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Old Jan 18, 2013, 08:45 PM
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Help!
ST 3000 Fuel

Is 15% nitro ok for this engine. I have read that many people run 5% nitro so I was wondering if 15% was good.

Mark
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Old Jan 18, 2013, 09:16 PM
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They have a reputation for being intolerant of 15% nitro but I do not have first hand experience.
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Old Jan 18, 2013, 10:35 PM
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Oh really.? That sucks.
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Old Jan 19, 2013, 12:10 AM
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What sucks?

They can tolerate 15%, but YOU should prefer 5%, because the power difference will be rather small and low-nitro fuel will last you much longer (also flight times).
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Old Jan 19, 2013, 09:21 AM
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the big Supertigre engines can use fuel with a 5% to 10% nitromethane content. During break in they use 20% oil or no less than 15% oil. After break in one can go as low as 15% oil to fuel ratio. Until they get broken in and the oil percentage in the fuel is reduced, they tend to not idle as well or have a good mid range transistion, but it isn't all that bad though. The reduced oil content lets them run their best.

Ref the SuperTigre owner's manuals http://www.supertigre.com/manuals/index.html
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Old Jan 19, 2013, 08:35 PM
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Alright thanks for that info. I have a 3000 coming and I'm hoping it runs better than the .90 I had. The .90 just didn't seem to have the power I expected from a .90
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Old Jan 19, 2013, 10:14 PM
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Well the 3000 is a 1.80 or 30cc size engine, so it'll be pretty huge in comparison to a .90 engine. Plus more heavy too. But it will develop more power than a .90 engine though.
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Old Jan 20, 2013, 12:28 AM
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Sure that's obvious, I meant I hope its the 3000 is what I'm expecting on power and reliability.

Had a buddy in savannah, ga that swore the .90 was an animal, I then bought one and I must have recieved a dud. The thing just seemed so weak compared to my buddies.
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Old Jan 20, 2013, 11:45 AM
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My first Supertigre 90 was used. I bought it at a swap meet. It ran Ok when I started it and when I tuned it up but when tried to fly, ... it didn't seem to have as much power as I had expected. It even would dead stick at the worst times and it prompted me to take it apart for inspection.

When I took it apart and found a few problems. The head bolts were slightly loose. When the engine warmed up, ... the compression would drop enough to loose substantial power. It was probably why the last owner sold the engine too. Could be the same thing on your 90.

I went through it very meticulously. I cleaned the carbeurator inside and out. There was little pieces of trash in the spray bar, needle valve, and fuel nipple. Not enough to stop the engine from running on the ground but it affected the perfomance.

Once I cleaned up the engine and carb, ... that thing really would light-up. It was like a brand new engine and snappy as a hornet.
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Old Jan 20, 2013, 12:45 PM
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One thought is that the cylinder sleeve may be twisted slightly off inside the crankcase. it does happen. The sleeve's exhaust port should be centered on the matching crankcase exhaust outlet. If the sleeve is off center a fair amount, it can really affect performance. Yeah as mentioned the head bolts could work loose a little too.
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Old Jan 22, 2013, 09:24 PM
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I have a 3000 in a 120 size Stinger. It did not run very good till I changed the carb and used 5% nitro fuel with oil content around 12%. It runs great now and has been very dependable. Factory carb is too large and creates fuel draw problems. ASP 108 or perry large (not the 3000) carb is what you need. Also need the sleve that supertigre sells for the smaller throat carbs to work.

Good luck,

John
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Old Jan 23, 2013, 11:19 AM
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Quote:
Originally Posted by earlwb View Post
the big Supertigre engines can use fuel with a 5% to 10% nitromethane content. During break in they use 20% oil or no less than 15% oil. After break in one can go as low as 15% oil to fuel ratio. Until they get broken in and the oil percentage in the fuel is reduced, they tend to not idle as well or have a good mid range transistion, but it isn't all that bad though. The reduced oil content lets them run their best.

Ref the SuperTigre owner's manuals http://www.supertigre.com/manuals/index.html
i remember many years ago they recommended 10% oil, what happened to make them increase to 15%?
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Old Jan 23, 2013, 11:33 AM
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I remember that the carb on the big Supertigre engines has too large of a bore to work well in some cases. It puts the fuel tank farther back from the carb and with bigger props turning lower RPMS it can lead to fuel draw problems. Usually increasing backpressure from the muffler helps aleviate the situation. But quite a few guys have put on Perry Carbs or OS carbs, etc to correct the problem too. The extra big ST G4500 has the carb at the rear of the engine so it works much better. But even then some folks still had carburetor issues.

I would suggest trying the engine as is first and see how it runs. Then if you have problems you can decide what to do about it. Not everyone would have a problem.

Yes, usually you use a fuel with more oil in it for breaking in the engine good. During that break in phase it can run poorly, with a high idle speed and not so good transistion through the mid-range. But after it is broken in good, one can start using the reduced oil content fuels and the engine usually starts to run great then even with lower nitromethane percentages. I think the carburetors on the big ST engines are really setup for less oil in the fuel thus tyhat leads to people having more problems with them. The Supertigre big engine instructions do mention this too.
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