I am suffering from a monster case of analysis paralysis. I am coming off a 6 year hiatus from R/C and need a little help. I assembled a .46 sized U-Can-Do, with a Saito .72 and APC 14X4 prop. I have no idea how much thrust this engine has but it carries the 6+ pound plane around, and up, really well. It flys nice at 1/3 - 1/2 throttle, and will climb straight up at full throttle (not a rocket, but a good climb). It has been a hoot to fly, and a great plane for me to transition back into the hobby.

Now I have ordered a 73", 10.5 pounds, Giles 202 that should be here today(NitroPlanes). I'm not ready for it yet, but that will give me a chance to take my time and do a better than average job of assembling it. I have to come to the issue of the engine for this plane, and that is where I need your advise. I would like to have at least the same level of vertical performance that I have now. I'm not into 3D other than the occasional brief hover at altitudes where climb-out is not an issue. I would like to start practicing IMAC maneuvers, and I may move up to a larger IMAC plane if I enjoy it.

Here is my short list of engines I have selected for this plane. You'll notice they will all be setup so I can mount the fuel tank near the CG. All will use some type of Pitts style muffler, or maybe the inline can for the YS. Fuel type is not an issue for me (heli friends buy good fuel by the pallet). While money is always an issue, I can swing any of these listed.

O.S. 120 Surpass III w/pump
Pros: O.S. reliablity, readily purchased NIB in the swapshop at a good discount ~$300, integrated fuel pump, low fuel use, lots of positive reports.
Cons: Heavy for it's size but inline with other choices, Pump my be finicky, lowest power - 15X8 to 16X6 reported, 17X4 possible?

YS 110FZ: Because it is within a few oz. and similar power to the O.S. 120, I have eliminated this choice.

Saito 150 + a pump or regulator
Pros: More power than the O.S., reasonable reliablity, pretty, easy maintenance, can turn a bigger prop, can be had NIB for ~$300
Cons: Will need a regulator/pump, more difficult to tune, increased fuel use, will cost more than the O.S. setup.

Saito 180 + a pump or regulator
Pros: More power than the O.S. and 150, reasonable reliablity, pretty, easy maintenance, can turn a bigger prop, can be had NIB for ~$350
Cons: ~$50 more, will need a regulator/pump, more difficult to tune, increased fuel use, will cost more than the O.S. setup.

YS 1.40 Sport
Pros: POWER!(probably more than is needed), presurized fuel system, throttle transition and response, weight is inline with the others, cool factor.
Cons:~$100 more, finicky fuel system, more difficult to tune, more maintenance?



Are any of my pros/cons incorrect? Based on the information I have given, which engine would you choose?


Thanks for all your help,

Kendall
Baton Rouge, La.

The Saito 1.50 or the 1.80 would be my choice, fuel consumption is a non issue if you set the Low Speed needle correctly, the regulator will make it a no brainer to adjust and then rarely touch.

If the Giles that you selected is their 1.40 rated model, I'd forget about the smaller displacement engines. They had two versions of this a while back. One was rated for a 1.20 and the other was rated at 1.40.

I'd have dropped the OS 1.20 pumper and kept the YS 1.10 in the line up for a 1.20 sized model. The 1.10 is more powerful than the OS. Central Hobbies sells the YS's much cheaper than some of the other places they are sold. I like the OS 1.20 pumper, but powerful, it isn't.

I would be tempted to buy an OS 1.20AX or 1.60FX two-stroke and fit it with a Cline type of regulator. You can burn 5% nitro fuel and produce the same power as all of the four-strokes that you have mentioned. Granted, throttle response won't be as razor-sharp as the YS engines burning 30% nitro, but it will only cost slightly more than half of the YS 1.40.

If you are going Saito, forget the 1.50. For just a few dollars more I'd get the 1.80, but also with a Cline type of regulator.

I just sold a NIB 1.40 Sport on eBay. It was like hanging a dead fish in the air over the side of a boat. Bids were coming in nearly as fast as emails of guys trying to get me to end the bidding early, or to ship it overseas for someone. It is a popular engine.

To me, the only two real choices are the YS 1.40 and the Saito 1.80. But that is just me. Good luck making your decision.


Ed Cregger

It depends on how adept you are with engines. If you are not to power hungry, The OS is a no brainer. Very user friendly and will run all day on 10% fuel and should give similar performance if propped correctly. A saito 180 with a Kline regulator will give you much better performance at the cost of slightley higher vibration, higher purchase cost and lower fuel milage due to a larger displacement. It may also be slightly more difficult to break in and tune. Unless you are an experienced 4 stroke operator, I would wait on the YS. The question you should really ask yourself: Where do you plan to end up in the hobby so you can buy the engine you are more likely to need down the road. Think ahead and save yourself some money down the road.

The Saito 1.80 can be ready to fly in about 45 minutes, with its needles set correctly, especially the low speed needle it won't burn any more than any other engine its size. It will also run very well on 10% nitro.

PPC, I would strongly urge you to hook up with some IMAC guys in your area (if you haven't done so already) and see what they are running. YS engines are very popular in serious pattern competitions where 1.40 - 2.0 glow engines are required.

For a 10.5 lb model, I would recommend the most powerful engine of the bunch you listed: the YS 1.40. At that weight, a 1.20 or even a 1.50 naturally aspirated engine will not provide the vertical performance to which you have become accustomed.

G'day Mate,
I had a Giles 202, see pix.
I used an OS160FX, with a Bisson pitts muffler, 10% nitro, and swinging a 17x10 APC prop, a 16x10APC works well too.
Easy plane to fly, once balanced, would easily do knife edge circuits with no coupling, at 2/3 throttle, a joy to fly & land.
But make sure your balance point is not forward, ie, nose heavy. Start off at the recommended balance point, then move your batteries back after a few flights, & feel the difference.
And with the 160FX, no need for pumps or regulators, just sit the tank in it's normal position & fly the thing.
As you can see from the pic inside the fuse, the battery pack was under the wing tube, for the first flight then I moved it back progresively, until it flew properly.

Wow! Thanks for all of the feedback guys.

After Hobbsy's reply I got what I thought was a good deal on a NIB Saito 180 for $300 shipped. However, after more of the replies started coming in, I changed my mind. I have since purchased a Saito 180 (3 flights supposedly) with a PSP muffler and unused stock muffler for $280. So now I have both, but will likely sell the 1.50. I will have to order a Cline or Iron Bay or Perry pump next. In my reading, it seems most prefer the regulator over the pump? If I go with a regulator instead of a pump, is it better to use crankcase pressure or muffler pressure?


Allan, thanks for the photos and balance tips. That is the one that arrived today. I thought about the 160FX or 120AX, and I have had success with the Super Tigre 2300. But I really wanted the sound of the 4 stroke, and I don't need that much power.

Harry, if there were more IMAC/Pattern guys around I would have chosen the YS. I only see these guys once every couple of months, and really just want to burn some nitro and get stick time right now. I like to tinker, but not right now. I do think that my next plane will be a H9 Extra 260 with a YS 1.60DZ. I plan to purchase one soon after the 1.70DZ is released and I can catch a 1.60DZ at a discounted price.


Thanks again,

Kendall

PPC, the Saito 1.80 using muffler pressure will bulge a stiff walled tank just like a YS does. I prefer to let the vent only be a vent.

Read the original post and skimmed the others. My experience is different from the comments on this thread regarding YS engines. You will get more power from the YS 110 than from the OS 120, no matter what OS claims. The YS engines are not difficult to tune, run and maintain. The problems that I have seen people have with the YS engines come strictly from their reluctance to actually read the operating instructions, believing that they know more than the folks at YS or at YS Performance

I'd vote for the YS 110.

So if I want the tank near the CG, are you suggesting a Perry pump instead? The VP-30 or VP-20? I have read positive feedback on both, and would think not tapping into the case for the VP-20 would be preferable if the results are the same.



That is probably true, but others have said that either will still be on the low side of the power requirements for a 1.40 sized plane. When I stated that in the original post I was simply implying that if the power was close, then I would rather have the less complex engine. And YS Performance no longer has a website, so I wasn't able to do much research there.




Kendall

I just got finished reading several posts, so it looks like the regulator on muffler pressure and wrap the tank with some packing tape for good measure.

Thanks,
Kendall

Unless you are mounting the tank on the cg, a regulator is really not needed. Saito's draw fuel well and don't even need muffler pressure if the tank is mounted correctly. All a regulator does is provide a constant fuel head for the carb to draw from.

PPC, basically I was saying that you could drag the tank behind the plane and there would plenty of pressure to operate the regulator with a Saitos muffler pressure. I personally do not like to fool with the vent, it has a very important job to do already. In planer words, muffler pressure is more than adequate.

Double L, I like to be able to set the HS needle without taking into account the lowering of the fuel level as the flight progresses. It makes the trasition clean and crisp from the git go.

I see. I thought you were saying that the exhaust created too much pressure. Any idea how much pressure the vent creates vs. the muffler? I would think that crankcase pressure wold be more consistant, but I guess any pressure over 1 psi or so is more than enough for the regulator to work properly. Ever use a plastic coke bottle for a fuel tank?


Kendall

Don't need no wrapping tape nor clips on the fuel lines unless they are large.

Don't need no wrapping tape nor clips on the fuel lines unless they are large. This from the Cline site. www.billsroom.com/pcfs/

The fuel tank is pressurized from 2 to 12 P.S.I. by a unique one-way check valve with the pressure from the crankcase of a two-cycle engine or from the exhaust of a four-cycle engine. This forces the fuel to the controller under that P.S.I.

The controller is mounted either beside or directly behind the engine. The carburetor’s fuel line suction acts on the diaphragm in the controller causing it to open the fuel valve in the controller. It is a demand controller; thus as the carburetor’s fuel line suction increases, the amount of fuel the controller passes increases. When the engine is stopped, no fuel can enter the carburetor.