I am at a cross roads with respect to which engine I will purchase for my new Dirty Birdy .40. I flew one of these wonderful planes about 25 years ago (powered by O.S. 40 FSR) and loved the way it flew. I have re-entered this great hobby and am in the process of starting consrtuction of this new plane. This has only been possible with the help of some great people here on this forum!! I found someone (on this forum) that had a set of plans for this plane. This thoughtfull person had a copy made of his plans and sent them to me!!! What a great forum we have here!!

Anyway, I have narrowed my engine selection down to (3) finalist, they are: Thunder Tiger PRO .46 ABC, the Magnum XLS .46, or the Magnum .52 XLS. I know that more power is better, but I am concerned about the physican size and weight of the Magnum .52XLS. I must also mention that I have no experience with either Thunder Tiger or Magnum engines in the past. The only engines that I have had experience with are Super Tigre and O.S. engines. I also am on a budget (under $100) for the engine.

Any comments/suggestions would be a great help.

Thanks,

Kestrel, I have flown models with all three of the engines you mention.

Powerwise, the ascending order is Magnum XLS, TT .46 Pro and, by quite a margin, the Magnum .52 XLS.

The .52 is definitely the strongest, seemingly by even more than its extra capacity would suggest. With an APC 11 x 6 as a test prop, the Magnum .46 will do mid elevens, the TT .46 Pro will do about 12K and the Magnum .52 will do around 13K.

Magnums can differ from engine to engine. Some can be sweet and others can be a little less than happy in their carburation. The .52 is a real hotrod, but will ultimately frag its stock rear bearing under hard use conditions and has been known to snap its crank between the bearings where the inlet port is machined. With new high quality replacement bearings, the .52 can be pretty reliable.

The Thunder Tiger .46 Pro is a real sweetheart and, although it's not as powerful as the .52 in static tests, it will unload really well in a pattern ship with a prop like the APC 11 x 6. Its bearings are durable and, at our field at least, the TT .46 Pro has proven to be among the most reliable and consistent of engines.

If you can sell the "CEO" a 10% overrun on your budget, consider the excellent AX .46 as well.

Edited to add: The .52 is essentially the same size and weight as the .46s. There's no penalty there.

Tom,

You picked all good engines. By the way if you had experience with Super Tigre, you may want to check out the Super Tigre GS .45 or the G .51 from Tower Hobbies. They are under your budget. On the .40 size Dirty Birdy, may I suggest swing a 10x7 rather than 11x6 for better ground clearance. One thing about Hot Rod motors is sometimes they get tough to tune. Oh yes, the G51 is also the same size and weight of a typical .46 sized engine. I like all your choices...

Harry,

Thanks for all your info!! I think I can convince the "CEO" to let me spend an extra 10%. Since writing my original post, I have looked at the "Engine Guide" section here on this forum and compared the (3) engines that I listed above against the OS 46AX and found that the OS 46AX had an overall higher rating then the other (3) that I was originally considering. Since I have experience with the OS brand (and have had great luck with), I just might go with the 46AX after all.

Thanks again,

Thanks for your suggestions!! I have owned Super Tigre engines in the past, but have had so-so luck with them. The best Super Tigre engine that I owned was the "Blue Head" .60 (in my Mach 1). That engine idled soooo nice, you could almost count the revolutions of the prop!!! Great engine. I also had a Super Tigre 46 about 20 years ago with limited success. Yes, you are right, the prop size will be a factor with the bigger engine. I guess I over looked that in my original evaluation. Thanks!! I have owned more O.S. engines then any other brand. I guess that I just had good luck with them. Anyway, I have not ruled out Super Tigre just yet, but I will have to make a final choice within the next couple of weeks or so.

Thanks agian for your suggestions,

Kestrel,

I was an OS "die hard" fan, but I find the older models to be much "sweeter" then the current ones. Don't expect the AX to be as good as your FSR. I'd take an FSR or SF over todays models any time.

If I were to buy a 46 today I'd buy the MVVS 49. It's true ABC and will last a life time. Lookup Dar Zeelon or PE for details.

JUST MY 0.02$ I AM NOT TRYING TO START ANOTHER "I HATE/LOVE OS" WAR.

One other thing about the Super Tigre engines, the stock muffler certainly takes away from the overall appearance of the engine. From what I have been reading about these (2) engines, they seem to be pretty reliable. I am still looking at these engines, but those mufflers....... Are there any other aftermarket mufflers that will fit the G45 or G51 at a reasonable price?

I had an O.S. .46AX in a Graupner Skylark, which is a .46 size pattern plane, I believe slightly larger than the DB40 (57" wing span). The .46 AX did a very nice job pulling it thru any pattern maneuvers you would care to do, and will do a great job with your DB 40.

Now, if you can really get the CEO to extend the budget.... I replaced the .46 AX with a .55 AX, and WOW!! Buckle up! Now it has "ballistic" type performance, and with the stock muffler no less. Much better than 1:1 thrust/weight ratio.

I suspect that you would get similar results from the Magnum .52.

Cheers,
Robert

Anyone have any experience with the JBA 46 engine? It has high ratings in the product guide/engine review area on this forum.

JBA and SK engines are great and cheapest.Take a look at www.kangkeusa.com

But I think you will get the same power from the Magnum 52 as th O.S AX 55, but the Magnum is cheaper and has ABC setup. Hence, no liner peeling issues.

The only downside to the Magnum .52 versus the OS .55AX is that the Magnum .52 must be permitted to rev-up, whereas the OS .55AX is capable of swinging larger lumber (prop) without a problem.

If one is planning on flying in the old pattern style of mostly full throttle most of the time, the Magnum .52 offers quite a lot of power on a smaller prop at an excellent price. The OS .55AX will do the same, but at a much higher price, but with some remaining versatility regarding large prop handling.

I have two OS .55AX engines, an ASP .52 (which appears to be the same engine as the hot Magnum .52 we are discussing), but I haven't bought the Magnum .52 version as yet. I'm looking for a NIB sample on eBay or elsewhere (RCU).


Ed Cregger

A few of us were wondering about the JBA line of engines, Ed Moorman started a thread where we looked very specifically at the JBA .56:

http://www.rcuniverse.com/forum/m_6762745/tm.htm

At $79.99 it's within your budget and a good match for your airframe.