Eganwp

My Feedback: (1)

LOL, I do have to say, when I originally started this thread I didn't expect to go quite like this...

I was planning on grabbing the remote needle valve version as the GMS .47 as the HS needle is about 1/2" away from the prop.... Real fun if you tune your engine every single outing at WOT like me... If I go with the non remote version, I'll see if I can mount the carb angled slightly so it's further from the prop. IMO it's just not worth losing fingers over which I have seen. I understand that the remote versions are going to be a little harder to tune (more latency in needle adjustment) and more chances for a leak, but if you clamp your lines and seal everything properly, I can't see why it'd run any different. At least the trade off for safety is worth it to me... :P

Sport_Pilot

If you weren't you wouldn't be calling it nitro!

landeck

My Feedback: (1)

Don't be too sure of that. While reading your post, there flashing on the screen below was an ad for "nitro" powered model cars and cycles.[sm=biggrin.gif]. Ground pounders use that term regularly for glow engines. I started my first glow engine (an OK Cub .049) in 1953 and have heard them called glow, nitro, and up until about 20 years ago, gas engines (or motors[:'(]!). All that really matters is that people understand what is meant.

Bruce

estradajae

And there are also search engines

In Spanish and German, there is no different word to make a distinction between an "combustion" engine and an "electric" motor....
They are just called motor/motores...motor/Motoren, but you say combustion..or electric...etc...linear whatever...

As far as I know the word motor comes from "source of movement" what makes something move.
In english the concept of "engine" comes from the source of the energy (Heat involved)???

MJD

My Feedback: (1)

You are correct estradajae. A motor is something that imparts motion to something. An engine uses thermal energy to provide mechanical energy to do work. That work might be motion. A motor can use an engine, as in an outboard boat motor. But it does not have to. And yes, the terms are horribly misused all the time - although everyone usually knows what the other is talking about.

fcomer84 - I bet you would not buy another if you got one of the examples with the bad carb. No matter how many problems a product has, there are always people who don't have the problem. That doesn't excuse the situation or make another person's purchase any less risky.

MJD

fcomer84

My GMS did not run well when I first got it. I did all the glueing and sealing already suggested here. I fought that engine tooth and nail. It would run and quit. When it would run! When it finally left the ground deadsticks were the norm. I kept fighting, and the whole time putting fuel through it. It got better over time just running it, hence my 19 gallons of fuel comment. The biggest improvement came with putting the needle on the carb. and the Uni-flo tank setup. Now, finally, is starts easily, almost never needs a NV adjustment and is reliable.
Now, the Tower .46. It was given to me, used in the box, and the guy told me he never wanted to see it again! Now, I never want to see it again! I replaced the front bearing, glued and sealed, drilled, rubbed, polished, sealed, glued, added head shims, took out head shims (PS Tower and GMS head shims will not interchange), changed fuels, swapped glow plugs, swapped carbs with the GMS, sealed and glued... anyway I lost a bunch of good flying time fooling with it. You know, it is a well made engine inside and out and I never really found anything wrong with it. Other than the fact it won't run, the Tower .46 is great!
I have seen posts where someone talks about how good their T46 runs, and six other guys at the field bought them because of how great they are, well that must be someone from Hobbico writing that crap because I don't believe it!!!
I would still buy another GMS .47 and I do not work for Hobbico.

Jezmo

I've got a Tower 46 and it took me some time to figure it out but once I did she's a pretty good specimen. I found mine likes an A3 or equivalent plug, 15% nitro, no bigger than a 10X6 prop and the fuel tank CAN NOT be low. It's a screamer, not a stump puller. Put a big prop on it and she just won't run right. Now I understand some will turn a big prop but mine won't. It has to spin up in order to run good.

fcomer84

I ended up with an A3 in the GMS with 10% nitro. No problems. It will go dead on the ground from time to time with an A8. It will pull the APC 11 x 7 just fine , but really comes alive with the 11 x 5.
I made so many changes on the Tower .46 I can't remember them all. But I don't think I tried any 10" props. I sorta think something is wrong with the port timing in the cylinder. I have seen 2-stroke motorcycle cylinders ported so wildly that they would not run at all. Or, it could be the intake port timing on the crankshaft. That may explain why some people love'em and some people hate'em. There seems to be no middle ground in the forums. 1/2 get good ones, 1/2 get what I got-a headache!

bigedmustafa

My Feedback: (2)

I've owned and flown the GMS .47 and I was impressed with its power and clean transitioning. I've broken in and flown the $49 Aviastar .46 available from Sig, and I thought it was a terrific engine considering the bargain price. My only complaint about either engine was they both tended to have cylinder head and/or backplate bolts that worked loose more easily than on premium engine brands. If you fly either brand of engine, just check the cylinder head bolts every flew flights.

The $59 SK .50 and JBA .39/.46, available from Kangke USA, are impressive performers and reliable. I've also had very good out-of-box experiences with the Magnum XLS .46A, the Magnum XLS .52A, and the Super Tiger GS-40/GS-45/G-51 ringed engines. Everyone knows what a great, reliable engine the Thunder Tiger Pro .46 is, which makes all the more a shame that the fantastic, powerful, easy to tune, and reliable GP-42 is too often overlooked.

There are a lot of great choices out there for 2-strokes under the $60 price. You may have to do a little bit of bargain shopping to catch a GS-45 or an XLS .46A on sale. I'd be happy to buy and fly any of the engines I've mentioned, but my choice for top quality and rock bottom pricing has to be the Thunder Tiger GP-42. It's a $59 2-stroke that doesn't have to make any apologies at all with regard to quality.

fcomer84

I agree with you on the GP - .42, great runner! Another sleeper engine I have is the Thunder Tiger GP - .61. I think it performs better than the Pro - .61! You are right, BigEd. There are some great bargain runners to be had. I don't think anyone needs the GMS .47 as a 1st engine. Mine was a bit cantankerous but ended up as a good piece. But, had it been on my trainer when I was learning to fly, I would be playing with model trains right now!!!!

hairy46

My Feedback: (1)

I also agree with the GP 42 being a great motor the two I have run beautifly! But at 7000 ft they are a bit under power for a 40 sized plane, It was taking 3/4 of our runway to get the plane in the air, once lifted off struggled to get altitude! They run really sweet so may go into a small twin airplane. But I can see why people like them, great runners and bet plenty of power down lower!

Eganwp

My Feedback: (1)

So since my original post my curiosity between the GMS .47 and ASP .52 got the best of me... I now have a brand new GMS .47 which I just finished breaking in, drilling the fuel inlet and fully sealing and am awaiting my shipment of a brand new ASP .52.

Stay tuned and I'll post full results, findings, comparisons, likes/dislikes, rpm readings, etc on these cheap engines for an overall winner for my own use down the road. Hopefully others can benefit from it as well.

fcomer84

Cool! Can't wait to see what you find!

bth9318

My Feedback: (24)

Eganwp isnt it amazing how you tried to get a answer to a simple question tower vs gms.And you specify that you dont want to hear about buying a o.s. you know they are good but you want to try a cheaper alternative but the o.s. army just cant resist hijacking the thread to tell you BUY O.S. theyre the best we dont care if you want to hear it or not,only idiots spend $50.00 on an engine,those chinese motors are garbage blah blah blah.The truth is most of those o.s. owners have never tried the cheap motors and dont know what the hell they are talking about. I have a magnum .52 xls it turns a 11x8 wood prop at 11800 rpm and idles like charm and runs fine at low rpm also its in a biplane and i like to do slow speed passes and it transitions smoothly right up to full throttle.I'm going to change the prop this year in it because the 11x8 makes the plane go to fast prolly go to a 12x4.I also have a evo trainer engine that runs beautifully also and it turns a 11x5 prop at 11600 rpm and idles like a watch. I run byron 15% in both.But for my next engine i think i'm going to try the aviastar .46 or .53 for those prices and a reputable dealer like sig i dont think you could go wrong.And for all the o.s. honks i got a o.s. max .50 fsr that i'm going to run in a biplane and i bet i dont get nearly the performance i get from the magnum.

aerofly0610

I have a gms 47 on my tower trainer and I like it.   It replaced an os 40la, so of course it has more power

hairy46

My Feedback: (1)

I have 6 GMS engines 3-47 and 3-61 and I really do like them allot! I just got an Magnum 61 not broke in yet but will soon and post what it does, I had mentioned before I had six for six great runners and someone said theres noway! But I am six out of six very happy with them! I do have OS and like them as long as they are not the LA's not enough power at 7000 ft. I like trying new stuff thats how I found the GMS engines I feel I get my moneys worth! The only OS guys can tell me the GMS is junk but sure love the power of the six planes they are on! I got six engines for the price of three, i'm happy!

Eganwp

My Feedback: (1)

Thanks for the comments guys, especially bth9318. It's nice to see people who support non-hijacking of threads. haha

I got my ASP .52 in the mail yesterday and it sure looks nice. I haven't had time to tear it down before I run it yet, but will shortly.

As a side note without giving away too much info away on my testing so far, I benched the stock GMS after break-in (fully sealed and properly tuned) and it turned respectable RPM. Next I completely tore it down, and spent a whole day with a dremmel. I took the timings of all parts of the engine (exhaust, intake, boost, crank) and then started modifiying. After flow modifications were complete I went even further and really ramped up the exhaust timing. It was so pathetic stock it's not even funny. I also boosted the intake timing as well. I'll save the details/results until my testing is complete for you guys however.

As a quick precursor so far I'm impressed with the GMS .47. After the mods I'm turning just under 16,000 rpm on a 10x7 prop. She's putting out some serious horses now. I'm actually scared this little engine is gonna destroy my OS 55ax! lol I can't imagine what this would do on a tuned pipe... Not bad for only my second engine (well 4th glow engine if you count car side of the hobby) as far messing with engines flow/timing characteristics.

Stay tuned.


Eganwp

Eganwp

My Feedback: (1)

Hey guys!

I had completely forgotten about this thread and remembered it after doing some engine testing for my new Viper 500 quickie 500 pylon racer arf I picked up last night. Went out and tested all 3 engines today. Here are the bench results!



+20*C, 3200ft ASL, 47% humidity, 0kph wind speed, 10% Homebrew @ 20% oil @ 80/20, all engines fully tuned and running on the $15 Tower Hobbies tuned pipe.

OS .55ax:
9x7APC = 16,440rpm = 175.4kph
9x8APC = 16,050rpm = 195.7kph

ASP .52:
9x7APC = 16,530rpm = 176.3kph
9x8APC = 15,990rpm = 195.0kph

GMS .47: (I've already done crank mods, sleeve mods and intake/exhaust ports durations modified)
9x7APC = 16,290rpm = 173.8kph
9x8APC = 15,720rpm = 191.7kph
Exhaust from 138* to 150*
Intake from 196* to 198*




The results are interesting and was a lot of fun to do the tests. Based on these results it looks like the ASP .52 w/ a 9x8APC turning 15,990rpm will be the ticket. Of course bench running is only part of the story, and it'll be a whole new ball game once in the air. I will also end up raising the exhaust ports to 170* or so on all engines before they go in, so that should give me a few more hundred rpm's as well.

Hope this helps someone else out there! By the way. I fully tore down both the ASP 52 and the GMS 47 (which I then modded) and overall I was impressed with both. I have full pics and stuff that I'll post another time, but basically you can't go wrong with either. Both nice quality, both run excellent, and both were less than $50ea. If I had to choose between the two, I still think I'd pick up the ASP .52 though for the simply fact that you dont have to drill the fuel inlet in the carb, is 100% ready to go out of the box (though I seal all my engines/carbs first), and turns more rpm due to the extra displacement. It's so close to the performance of the OS 55ax in fact, that I can't recommend it more. Mine's had 3 gallons or so though it, and runs perfectly. The fact that it turns just a hair more than the OS 55ax is icing on the cake!!!

Cheers guys! Hope this helps someone out there!

Egan

w8ye

My Feedback: (16)

Be careful about changing the ports on the 55AX. the cylinder sleeve is nickel coated inside and out. When you change the timing, you disturb the integrity of the nickel plating and the result will be nickel peeling above the exhaust port.

Chrome doesn't have this problem.