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Old 03-13-2007, 01:23 AM
Harry Lagman
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Default RE: SuperTigre mid-range problems?

Ed (RC34074), my response is in no way directed at you personally, but I am using your post as the basis of a point by point response because it is comprehensive in nature and embodies much of what the Super Tigre Alumni offer in defence of the marque...

I have 6 g90s. they are up to 9 years old. They all run very well. I have 3 chinese built 2300s. I have run two of them, and they run even better than the g90s. In fact they tune/run better than the OS61sf, which up to the time I bought the first 2300 was the best tuning engine I had had.
looking good so far.... but...

If you expect them to tune like you want them to tune or as you would design them it's not likely to happen. They are a very good design. You need to learn how to tune them. They do not tune like a Saito.
Bang!! There it is... This is where denial of the ST's less than ideal carb calibration takes place but, ironically, where it's revealed that they do indeed have strange quirks. Editorial comment: a good glow engine should tune like another good glow engine (in this case, the Saito); knowledge of tuning a Saito, an OS or a TT should be relevant to an ST.

Proper back pressure from the muffler makes the tigers tune and run best.
Here's another implicit revelation. What many of us read into this is... "the carb is not calibrated correctly and needs the band-aid of higher than normal tank pressure to help mitigate this". Editorial comment: A good engine should carburate properly with an open header, a normal sport muffler, a tuned pipe and a properly designed Pitts muffler. If it needs pressure to function properly, the carb is too big or is not drawing fuel satisfactorily for some other reason.

They do not take a low idle until they are broken in well, as the ring isn't seated against the cylinder well enough to pull fuel well until they are broken in.
Hold the bus: here's another between-the-lines revelation: they won't idle when new, like we expect good engines to. I don't know about you, but I'd prefer to buy an engine that is ready to use in a plane with a minimum of pre-running. Likewise, I'd prefer an engine manufacturer to provide the engine to me with its machining complete, rather than my having to burn up large quantities of my own fuel finishing the job off for them.

A good engine will idle and run well with a tank or two through it - in fact in the time it takes to run through a couple of heat cycles and set the low speed needle for a decent idle, it should be ready to fly. OS, Saito, YS. ASP, Magnum, GMS and TT can do this; why can't ST?

So you need to either run them with an high idle at first or break them in well on the ground. Then you can tune them in for a low idle - low being 2k- 2.5k rpm, at least for the props I tend to use.
Other engines are ready to go and idle at less than 2000 rpm with little more than 8-16 oz of fuel through them from new. All of my engines idle at 1800-2000 rpm. I have a YS 1.10 in a 5.5lb model with a 13x11 prop - I thank my lucky stars that it idles at 1800 rpm and not 2500 rpm, because it would never land at 2500 rpm. This engine has idled like this right from its first tank. A flying buddy's GMS .47 with a 12.25 x 3.75 APC prop can be made to idle reliably at 1400 rpm on demand.

So why hassle Super Tiger?
Some of us think that they have some work to do on their carbs

So this thread more properly should be labeled Muffler Design Problems, not Super Tigre mid-range problems.
Some of us respectfully disagree.