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Tower .75 v's ST G90
I have a question for Tower .75 and ST G90 pilots. How much stronger is a G90 than a Tower .75? I have a GP Shoestring that I have run 10 gallons through this summer with my TH .75, but I am looking for a little more speed. The TH .75 turns a Pro Zinger 12-8 at 12,000+, and a 13-6 APC at about the same, but I want more speed. A 12" prop is the smallest dia I would like to spin. The Tower/Bisson combo has worked flawlessly, but I aquired a G90/Bisson in a plane deal lately, and it is laying on the bench. I am a little hesitant to swap them do to the stories I hear about G90's and there midrange, and if it isn't really going to be any stronger. I am not looking to spin a 14" prop, I would like to spion something in the 12-9 12-12 range.:D
I can bolt it to the stand and run a gallon through it to finish the breakin. I think it is a really low time engine. The clyinder and ring look like new.:D |
RE: Tower .75 v's ST G90
The ST G90 is more of a torque engine than the TH 75. Probably should use a little more prop.
I run a APC 14-6 on mine. It does 11,000. It would wrap up pretty tight with a 13-6 so I settled on the 14-6 for my kind of flying Many people use the G 90 and have no trouble with the midrange or with adjusting the carb. |
RE: Tower .75 v's ST G90
Just bought a ST90 and really like it. Still breaking it in and have experienced the rough mid-range. I read up on the engine and the fix was remarkably easy. I installed an OS F plug and took about 30 seconds of my time to rotate the spray bar about 15 degrees. After a re-tune there was a marked improvement in the mid-range. I expect a nominal running quality improvement as the engine continues to break-in. The engine is definitely a powerhouse. There is a Super Tigre manufacturer forum on here that will support my comments.
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RE: Tower .75 v's ST G90
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RE: Tower .75 v's ST G90
So your saying it probaly would not be worth the effort to repower it. I was just thinking of a few extra cubes.:D The Tower .75 likes to turn up some pretty good rpm.:D I thought somebody might have some insight on a 12-10 or something similar.:D
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RE: Tower .75 v's ST G90
Get an OS .90 or 1.08 FSR, or a YS .91 or 1.10 if you want horse power. ;)
The S.T. .90 is a good motor, but it's not a speed motor. FBD. :D |
RE: Tower .75 v's ST G90
I will probaly just stay with the Tower .75 then, it was just a thought since the G90 is just sitting here.:D You cannot beat the way the .75 runs though. I have never had any issues with it at all.:D
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RE: Tower .75 v's ST G90
I really don't think you will see much of a difference. I love my ST .91, but the muffler on the Tower .75 tends to help it unload with a tuning effect. I hear the ST is a torquer all the time, but mine loves the smaller apc props (13x6 and 12x8). I also run a 14x4W APC on it and it runs great at higher rpm.
I've also heard the ST needs a long break in time, but that was not the case with mine. With the 13x6 prop I was in the air after about 3-4 minutes on the ground. I immediately went to full throttle, set the high needle, pulled it back to idle and got that close. I bumped the throttle to full and it transitioned great. I did this a couple times and it ran unbelievably well for a first run on a ringed motor. I decided why not fly it and launced my chipmunk. The motor ran great that day, and every time since. Probably my most reliable motor I have. Mine may be exceptional, but I would not hesitate in recommending this motor for general sport use to anyone. And mine is a Chinease version to boot! |
RE: Tower .75 v's ST G90
motorman37
It is a shame that Super Tigre has been bashed on RCU. Stories about mid-range problems, bad idle characteristics and the like. The Super Tigre is a fine, precision buildt engine that does not deserve the bad reputation it has acquired because of persons who don't know how to tune them. There is post after post after post on how to tune the Super Tigre plus a whole forum dedicated to it's support. Yet a few complaints by people who obviously don't know how to tune them or don't know how to read and the first thing you know you have to buy an different carb or have change the muffler to get them to run right. The Super Tigre has a long break in period due to it being a precision built, close tolerance engine, but once it is broken in, IMO there is no finer engine on the market. Especially for the price. Mount it, tune it, and fly it. Once it is broken in and properly tuned, you will love it. Regards, doubledee |
RE: Tower .75 v's ST G90
ORIGINAL: doubledee It is a shame that Super Tigre has been bashed on RCU. Stories about mid-range problems, bad idle characteristics and the like. The Super Tigre is a fine, precision buildt engine that does not deserve the bad reputation it has acquired because of persons who don't know how to tune them. After carefully examining the ST carburetors, I can see *why* these engines have a fat midrange and it *is* a design fault, probably a legacy from the days when engines didn't need low idles and most people treated the throttle like a switch. SuperTigre engines are well built -- there's no question about that -- but their carburetors are just 20 years out of date, that's all. There is post after post after post on how to tune the Super Tigre plus a whole forum dedicated to it's support. Yet a few complaints by people who obviously don't know how to tune them or don't know how to read and the first thing you know you have to buy an different carb or have change the muffler to get them to run right. The Super Tigre has a long break in period due to it being a precision built, close tolerance engine, but once it is broken in, IMO there is no finer engine on the market. Especially for the price. Ringed SuperTigre engines take longer break-in than your average ABC engine but that's because you're wearing steel against steel rather than aluminum against chrome. It's also because an ABC engine tends ot be made to far tighter tolerances -- quite the opposite of what you're saying. The truth is that the ST engines are well-made but have a poorly designed (outdated) carburetor which makes their tuning a far more complexs and difficult task than it should be. If they made the move to a more conventional (modern) design, they'd turn a good engine into a great engine and you wouldn't see people having to fart around with 4-stroke plugs, fruitlessly twisting spraybars, wasting gallons of fuel waiting for them to wear enough that they'll transition half-well, and generally *****ing about a fat midrange that shouldn't be there. I have several STs by the way and will buy more -- they're good value but far from the best 90-sized 2-stroke on the market. |
RE: Tower .75 v's ST G90
What makes O S better in the minds of some is their carburation. They set out to capture the market with an easy to adjust, non critical carb. S T has just modified a very old design, but it works very well. The problem, and I say this with hesitation is that the user has to be smarter than the engine to get it work right. S T is not a beginner's engine, and if they wanted to makeover their carb design, they would have done so long ago. S T also was the first to utilize true ABC constrution and the no no with the older(early 80's and back) engines was never to turn the engine over and leave it at top dead; the rod would sometimes take a hit, the sleeve fit was very tight. The pattern guys running the 61's took as long as 6 months to break in the engine, meaning the character of the performance would change over time.
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RE: Tower .75 v's ST G90
ORIGINAL: XJet ORIGINAL: doubledee It is a shame that Super Tigre has been bashed on RCU. Stories about mid-range problems, bad idle characteristics and the like. The Super Tigre is a fine, precision buildt engine that does not deserve the bad reputation it has acquired because of persons who don't know how to tune them. After carefully examining the ST carburetors, I can see *why* these engines have a fat midrange and it *is* a design fault, probably a legacy from the days when engines didn't need low idles and most people treated the throttle like a switch. SuperTigre engines are well built -- there's no question about that -- but their carburetors are just 20 years out of date, that's all. There is post after post after post on how to tune the Super Tigre plus a whole forum dedicated to it's support. Yet a few complaints by people who obviously don't know how to tune them or don't know how to read and the first thing you know you have to buy an different carb or have change the muffler to get them to run right. The Super Tigre has a long break in period due to it being a precision built, close tolerance engine, but once it is broken in, IMO there is no finer engine on the market. Especially for the price. Ringed SuperTigre engines take longer break-in than your average ABC engine but that's because you're wearing steel against steel rather than aluminum against chrome. It's also because an ABC engine tends ot be made to far tighter tolerances -- quite the opposite of what you're saying. The truth is that the ST engines are well-made but have a poorly designed (outdated) carburetor which makes their tuning a far more complexs and difficult task than it should be. If they made the move to a more conventional (modern) design, they'd turn a good engine into a great engine and you wouldn't see people having to fart around with 4-stroke plugs, fruitlessly twisting spraybars, wasting gallons of fuel waiting for them to wear enough that they'll transition half-well, and generally *****ing about a fat midrange that shouldn't be there. I have several STs by the way and will buy more -- they're good value but far from the best 90-sized 2-stroke on the market. In the "olden days", the only time you had to mess around with a ST carb (adjusting the midrange) was when you were trying to smooth out the transition between high and low speed when using a tuned pipe. The older carb designs were just fine when ran with a muffler. These newer, different looking ST carbs do not work the same as the older designs that were on the G60 Bluehead and even X series of engines. I agree that these newer carbs should be replaced with a better design. Of course, if they did that, they would then increase the price, I'll betcha. <G> |
RE: Tower .75 v's ST G90
. . and just why doesn't Tower have a 90?
I can't figure it. |
RE: Tower .75 v's ST G90
Wait, let me get my fire extinguisher and put out the fire I started. I didn't say other engines were no good and I also entered the caveat that it was my opinion the ST engines were the finest on the market for the price. I have tried other engines and they ran well, but I still think the ST is the best. I haven't done any side by side comparisons but I do know what I like and don't like, and I like Super Tigre and will continue to buy them exclusive to others. Ease of tuning and short break in period does not necessarily make an engine better. But I guess in these days of instant gratification that is the way to go.
Everyone is entitled to their opinion. All I was trying to point out was, Super Tigre engines are fine engines and if properly adjusted will run fine, develope a lot of power and last a very long time. I was not bashing or flaming any of the many other brands available out there. After all, the original question was about the Tower .75 and the ST G90, no other brands were mentioned. Regards, doubledee |
RE: Tower .75 v's ST G90
I am not asking about the build quality or heritage, I am asking about the performance. The tower .75 has been nothing but spectacular from the first tank through the tenth gallon so far this summer, I was just asking how it compares to the G90 power wise. My TH.75 is truning a 13-6 @ 12,000 plus on WC 10% with a Bisson pitts, and the transition is instant.:D
I have no doubt, the ST G90 is harder to adjust but that does not worry me. I have never had an engine that I could not tame. But is it worth the swap if there is only a negliable difference.:eek: I am not looking for big prop performance, a 12' or 13" prop is what is required for the 7 lb "Shoestring'. What does it spin a 12-8,9,10 or a 13-6,8?:eek: |
RE: Tower .75 v's ST G90
I have mine on a 60-1.08 sized Ugly Stick. Believe the plane started out as a Joss Stick. Wing has been beefed up as well as the fuse and it has a great big set of home-made landing gear on it that you could swing a 20" prop with if you wanted...so it's a heavy beast. With my ST 90 I am swinging a 13x6 MAS right at 12,000 RPM static on a 90 degree day. Am still a little rich but not much. That translates into being able to have a short take-off run and pull straight vertical and accelerate rapidly. This should give you an indication of whether it will fly your plane. I really like the engine and have yet to ever have a dead stick. Not quite a gallon through it yet. As I understand it there is a baffle in the muffler that, when removed, gives additional performance. Am satisfied with mine so will leave it.
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RE: Tower .75 v's ST G90
The point is, I am allready getting 12,000 on a APC 13-6 with the Tower .75. I guess there is not much of a difference.:eek:
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RE: Tower .75 v's ST G90
I think generally, you might have to do a basic addressing of the prop sizes commensurate to the engine displacement. Without ever running the .75, I would think a 13" prop would get you close, where the 90 might look at say a 14/8. BTW, a few years back, M.A.N. did a 60 size shootout and if I'm not mistaken, the Tower engine was there at the top. I don't think we can characterize the likes of the Tower 75 as an off brand engine anymore.
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RE: Tower .75 v's ST G90
how about 12700 rpm on apc 13-6? 91 fx fitted with tower 75 muffler and os hyper 50 helicarb. I know this isn`t exactly on topic but it is pretty good, ehhh???
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RE: Tower .75 v's ST G90
ORIGINAL: Flyboy Dave Get an OS .90 or 1.08 FSR, or a YS .91 or 1.10 if you want horse power. ;) The S.T. .90 is a good motor, but it's not a speed motor. FBD. :D -------------- You're as old fashioned as I am, Dave. They don't make the 1.08 FSR any longer and haven't for a while now. <G> :D |
RE: Tower .75 v's ST G90
One major problem area with tuning ST carbs is in the range of low speed adjustment. The range for a perfect three minute idle without loading or drying out is within 1/8th turn, or for older ones, three clicks. Once you find that they will usually still fourcycle around 50%. There are some manufacturing variations, some worse than others. If you like to use part throttle allot then they are almost never ideal. Tower should have made OS the cheap line and ST high-end.
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RE: Tower .75 v's ST G90
Why take a chance on an engine that has so many reported problems (Super Tiger). The Tower Hobbies 75 on the other hand is an engine that is hard to beat and ready to run anytime you take it out. You may have noticed but it pull rust as well or better than a 90. If Tower would get their China manufacturer to build a 91, what do you think it would pull like, probally a 100 or 120 size??? Anyway for $90 I haven't seen another engine that can beat the 75.
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RE: Tower .75 v's ST G90
Motorman37,
There is an old adage, "If it ain't broke, don't fix it", if you are getting good performance out of your Tower .75 leave it on the airplane and enjoy. Apparently everyting is set up and it runs fine, I personally would leave it alone rather than swap out engines for limited, if any, gain. Regards, doubledee |
RE: Tower .75 v's ST G90
Well, I will put it up for sale shortly.:D I also really wish Tower would make a .90.:eek:
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RE: Tower .75 v's ST G90
Isn't the G90 a bit HEAVIER than the Tower 75? Balance issues, etc....
Thanks, Ernie |
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