Thunderhead

Ive got a Sig SE with a OS 46FX. It just doesnt have the umph Im lookin for. I saw Tower was selling GMS motors. I've never known anyone thats owned one. The 76 BB was $99, and I got to thinkin that might be a good engine for my SE. Has anyone owned this paticular motor, or any GMS motor for that matter?

wildnloose

rumor is they are manufactured at the same factory as tower engines (they do look similar). I have seen the tower .46, .61 and .75 perform, they do fine (yes, air leaks have been a problem for a few .46 and .61).

Curious, exactly what type of performance are you looking for??? I had this same combo and it had unlimited vertical with 12.25x3.75 or 12x4 prop. I preferred the 11x5 or 11x6 though...

Peter G.

Woooo.......... I have a SE and a GMS .76 but would never marry them. I have unlimited vertical with a TT46. I can see some guy'e would like more. One fellow at our club has a Ervine 53 that has lot's more jam.
Even if you could get the plane to balance without adding a ton of lead, I would be leary of the added strain on that light airframe.
As far as GMS goes............ Boy is that a loaded question here on RCU. Some guys love them, some guys hate them with a passion. I like them, good bang for the buck. I don't claim they are the best. My GMS .76 is only slightly more powerfull than a reg. .60 size. Not the powerhouse the .47 is when compared to the other .46's. Anyway it runs good and that's all I care about.

Peter

Thunderhead

Air Leak? Explain more. I have another thread started and someone suggested that was the case with my 46FX. Read this thread
http://www.rcuniverse.com/forum/46FX...1220541/tm.htm

So then is the GMS 47 more of a powerhouse then say the 46FX? I run a 12X6 on my 46Fx and my SE DOESNT have unlimited vertical. Read the thread above and it might explain. Im even running 25%. This is why I thought about the GMS 76. The 50SX was too much $$ for what it is IMO, so thats what turned me on to the GMS.

SMALLFLY-

My Feedback: (19)

IMO you need to plunk down the bucks for a saito 72, ys 63 etc. The gms is way to heavy for that airframe. Have you removed the muffler baffle. You should investigate the ultrathrust or Jett muflers as well. They will give you lots more rpm. Oh and a 12 x 6 is way to much prop for a 46 IMO. Drop down to a 12 -4 or an 11-5

Thunderhead

Oh, my fault, sorry. I meant to say Im running an 11X6. Ive ran a 11X5, 11X6 and 11X7, and the 11X6 seems to work ok, but not the "unlimited" performance everyone says.

Crash King

My Feedback: (24)

Been there and done that!
Well close. I had a 91FX on my SE. When it ran well it was a great flyer. Problem was just as mentioned above. The airframe was not designed for a 76-91 size engine. I have an OS-70II on her now and it works fine for me, but the 91 was too much. On the last flight with the 91 FX on her I broke two CA Hinge joints and almost lost the aircraft. You will also need a new set of gear as I did and this also changes the characteristics of the airframe. I do have to admit, it was a blast to hover @ 1/3 Stick! But not much else worked. We have a couple of the GMS 76 around and they are good engines. Dykes Ring I think so need some time to break in. The tower is a ABC or ABN, and a bit lower on the power output per my untechnical observation.

Thunderhead

Well, I do have acess to a Saito 65, but would I notice any difference from the 46FX I already have?

Peter G.

Boy Thunderhead something does not sound right. As I said my SE has unlimited vertical with a TT.46 albeit not lots. I fly a 11x5 APC. I would try a 12.25x3.75 but I don't think I have the ground clearance. How heavy did your SE turn out?. What prop and rpm are you getting?

wildnloose

I had almost the exact same problem with another engine of mine. It was my old trusty tt .46. I had just cleaned it from a crash, put it on a used plane I bought, and just could not get it running right. It would never have a smooth transition, and you could not tune it out, so I assumed something happened in the crash.

Well, after I crashed the next plane(aileron failure), I noticed there was a hole in the fuel tubing, close to the clunk. I did a test, put this engine on my SE and it ran like a clock(just like it used to, brought a tear to my eye). I put the os 46 on this plane to break it in...

An 11x6 will give you good vertical, not unlimited. A 12x4, 12x5 would be better. A 12.25x3.75 would work, but its difficult to take off and land on grass(very).

I have seen mixed results with removing the baffle and drilling holes in the baffle. I removed the baffle on mine without problem (slight rpm increase). I think it boils down to trial and error.

IMHO-Before you try anything else, try to figure out whats wrong with this engine...or sell it and buy another one...