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-   -   2 stroke VS 4 stroke (http://www.rcuniverse.com/forum/questions-answers-154/3602210-2-stroke-vs-4-stroke.html)

av8rdavid 11-30-2005 06:41 AM

2 stroke VS 4 stroke
Hi, i'm just wondering what people prefer and why...2 or 4 stroke?
i'm running a saito .65 on a 40 scale decathlon and lack the power for some reason...Before i upgrade, want to make sure i should do it 4 or 2 stroke.


Zippi 11-30-2005 09:51 AM

RE: 2 stroke VS 4 stroke
I've ran 2 stoke engines for years, mainly OS, Super Tigre. I bought my first 4 stroke last year and it was a Saito .82. It was one of the best engines I've ever come across. I liked it so well that I bought a Saito 1.00 and put in my Edge 540. There is nothing to these engines, just 40 min. break in at half throttle and your ready to go. I have never had one die on me or not want to start. These are very good quality engines and well worth the price and looking forward to the new Saito 1.25 coming out in December to put on my Seagull Laser 200. You can't beat the sound of a 4 stroke over a 2 stroke engine. They cost a little more but IMO they are well worth the money.

2slow2matter 11-30-2005 09:53 AM

RE: 2 stroke VS 4 stroke
Four strokes are Awesome! I like the crisp, sharp, powerful transition from idle to full throttle. I don't get that with my two strokes. I also like the way they spool down faster. Generally, you can run a larger prop on a four stroke, and it doesn't sound like a flying weed eater.

As for upgrading--the saito .56 is not a powerful motor. I mean, it's powerful for it's size, but it WILL NOT win any pylon races. It would be right at home on a little 4.5 lb 3d plane spinning a 13 X 4 prop. For the decathalon, I'd go with the saito .72. Much more power, and the same sized case. When you take the .56 out, the .72 will mount right in without re-drilling anything, and is overall about the same size and weight. A little heavier and taller, but not much. Mounting dimensions are about the same! Talk about waking a plane up!!!

Gringo Flyer 11-30-2005 11:21 AM

RE: 2 stroke VS 4 stroke
I just bought my first 4 stroke and love it, it is awesome. For me the 4 vs 2 stroke depends on the plane. For a small combat plane and small 2 stroke is the way to go. For a trainer or general sport plane, again 2 stroke is great bc they are economical and a breeze to setup. But if you want a warbird or a barnstormer biplane a 4 stroker is the way to go. Also, for awesome 3D a profile with a 4 stroke is incredible.

For the decathalon a 4 stroke would be great bc of the more scale sound. Although you could save a chunk of change with a 2 stroke. (For $80 you could buy a TTpro 46 and it would fly fine or you can spend over $200 for a new Saito 4 stroke)

For me it depends on the kind of plane and funds available.

js3 11-30-2005 12:37 PM

RE: 2 stroke VS 4 stroke
If you want to win races, two stroke motors are the way to go.

britbrat 11-30-2005 02:31 PM

RE: 2 stroke VS 4 stroke
As with just about anything, there are lots of compromises to be made in engine choices.

Glo 2-strokes are generally cheap & make tons of power for their size -- that means that to get the best out of them you have to twist their tails pretty hard. For a given displacement, 2-strokes will outperform 4-strokes -- by processing a lot of fuel in a hurry. They prefer props that let them wind up until they squeek -- which sounds a bit odd in some types of aircraft. However, contrary to popular opinion, they CAN turn big props, but they just aren't doing their best work -- they run a little hotter than usual & you lose a bunch of potential HP -- dropping them down in output to that of a similar displacement 4-stroke, but without getting the nice sound & fuel economy of the 4-stroke.

Glo 4-strokes are costly to buy & usually cheaper to run. Because they don't need the massive muffler of the 2-strokes, they can actually be lighter in weight despite the larger number of internal bits & pieces. This is particularly true in the larger sizes. They don't rev like a 2-stroke & if you try, it will kill them as dead as a rock. They do turn a nice big prop, or a steep prop, quite comfortably. They sound neat in the right applications, but like the 2-strokes, they can sound silly in the wrong applications.

Gas 2-strokes are a bit different again. They usually don't like to rev like a glo 2-stroke, but unlike a 4-stroke they will survive occasional forrays into never-never land. They spin big props like a glo 4-stroke, but they burn lots of fuel --- which isn't a problem, since it is cheap gasoline. They are great for large-scale models

jlobster88 11-30-2005 02:54 PM

RE: 2 stroke VS 4 stroke
I just bought my first 4-stroke, it is a Magnmum .91. I have only flown about 5 times with it but i love it. It is Quiter, and they have more torque. I prefer the 4-stroke because of the torque and not speed. my advice would be to go with the 4-stoke it is worth it in the long run.:D

JohnW 11-30-2005 04:01 PM

RE: 2 stroke VS 4 stroke
Britbrat - "As with just about anything, there are lots of compromises to be made in engine choices."

That pretty much sums it up.

I really don't have anything significant to add to the previously posted general personalities of 4S vs 2S. However, one should note that these are very general, and many engines do not fit well into their class description. For example, a YS 4S. True to 4S nature, they produce very good power at low RPM, but unlike many other 4S engines, they are fuel hogs and are not cheap to run. Also, the lines between 2S and 4S tend to blur as displacement increases. For example, a YS160DZ 4S is very similar in performance and response to a 1.60 2S OS with pipe. Both turn about the same prop at the same RPM, etc.


av8rdavid 11-30-2005 05:05 PM

RE: 2 stroke VS 4 stroke
Very true and very informative what everyone has posted....I think i might just upgrade my .65 saito and stick with the 4 stroke family since my application (the decathlon 40) would be better off.
NOW>....Should i go with SIATO or OS ???
Hope i didn't open a new can of worms...hahaha!
Thanks to all for the priceless input.


iaclmac 11-30-2005 05:46 PM

RE: 2 stroke VS 4 stroke
I have beed reading this thread with a lot of interest. It seems that the majority are in favor of the 4 strokes. My first 4 stroke was a magnum 30 that I put into a 500sqin scratch built. It was really good. Now I have a Saito 56 in a Kadet and am planning on using Saito 100 in a Stinson Reliant that will also be scratch built.

Now I see you are asking which 4 stroke Saito or OS. In my mind, it really depends on your application. In my case I am a big time scratch builder. Some of the perils you face as a designer/builder is the engine choice. I use the OS 2 stroke 35's, 40's and 46's because they share the same mounting holes. When it comes to 4 strokes ... Saito is king for me. They have grouped several of their engins in the same size case. For example the FA46, FA50, FA56 have the same mounting holes. The FA65, FA80 and FA91 have the same mounts. The FA72 and FA82 are the same mounts. Then when you get to the bigger engines, the FA120, FA150, and FA180 all share the same mounts. So for me, if one powerplant is not hauling the plane like I want it to, I simply get a bigger size. I don't think anyone could talk me out of the OS for 2 strokes or the Saito for the 4 strokes. Like the other responders to this thread have said ... The Saito costs a little more but it is well worth it. If that hasn't sold you, I can put it another way ... You spend a lot of time working and building your plane. I lot of hidden costs in time and sweat equity go into that bird. Why on earth would you "half ass" the decision over the proper engine vs a few bucks. It is a sad fact of life ... good engines do cost a little more, but, the end result is really worth it. Geez I should be a salesman for Saito ..... LOL
Good luck with your decision

mirwin 11-30-2005 05:58 PM

RE: 2 stroke VS 4 stroke

ORIGINAL: av8rdavid ". . . . Should i go with SIATO or OS ??? . . "
Dave, that's like asking who makes the best vehicles, Ford or GM. You'll get no definitive answer.

Saito's are good engines and so are OS. If you also consider a Magnum 4-stroke, then you're adding Chrysler to the Ford vs. GM mix. I have Saito, OS and Magnum 4-strokes. Even compared to my new OS 1.20 4-stroke with pump, I think the little magnum .80 4-stroke runs smoother at all RPMS. I believe the OS 1.20 4-stroke has more "grunt" than a comparable Saito.

At the end of the day, I believe they're all very good quality engines that, if properly cared for, will last many years.

By the way, that Magnum .80 4-stroke is on a .40 size warbird, and it is a real performer.


ace0811 12-01-2005 12:58 AM

RE: 2 stroke VS 4 stroke
Opinions are like butholes, everyone has one and they usually stink. Well, here's mine. I have owned supertigre .51,.61 and 2300, thundertiger.46and .61, os .40 and .61 and magnum .40 2Strokes as well as OS70surpass, magnum 91FS, saito 1.00 and 1.80, and YS 1.10. Everyone of them has had thier tempermental moments and everyone of them has run absolutely fantastic. Engine choice for me is generally determined by application. If i want to scream across the sky at a thousand mph I'll run a 2 stroke. If i want to slow down and still have power to pull vertical into space I'll run a 4 stroke. I prefer 4Stroke for 3D and 2 stroke for some fun old sport flying. Which brand I buy is generally determined by how much money mama will let me spend. All the info in this thread is very good. I think you'll just have to experience both and form your own opinions.

JohnW 12-01-2005 02:44 PM

RE: 2 stroke VS 4 stroke
"Dave, that's like asking who makes the best vehicles, Ford or GM. You'll get no definitive answer."


Both OS and Saito make good engines. Both are major players in the 4S glow market and I'd consider them in the top 3. (YS rounds out my personal top 3 4S glow list.) You really can't go wrong with any of these three.

jeffk464 12-01-2005 08:49 PM

RE: 2 stroke VS 4 stroke
I think the 2 stroke glow engine fit a lot better under the K.I.S.S. philosophy on engineering. They are cheaper, simpler, and produce lots of power for their size. Just remember your hearing protection because they seem a lot harder on your hearing.

Machinegun21 12-01-2005 11:45 PM

RE: 2 stroke VS 4 stroke
Well, personally i am running a Magnum 91 4-stroke in my Hobbico SU-31 and the thing is auwsome. it has more power than i could imagine and it is fast.

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