Which 4 Stroke Do I Use

I am finally going to get around to building my Umland Magician, and am thinking about trying a 4 stroke engine. What would be the best make and size engine for such a plane? I would like it to be versatile enough to be also used on slightly larger built up models.

Only one choice as far as I know.. The Saito 40.. Run an 11-4 on 10-22 and when you put it in a larger plane just move to YS 20-20 and maybe a larger prop. The only other prop I have tried was an 11-5 and it was a tad fast.

Don - I have a 4 Stroke information exchange with around 80 subscribers. We share and pass on the various experiences and knowledge we've accumulated over time. Most are sport flyers but there are some serious competitors who are developing considerable experience with the larger engines. If you want to be on the list, just contact me: If it's not to your liking, I will remove your name as you wish.
I agree with Bob Reeves - the SAITO .40 is one of the best engines I've ever used. It's seems ideal for many .35 to .40 size planes.
Bob Z.

If you haven't already, see the Airborne video thread. This is a Saito 40 hauling a 47 ounce Twister through the entire AMA stunt pattern on a fairly windy day with relative ease.

Check out the flags, in the top right of this photo.

I agree with all the above - Saito .40.

Bob, what are you using to hold that tank on? Those are nicer looking rubber bands than the ones I usually see. Pretty slick looking.

Ron,

They look like normal zip (wire) ties to me.

I'd be interested in why you are so enthusiastic about the Saito 40. Not as a test, I do not own one for example. But they are tempting, you and I have similar backgrounds and it is so difficult on this or any site to determine who has credibility, who is just blowing smoke.

Yep, just plain old wire ties...

Dan, I think you are asking Ron but just to add some experience with the Saito 40.

The Twistmaster has been campaigned in Intermediate, P-40 and Advanced for the last 3 years and has gone through more engine changes than my wife does purses. It has also had more practice and contest flights than any airplane I have ever owned. I know what to expect from this airplane in almost any condition.

The engines....
OS 35 S reworked by GMA.
OS 40 FP somewhat stock.
Saito 30 FS
Brodak 40
Saito 40 FS

The worst was the 40 FP and the best is the Saito 40. When I say best I am saying the best all around performance under all conditions with constant lap speeds around 5 seconds, minimal wind up and the ability to pull the vertical eight when it gets windy. I can just about assure you no other engine in this group except maybe the B-40 could have carried the mail on the day I did the tank video.

I really like the B-40 but the Saito was loafing and the B-40 would have been doing all it could do. The Saito still had ponies left and I was only running 10% nitro. On YS 20-20 it really turns into an animal. No it isn't an LA 46 but for what Don wants, it is the right choice. Thank goodness we have so many great choices of engines these days, much better than even 3 years ago.

I have been using the O.S. .40 F.P. for 20+ years, 11/5 prop, scratchbuilt Biplane; "I always know what to expect" Cripes, I hope I find a Saito pretty quick! If they're that much better, it'll be like when I replaced the McCoy .29 with that K&B .35! On the Super Ringmaster! When I was 14!!! Yeow. Seriously, this O.S. has the torque of a GMC 6! (that would be pre-'60s for the young 50-yr.-olds)
I can't fathom it getting any better, but the Sig Mustang opened my eyes after flying a lot of Ringmasters! Gotta try it...

No reason to be a smart a@# just because your experience has been different than mine. I have seen FP 40's that ran great but I was not successful even following Brett Buck and others advice through several phone calls.

I got killed at a Marietta GA contest because my FP wouldn't pull the overheads in a 15 MPH wind, yet there were other FP's there that were doing fine. For me it was either run-away city or a dog depending on whose setup advice I tried to follow. I almost wasted a whole contest season messing with FP's, even tried to get a rework from Leonard but that didn't happen. Ended up selling every FP I had above a .25 and have never looked back.

I am glad you like your FP and hope it keeps working for you, I will stick with what works for me and offer an opinion when I feel it may be of some help to some other struggling wannabe stunt flyer. I didn't see anything in your post that added information to this thread topic, at least I tried to help answer the question.

Bob – I did something similar to the Twistmaster. I built “The Plane” as a simple profile test bed for 4S engines and other interesting goodies, including retracts and throttle. Check out the powerplant list:

SAITO .50 (2)
SAITO .30 (2)
ENYA .46 (2)
Merco Rustler .40 (what, no valves?)
SAITO .56
SAITO .40 (old style, large case)
SAITO .45
OS Surpass .40
OS Surpass .48
RCV .58 (Dan Banjock used this to win Expert Profile at Brodaks)
SAITO .40A (the new one).

The weight obviously varied with the particular engine, from around 51 to 59 ounces. Three ounces more with the retracts. I should mention that ALL of the 4S engines were run with the carb, either wired wide open or throttle controlled.

In any case, the .40A was clearly the best engine for that setup. It did everything better from start to flying to overall economy. It actually used about the same amount of fuel as the .30s.
The next best results were with the OS .40.
The worst performance was with the old style SAITO .40 – It just did not have the power.

Bob Z

Dan,

Thanks for the tie wrap tip. I hate gooey rubber bands.

I have a feeling you are correct about our backgrounds. I was the typical "car freak" growing up. I raced dragsters and motorcycles until I came to my senses and realized I couldn't afford to be competitive and didn't want to get hurt. (My drag car burned eight gallons of nitro each run.) I also used four strokes in my RC pattern ships and when I discovered that some were trying them in CLPA I was hooked again.

I went through the same learning curve as everyone else, but the trick for me was to give the engine more break in time. In RC, we can stuff it into a plane and let it break in while we are flying. If it doesn't sound right, chop the throttle and land. In CL, you are committed once you signal for release.

There is another thread on the SSW with Doug Moon and Brad Walker using the O.S. .52. That's the first four stroke I tried in CLPA, but shelved it in favor of the Saito .56. I now realize I didn't break it in enough. I'll pull it back out and give it more time. I still have to build a plane for it, so it will be a few months before I learn some more lessons.

Why do I like the Saito .40? I almost gave up on this one too. I thought I broke it in and put it into my Twister test bed, but it didn't run good enough. Being the stubborn idiot I am, I decided to give it another bench run. Voila! the darn thing just smoothed out and chugged. I could not believe the difference.

The Saito .40 is incredibly smooth. It's got plenty of power and is also very quiet. It's economical; I get better than two minutes run for each ounce of fuel. I think I finally got the carb leaks solved, but ran out of fuel and crashed on Monday. (Another lesson learned: four strokes just quit without warning when they run dry.) I'll put it back into the Twister and try again this weekend.

Now to the flying - I am a beginner in CLPA and have been a beginner since 1961. I still love the event and will keep trying until I die. After all these years in the hobby, my building and mechanical skills far exceed my stunt flying ability. I own a Beech Bonanza and it's a great release for after work stress, but I can't go down into the basement and tinker on it after dinner like I can with the models.

Sorry for the long winded response. I followed your columns in Model Builder for many years. If you saved any issues, I am in Ray Hostetler's helicopter column in the December 1982 issue. Too bad we live on opposite coasts - maybe we can both get to the same event sometime.

Ron,

Best thank Bob Reeves for the tip on zip ties, all I did was identify them as such.

I actually don't use them, nor do I use rubber bands very often. Whenever possible I will use serving wire to secure loops in the ends of silicone fuel line (Prather "medium") and use these as a rubber band substitute. Ya don't get near the stretch out of them, but much longer life is assured. Definitely the hot tip for securing a tank which is laying directly beneath a tuned pipe.

If you listen carefully, most four-strokes will give you a warning, even if those of us raised on two-strokes need practice. A trick I learned from PW with both the Saito 56 and 72 sipping fuel from your normal Arcey plastic tank with clunk is to go up to about 40 or 45 degrees a few laps before you think the fuel will be gone. If you listen closely it will be apparent when the engine goes just a bit lean. Pull down into level flight and it ought to quit about a half lap later.

The explanation is that with the model elevated, both the clunk and the remaining fuel are in the same place. When the motor goes lean, if you drop the model to level flight that little bit of fuel remaining gets spread out all over the side of the tank. And the motor quits.

Takes some practice to first hear the right tones from the engine and then to determine where to get the model into level flight. But it is predictable enough that one soon learns not to miss the good old cut-off loop at all.

You are assuming I can hear well enough to learn the difference

I will try your idea and see if I can work with it. I am deaf in one ear and have a little trouble with competing noise sources. Believe it or not, the Saito was quiet enough the other day that I had trouble hearing it over the traffic noise from I-66, which borders our flying site in Bull Run Park (VA). It also has a lower pitch tone, which I might not be picking up very well, either.

This could also explain my fascination with these engines. Their noise doesn't bother me.

Thanks.

Ron - Glad to see you're a Bonanza man. I spent time in one while accumulating complex time for my commercial rating. Most of my sport flying is done in my Piper Warrior.

In the early 70's, I learned how to make a small fortune racing cars: Start with a big fortune and quit early! I found that motorcycle racing was much more affordable in that a local dealer sponsored me in a Bultaco Pur-Sang motorcross racer. That and enduro racing kept me busy and often in considerable pain.

Anyhow, back to model aviation: as you may be aware, I fitted the SAITO .40A into my Brodak Nobler as an ongoing experiment. Previous engines included a Fox .35 (that's really different, isn't it?), a SAITO .30, a Surpass .26 and finally the .40.

Bottom line - the .40 is so superior to everything else I've tried, it's not even a fair comparison.

I just bolted the .40 in - no trim changes were done.

The first flights were with a homemade non-uniflow brass tank which did not work all that well - too deep, I suspect. I tried it with and without muffler pressure, and also 5 and 10% Powermaster fuel. A bit disappointing.

Last week, I installed a good old Veco 2 1/2 ounce tank, the one with the longitudinal baffle. I put in two vents, both at the front, upper, inboard corner of the tank. I fill through a vent bent into the slipstream and then cap the other one.

It's a perfect set-up. I did a few flights last night and although a bit fast with a Top-Flite 10-6 wide blade wood, it was the absolute best the Nobler has ever flown. I will try longer lines and/or a 5 pitch prop.

I'm really excited about this setup. It proves what we have found since starting to use the 4S engines: the performance of EVERY plane we've tried has improved with a 2S to 4S conversion. WHY? I really don't know or care but it's true!!!

I guess you're down in the Virginia area. I fly into Manassas on occasion.

Please give me any feedback that you might have on this or similar applications. OK?

Bob Zambelli