I was going to my LHS today to pick up my h9 SHowtime 50 with a Saito .91 4 stroke. After reading this post.....

http://www.rcuniverse.com/forum/m_64..._1/key_/tm.htm


....Im now confused. I thought a 4 stroke was best for an aerobatic pattern/3D plane. I might be reading too much into it...but any help would be appreciated. Would I be better off with the 4 stroke over the 2?

Almost everything you read in these forums is opinion. Sometimes it's opinion based on first hand experience and other times it is just opinion.

I have two 2-stroke engines and three 4-strokes currently on planes. All of my 4-strokes (OS & Magnum) seem to run consistently throughout the range of throttle settings. They idle forever if I want, and transition from idle (or any low setting) to a higher setting is always smooth. My 2-strokes are less consistent. My TT-61 Pro idles great and runs great at full throttle. Transition from idle to full is pretty good but not great. It tends to "gurgle" at part throttle and transition from a low setting to a higher one is usually not smooth. I have an ASP 61 and it seems to throttle better than my TT and it does not "gurgle" at part throttle. The ASP is pretty new so only time will tell how well it works long term.

Since the Showtime appears to be something that would need to run at lots of different throttle settings, my opinion based on experience with my own engines is that a 4-stroke would be a better choice than a 2-stroke.

One of our club members would not run a 4-stroke if it was given to him. He'd sell it and buy two 2-strokes. He likes the simplicity, and price, of 2-strokes. He tends to fly sleek, fast, models. He doesn't treat the throttle like an on/off switch, but I think most of his flying is done above half throttle.

Just got my Showtime 50 and I'll install a Satio 1.0 in it. Probably use like a 15x6 APC, so I'll get the best of pattern flyilng and be able to do some 3D stuff. 4 Strokes might take a little more work than a four stroke, but for flat out torque and power, its there right now, it takes a 2 cycle a bit to get going. Sort of like in pattern flying, 2 stroke planes tend to need to build up speed to get though a maneuver, verses a 4 stroke, where you're swinging a bigger prop and you have power quicker. Its all a preference, as everyone will have an opinion. I fly both kinds of engines but the 4 strokers when working right make flying funner and of course, they sound better too.

Thanks guys.....Ive decided on the Saito 91.....Now im torn between that and the Saito 100....ARRRRRRRRRRRRRRGGGGGGGGGG

Picking components is torturous in this hobby> To many choices!

As you move up, the 4 strokers gain an upper hand.

In the .50 region though, the 2 stroker will do just as well when properly propped.

You do not have to worry about it "taking longer" to get up to speed, etc. The 2 strokers do just fine. You will NOT be racing with a Showtime that's for sure...


The "swinging a bigger prop" is a bit of old' marketing hype.

Take a 2 stroker of EQUAL displacement to a 4 stroker and you'll see that the 2 stroker calls for a larger prop than the four stroker or at worst varies very little... Ooops.

To offset the power differences, you have to go with a larger displacement on the four stroker to "swing that larger prop".

So you are not really comparing apples to apples.

As you move up from the .60 sizes however fuel consumption becomes a bigger and bigger issue, and the four stroker's eat fuel at a slower rate giving them a marked advantage.

Now all of that said, four strokers sure sound nice, and nowadays most of them are as reliable as 2 strokers.

What I said almost as reliable?

There was a time not too long ago that 4 strokers were looked down upon as less reliable.... it seems we are past that though as at least my experience with most 4 strokers has been very good.

I've seen Showtime .50's fly with both Saito's and 2C engines w/o problems.

I am installing the new YS63S in my Showtime. Should have it done next week. Fits nice in the cowl.

Let me know how it goes....would love to heat.

Let me know how it goes....would love to hear.