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Hello all,
I've done a search of 4 stroke OS and Saito engines to decide which one to put in a size .60 300 Extra (GP). Since this is my first four stroke I am trying to make a educated decision. A post which I found brought up some interesting facts in which I'll just repeat and then hopefully some of you could please clear up and add to so even I could make a decision, LOL. The post also started by asking which engine would be best for a .60 Extra, and was replied by stating the facts of: The Saito 1.00 being much lighter, put out the same rpm with the same prop as a OS 1.20 and Saito 1.20. With an additional reply stating in a review in RC report found Saito 1.00 produced 198 oz of static thrust, Saito 1.20 produced 190 oz of static thrust, and OS 1.20 non pump (no model stated) produced 217 oz of static thrust. (anyone know what model that is) OS touts its 1.20 E non pump @ 1.9 hp @11,000 rpm and OS 1.20 III with pump @ 2.1 hp @12,000 rpm. Again all of above information was copied here on the forum search. I was leaning toward the OS 1.20 III with pump but wasn't sure of it's reliability, so some pros and cons of these different engines would be great. If I could get some added input on the above statements that would help, and I'm curious what OS 1.20 non pump model that was that produced 217 oz of static thrust. After any input you may add, another question to you is what engine would you put in your GP .60 size 300 Extra after reading all this. I appreciate your time and help.

Thanks in advance,

Pat

Edwin

My Feedback: (2)

I debated about a year before deciding to go with saito's (120 in this case). I have 3 now and dont regret it one bit. I had heard about pump problems in the beginning with the OS 120 engines and knew someone personally that had problems. I also have a GP Extra 300 kit that will get a saito 120 when I get around to building it. I've heard all the hype about the saito 100 and its probably true to a point. Dont know anyone with first hand experience. Be aware of the rpm ratings for horse power. You dont want to really run a 4-stroke at 11k rpm on a regular basis. I get my best performance on my 120 with a MA Classic 16x8 at about 7400 rpm. The engine is pretty happy there. And the engine runs inverted with no on board glow driver. Thats what I run in my Rascall 110. Another guy in our club has the same plane with a magnum 120 but has to run an on board glow driver to keep it from quitting at idle. I told him he could have bought a saito 120 for the price of that magnum and glow driver.
Edwin

foxx

My Feedback: (2)

I am really surprised that you are thinking about put a 1.20 engine in a .60 size plane , this is way over kill. I personally don't like 4-stroke in a .60 size plane because of excessive torque on the airframe. I think .60 size planes fly much smoother on 2-stroke, specially arobatic planes

Edwin

My Feedback: (2)

Because I want it way overpowered. I like it.
Edwin

ParticleMan

My Feedback: (24)

My GP extra 300 has a Saito .91 swinging a 14x6 prop. I built the plane completly stock and it has unlimited vertical at full throttle. For me that's all I need for a plane like this, it will hover, but the .91 won't pull it out at a safe enough rate for me, so I keep it up high always. With a 1.20 your going to be looking at servos in the tail or something along that line to balance correctly. If I could pick any engine for this plane, it would be a Saito 100.

I know of one person on this board that has an OS 1.20 Surpass III on his extra. SundevilPilot is his name, search for some of his post, lots of info about it.

J.Paul Saure

I've seen the GP.60 Extra with a YS120 and a OS.91.
With the YS120SC it was just too much. The OS91 had enough for big loops and decent climbs. A Saito120 or 120 Surpass would be the right choice, I think.
Anyway the manual recommends a 120 4-stroke (or a 90 2 stroke) for best performance, so it's no overkill (it even withstood the YS). Just remember the throttle.

A friend has the 120SurpassIII on a CG sukhoi and it runs very well, although he is still running it in.APC15x8
I'm sold on it, I'm getting one for my Typhoon 909.

Good luck!

elevator_up

I have the 4*60 with the GK100 and its somewhat overpowered, but you have to hate buying the 91 at nearly the same weight as the 100. I went for long term usage.

outssider

My Feedback: (23)

the great planes 60 size extra kit is a little big to be considered a true 60 size plane.....If you want to just fly it around and do regular aerobatics the saito 100 will do....if you keep it light!! around...8lb or so !
if you want some real performance (3d) ...I would wait and get the new ys110.

David Cutler

I see somebody suggested a Saito 120.

That's fine if you really want to overpower it, but it's worth saying that the step from a Saito100 to a 120 is quite a big one (I reckon it's the biggest step in their whole range), especially in size and weight.

The step from, say, a 72 to a 100 isn't really much, and you get to use the extra power without much compromise, but, if you look at a 120, it's a lot bigger, and the extra weight might compromise a 60 size aircraft more than you are prepared.

-David C.

bgi

My Feedback: (7)

It's a half pound heavier. I'm pondering the same question, myself: Which 4-stroke for the GP 60 Extra? Hmmm...

Opinion: TT 91 FS is pretty heavy for it's size, but powerful. Need to keep this plane light, so it's out.

Saito 120 is 8 oz heavier than the 100. I had just about settled on the Saito 120, but that 8 ounces will make some real difference in the handling. The Saito 100 may be the ticket. Just opinion. Besides, I haven't seen any full-scale Extras torque rolling.

Which .91 2-stroke would folks recommend?

David Cutler

You can't go far wrong with the Saito 100, and for a 91 two stroke I would recommend the OS 91FX

2.8 horsepower is a pretty useful amount for the weight, and I have nothing but praise for mine in its reliability / ease of starting.

It'll probably change tomorrow when I fly, but I am still counting the number of consecutive times I have started it on the first flick with a chicken stick, and I'm up to 15 right now, even from dead cold when I first arrive at the field.

-David C.

Edwin

My Feedback: (2)

I have a saito 120 in 60 sized sukoi (~62 ws). I just mounted the gear further back and needed no extra led to balance. Great fun. I like getting a little wild and wooly once in a while. Besides, its just a 60 sized aerobat. Would take only a couple of months of evenings to build that great planes kit. They practically fall together. Its not like scratch building. Its the kind of plane I like having around when I want to try something totally new or just let loose.
Edwin