harphunt

My LHS has both of these engines on sale @ $60 each. Any preference? Going in a Mid-Star. Thanks.

TT GP 42 ABC bushing
http://www3.towerhobbies.com/cgi-bin...?&I=LXKF92&P=0

ST BB ringed
http://www3.towerhobbies.com/cgi-bin...?&I=LXFV69&P=0

peace

w8ye

My Feedback: (16)

While they are both very good engines, the Super Tiger 40 has more power and would be your better choice to give you more flexibility in the future

spaceworm

The TT pro with ball bearings would be a better choice than the TT GP. I would go for the Super Tigre, because of it's heritage and also because it has ball bearing supported crankshaft. Likely this one was made in China instead of Italy, but I have heard the quality and running characteristics are still there. JMHIO.

Good luck.

Sincerely,

Richard

RCPAUL

My Feedback: (1)

I have both and like both. The carb on the ST is a little more difficult to adjust for some people. The TT is surprisingly powerful.

Paul

Konrad

I can't say if the ST has more power as I haven't plotted ether engine. I will say that the Super Tiger is the more desirable engine as it come with an automixure carb. This gives the engine much greater tractability in partial throttle settings, makes the engine much more tolerant to fuel tank placement and aircraft attitudes (It is much easier to work on your inverted maneuvers).

The TT GP series come with what I see as a crippling airbleed carb. It's strong point is that the bearing will hold up to the beginners tendency to use the prop as a landing aid or the engine as a ditch digger (ball bearing don't hold up well to impact damage). I think this engine uses ABN piston and cylinder construction as such it will break in (run in) much easier and faster than the ringed ST.

All the best,

Konrad

P.S.
I too second the Thunder Tiger Pro series of engine for the beginner.

As I suspected the Tower Hobbies site is mis leading. The engine is of an ANB construction NOT ABC.
http://www.tiger.com.tw/product/9041.html

rambler53

My Feedback: (494)

I'd take one ST 40 and give away 2 TT GP engines in a trade, and think I made out better.

Konrad

You and me both!

Add to that, the Super Tiger carb offers some ability to adjust the mid range fuel mixture and it becomes very hard to beat as a sport/beginners engine.

All the best,

Konrad

harphunt

I really appreciate the input! I had my eye on one of the TT Pro series at first, but considering either one is $30 less than its superior and the Midstar isn't really a speedster, I thought these would be a good deal.

peace

bigedmustafa

My Feedback: (2)

I own both and really like both of these engines. The Thunder Tiger GP-42 is very powerful and easy to tune. The Super Tigre GS-40 ringed is also very powerful and reliable, if a bit trickier to set up (throw away the exhaust gasket, thread lock and double-nut the exhaust bolts) and tune.

The biggest difference between the two? About 6 ounces of weight. The MidStar kit doesn't normally build particularly tail heavy, and the plane will likely balance more easily with the GP-42 (13 ounces w/ muffler) than the GS-40 (19 ounces with muffler). I'd recommend the Thunder Tiger GP-42 specifically for this reason.

Good luck and good shopping!

Konrad

The $30 of the PRO is well worth the price for an automixture carb. Please remember that the TT GP series and the OS FP/LA series of engines are built to a price point. I'm of the opinion that all R/C engines should have automixture carbs. If for no other reason than it helps with tank sep up and maintaining a much more consistent engine run while inverted. Yes, all trainers should allow a pilot to explore inverted flight!

earlwb

Well although the SuperTigre engine is likely the way to go, depending on the airplane or usage, the GP42 might be good to use. i can see using it on a trainer plane for example. Or where weight might be critical, the GP42 weighs less than the ST engine. So it is useful in certain applications.
But if you are a beginner and haven't used glow engine much if at all, the GP 42 might be the better way to go at first.
otherwise go for the ST engine.

bigedmustafa

My Feedback: (2)

Only the best engine manufacturers even offer plain bearing engines or air bleed carburetors: K&B, O.S. Max, Thunder Tiger, and Enya. Cheap engines from the People's Republic of China all feature twin needle (automixture? what is automatic about these?) carburetors and dual ball bearings: Aviastar, GMS, SK, JBA, VMax, Magnum, Sanye, Evolution, Super Tigre, Tower Hobbies, and ASP all feature dual ball bearings and twin needle carbs on their entire engine line.

Why do the top engine manufactures still offer air bleed carburetors? They are simple to tune, for one. Most Thunder Tiger GP-series engines run perfectly well with the air bleed screw simply turned to half open/half closed.

Air bleed carburetors are also less prone to being thrown off by minor weather changes when temperature, humidity, or barometric pressure varies from day to day. You can often tune an engine with an air bleed carburator once and then fly for weeks or months before adjusting it again.

An air bleed carburetor is just as capable of producing high power output as a twin needle carburetor. The Thunder Tiger GP-42 typically turns a 10x6 Master Airscrew S2 Scimitar prop at 13,500 rpm right out of the box on its first tank of 10% nitro fuel and the supplied Thunder Tiger glow plug. This is more similar to what the O.S. Max .46 AX turns rather than the O.S. Max .40 LA. Enya's air bleed carburetors are also no hinderence to reliability or high performance.

Ball bearings and twin needle carburetors have their advantages, but neither is a guarantee of quality or performance.

If harphunt is interested in a dual ball bearing engine with a twin needle carburetor for his Sig MidStar kit, he could look at the Thunder Tiger Pro .36 engine. It should be priced under the cost of the Pro .40 or Pro .46, but would still provide plenty of reliable power for the MidStar. The Pro .36 weighs in very close to the GP-42's 13 ounces, and should balance the plane nicely without needing to add tail weight.

Konrad

Mid Star?
This is a mid wing aileron trainer? If so there is little benefit to using an air bleed carb. The sleeve bearings still have some desirable characteristics. As for mass and balance I seem to recall that a 4 cell 1200mAh battery pack back at the trailing edge of the wing would balance heavy cased engine rather well. I think I have seem this ship with light cased engine needing the battery placed under the fuel tank.

My disclaimer I have never owned a Mid Star.

Something else to think of The ST or the Pro will allow you to grow with those engines. That having been said it might be wise from a long term view to step up to the 7.5 cc class of engine.

All the best

harphunt

I didn't even consider the carb type. I was more concerned with non-ringed vs bushing/ball bearing vs ringed. Great info. Thanks.

peace

Konrad

For the same choke area the automixture carb is no more sensitive to atmospheric changes than the air bleed carb.

Now because the automixture carb automatically restricts the fuel metering orifice as the throttle is closed. It allows the engine designer to choose a carb with a greater choke area and still control the fuel mixture very accurately at partial throttle. An air bleed carb can't handle near as wide of a power or RPM swing that the automixture carb can. An auto mixture carb can be designed to handle the reversionary pulse at idle much better than an air bleed carb. As a result it can allow for more radical crank inlet timing while still maintaing good mixture control though out the whole throttle range.

While some might think that an air bleed can produce as much power as an automixture carb it really can't and maintain near as actuate a mixture control as the automixture carb at part throttle. As for peak power it is the choke area of the carb that limits the airflow not the fuel metering circuit. (Most speed engines actually just use a fixed venturi (opening) of one given size)

Because of the inherent design constraints with the air bleed, you now only find them on modestly powered R/C engines (entry level or low powered four cycles)

I actually find air bleed carbs rather difficult to tune as the fule level is hyper critical. There is often a huge performance change going inverted unless the fuel tank is on center. ( I size my power plants so most of my flights are in the 3/4 to full throttle position).

Please don't confuse an automixture carb with air bleed idle adjust ( like the Fox easy adjust caeb or the early Saito 1.20 carb or many of the Enya "G" carbs) with an air bleed carb that has no way of changing the fuel metering orifice (such as the many earlier engines from the 60s and the carbs found on the OS FP/LA series and Thunder Tiger GP series). Today the true air bleed carb is found on engines that are built to a price point.

I use the term automixture to cover any carb that automatically adjusts the fuel metering orifice as the throttle position is changed. There are many types of carbs that do this. Today the twin needle, tube over slot and slotted disk are all automixture carbs.

I think I got the term from Peter Chinn.

Engine quality is another issue I'll save for another thread. But I will say that most of the engines from China (both Chinas) are often much better than those coming from a two letter engine manufacture from some island nation in the pacific ocean (well for the sport flier). I still think that the high performance market is still best served by American and European engine manufactures.

All the best,

Konrad

NM2K

My Feedback: (14)

Both are good engines, but the Super Tigre will run well on a wider selection of fuel types, where as the plain bearing TT 42 GP will get hot when running mostly synthetic oil. Especially if the synthetic oil is less than 20% by volume of the gallon of fuel. Adding 4 ozs. of castor oil would go a long way in extending the TT's useful lifespan. Another disadvantage of the TT .42 GP is the plastic backplate. The first ones used a plastic backplate that was notorious for leaking air and causing a multitude of problems. I don't know if TT changed it out for a metal backplate or not.

The Super Tigre GS-40 will amaze you with its power once broken-in. Once broken-in and set properly, it will only need an occasional tweak of the high speed needle (HSN) valve. This ST GS-40 is a revver and runs best while turning a 10x6 propeller. Of course, you can vary the propeller to suit the model. You won't hurt the engine by using an 11x5 or 6 or even a 12x5 or 6. Just be sure to keep the high speed mixture a little on the rich side, regardless of the size propeller that is being used.

I have a bunch of engines, but I don't have a Super Tigre GS-40, though I have helped others get theirs broken-in and flying successfully. I'm going to have to scour eBay for a deal on a NIB sample.

Don't worry about the few ounces of weight that the ST has over the TT. Rossi engines are heavy too and for the same reason. Heavier constructed engines will hold up much longer than ultra light weight engines. Just ask those fellows that are constantly replacing ball bearings in the really lightly built engines.



Ed Cregger

Konrad

Another fine point in favor of the heavy cased (full size) engine.

All the best,

Quikturn

My Feedback: (12)

I have owned a midstar 40 as my second airplane and I put a used OS 40FSR ABC engine in it. It flew fine on this engine but I ended up wanting more power for grass field take offs, better climb and more speed. I then put a Tower Hobbies 46 (dual ball bearing, ABC) in it and it flew much better. CG was not an issue.

Taking a long view approach, I would recommend a good ball bearing engine such as the Super Tigre GS-40, or better yet the GS-45. If you need it, have someone help you break it in and set it up.

As you get use to the airplane, you'll want more power.

BTW, about 2 weeks ago I watched a club member fly his 4 star 40 with a ST 40 engine in it and was surprised how powerful and fast it was.

bigedmustafa

My Feedback: (2)

carburetor = twin needle or air bleed

crank shaft support = ball bearings or plain bearing (bronze bushing)

piston/sleeve type = ringed or non-ringed/ABC

In a nutshell (and there will be plenty of exceptions to the generalities I'm about to make):

-a twin needle carburetor can be more finely adjusted, but often requires more frequent tuning than an air bleed type

-an air bleed carburetor doesn't require frequent adjustment, but can't be tuned as precisely as a twin needle carburetor

-a ball bearing supported crankshaft engine doesn't need castor oil for lubrication, but is more succeptable to corrosion if not maintained properly compared to plain bearings

-a plain bearing supported crankshaft engine runs better and lasts longer with castor oil in the fuel, but is lower maintenance and won't rust compared to ball bearings

-a ringed piston/sleeve set will require a longer break-in, but will last a long time and be easy to rebuild when the ring wears out compared to ringless ABC/ABN

-a ringless ABC/ABN-type piston breaks in quickly, but will be more expensive to rebuild when the piston/sleeve wears out than a ringed engine would

As for the Thunder Tiger GP-42, it has a metal backplate. The higher compression is one reason why the GP-42 is more powerful than the O.S. .40 LA or .46 LA (the O.S. LA-series engines have plastic backplates); with the GP-42 out-turning the .46 LA by about 1,500 rpm on a Master Airscrew 10x6 G3 with the same plug and fuel (at least at Omaha's elevation, anyway). I own two GP-42s and an old GP-40, along with two GP-07 engines and a GP-61. I've never seen a Thunder Tiger GP-series engine with a plastic backplate, but they certainly could have built them that way at one time.

In any event, I'm not trying to drag out this discussion any more than I already have. Like I said, I own both engines and I like both engines. If harphunt was looking for an engine for a Goldberg Tiger 2 or a .40-size warbird, I'd have recommended the GS-40 instead, because on those airframes the extra nose weight would more likely be advantageous.

mikegordon10

The ST takes longer to break in and thus lasts longer.

THERCAV8R

My Feedback: (283)

OK You asked for an opinion so here is mine based on facts. In Short between the two engines you asked about the Super Tigre is by far the best. It has dual bearings and the TT does not. I have had several super tigre engines and have two on my P-38. Super Tigre engines are very reliable. I have been competing in the club forty races this summer and the TT42 is the engine that the novice calss uses and I have seen nothing but trouble out of that engine. Rarely do all the pilots in each heat finish the race usually one or two have to land beacause the engine leans out or quits all together. First it has no power if you can get it to run consistanly. Second the carb seems to be very hard to dial in. The bushing engine over heats easier than a bearing engine and causes the mixture problem so you have to leave a little rich. I fly in the advanced class and use the TTpro40. I have been very impressed with this engine it has plenty of power and is very fast and easy to break in and has Ball bearings. Really in short bushinged engines will fly a model if you take the time to break them in and adjust them but their life is short because on no bearings.

Konrad

Not a true statement. There is no relationship between the breaking in cycle time and the longevity of the engine design. Now a properly broken in engine will out last and out perform an improperly broken in engine.

All the best,

Konrad

jaka

Hi!
Both are good engines that will fly your plane just fine. The Super-Tigre is a little more powerful if propped right (Using an APC or RAM 10x7 , 11x5 or 11x6) than the plain bearinged Thunder Tiger,and both will throttle exactly as good and hold up equally good over time.
The plain bearinged TT.42 has much simpler carb that is very easy to set as it doesn't have an idle needle that controls the incoming fuel , just a air bleed needle that controls the incoming air to the carb at idle.
It's a fool proof carb, dead reliable!!

Konrad

Actually the throttle barrel controls the air supply to the engine at both idle and full throttle settings. The air bleed controles the pressure drop across the fuel discharge port ( at the spray bar) This weaker pressure drop at idle is what retards the fuel flow. A major problem with our toy engines is that at idle one needs all the pressure drop one can muster to help with fuel draw. By the nature of the air bleed design carb much of this needed pressure drop is lost. Again this is why tank placement is so critical with the air bleed carb.

All the best,

Konrad

Taurus Flyer

Gents, facts, no opinion but one advice,

Added is a piece of the article of Tom Brett about his visit and winning the World Championships in 1962.

As normally he did fly his planes with the K & B 45 RC, to compare with the TT GP 42 ABC bushing
Very reliable engine, plain bearing for crankshaft and bleed air carburetor you can be world champion with that type of engine, I have only one advice, never combine exhaust pressure with a bleed air carburetor.

Cees