Ed_Moorman

My Feedback: (1)

Mini Comparison Test: OS .46AX GMS .47 Magnum .52XLS Tower .46

I mentioned in an earlier thread I would run a short test when I got the chance and here are the results.

Prop: APC 12.25-3.75 Fun Fly
Fuel: Omega 10% Castor blend
Same day, same time, same prop, same test stand except for Tower which was mounted in a Fazer profile on floats.
Temperature: About 60 deg., low humidity.


OS .46 AX 12,400
Magnum .52XLS 12,800
GMS .47 12,100
Tower .46 11,900

Notes:
1. All rpms were max steady rpm. 1 run only.
2. All engines were new with a short bench break-in with the following exceptions.
a. The Magnum had 3 flights of about 8 minutes each since its break-in.
b. The Tower is old and probably over-the-hill. I bought it when they first came out. It has been in several planes.
3. The GMS has the "stock" muffler and not the "tuned" muffler.

Comments:
1. The Magnum .52 was the fastest as I expected, but it was not that much faster.
2. The OS .46AX did very well for a new engine with the smallest muffler.
3. The GMS did much worst than I had expected. All the raves about the GMS must be due to the "tuned" muffler.
4. The Tower is old and low on compression and did the worst , but it had the "tuned" muffler.

The first photo shows the OS on my test bench.
The next 2 photos show the 4 mufflers.
In the rear view, the fat muffler on the end is the Tower, so-called, tuned muffler. This same muffler comes on some GMS .47 engines. It added several hunderd rpm when I tried it on the OS with a 10-6 prop.
The muffler on the left with the torpedo fins near the exit is the new OS AX muffler.
Next to the OS is the GMS standard muffler.
The muffler with the short extension in the middle is the Magnum muffler.

Muffler comments:
1. The Tower muffler has a much larger volume than the others.
2. The OS muffler is the quietest and appears to be the smallest, but is did very well in the rpm test.
3. Without the extension, the Magnum muffler would be tiny.

A final note: I have ordered 2 more Tower "tuned" mufflers. I will run the test again with all 4 engines equipped with the Tower.

Spaceclam

had the os engine been run for 24 minutes longer like the magnum it probably would have topped the list.

Ernie Misner

Great testing work Ed!!!

On my magnum 52XLS muffler, I drilled out the holes in the muffler baffle a couple of drill sizes and drilled out the muffler exit hole a couple of sizes. Since I do not have a tach I cannot say how much this improved it.

Ed, if you make these mods please let me know...:-)

Ernie

Volfy

My Feedback: (23)

Nice work, Ed. Now a simple Power/Cost comparison should put things in much better perspective.

Spaceclam

it isn't just power you guys! you should also take into affect the break in period, reliability, ease of tuning, and weight.

ZM2000

My Feedback: (1)

Excellent work by Ed.

As I said before, regarding superior metallurgy, who has done the lab test? I found the answer.

One of my friend being a mechanical engineer took the OS and Mangum engines to an aerospace engineering lab and reports that:

a) The process of moulding Magnum is ordinary while OS goes through some superior electrical method (I am awaiting elaboration on this).

b) The microspopic analysis of cylinder liner and piston reveals that the surface of OS is much finer than Magnum.

So it appears that OS is better in metallurgy.

-ZM

seanychen

My Feedback: (4)

When I put the Tower muffler on my Magnum 52 XLS, the max rpm for 12.25x3.75 jumped from 12800 to 13700.

I love to see what the OS AX does w/ the Tower muffler. In fact, the tower muffler should fit all 4 engines in your test. Would you care to do a run on all 4 engines using the same Tower muffler? It would indicate the engine power comparison apart from the exhaust type.

old bird

Ed Moorman, that is very good information. Just the kind of research that means something real to the hobby. Thanks, and thanks for the info on the Saito .72 break-in. We have a couple of .46 FX engines and they have been good to us, plenty of power for our trainers and easy to start and tune. That stuff means a lot to beginners.

Regards from old bird.

Ed_Moorman

My Feedback: (1)

I have 3 Tower mufflers on order. The problem with them is the very fine threads on the muffler bolts combined with the soft aluminum of the muffler strip out. I end up re-tapping them with 6-32, but they finally strip, too. I always use Lock-tite.

I plan to run the test again with the Tower muffler on all engines. I am also going to try to test a TT .46 and an OS FX that a buddy owns. My TT .46 is in another buddy's scale plane with a custom muffler on it. He builds, I fly, so I loan him a lot of engines.

Here is an interesting thing about the OS AX. In their instructions, they recommend you disassemble the muffler and put it back together with hi-temp silicone to prevent oil oozing out the center joint.

rcglert

In regard to the superior mettelurgy of the OS engine versus the Magnum......performance is what counts. OS and Magnum are both very good performers. Although the Magnum will give you much more bang for the buck, some folks feel comforted by the OS name and a feeling of lightness in the hip pocket area where their now empty wallet resides after buying an OS engine.

LOL,

Tom

Spaceclam

keep in mind. the better metalurgy means a quicker break in period. it also means it won't be so finigy during the break in period, and sure a more consistant outcome.

Ed_Moorman

My Feedback: (1)

Before I go to the second of my test runs, let me say something about metallurgy.

First, In all my years since 1950, I have never heard any model engine expert, not an engineer in another area, and I am an engineer myself, say that nickel plating was better than hard chrome plating. The racing engine manufacturers, Nelson and Jett, use hard chrome plating. The electroless (meaning cheap) nickel plating is not as hard, as I recall. OS did have a large problem with it peeling on SF series engines and the early years of the FXes. To their credit, they did work out a solution. This was covered in full page ads touting a new process without mentioning it was a fix for a fatal problem. As I understand, the use a copper plating first, then the nickel. This is their "Advanced Bi-metallic Liner" they now advertise.

As for casting, if the parts fit in it correctly, the quality of the casting, and the finish, has nothing to do with power output. To be sure, OS engines have great castings and great finish. Personally, they can save the polish and cut the price $20.

For my part, I have never had a problem with any engine I have owned, and I have owned many. All were flyable and reliable. I just did not like paying the price for the present OS engines although I have owned several in the past. I take one of those back. The OS .91FX I own was junk until I put a K&B remote needle on it, but we are talking about .46 sizes.

I do break all my engines in the same, on the bench. I find I can control the conditions better, giving the engine short, fast runs on a slightly smaller prop with cooling in between.

Ed_Moorman

My Feedback: (1)

CONTINUATION OF TEST

Courtesy of by buddy, Ugo Ferrari, I have added an OS .46FX and a Thunder Tiger .46 Pro. Both of these engines have been well run and are probably in the category of my old Tower .46, near the end of their time. I say this after running them. They were not up to the level of the 3 new engines.

Temp: 60 deg.
Humidity: Low
Fuel: Omega 10% castor blend
Prop: APC 12.25-3.75

Just to be sure 1 day didn't make a difference, I re-ran the OS .46AX, the engine we are comparing to with the same prop.

OS .46AX Stock (P-BOX) muffler 12,500 (100 rpm higher than yesterday)

OS .46FX Stock muffler 11,400

Thunder Tiger .46Pro 11,500

I am glad I re-ran the AX so I can say the change in weather did not cause lower rpms. In fact the AX was a steady 100 rpm faster.

As you can see these engines are probably not representative of the same engine that is new. A thousand rpm down is a bunch, but they were all I had available.

ONE FINAL TEST: I got out the Tower muffler, the one I have with the stripped thread for the rear bolt and tried it on the OS .46AX.

OS .46AX Tower "tuned" muffler 13,100

Is 600 rpm worth $15? I think so and, as I said, I have 3 on order.

My final thoughts. You guys who like OS better save your pennies, sell your FX and grab one of these. The .46AX, at least the one I have looks like a killer engine in the sport .46 class.

JNorton

My Feedback: (2)

Ed,
Thank you for posting your results. I realize that it is not all inclusive, however it does point out some very good alternatives to O.S. It also shows that O.S. can still design a very good engine. Although I still don't like the idea of a 4 bolt head!
John

Spaceclam

i still say i'm never going two stroke again. ys is the only way to go.

Ernie Misner

Hi Ed,

I do hope you re-test the Magnum .52 so we can see what it will do with the Tower muffler. Since the Magnum muffler has extra volume already, would pulling the baffle out of it be about the same as the Tower muffler?

Has anyone had any problems with the Tower muffler not giving enough pressure to the tank? I have heard of this before since it has no baffle in it.

Ernie

rcglert

I had a ton of trouble with a Tower .46. It was really tight (possibly a good thing), but it would not hold a high speed needle setting. I had an identicle engine that worked very well......go figure. I broke them both in the same way as Ed described above. I wonder if muffler pressure had anything to do with it?

Tom

seanychen

My Feedback: (4)

Hi,

I do have the result of Magnum 52 w/ Tower muffler on 12.25x3.75, but fuel is different: Omega 5% nitro, 17% oil (80/20 blend), peaks at 13700. That's after about 1/2 gallon of running.

The Tower muffler gives the Magnum 52 adequate pressure. In fact, needle setting hardly changed switching from stock muffler to Tower muffler,...maybe 2~3 clicks. But I can easily richen the engine, which indicates there is enough pressure.

It does sound like the AX is a worthy competitor for its price if the transition is smooth. I find the Magnum 52 transition is less than desirable. Sometimes it's instantaneous, sometimes it lags slightly, that's w/o any adjustment. Maybe it's the airleak that I haven't found, which is causing the engine not to be shut off. Also, the Magnum 52's stock muffler, while quiet, leaks, and after tightening as much as I can, still leaks a little.

seanychen

My Feedback: (4)

I just tached the Magnum 52 w/ Tower muffler using Pro Zinger 13x4 prop. Max RPM is 12600. But the thrust doesn't seem to be as much as the 12.25x3.75.

ShempHoward

My Feedback: (3)

Ed - I would like to hear your opinion about the 4 bolt head on the AX as any here on RCU seem to feel that its merely an OS "Cheap-Out" design althoug not too many seem to mention that Super Tiger used this same 4 bolt head on many of there engines.

As many of us need to be concerned about db levels I wonder how these engines all stacked up against one another in that department as well?

Ernie Misner

.....<<I do have the result of Magnum 52 w/ Tower muffler on 12.25x3.75, but fuel is different: Omega 5% nitro, 17% oil (80/20 blend), peaks at 13700.............

13,700 on 5% fuel is outstanding! Especially for a $99 engine. I like it.

Ernie

Daryl Martel

My Feedback: (3)

Very nice work Ed. Too bad that O.S. FX is not newer - I'd like to really see a completely honest, "on par" comparison to see if new actually equals better or not. Re the new AX 4 bolt head design, as found on Super Tigers which also used to be 6 bolt years ago, maybe there is a good engineering/design reason for it vice just being easier and cheaper to manufacture. The "other" thread referred to (here: http://www.rcuniverse.com/forum/OS_4...1346165/tm.htm) shows a good comparison picture of the front of the cylinders on the FX and AX clearly showing the larger transfer port on the AX. It appears that going to the 4 bolt head allows more room for that transfer port... From your test it sure looks to me like those other non O.S. engines are a good value offering roughly equivalent performance for substantially less money. The comment by seanychen is interesting - the airleak and poor midrange transition he speaks of with his Magnum are not the kind of thing you hear much about with O.S. engines. Yes, they've obviously had a peeling liner issue (apparently addressed), but their overall quality and especially carb metering sets a pretty high standard, if not THE standard. Don't get me wrong here - I like O.S., and I really do think that they are very good, but there are also lots of very good alternative engines available now.

Razor-RCU

My Feedback: (50)

I would love to see the Irvine-53's numbers compared to these...

Thanks for the info. Here is some info. about 46 sized engines- Price, mileage, and RPM's may vary [X(]

Engine Manufacturer Price Weight HP RPM's Muffler/Pipe Dimensions
ASP-46 ASP $88- 14.5 oz. 1.3@ 17,000 Muffler/Pipe 17.5 x 42mm
ASP-52 ASP $98- 17.6 oz. 1.7@ 17,000 Muffler/Pipe 17.5 x 42mm
Enya-50 CX Enya $109- 13.4 oz. 16k
Enya-50SS Enya $99- 11.1 oz. Muffler/Pipe
Evolution-46 Horizon? $90- 13.10 oz. Muffler/Pipe
FOX-46 ABC Fox $105- 13 oz. 14.5k 10x6 Muffler/Pipe
FOX-45 BB Fox 12 oz. 13.5k 10x6 Muffler/Pipe
GMS-47 Mecoa $70- 12.86/16.14 oz. 1.47@ 16,000 Muffler/Pipe
Irvine-46 Irvine $110- 13.9 oz. 1.3@ 17,000 Muffler/Pipe 17.5 x 44mm
Irvine-53 Irvine $123- 14.1 oz. 1.7 @ 18,000 Muffler/Pipe 17.5 x 44mm
Jett-46 Jett Engineering 17.2 oz.RTF 10 x 6 15,500 Muffler/Pipe 17.5 x 44mm
Jett-50 Jett Engineering $260- 16.4 oz. RTF 17,000 Muffler/Pipe 17.5 x 44mm
K & B-48 K&B $139- 19 oz. 2.0@ 15,000
Leo-46 Leo 11.99 oz. 1.43@ 16,000 Muffler/Pipe 17.5 x 44mm
Magnum-46XLS Magnum $90- 13.1 oz. 16 oz. 1.43 Muffler/Pipe
Magnum-52A Magnum $120- 13.6/ 17.4 oz. 1.54
Mecoa-46 Mecoa $70- 12.4/ 15.10oz. 1.4@ 15,000 Muffler/Pipe
Megatech-46 Megatech $73- 1.47@ 16,200
MVVS-49 MVVS $140- 13.40 oz. 1.54@ 17,000 Muffler/Pipe 18 x 41mm
Novarossi-50 Novarossi 2.2@ 18,000
OS-46FX OS $110- 13.2oz. 16.45 w/muff. 1.62@ 16,000 Muffler/Pipe
OS-50 FSR/Heli OS Discontinued unk. 1.8@ 17,000 Muffler/Pipe 17.5 x 44mm
OS-50SX OS $160- 13.8 oz. 1.8@ 17,000 Muffler/Pipe 17.5 x 44mm
Rossi/Powerhouse-45 Rossi $140-$150 15.1 oz. 2.1@ 16,000 Mini-Pipe 24 x 45mm
Rossi-53 Rossi $190- 15.5 oz. 2.2@ 18,000 Mini-Pipe 24 x 45mm
ST-45 Supertigre $95- 13.22 oz. 18.5 w/muff. 1.45@ 16,000 Muffler/Pipe
ST-51 Ringed Supertigre $110- 12.73 oz. 18.4 w/muff. 1.48@ 15,500 Muffler/Pipe
Tower-46 Tower Hobbies $80- 16.9 w/muff. 1.75@ 16,000 Muffler/Pipe
TT Pro-46 Thunder Tiger $77- 17.01 w/muff. 1.43@ 16,000 Muffler/Pipe
Webra-50 GT Webra $154- 11.2 oz. 1.5 @ 16,500 Muffler/Pipe
YS-45 YS Engines $180- 14.1 oz. 1.5@ 18,000 Muffler/Pipe

Volfy

My Feedback: (23)

To me, the absolute best bang for the buck in this category - taking into consideration everything including fit, finish and overall quality - is the Thunder Tiger Pro .46.

OS engines are nice, but I see no reason to pay premium for them, and then have to come up with all sorts of justifications for spending the extra bucks. For the same price as the OS .46, AX or FX, I would rather buy an Irvine .53.

There's nothing wrong with 4-bolt heads. I have owned many Super Tigre of all sizes with 4-bolt heads, and haven't experience any problems which can ve attributed to the head bolt count. As long as the head is designed to be rigid enough, AND the head bolts are torqued down properly, 4-bolt works just fine.

As for the talk about metallurgy, well, surface roughness at the microscopic level isn't necessary a bad thing. The engine's internal bearing surfaces rely on thin-flim lubrication in normal operation. The mating suefaces never actually come in contact with each other - if they did, the engine will gall and seize up in a matter of seconds. As long as the surface roughness is less thn the oil film thickness, it's not a problem. In fact, some roughness can actually be beneficial by aiding oil retention on the bearing surfaces. Ed, it's good to see a fellow engineer help put the subject in proper perspective.

Ed_Moorman

My Feedback: (1)

If you will read the original thread about the OS .46AX, I think you'll see the reasoning behind the 4-bolt head. The AX does have a wider front transfer port. Also, the head fits on differently, the cylinder is higher on top and the head is deeply grooved, to compensate for the wider bolt spacing. I don't forsee a problem.

Orig. Thread: http://www.rcuniverse.com/forum/m_13...tm.htm#1346165

As for the Irvine, I don't own one and I don't think anyone in my club owns any Irvine. Usually we have a snowbird who flies a smaller Irvine come down in the winter.

As for the FX, I know the one I tested was old and about used up, but given a choice, I would go with the AX. Guys hung on to their SFs, too. The big thing with the FX was to fix the liner peeling problem. Now that OS has that worked out, they can introduce several fixes in a new model. No more built-in remote needle; it bolts to the back plate. The plastic needle valve housing, while you may not like it, will probably work better than the old one. I read about people using plastic ones from the LA engines to solve the air leak problem. I'm sure OS heard this, too, so why not put it on the new engine, but give it a nice metal bracket that'll bend instead of break. It'll probably work well.

As for the 4-bolt head (again), in my experience, OS has a tendency to sneak in improvements in a production line without telling anyone. I had the crankshaft break on an old OS .60FSR years ago. I bought a new one and found it wouldn't fit. They had gone to a larger crank and bearings so I had to but a whole new front end to get my engine back in operation. The original thread mentions the larger transfer port in the cylinder block, but says the port in the sleeve is the same size as the FX. In a couple of years, I suspect if you go back and cheack, the porting in the sleeve will have been enlarged for even more power.

As for advertised horsepower and rpm, I never believe any of it.

As for comparing engine tests on different days, I am skeptical. that's the reason I ran the AX on the second tert, to set a new baseline. The best magazine tests I know of are from the magazine I write for. And I thought this even before I started writing my column. Brian Lee does an excellent job testing and supplies a weather compensating factor so you can compare different tests done at different times.