4 or 2 Stroke

4 or 2 Stroke
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4 or 2 Stroke - 9/21/2004 9:22:37 PM

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I am looking for a motor that will power a Funtana 90S. I see and hear alot of people who prefer to use large 4 strokes over 2 strokes. I don't know exactly the reasons why more people use 4 strokers over the the 2 cycle but I am looking at a few large 2 strokes in around 1.20 size.

I want to buy the 2 stroke for no other reason than ecenomical reasons.

I basically understand size comparison and HP and torque differences but cannot find any good reasons why not to buy a 2 stroke.

Someone please shed some light on this for me.

RE: 4 or 2 Stroke - 9/21/2004 9:28:02 PM

William Robison

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Rob:

If you are happy with a two stroke engine there is absolutely no reason to add the complexity and expense of a four stroke engine.

Bill.

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RE: 4 or 2 Stroke - 9/21/2004 9:52:52 PM

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Ditto. Do like the four strokes, but usually you can find a two stroke that will do the job as well.

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RE: 4 or 2 Stroke - 9/21/2004 9:54:03 PM

djlyon

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On that airplane a 2 stroke Webra 120 will run circles around any 120 4 stroke and at least one circle around a YS120 4 stroke. And it will be at least as reliable as any of them. Unless your into cool sounds go with the Webra.

Denis

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RE: 4 or 2 Stroke - 9/21/2004 10:41:39 PM

Hobbsy

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Also, the Webra 120 is easy on fuel for some strange reason.

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RE: 4 or 2 Stroke - 9/22/2004 10:13:19 AM

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2-strokes are great when HP and cost is your main concern, while 4-strokes sound soooo good and give u more flight time per tank than an equal sized 2-stroke. They both have their pros and cons, so I can't say which is better. Kinda like comparing between a 2-stroke dirt bike and a Harley. The dirt bike gives economical, high-reving bursts of power, coupled with more smoke and thirstier consumption, but u have to be in the "powerband" to harness the power of the engine. The Harley on the other hand is torquey right from idle, great-sounding, and ideal for long distance cruising.

I guess it boils down to individual preference and application.

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RE: 4 or 2 Stroke - 9/22/2004 5:30:53 PM

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Well, this is probably the wrong forum to say this, but if I were going to use a two stroke of that size, I'd go for a gasser instead of a glow engine. For me, there would be no way to justify the expense of the large quantities of glow fuel on any engine larger than a .91 unless I was after the sound of a 4 stroke or using a 4-stroke radial for scale appearance. Charlie

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RE: 4 or 2 Stroke - 9/22/2004 6:40:11 PM

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I have a 2 stroke and is great but sometimes you just need the sound of the 4 stroke. Also, I have a question for anyone. I have a AT-6 Texan 60 with a Saito 100 up front. Because of the torque the plane kicks left as soon as i add power. It dosen;t matter how fast or slow the power is aded. I have heard about puting 5 degrees to the right on the engine to counteract this, Any information and how to do this?

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RE: 4 or 2 Stroke - 9/22/2004 7:00:45 PM

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HercDoc,

Be sure to consider how this plane should be flown. You cannot overspeed the FuntanaS airframe or you will face catastrophic failure. This plane MUST be flown slow. You want low RPM torque and instant throttle reponse for this plane. I would go with a 4-stroke...and I did. I have a Saito 180 on the front of mine. Now, this is way more power than needed but I had the engine and couldn't spend another $300 for a new one. I am very happy with it thus far. If I were to buy a new engine for this plane I would go with the YS 110, although the Saito 120 will fly it nicely. Good luck!

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RE: 4 or 2 Stroke - 9/22/2004 9:54:33 PM

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There's nothing wrong with using a 2 stroke, especially when money is the issue. A 2 stroke will work just fine.

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RE: 4 or 2 Stroke - 9/23/2004 12:53:10 AM

djlyon

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You do it by adding washers or spacers under the left side of the engine mount. I would start out with 2 or 3 degs at first and see how it goes. Most of your problem is your plane is a tail dragger probably swinging a large diameter prop. It isn't so much engine torque you are seeing as prop "P" factor turning the plane the left. The blade going down on the right side is at a higher aoa than the blade coming up on the left. This can properly be called torque but it's not engine torque. It's the plane of the prop not being perpendicular to the air stream.

All of this has nothing to do with 2 or 4stroke

Denis

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RE: 4 or 2 Stroke - 9/23/2004 6:24:39 PM

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I am currently flying a OMP Yak 54 at 7.5 Lbs. with a Webra 1.20. I cannot imagine a better combination. I am using an 8 Oz. fuel tank and commonly land with 3 or 4 Oz. remaining after a ten minute flight. In over 25 flights now have never used full throttle. With the Bisson sport muffler if there is a 4-stroke in the air you can't even hear the Webra running, probably because it is never running over 5 or 6 thousand RPM. I am strongly considering a Funtana 90 for this engine if and when I dork the Yak.

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RE: 4 or 2 Stroke - 9/23/2004 6:48:49 PM

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quote:

ORIGINAL: mattfaulkner

Also, I have a question for anyone. I have a AT-6 Texan 60 with a Saito 100 up front. Because of the torque the plane kicks left as soon as i add power.

On the ground or in the air? If it's on the ground, use rudder to counteract the torque. Proper use of rudder on any warbird is a must.

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RE: 4 or 2 Stroke - 9/23/2004 9:15:22 PM

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quote:

If you are happy with a two stroke engine there is absolutely no reason to add the complexity and expense of a four stroke engine.

This may be true, however, if you don't have any experience with the 4 stroke, how can you make the judgement on which you prefer. I know I couldn't until I flew a 4 stroke engine (OS 70 II). I wouldn't fly anything else now...that's just me.

quote:

Kinda like comparing between a 2-stroke dirt bike and a Harley. The dirt bike gives economical, high-reving bursts of power, coupled with more smoke and thirstier consumption, but u have to be in the "powerband" to harness the power of the engine. The Harley on the other hand is torquey right from idle,

Herein lies the truth to why 4 strokes (in my opinion) are better. They produce most of their usable power lower in the rpm range, as compared to 2 strokes. This is why they may seem to have more torque. They pull better at a lower rpm. This is a feature that lends itself to 3D flying type planes too. Slower flying than usual is what these planes do well. Like the Funtana. If you had the chance to fly the Funtana with either type of engine, you would probably not want to take the 4 stroke off when you were finished flying.

As for...

quote:

I want to buy the 2 stroke for no other reason than ecenomical reasons.

I would say buying an engine cause it's cheap, or cheaper may not be more economical. The initial expense of a 4 stroke may be more in some cases, but I believe your fuel savings would offset that difference in time.

Jim

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