cybertech

I would like to know what people like better between 2 STROKE and 4 STROKE engines? Are 4 strokes alot more fuel efficent? Whats the pros and cons to both?

orenda635

Depends on what you'll be using the engine for.

Four strokes are more fuel efficient. They have half the horse power of two strokes of the same displacement but have much more torque. Therefore, they are ideal for scale planes and 3D flying where you want to "hang on the prop". More torque allows four strokes to swing bigger props.

Two strokes have more horse power and turn at a higher RPM. If you want speed, a two stroke is what you want. Generally, two strokes are lower maintenance and easier to set up. They're idea for any application really. It's a jack of all trades engine.

Sneasle

4 strokes can be used for speed as well. Not only can they turn a larger Diameter prop, the can turn a higher pitch... a 12X12 prop can get going mighty fast on a 4S.

khodges

My Feedback: (1)

I like everything about a 4-stroke better than a 2 stroke:

Quieter, more fuel efficient, swings a bigger prop for a given displacement, appearance, exhaust note more pleasant (did I mention quieter?) I don't own, or intend to own, a 2-stroke glow engine.

LANNYBOB

2 stroke all the way and 4 stroke no way. their loud, scream with rpm's and no adjustment required. god bless 2 stroke

masonman

Thats like ford vs chevy....Or futaba vs jr. Diffrent strokes for diffrent folks

orenda635

Very true.
After five years of flying with two strokes, I finally bought my first four stroke. They're more expensive but I managed to pick one up for cheap.
So far, I'm liking it.

masonman

635. i have both one works great in one app an the other works great for something else. I have a little toni with a jett 91 in it. This thing screams an i love it. I have a funtana with a saito an i love it swinging that big flat props. They both have there place. Now if all that was reverse, it would be like going to a top fuel drag race an watch a car go 330 mph but sound like a lawn mower doing it...........

B.L.E.

You do realize that top fuel cars that go 330 mph at the end of the quarter mile are powered by "low revving and quiet" four stroke engines, don't you?

Yep, four stroke engines are strickly low rpm engines, to drive home the point, this video of this four stroke powered car is worth a thousand words.

http://www.youtube.com/watch?v=tE0vBFSsx9o

masonman

why do the guys standing at the starting line at a top fuel event wear ear plugs? cause they are quiet?. when you say low reving four stokes you mean the 8000hp nitro burning engine that turns almost 12000 rpms.......I have never seem a car that its tach even came close to 12000. hardly a low reving an quiet event

armody

My Feedback: (10)

Idle of 4 stroke is much more better than 2 stroke as well as transition, I never used 4 stroke, don't own, but in future I would naturally cost is killing. Only the flaw in 4 stroke I see is the front valves, they seem pretty susceptiple in the case of crash, chances are very rare of saving a 4 stroke from being damaged where as 2 strokes have more chances of not being damaged at the time of crash.

Mody

masonman

Yeah they do seem like they are in a bad place, but i have screwed a .o.s. 70 an a saito 82 nose first in the ground an only suffered a cracked a valve cover on the saito...........But i watched a guy drive a pretty big 540 into the ground an the saito 180 did not make it.It was junk iron after that.

bigtim

My Feedback: (13)

here's a tip for using a 4st don't crash and you will be fine.
not using a particular engine because your thinking you will crash?are you crashing alot then you need more practice is all.
you would be surprised how tough and weak both types are if you hit the ground hard enough both will break I have seen 4st engines survive larger impacts than 2st and vise versa.
I don't discriminate 2st for sport planes,4st for warbirds is how I use my engine choices

armody

My Feedback: (10)

Crashing a plane is not an option, it just simply happens, sometimes we end up thinking for a long time how did it happen was it my fault or technical fault?

Well, many times its considered pilot's mistake. I saw senior and very carefuly flyer & I would consider him expert crashed his yak54 brand new at the field, elevator didnt respond, at particular area signals didnt work caused that huge gasser crashed. I had P51 Mustang PTS, crashed due to receiver failure, IF of receiver burned and it was JR's R700 slimline. I had a nose dive crash of my 40 size trainer with ASP .46 engine, luckily engine was safe nothing happened. I was flying my trainer quite well, suddenly all controls lost, plane didnt respond and took a nose dive then stopped on the ground, but anyway, plane crash can happen anytime anywhere nobody knows, as far as practice is concerned, yes it's a great thing, I have controlled my plane in such faster winds even 20mph. Enya's 4 Stroke engines have valves at the rear not at the front like all other manufacturers.

Mody

B.L.E.

Don't you know sarcasm when you read it?

Yes, I know full well just how loud a four stroke powered nitro burning top fuel car is. Even with ear plugs and ear muffs together, the noise hits you in the gut. You can literally feel the noise.

Notice the people cupping their hands to their ears so that they can better hear the sweet music of this four stroke powered retro rail.

cybertech

There definitely is some extremely high revving 4 stroke engines in auto racing.

masonman

Oh sorry about that B.L.E. I thought you were tossing me under the bus on that one. No harm man.

B.L.E.

The whole point of all this is the fact that there is a lot of misinformation, fallacys, urban myths, and just plain old BS surrounding four strokes verses two strokes.

Think that a four stroke puts out more torque than a two stroke? Put the prop you run on your four stroke on a two stroke of the same displacement and measure the rpm. My bet is that the two stroke will spin it faster. In order to do that, it has to make more torque.

Think that four strokes are quiet? Walk a mile away from your flying field and see which engines you still hear!

The torque needed to turn a prop quadruples when the rpm is doubled. Because of this, it takes more torque to spin a 10x6 14,000 rpm than it does to turn a 12x6 at 9000 rpm. Not understanding this fact about props leads to the common misconception that four strokes make more torque than two strokes do. The optimum prop for maximum performance out of a two stroke is usually smaller than for an equal displacement four stroke but it is not because the two stroke makes less torque. It's because it takes a lot of torque to spin even small props at 14-16000 rpm.
When you get up to the 1.20 size and up engines, the two strokes are tuned to pull best at under 10,000 rpm and hence they use the same or even larger props than their four stroke counterparts do.

Sometimes a little humorous sarcasm is the best way to get a point across.

forestroke

hmmm.... interesting... instead of commenting on previous posts, i'm going to just start afresh:

2-strokes
simple mechanics =
less temperamental
less maintenance
lighter engine
combustion on the very stroke =
higher rpm over higher torque

4-strokes
more complicated mechanics =
prettier to look at (particularly open rockers and saito hemis)
more rewarding to work on
combustion on every other rotation =
more efficient on gas
more complete burn (no exhaust gases)
deeper more pleasant exhaust note

overall the 4-strokes of the same displacement will turn a prop larger than a 2-stroke at the same RPM. yes 2-strokes can turn a tiny prop at huge rpms but for all around tractability, a 4-stroke will kick the pants off a 2-stroke. I would assume that's why most 3D and F3A prefer 4-strokes over 2-strokes. just my two cents.

B.L.E.

The only 1.40 or 1.60 size four strokes that can turn the same diameter prop at the same rpm as OS 1.40 or 1.60 pattern two strokes are the supercharged YS engines. When you get to the larger sizes, two strokes are generally tuned for low rpm (7000-9000rpm) power, especially the ones designed for F3A.

Electric power is being used in about 1/3 of the F3A planes overall and by about 1/2 of the world's top ten F3A pilots the last I have heard.

Also, most two strokes are quite happy with low nitro fuel, not that four strokes can't be built for low or zero nitro.

armody

My Feedback: (10)

Just asking one thing for the knowledge,

2 Strokes High RPM lower torque right?
4 Strokes High Torque lower RPM right?

Higher the rpm means higher the speed?

Higher the torque means higher the thrust?

What is the advantage of higher RPM and what is the advantage of Higher torque? Can anyone explain it in detail.

Thanks for that, and sorry if Im bothering.

Mody

LT-40

My Feedback: (2)

Right now I only have two strokes, but to tell you the truth, I can't wait to hear one of those four bangers in my new plane! I am also looking forward to less glow fuel cleanup.

LT-40

8178

My Feedback: (17)

I only take four stokes in a V configuration with eight cylinders, 4.4 liters and 5.7 liters.

bigtim

My Feedback: (13)

4st engines are much cleaner than there 2st counterparts the smaller amount of slime I clean off my planes tell me that,also the props I use on my 4st engines will bog the 2st equivelent reducing the HP produced through higher rpm.
if you are crashing your planes then you need to either inspect them closer for potential problems and correct them before they become fatel and practice more, things happen of course, but it seems alot of them could be avoided through due dillegence something my club preaches quite a bit.

BIGMIG

Don't know about all the tech-mumbo jumbo but I can tell you this.Take 2 motors about the same size,lets say a 70 size.One a two and the other a four stroke,put a 14 inch master air screw prop on both of them.Stand off to the side and pop the throutle back and fourth and watch the prop flex back and fourth on the four stroke.Then do the same on the 2 stroke.You will then understand what torque is.