My top choices are: (not in any order)

1) O.S. .40 FX
2) Thunder Tiger PRO 46 BB ABC
3) O.S. .46 FX
4) Magnum XLS-46 BB ABC
5) O.S. .46 AX

What do you guys think and why?

Thank you.

the OS 40 and 46Fx are not offered by tower any more your LHS might have one for sale.
TT pro 46 which seems like alot of guys like.
the magnum which is a OS clone and takes a bit of break in time to really get running solidly there also suposed to be good runners once the break in process is done.
the 46AX

my choice would be the 46 AX if you don't mind spending the 104.00 worth every penny IMO, easy break in and loads of power.

I would choose the OS 46 AX. I have three OS 1.20 AX's and two OS 75 AX engines, as well as a few other OS engines. All run well and are very strong. I would choose the OS, if it were me.

CGr

The .46-AX is probably the best engine in it's class and a really good value when you consider power, reliability and ease of use. Your Tower trainer will also fly just fine on an OS .46-LA if you aren't ready to got for the AX just yet.

Decisions like this are tough, I just went through all of this 2 mos. ago, so I can share my experience and hopefully it will help.

I got the Nexstar trainer ($100) OS 46AX ($105) and Futaba 6EX FM ($230). The only thing I would have done different is get the Tower Trainer, not the Nexstar there's no need to spend $100 on a trainer, not that the Nexstar is a bad plane. My plan is to fly something I really like/want to fly for my second plane. I will take all the electronics and engine out of the trainer and put it into a (low wing, nice looking) second plane, so it was definitely worth spending the few extra dollars on the OS it will be a reliable, well performing powerhouse for my next planes. Personally, I get this funny feeling of confidence and pride when I see the OS stickers on the side of my plane, and to me that's worth a couple of bucks.

Another thought is the needle valve this is a part of the engine, connected to the carburetor, that controls the amount of fuel flowing into the engine. When you are tuning the engine, this is where the adjustments are made. The OS and the Magnum have a 'remote needle valve' meaning that the needle is mounted at the rear of the engine. This gives your hand/fingers about 3.5 in. of clearance from the spinning propeller, which can really cause some damage. The Thunder Tiger has an angled needle valve, which might be a little more efficient, but doesn't give you as much clearance from the prop (maybe 2.5 in). I just started my engine for the first time, and I am really glad I didn't have to put my fingers anywhere near the propeller. People might say there is the possibility of the back plate of the engine breaking during a crash because of the remote needle. OS has made a change so this doesn't happen. I don't know if Magnum did the same.

Both Magnum and Thunder Tiger require a glow plug, which adds ~$5.00 to the cost. OS comes with one. Magnum requires a smaller prop for break-in, which adds ~$3.00. This means OS is really only $5.00 more than Thunder Tiger.

The Magnum manual says that fuel with Castor oil, more expensive, is REQUIRED for break in (you can ask about this say it's not mandatory, but if the manual says to do it, you should. These engines are probably not made with the same tolerances as OS and maybe need the extra lubrication to get things settled so as not to loose performance in the long term, also maybe this is why people say break-in is a little longer). Thunder Tiger recommends this fuel. OS 'suggests' it, but also says you don't really need it in the manual.

Again, it's a tough call. You can go to the top of the page, under User Reviews > compare products > compare engines and compare all 3. You will find people really like all of the above options, but OS has been around the longest, and has the most satisfied customers.

OS is made in Japan, Thunder Tiger in Korea (I'm pretty sure), and Magnum in China.

Hope this helps!

If you are like most of us, you will end up keeping the trainer and getting a true second plane. There are two thoughts on why.

First, you will always have a backup plane... just in case.

Second, most likely you will go back to the trainer and fly it, just for fun, and to get you back to basics of RC flight.

There is also a third one, but this is more up to the particular pilot. You may want to train someone some day and you will have a ready package to do just that for the person that does NOT have his/her own trainer. I've gone through that. I sold my Nexstar about two years after I solo'ed to someone that destroyed his trainer and needed one that he could just fly and not have to pay a high price. The guy was not working and had limited income (he was out of work because of a medical problem that he developed). So, I sold him my Nexstar for a real rediculous price.. but it was worth it.

Aaanyway, last year, I really wanted to get back to basics (see #2 above) AND we needed a club trainer, so the LHS gave me an excellent deal on a Hobbico Super Star RTF trainer that I still have, and still fly on occasion. It's fun and, as I said, gets me back to basics after flying some of the 'easier to fly' advanced stuff. (meaning, they fly straight but you HAVE TO FLY THEM, not glide when you feel threatened by mistakes). And, I've had several people up with it so far as an introduction to RC, using the buddy box, of couse.

Anyway, this is just a suggestion based on my several years of experience.

I see your in Utah. Riverton seems to be around 4500ft. Elevation plays a big part in this stuff. Now your not obligated here but these are just thoughts of what many do around New Mexico

There is an approximate 3% loss of power or performance for every 1000ft elevation. You install a 40 in your trainer and you'll have a flying POS. Don't go less than a 46. Also when choosing engines inthe future. Most planes have recommended engines sizes. Go with the larger of what is recommended.

Example of a 60-90 size engines are mainly the same casing size. I go with 90's. Nothing like spending $300 on an engine and be disappointed and thenstuck with it. With your altitude, you always need to consider the better of the choice

my favorite would be a super tigre .51 i have owned 3 of these engines and they purr like kittens. also you can re-use it in your next project, a .40 sized low wing or more lively model. also the .51 is the same size as a .45 just bored out. so mounting it is no problem.high quality and low cost. anyway thats my nickels worth of wisdom. . .

The best engine for the Tower Trainer .40 MkII ARF should weigh in around 12 to 13 ounces with muffler. Anything heavier than that will make it difficult to balance properly and the plane will be very nose heavy. Good choices for this airframe in no particular order include:

-Super Tigre G-34
-Magnum XLS .36
-Evolution .36 NT
-Thunder Tiger Pro .36
-Thunder Tiger GP-42
-O.S. Max .46 LA

The new O.S. Max .35 AX will be a good fit once it's available.

Engines that aren't good choices include most every .46 ball bearing 2-stroke on the market. The Tower Trainer .40 MkII ARF is a lightweight airframe that doesn't need the extra power to fly fast and it won't balance properly with a 16-to-19 ounce engine on the nose.

Good luck and good shopping!

My neighbor has an OS 40LA in his and it has power to spare.

Good call, i have a TT PRO.36 turning an APC 11x5 on my avistar and it flies it quite well, most people ask if it's a .40 or .46, my avistar is just under 5lbs and it did balance perfectly. I also have a TT PRO.46 but i think that would have been overkill, it's happy on my twist.

The Tower Trainer was desiggned with the Tower 40/46 in mind. The fuel line exits the firewall in the middle of the engine mount and routing it to the RNV or standard NV can be a problem. The tower NV is easier to get the fuel line attached than the others. If you choose another engine, orient the RNV so that the fuel nipple points up and not to left (facing the engine). Another annoying quirk it that the tank is so tight that it is necessary to remove the engine and push it back from the front. This has been my experience. The other thing that I might mentioned is that the engine is secured by straps and not actually bolted the the mount. The straps are bolted to the mount. This does allow you to move the engine forward or back a little to help with balancing the plane. Oh, and it will fly well with a 40, with the 46 you will be flying at half throttle most of the time.

I forgot to mention that I live in Utah and the average altitude is like 4327 feet....

Given that the "standard" "loss" for power is 3% per 1k feet, that gives me about a 12% "loss" in engine power....

.12x givin bhp of engine will give you my approximated hp rating.

I already figured it out for the .46ax to 1.44nhp and 1.06 for the .46la

so, if I were to get a 40 size engine, it will be underpowered for my application in SLC