like this and has more power like DLE 20,also a better idle.What I should expect more from an old alcoholic?
Nitro carburettors can become critical when using muffler pressure. It's OK when on a test stand but different story when up in the air. Evolution engines used muffler pressure and are now changing to a pump.
A simple and effective solution is to create a pump from a rotary carburettor taken from from garden tools, remove the barrel (2 screws) and use crankase pressure to pump gas to the nitro carb, works very well.
Old 03-12-2015, 03:23 AM
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I think you do not read carefully my previous posts.You keep telling me about pump/pumped carburettors.I say again and hopefully for last time:I want to keep it running as simple and cheap it can be.This is the purpose of the whole story.I have on my working table(from a very long time,if not a decade) a Walbro carburettor which has been modified just for using it as a regulated pressure pump and I will not use it on this setup because it works like this.Period.
I will not put an engine on a plane untill I am not sure it works.This one works in any attitude.I dont know if it will work after extremely complex 3D figures but I do not fly like this.Still not found anyone to take me on the camera with the stand in various position upside down and simultanously throtelling the engine at various rpm.If it works like this,probably it will also fly well.
I dont try to invent the hot water here but some things can be acheived using simple approach.
Americans spent 30 million usd only for flight control of one Raptor(not avionics,just flight control) but the Russians made a plane wich costs entirely 25 million usd and is still today unmatched in flight maneuvering WITHOUT 30 million usd ultraexpensive flight control system because they did it ...SIMPLE ...
I am a trained Service Technician with more than 25 working years for few world known brands and I can assure everybody that I know very well how an engine works and its systems(and I really mean well) so what I am doing and want to show everybody is pure fun from my side.And maybe somebody learn something as I do from my experiments,without spending his own time and money.
Here is another video of TT 120 Pro on Gas with compact muffler Power Box from an OS 120 AX,internal baffle removed.Looses a lot of power but is a little easier to tune.
I will not use this muffler only if I am forced to do so because of design reasons.
https://www.youtube.com/watch?v=LA-OsuUb508

Last edited by nitrometan; 03-12-2015 at 03:25 AM.

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