I have a Saito 115 in my four star 60, its what I had available, and would say its well overpowered a 90 fs would be my choice.

Lovely flying plane by the way,,,total ***** cat!.

John

Given the OP's engines ... OS is the rational choice.


I've started using a Perry pump in conjunction with my older YS 1.20.

Thus, I am by-passing the YS' pump/regulator and also avoiding the requirement to pressurise the fuel tank.

Reliability. I would much rather have a weak engine that I know will one-flip until the sun goes pop than have a screamer that barely runs an entire tank through before failing. That's why my daily driver is 26 years old. I'd trust it to run through Fallujah, despite the fact that a headwind is enough to cap it at 67MPH or so.


Kind of boggles my mind that anyone would choose the screamer in this situation. The power would be nice but having to fix it more often than it runs? Logic defies owning that thing.

Either Mikes choice of the Saito 1.00 or the new Saito .82b would be a great choice. When you look at the bore and stroke of the .82 your first thought is that the .82 is a revver but in reality its a real torquer.

Can the choice be equated into costs for those of us who aren't quite ready to pay a major difference between what I think are reliable and "inexpensive" engines?  Isn't "cost" the fulcrum for exception performance and reliability?  Do a post about what it costs to have an engine that is rated best for those two qualities please.

Reliability. One can always get a bigger engine for more power but one cannot make a smaller engine more reliable. HIgher powertypically equalstighter tolerances equals mor fiddling. High power also equals high stress equals less reliable. Even the engine manufacturers offer smaller, or no, warranties on their more powerful engines.

Hi!
???????
If you would sit in the plane yourself it's would be an easy answer! Wouldn't it! Reliablity of course!
But...In the R/C flight modelling world we can have it both!

All sport engines (OS, Enya ,Kyosho, Y&S, Saito, Magnum, Rossi etc) are reliable! And all sport engines are good performers!

I don't see it as a trade off today. In most models, at least the one's I've chosen, the designs are such that you can physically fit a larger displacement engine in the model than it was designed for without being too punitive on balancing issues, wing loading, all-up weight, etc...

I've never been faced with a situation where I had to make that choice. Pick an engine brand with a good track record and stick the powerplant into it that achieves the desired flying characteristics...

It would be interesting to hear the views of an engine expert ... I mean someone who really knows how to design engines.

I'd like to know what are the real trade-offs between power and reliability, and why they occur. ISTM that aggressive valve timing must be a factor, as must carby dimensions and compression ratio.

The only really powerful engine that I've owned (YS 1.20 supercharged) also "happens" to be my only engine which has eaten its main bearings and which regularly throws props. Now, I have tamed it, somewhat, by reducing the compression ratio and running it on straight fuel.

Reliability.

I can choose specific applications / methods that allow me to equalize power needs for an airframe. With experience, you will be able to get those 'stuborn' engines to run more consistently.

I enjoy the reward of getting an engine setup properly. With that being said, there are some that have a tough time getting consistent runs and get really frustrated.

Hey,
tell the guy I'll take the YS91. Probably the best 91 even made both for reliability and performance...absolute stump puller with a tick over idle, and instant accel anywhere in its powercurve. It will swing a 18" prop if you played with the pipe setting a little. Yep I want that one

Hypothetical choices or whatnot.. I go for reliability every time. Too much time & money poured into my planes to risk losing to errant equipment. I prefer to minimize the odds of a loss as tight as I can, then come what may.

Sure was a convoluted route to get to the question.

jess

If money is an issue, an LA .65 new is probably about what you'd pay for the others used. The LA .65 is a very easy handling and reliable unit.

I agree Jess. It was a convoluted route to get to the question but I think I would have gotten different results if I had just asked the question of which engine you guys would buy given the choice between a YS .91 and an OS .91. But in retrospect I think I did it all wrong. I assumed guys would be able to separate a hypothetical situation from reality, but for many that seems not to be the case. One after another kept insisiting that even the finicky engines are reliable, and , to a degree, that is true. However, I do believe that an OS engine is more user friendly than a YS is but does not produce quite the same power. And cutaway, I wanted a four stroke on this airplane. I have a 40 size Four Star with a .40 HP on it and it is the best performer I have in my hangar. For that reason, I bought a 60 size and wanted a four stroke on it. If I wanted a two stroke I already have a new .60 FP and a good used .61 FSR so two strokes were available. I also have a Saito 1.00 in a Seagull Ultimate Bipe that is not quite enough engine for that plane and I could have used it. But you guys all know how we RC addicts are. If you guys were offered the deal I was offered, you would do whatever you could to snatch them up even if you had no immediate use for them. As it was, I could only afford one right now and I had to decide which one. Given the choice I had I wanted the OS right from the beginning, but I guess I needed some guys in the hobby to tell me I wsan't terminally stupid. I will want that .91YS for the rest of my days, but I took the OS. When I went to pick it up, the choice was not easy. I was tempted to take the YS. Like I said in an earlier post, I am confident neither had been mounted or run, and that YS was awfully purty. But I still think that for sitting on the tail gate of my truck and bopping around the sky in my Four Star Sixty, the OS was the hands down choice.

Now you are mistaking and/or mixing expertise with reliability.
A high performance engine is not for a beginner, because the window of operation is much smaller and the engine is unforgiving if operated outside that window. Yet in the hands of an expert flier the engine performs without a hickup.
Those that make it to the chequered flag in high demand situations are reliable AND powerfull, handled by experts, not unexperienced rookies.

Your question indeed should have been," for a beginner, which engine is better"
The YS beats the OS every time IF YOU KNOW HOW TO HANDLE IT!  IN THE HANDS OF THE ADEPT, THE ENGINE DOES NOT LACK RELIABILITY.
In the hands of a beginner, it is pure misery and a sorry investment.

Reliability, longevity, and ease o operation can be separate items.

The determining factor can well be end use. If, for example, absolute top speed is the objective longevity may well have to be sacrifices along with low idle speed.

I think that very often people are disappointed with certain engines, not because of failings of the engine but because they have chosen one that is not optimized to the application.

jess

Hi!
But all engines on the market are both reliable, hold up well and perform well , so what is the problem? I could understand the question if we spoke pylonracing engines here like MB, IR or Cyclon .40 engines...but when it comes to ordinary sport glow or gas engines like OS , Saito, ASP , Rossi ,TT, Y&S both two and fourstroke you name it...then they all are reliable, hold up equally well and perform well!

Someone who is not able to handle those engines without problems should not blame the engines!

Very good comment!

How often are you asking every ounce of thrust out of an engine , VS how much of your average flying is done at less that full throttle ? Cause once ya aint at full throttle , it'll be the reliability that keeps your plane in the air . Yes , Ive always heard of the YS as being "tinkerers" engines , and if you like tinkering on your engines (I do for me , the mechanical aspects of our engines ARE what keep me from going all electric) then I guess it could be an acceptable choice . But , given all printed reports , if your lookin for "flip and fly" user friendliness , well then go with the OS .....

So do you like a mechanical challenge from time to time , or are you just lookin for it to run everyday ?

I have a friend that uses YS only. He does not tinker with it. He knows how to adjust the engine and just flies it.
Then again, he is an engineer by trade, does not believe in hearsay, and his signature is:
you can tell an engineer, but you can't tell him much.

I hope you read this Brian?

edit: spelling error.

I would pick the one with the highest performance and then fix the reliability, it would be something simple like a bad plug or something...

If you fly competitively, you need both reliability and performance. The engine needs to be congruent with your particular application and perform as needed for that application. Reliability comes from familiarity with the engine. A competitor needs to be able to fly, either in practice or in competition, without having to fiddle with things. When all is well, I don't even hear my engine running. I am focused on flying the airplane, and ignore the engine which is out there doing its thing in a competent manner.

Pe,
I too never had problems with YS's either. The YS's that I had are the only engines this side of a Gas IC engine that ran the same everyday, and very seldom needed any adjustment whatsoever. Almost every person that I have ever heard of have problems, either does not follow the instuctions on fuel, plug's, plumbing, after run oil, lacks experience, or purely thinks they know everything and tries to treat it like a ordinary 4 stroke which it is not. A YS will litteraly blow the doors of a Saito or OS when handled by an experienced user. If I was flying fourstrokes which I am currently not at the moment, it would be a no brainer, since there would only be one option.
I think its pretty sad when I visit this site and hear people slam YS's, when they apparently have little knowledge of there correct operation, or are so stubbern and set in there ways that they do not want to follow the proven steps that make them snort on an everyday basis.