pilotpete2

Hi Ed,
I have a new (china) G90 that I will be breaking in this spring. I hate to have to schlepp 2 different fuels, and I normally run 15%, (my Saito loves it) and also we are in a cooler climate, should I try to lower the compression by adding shims (engine has one already, as shipped), I have a "Mike", so how much shim should I add for 15%?? or will I be better off schlepping/juggling two different fuels
Regards,
Pete

buzzingb

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Na, it will run 15% just fine but it doesn't need it. I believe the owners manual says us to 15% but not sure now since it's been awhile since I read it. I like to get as much life out of my engines as possible and therefore use lower nitro when possible. The nitro helps on rpms a little but it will increase rust, cause hotter runs if the fuel gets lean for some reason, and a few more negative side effects.

buzzingb

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I do believe running a fuel with some castor in it. At least 20% of the total amount of oil content should be castor if not more. I used SIG fuel for a while and it had 50%50 castor with 20% total oil content and it appeared to leave a film on the crankshaft, bearings, and case. That could be good if rust is a problem. I now add a couple oz of castor to my fuel to help prolong engine life.

buzzingb

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Ok here to report back from a long afternoon of flying about 2hrs in the air time. I can honsestly say I am more impressed with the Super Tiger 51 than anyother engine I have had. After I mounted the 12X6 on front I never thought it would pull it a as I tacked it under my carport but it almost hit 11,000. I still had reservations on how it would pull the 12X6 in the air. I thought it might bog down and not want to transition fast enough. Well, I can say it is one monster of a motor with mega torque through out the rpms low and hight. It pulls the Ultra Stick like there is no tomorrow with the 12X6. The thing transitions like it was a 11X6 from idle in the air to full throttle is pretty much instanious. The 12X6 can't even hold this engine down on the topend. The prop will began to resonate supersonic waves as it circles the field in level flight. Never, would I have thought the 51 would reach these rpms in the air with a 12X6 on the front. I can fly for over 20 minutes at these kind of fast runs and climbs and still have plenty of fuel to land. One day I want to experiment and see just how long I can idle around the sky, I am going to say 30 minutes easy.

NM2K

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Sorry I didn't get back to you sooner. It looks as though you have answered your own question. <G>

It sounds as though you are running 15% without a problem. Keep an eye on it when it is hot and humid. If you hear a sound like frying eggs when it is hot out, you can either back off of the nitro, or back off the prop load a tad until it goes away.

I've never owned a Super Tigre .51. I think I am going to order one and add it to the collection. I missed the .51 and .56 sizes the first time that Super Tigre offered them in the Sixties. Better late than never.

Oh, is the 12x6 an APC sport prop? That is one small prop. I'll bet that is why it turns up so well. I hope I'm not misremembering this prop. <G>


Ed Cregger

buzzingb

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The prop is Master Airscrew 12X6 K Series that I use to run on my Saito. It is a wide blade prop and heavy. I don't know the in air rpms but I have a chart as to where it starts to resonate at point of 0.6 and above the speed of sound. It said the speed at 0.6 waw 13,000 so I am assuming it is just above 13,000 in the air. All I know is it starts to scream in the air and you defenatly can hear the prop. I never would have thought this but that is what happened this afternoon. I usually only make one or two rounds around the field at wide open throttle untill the engine gets fully broken in. I am still running rich but only just a tad. It is 2 click abouve gurggling on take off but it deffenately leans up in the air. You can see a destinctive vapor trail as it goes away from me and even straight up. I also add 2 ounces of castor to the Magnum 15% for plenty of oil content. I wish someone else would report their findings with the 51 and a 12X6 as I can hardly believe it. I wouldn't blame someone if they read this and didn't believe because I would have to witness it myself before I would believe it.

buzzingb

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I have now heard others say their 51s will pull a 12X6 also. My next experiment with this motor will be to see if it will run well on 5% Nitro. Have any of you used this motor on low or no nitro fuel?

Not24

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Buzz,

I can understand using low nitro fuel in the larger engines, but a little 51 won't save you much money per flight. I believe the higher nitro is better, because it runs at a more rich setting, thus increasing the lubrication. When I ran the 2300 on no nitro I had to really close down on the needle. I think it would be easier to burn one that way that on the higher nitro. I know temp tests are subjective, but my 2300 runs cooler on 15 than on 5. It also runs cooler at 9500 than at 7500rpm. Go figure!

buzzingb

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I believe you are right Not24 as I have observed the same thing. I just want to know what fuel the little 51 will run on. I have just purchased 2 cases of 15% and I will be burning as much as possible in the near future. The way the 51 and 2300 sip fuel I would imagine I can make it till spring anyway. I am just about ready to get a 90 in the air on a 40 Ultra Sport Plus and I know this is going to be a winning combinationa as I had a Ultra Sport Plus a few years back and loved it with a 61FX.

buzzingb

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Ok I need some opinions here. What can I expect if I decide to go with a tuned pipe (Jett Muffler) on this motor? I just keep thinking this motor has more potential even though I don't know if another engine on the market can beat it in the 50 size range that would be less than $200. I know what you are thining the tuned pipe will cost more than the engine and you are correct so I don't know if I can justify buying one or not.

RVman

Expect about 1000-1500 more rpm (depends on prop), usually a cleaner midrange, and better transition. I have a 50 webra than will keep up with the numbers you posted, 13-4 APC at 12000 (incowl exhaust), and its finally wearing out, probably a couple hundred hours, most of them with a pipe.

speedster 1919

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I fly everything on 5% nitro and have 3 ST 51's. Most of my club is on a 15% nitro kick and can't believe I can keep up on just 5%.

NM2K

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And this is precisely what causes the engine to run rich in the midrange, where there is no adjustment screw to lean the midrange out.


Ed Cregger

buzzingb

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What is the largest prop that this engine will spin?? I know it is at about its limit with the 12X6 but I think it will spin a 13X6 but will be a little sluggish. Has anyone used anything larger than a 12X6 to give us a report?

buzzingb

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I have notice that the Super Tiger engines need a little warmup time before going full throttle. Have any of you noticed this?

buzzingb

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The weather has just been to bad to do any testing with the 51 the last week. Maybe the weather will break soon.

buzzingb

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Just got through testing a Super Tiger 90 and will be giving a report on that later. I have a 13X6 on it now and it doesn't even know that there is a prop on the front. I am thinking a 13X10 will be about right but we will seeeee. The plane is an Ultra Sport 40+ and will not be much of a load for this beast of an engine.

asmund

please tach that 13-6, is it an APC??

buzzingb

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I will get the tach on it soon but by the sound of it, I can't complain. I still have it rich, as it is 2stroking but not by much and a cloud of vapor was coming out the exhaust. I looked at the manual as saw that the break-in prop is 12X8 or 13-6. Recommended Prop Range for the 90 is 11X8through 13X7.

buzzingb

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To me the little 51 runs more like a 61 but it is far from the 90.

buzzingb

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I have been reading about wood props being lighter and better. I wonder if the 51 could spin a 13X6 in wood. One I ran a wood prop that I took the dremel to and smoothed it up some to look more like an APC but I wouldn't rev it up on the ground in fear of my life. I ran very well and never had a problem with it.

buzzingb

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Ok I need the help of some experts. I am reworking a Four Star 60 that a man crashed and plan on powering it with a low power engine I was thinking of maybe a 40 or 30 size but don't want to send extra money now being after Christamas and broke. I have to spare engines in the hangar and thery are a new Super Tiger 51 that I boutht with this one and a Laser 70 a fourstroke engine made in England. I am thinking about useing the 51. What do you think, I fly off of grass and don't want much power. I want it to just have enough power to take off of grass. I know the way the 51 runs it probally will excede this expectation by a lot as it runs like most 60 out there. The SIG company says to use from 60-75. I came up with this idea after helping an older gentleman get a trainer in the air with a low powered 40. Man we just barely got that thing in the air.

buzzingb

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Man OH Man the SAga continues as I have just traded for a Super Tiger 61 ABC and will be running it shortly. How does the 51 compare to this engine on a 12X6 APC??

pilotpete2

Hi Buzz,
I fly a 4 Star 60 with an old Saito .65, flys beautifuly, but no vertical performance. I would be inclined to try the .70 4 stroke you have on hand, the 4 Star series were designed with 4 stroke power in mind, fast flying is not what they are about.
Good luck,
Pete

buzzingb

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Just chiming in here to give a flight report. The 51 now has a few gallons through her and is running stronger and stronger. I now run it wideopen for much of the flight and the 12X6 is screaming much of that time. Ofter on landing I check the temp of the engine by feeling of it at different locations and it doesn't appear to be even breating hard to pull this 12X6 at these speeds. RPMs are at 11,200 on the ground and much more than that in the air.
I like to get the Ultra Sport pointed into the wind this time of year and just watch it fly stationary or sometimes even backwards. The Ultra Sport is a great plane to do touch and go landings also. Man the Ultra Sport is getting a workout.