How long have these engines been in production, and what sizes are they available in?
Thanks

the ax motors are only a year or two old. they are powerful motors and refined form the fx motor. So far all that tower hobbies has right now is a .46 ax

Nothing bad has been reported about them so far.

Enjoy,

Jim

Check out the reviews of the engine on this site. Everything is positive. Its supposed to be an improved version of the 46FX. I have a 40 and a 46 FX and they are great engines!!

A couple of AX on my field and they are running great.

I haven't heard of any problems with them.

However, I have some reservations. The plastic back covers on the LA line have proven to be prone to cracking or leaking over the long haul. The plastic needle valve assemblies on the LA's have also been problem spots for some folks. I don't know if they improved those parts for the AX. I hope so. So far, I haven't heard of any having problems, so that's a good sign.

I also don't like that the head is held on by just 4 bolts instead of 6. Again, I've not seen any leak around the head, but it's something to watch for.

Personally, I'd have paied an extra few bucks for metal parts. But that's just me.

Well, the AX has an aluminum backplate so that isn't a factor I guess. I have not heard of any needle valve problems on the 2 AX engines on my field. They are very happy with them. No head leaks either. This is not the LOW end LA engine, this IS a good engine. I would assume that OS had a reason for switching to 4 bolts on the head and I doubt that it was to save money. An engine that leaks and gets bad mouthed won't sell and THAT doesn't save money. They say they have redesigned the needle valve for easier tuning also.
Guys on my field don't need to fiddle with theirs at all, it seems

Super Tigre had some 4-bolt heads on .60s many years ago. the reason they worked and also the reason the AX should be OK is the cylinder and head are designed differently than for a 6-bolt head. The cylinder extends up above the block/crankcase and the head is grooved or machined out to fit down over this. If you take the head off an FX and an AX you'll immediately see the difference.

The reason for the 4-bolt head is the wider front transfer port passage which would have not been possible with a 6-bolt head.

The plastic needle valve assenbly seems to be air tight, at least. The fuel nipple is also 90 degrees from the needle, making it easier to hook up the fuel line after re-fueling. The plastic needle assembly can also be replaced. The cast-on FX backplate/needle assembly required you to buy a whole new backplate. The AX one can also be rotated to different positions and screwed to the firewall.

Finally, the lower portion of the AX needle assembly is relieved so you have a straight shot at the upper right engine mount bolt. I consider that great enginering from a user standpoint.

46AX superceded the 46FX and has been available for about a year. AX is currently available only as the 46.

IME it is as reliable as its predecessor, and marginally more powerful. Only issue I can fault with it is the adjustment of the low speed needle. With prolonged ground idling with that enlargened boost port and typically high contemporary timing, the AX tends to splutter when the throttle is advanced before it picks up, and judiciously conservative rate of advance makes no difference. Adjusting (leaning) the low speed needle to completely eliminate this will result in too lean a bottom end for normal (in flight or non-prolonged) idle operation. The workaround is to set the idle RPM itself higher than I perceive as desirable, which masks the problem and reduces the severity (dead cut) in effect. Though the OS AX carb is superior to the MAG and doesn't present the problem in transition, the symptom is typically Super Tigrerish, arguably unavoidable in accommodating that huge boost port from where the AX undoubtedly gets its "more powerful than the FX" grunt. It's something it appears we just have to live with, adapting minimum idle RPM and throttling technique to accomodate it. Either that or buy a TT Pro-46?

I have 2 of the 46AX engines... one in a profile fun fly and the other in a pattern plane. Both work great. Start really easily, and run well. (no deadsticks besides setting the low end needle too lean once) My fault ! Had them almost a year now.

I also have 2 OS .46 AX's, one in a Tiger 2 and the other in a U Can Do 46. The one in the U Can Do has been crashed about 5 times.
Once, left overnite in a damp cornfield. Darn thing always starts and after one tank of running, don't even need an electric starter, will start with a twist of the spinner. Both of these run extremely well unlike the finnicky evo .46 I have in a H9 Twist.

Dave...

I have an .46AX and it is reliable and powerful. Best bang for the buck as far as .46's go. I had a crash with my Big Stik and broke off the needle valve. Does anyone know where I can get a replacement or if some other needle valve will work with it?

Best I could find was complete valve assy. os does not list just the needle.
In fact the Tower pg below states the needle is not available as a separate item. If you use different needle, you will probably compromise tuning, your choice.

http://www2.towerhobbies.com/cgi-bin...00&FVPROFIL=++
$18

if you need bracket, here it is:
http://www2.towerhobbies.com/cgi-bin...?&I=LXGCV2&P=V

Good luck.

Whilst concurring heartily that the OS .46AX is generally reliable and certainly powerful, your intel sources are providing you with effective disinformation if categorising it "best bang for the buck" as far as .46's go". Perhaps 20 years ago OS were that, but unquestionably Thunder Tiger's Pro-46 dominates that title today. After you've tried one, you'll never return to an OS .46 for any logical reason. All of what the OS is without the precedental (FX) risk of liner peeling problem and the advantage of a front mounted N/V, but at 70% of the OS price in the US. For those of us buying internationally (AU), the price advantage is even better. Effective cost of the TT unit for me is about 55% of local distribution OS .46AX retail street pricing.

First I am not downplaying TT engines as I have no experience with them.

The AX engines are ABL plated and not ABC as FX were. I also have seen no problems with either BTW. I have heard that some have had trouble.

The discount is nice for you but I don't believe worth flying to Australia to order an engine. Nor am I going to worry about the relatively small difference in the U.S. to determine MY choice.

I certainly find the AX among the Best-Bang-For-The-Buck engines.

Thank you for your effort. After writing the post I went to tower's site and found it. I ordered one today.

I will take your advice and try one if I buy another .46 2 banger. I think I may try to go bigger on my next project and with a Saito 100 4 stroke. I will also probably get the Hangar 9 p51 so that I can put those cool pipes on it that stick out like real headers from the cowl.

The TT Pro-46 IS a better engine for the price.... But the OS's I have had FSR, SF, FX have been great---- The AX's I have seen run and flown (others) have been great also-

HEY i wanted a prop like that !!! what sixe is it ?

I have the AX on my ultrastick 40 with a Pitts Pipe ,, that thing S-C-R-E-A-M-S !!! the engine has oh......3 gallons of fuel through it and WOW i love it . If they made a .50AX i would buy it in a second flat ...

You will get more power and generate more thrust from a 2 blade prop than a 3. My experience tells me that APC props are better than MAS.

Generally you would go down an inch in dia. when moving to a 3 blade. e.g. 11x6 (2 blade)=10x6 (3 blade).

Flieger Abwehr- Pardon the intrusion but he asked for the brand, size and where to get it, not a propulsion theory lecture. Maybe he just likes the way it looks and wants one for show. Not flaming, so don't take as an attack.

and they dont even make 10x6 3 blade [&o]

Don't know which "they" you are referring to. Try this if you want :

http://www2.towerhobbies.com/cgi-bin...23&FVPROFIL=++

Yes, not MAS or APC but still 10x6 3 blade

Bruce

OK. duh...Sorry. It is an Master Airscrew and you are probably right. I think it's an 9x7 or 8. I will double check it and ring back in with an answer. The reason I bought it was to provide additional clearance for the front ski with the trike gear. With the 11x6 props installed I hit a couple of bumps that caused the front ski to rotate too far forward (even with set screws super tight) and broke a couple of props. The shorter 3 blade corrected this problem but reduced thrust significantly.