difference between 2and 4 stroke engines?
 

what is the difference between a 2 and a 4 stroke engine?

RE: difference between 2and 4 stroke engines?
 

in the simplest of terms a 2 stroke fires on every rototation of the crankshaft and a 4 stroke fires on every other rotation.

RE: difference between 2and 4 stroke engines?
 

is there any difference in power, price, reliability?

RE: difference between 2and 4 stroke engines?
 

Four stroke engines seem to have more low end torque than 2 strokes. They make good 3D engines. They get better fuel economy than two strokes but initially cost more money. Most four strokes are quiter than most 2 strokes. The four strokes are not as exhaust restriction sensitive as the two strokes are.

Old timers tend to like the more casual easy going sound of the four strokes for their kind of flying. Four strokes sound more realistic in scale models..

Two strokes make more all out power and are cheaper and easier to maintain. Two strokes hold up better in a crash and are cheaper to repair than four strokes.

Enjoy,

Jim

RE: difference between 2and 4 stroke engines?
 

I like two stroke engines for everything that the 4-stroke isn't (cheap, cheaper, cheapest). I own both types of engines and I don't see all the "hoopla" about the 4-stroke. For my flying money, the cheapest 2-stroke wins (I haven't found a 2-stroke I didn't like).

As Jim stated about crash worthiness, 2-stroke engines are better for beginners and the rest of us "slow-thumbs" (because we all know, sooner or later, that plane will be recycled back to mother earth). With the price of the 4-stroke, you can get two or three of the 2-stroke for the same amount (for ex. Saito 40 is $180 from Horizon Hobby, Super Tigre 40 is only $50 from Tower).

I say "Keep it simple, and cheap".

Both types of engines will power your plane. As long as a plane is flying, there will be smiles all around.

Fly and be :)

RE: difference between 2and 4 stroke engines?
 

Four strokes sound better! :D (imho)

RE: difference between 2and 4 stroke engines?
 

My buddy just flowed his YS 63 four stroke in a GP Mustang straight down into the ground at full throttle due to a radio hit. The engine was about a foot underground and he had to dig it out. The engine mounting flange broke off and the engine was full of dirt. Yet, after he cleaned it up, it ran much better than before. I had two mid airs with my YS 110FZ, and both times the engine fell from 300 feet into the ground. That engine is still running great to this day. Some four strokes can handle crashes just fine.

RE: difference between 2and 4 stroke engines?
 

$$$$$$$$$$$$$$$$$$$$Spaceballs$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$$$:D

RE: difference between 2and 4 stroke engines?
 

Like I said, we all have our less than fortunate moments. Maybe YS should include "crash-break-in" procedures to improve performance. :D

Some of us prefers to see how indestructible $250 (YS63) or $350 (YS110) engines are. If I plant my ST .40, I'll just buy another one and still have $150 left over for 3 additional spares.

As long as it flies, everyone is :)

RE: difference between 2and 4 stroke engines?
 

You cant beat the cool factor of a 4 banger though. Although my budget keeps me to 2 strokers. I can buy a 2 stroke engine and the model and some radio gear for what the equivalent sized 4 stroke motor alone would cost me.

Although there are some planes that really look better flying with the sound of a 4 stroke (scale, some bipes, etc)

For more technical info on the difs do some searches here on RCU. Plenty of info is already out there.

RE: difference between 2and 4 stroke engines?
 

All the above. 4-strokes are more complex, have more moving parts than 2-stroke, need more maintenance than a 2-stroke. If all out speed is what you want, go 2-stroke. If you've got a warbird, want to turn a scale diameter prop, go 4-stroke. 3-D and pattern can go either way, I've seen both types engine in both types plane and they both work well.

How the engines deliver their power is their biggest difference. A 2-stroke has less of its compression stroke length to compress the mixture, and less of the power stroke to deliver its power to the movement of the piston, due to the covering and uncovering of the intake, transfer, and exhaust ports by the moving piston. The 4-stroke power stroke "pushes" the piston longer, making more torque at lower rpms. It's like the difference between a slap on the face or a punch in the jaw.

To each their own, I love 4-strokes and probably will not own a 2-stroke unless it is a gas engine.

RE: difference between 2and 4 stroke engines?
 

I like the power from the lower RPMs of a 4 stroke better than waiting for a 2 stroke to wind up to 10,000 or so. I'm flying both and have to adjust to the power output differences of each.

RE: difference between 2and 4 stroke engines?
 

$$$$$$$$$$$$$$$$$$$$$

You need to pay more attention to a 4 stroke than you do a 2 stroke. They do not take the abuse that a 2 stroke can.

RE: difference between 2and 4 stroke engines?
 

Yep, cool factor is what this hobby is all about. This is why warbirds have retracts, scale wheels, scale pilot, sliding canopy, bomb drop, etc... I only use 4-strokes in my warbirds. When Fuji comes out with their 4-stroke gassers later this year, I will probably get one of those also.

RE: difference between 2and 4 stroke engines?
 

You guys are making it too complex.

It's very simple:

Different strokes for different folks.

Four strokes have always been better for me than two.

RE: difference between 2and 4 stroke engines?
 

The 2 strokes and 4 strokes fu have one thing in common. Whe running in reverse, they are both doing the "Back Stroke":D:D:D[sm=spinnyeyes.gif]

RE: difference between 2and 4 stroke engines?
 

:D:D:D:D:D! ROTFLMAO!

RE: difference between 2and 4 stroke engines?
 

after all this, what do u suggest for a beginner to put into a top flite cessna 182 w/ 84" ws p.s. glow or gas what is the difference

RE: difference between 2and 4 stroke engines?
 

Here is a rule of thumb:

* Trainers, fun-flies, sport planes: 2-stroke
* Scale planes: 4-stroke
* Large planes: gas

I would go with gas for any plane with 80" wingspan or larger.

RE: difference between 2and 4 stroke engines?
 

Hello; The two cessna's that I have seen both had 91 four strokes in them. One a Saito the other an OS. Both flew very convincingly.

I prefer four strokes for the scale sound and performance, but whatever you enjoy would work for me too.

I fly at sea level where the air is very dense with a high oxygen percentage, other fellows that fly at high altitude will tell you that youneed a 150 minimum.

RE: difference between 2and 4 stroke engines?
 

forgot
* 3d - 4 stroke

as always, just a rule of thumb, but most 3d'ers prefer a 4 stroke.

RE: difference between 2and 4 stroke engines?
 

I totally agreed.

RE: difference between 2and 4 stroke engines?
 

I am a big 4-stroke fan, as well, but altitude has nothing to do with which one (2- or 4- stroke) runs better. Oxygen percentage does not change with altitude, it is always 21% of total air volume. The partial pressure changes with altitude, as well as total density, which means that at higher altitudes, an engine is effectively taking in less total molecules of air, but the percentage of oxygen within that thinner mix stays the same; is why supercharging or turbocharging helps engines maintain power output at high altitude.

RE: difference between 2and 4 stroke engines?
 

Hello; Our oxygen percentage is 27% here on Vncouver Island. Living among thousands of acres of virgin timber raises the percentage. Our air is un-polluted as it comes straight off the pacific and passes no industry and very few cars before it gets here. The denser air gives the prop more to bear against, it makes the plane more buoyant i n the air. I have flown at higher altitudes and have seen the difference.

The point is that I can get away with a smaller engine then a fellow at 5000 feet altitude could.

RE: difference between 2and 4 stroke engines?
 

You implied that as altitude increases, the percentage of oxygen in the air decreases, which is not so. Sure there are variations in the specific percentage in specific areas under specific conditions but the average is 21% oxygen, 78% nitrogen, and 1% other gases, and that remains constant from the surface up. The decrease in atmospheric pressure as altitude increases is also a variable to a small degree, dependent on weather patterns, but the overall rule is the higher you go, the thinner the air, or lower the atmospheric pressure is, which is an AVERAGE of 14.7 pounds per square inch at sea level. Places such as Death Valley and the Dead Sea have higher base atmospheric pressures due to being below sea level. This effect of decreasing pressure affects the human body as well as our engines, although the mechanism is quite different. You can compensate for an engine making less than adequate power by increasing the engine size, but even that engine is making less power than it would at a lower altitude. In a human, supplemental oxygen is necessary at higher altitude not because the percentage has dropped, but because the partial pressure of the oxygen has dropped, and our lung transfers oxygen to the blood by a partial-pressure differential mechanism, which can be compensated at lower pressures by a higher concentration (percentage) of breathed oxygen. In effect, you could also do this to your engine to compensate, this is the hot-rodder's reason for Nitrous Oxide systems, except for the obvious weight disadvantage it poses for our models

You probably make a good point about more oxygen in a dense forest, maybe that's why a hike through such an area seems to invigorate you more than just the exercise alone does, and it would apply while down inside the canopy, but once the air gets stirred by even the slightest breeze, it mixes and dilutes that percentage. Not only in virgin forest, but any woodland where trees are actively respiring would this be true.