What is the Difference between two cycle engines and four cycle engines?

Answer 1

Answer:In order to function, an internal combustion gasoline engine must 'inspire' (breathe in) a fuel/air mixture, compress that mixture, burn it, and exhaust the waste gases. Those four steps -- intake, compress, burn, exhaust -- are the fundamental building blocks of modern gas engines.

Two-stroke and four-stroke engines do those things somewhat differently. But the common terms "two-cycle" and "four-cycle" are incorrect. A two-stroke engine has a 'cycle' comprised of two strokes -- one stroke down, one stroke up; a 'four-stroke' engine uses four strokes of the pistons -- one down, one up, one down, one up -- to accomplish a 'cycle.' In other words, both types use a defined 'cycle' of piston activity, but it's the number of strokes of the piston that define the difference. Actually, both types are 'one-cycle' engines. Are we totally confused yet? Good!

I'll take the four-stroke example first because, believe it or not, it's easier to understand and explain. Keep in mind that the process is the same regardless of configuration or number of cylinders.

STROKE 1: A four-stroke 'cycle' begins with intake, as a piston moves toward the crankshaft, drawing the fuel/air mix into the cylinder through the open intake valve. The exhaust valve is closed.

STROKE 2: At the bottom of that travel, the intake valve closes, and the piston moves away from the crankshaft, compressing the fuel/air mix to anywhere from 7 to 12 times its atmospheric density. The exhaust valve remains closed.

STROKE 3: Near the top of Stroke 2, an ignition device fires (spark plug) and the piston is driven back toward the crankshaft under extreme pressure. The exhaust valve opens; the intake valve remains closed.

STROKE 4: The piston travels back away from the crankshaft, pushing the waste gases (exhaust) out of the cylinder through the open exhaust valve.

At the end of stroke 4, the exhaust valve closes, the intake valve opens, and the cycle begins again. So simple!

But note the mechanical complexity! A four-stroke engine requires a rather elaborate valve-train, geared to move at a rotation rate different from the crankshaft, and involves dozens, even hundreds, of moving parts.

A two-stroke engine accomplishes much the same result -- a spinning crankshaft powered by gasoline -- but in a different and decidedly simpler way. A two-stroke trades the beauty and fuel efficiency of the four-stroke arrangement for a hefty fuel appetite and a serious reduction in weight.

STROKE 1: The piston is moving toward the crankshaft, driven by an ignited charge of fuel/air, and as it goes it draws in a new charge of fuel/air.

STROKE 2: The piston travels away from the crankshaft, expelling the waste gases, but at the same time compressing the new charge of fuel/air.

At or near the end of Stroke 2, the spark plug sparks, the fuel/air goes BOOM, and the cycle begins again.

That's it. It sounds like a crowded arrangement because it is, and that crowding, that mixing of functions, results in the two-stroke's appetite for fuel. The two-stroke engine is not the most fuel-efficient design. When comparing engines of equal power output, two-strokes will use MUCH more fuel than their four-stroke cousins.

But the difference in function also accounts for other physical differences. Two-stroke engines of a given power rating are generally smaller, lighter, and easier to maintain than their four-stroke equals. They also don't have valve trains or crankcases or oil galleries, depending for lubrication instead on oil that is mixed with the gasoline fuel.

Two-strokes are favored for applications like chainsaws, string trimmers, leaf blowers, hedge trimmers, and other hand-held gasoline-powered equipment. The power-to-weight ratio GREATLY favors two-strokes. A four-stroke string trimmer would be unsellable because of its inherent weight.

2 stroke engine fires1 time in each revolution whereas a 4 stroke fires1 time in 2 revolutions. 2 stroke is simpler and lighter, but less versatile.

In place of valves in 4stroke engines ,ports are present in 2stroke engines

2 stroke has no valve, the piston act like a valve to control the flow of fuel

3. light duty engines are 2 stroke used commonly, for heavy duty 4 stroke are using

TWO STROKE & FOUR STROKE ENGINES ARE THE CLASSIFICATIONS GIVEN TO INTERNAL COMBESTION(IC)ENGINES. THE TERM STROKE IS COMING FROM THE WORKING OF A IC ENGINE.ITS THE LINEAR DISTANCE,MEASURED PARALLEL TO THE AXIS OF CYLINDER,BETWEEN THE EXTEME UPPER & LOWER POSITIONS OF THE PISTON.

The two-stroke internal combustion engine differs from the more common four-stroke engine by completing the same four processes (intake, compression, combustion, exhaust) in only two strokes of the piston rather than four. This is accomplished by using the beginning of the compression stroke and the end of the combustion stroke to perform the intake and exhaust functions. This allows a power stroke for every revolution of the crank, instead of every second revolution as in a four-stroke engine. For this reason, two-stroke engines provide high specific power, so they are valued for use in portable, lightweight applications such as chainsaws as well as large-scale industrial applications like locomotives. Invention of the two-stroke cycle is attributed to Dugald Clark around 1880 whose engines had a separate charging cylinder. The Crankcase scavenged engine, employing the area below the piston as a charging pump, is generally credited to Joseph Day (and Frederick Cock for the piston controlled inlet port).

A 2 cycle engine you mix the fuel with the oil. And don't put any oil in the bottom of the motor. Because the gas and oil mix lubricates the motor as well as runs it. A 4 cycle engine you put the fuel in the gas tank and you put the oil in the bottom of the motor.

2 stroke engine fires1 time in each revolution whereas a 4 stroke fires1 time in 2 revolutions. 2 stroke is simpler and lighter, but less versatile.

In place of valves in 4stroke engines ,ports are present in 2stroke engines

2 stroke has no valve, the piston act like a valve to control the flow of fuel

3. light duty engines are 2 stroke used commonly, for heavy duty 4 stroke are using

Well i do know that a four stoke engine which is more commonly used today due to emmisions. The term four cycles hence the four strokes has four stages. The First cycle is intake where the air and fuel is mixed into the cylinder. Second is the compression stage where the air-fuel mixture is compressd by the piston. The third stage is the power stage. The power stage is where the compressed air-fuel mixture is ignited by the spark plug forcing the piston back down. Finally the Fourth stage is the exhaust where the carbon monoxide exits out the exhaust pipe. You can remember the stages easier by knowing Suck Squeeze Bang Blow

one you mix your gas withoil and the other yo dont! and the 2 stroke sounds hella nicer

a two stroke engine "fires" each time the piston travels up and compresses the fuel/air mixture. A four stroke engine fires every other cycle. With a four stroke engine, the piston travels up, engine fires piston travels down then back up, exhaust stroke to clear the cylinder then the cycle repeats.

A four stroke engine generates a power impulse every other revolution of the crankshaft. (For each piston) Each up or down sequence of the piston is called a stroke, which is why it is called a four stroke engine. The first stroke is intake. The piston moves down while the intake valve opens, letting in fresh air and fuel. Then the intake valve closes. The second stroke is compression. The piston move up with both valves closed, compressing the air/fuel mixture. Near the top of this stroke the spark plug fires. The third stroke is power. The piston moves down with both valves closed, forced by the explosion of the air/fuel mixture that the spark plug ignited. The fourth stroke is exhaust. The piston moves up while the exhaust valve open, discharging the spent air/fuel mixture into the exhaust system. Near the top of the exhaust stroke, the exhaust valve closes and the intake valve opens, and we repeat with the intake stroke. A two stroke engine generates a power impulse every revolution of the crankshaft. (For each piston) Since the piston goes up (one stroke) and down (another stroke), it is called two stroke. Things happen at the same time. When the piston moves down from the explosion of the air/fuel mixture, the exhaust ports are opened, discharging the exhaust, followed by the intake ports opening, which lets new air/fuel mixture in. The compression stroke is the same. The piston moves up and compresses the air/fuel mixture. In order for power, exhaust, and intake to be combined, some interesting things happen. Some designs use a reed valve between the carburetor and the intake port, which does not open until the exhaust pulse is completed. There are losses in the two stroke design. Some air/fuel is discharged into exhaust before being ignited. This is minimized by the design of the various parts, such as the shape of the piston top, and by the timing of the various ports that open and close. The advantages of the two stroke design is you get more torque, because you have twice as many power strokes per revolution, and you don't need valves or a camshaft. Some designs, of which Suzuki is one, uses the compression volume under the piston to aid the cycle. The carburetor supplies air/fuel to the lower space, which is opened by a port controlled by the piston skirt as it reaches the top of the compression stroke. As the piston goes down during power stroke, the air/fuel under the piston is pre-compressed. For this to work well, the volumetric space under the piston must be minimized. The crankshaft throws are solid discs, which enhance the pre-compression. (And also provide mass to aid in the flywheel effect.) During power stroke, the piston top edge opens the exhaust port, letting exhaust out. Later in that same stroke, the top edge opens the bypass port, letting the pre-compressed air/fuel charge to enter the area above the piston. As the piston goes back up, the sequence starts again. To lubricate things either the fuel is mixed with oil, or there is an oil injection system.

a 2 stroke engine sounds higher pitched than a four stoke but a four stroke does not have as much problems as a 4 stroke

Any way a 2 strokes piston goes up and down twice per cycle as a 4 stroke goes up and down 4 times per cycle..

many differences but the most obvious is the combustion cycles.

A 4 stroke cylinder goes through-4. intake, compression, ignition & power, exhaust.

They tend to be more fuel efficient and offer better longevity but lower top rpm limits due to the increased number of parts and mass of rotating hardware. They can cost much more.

A 2 stroke engine goes through 2. intake/ignition and power exhaust.

They tends to rev much higher due to less parts and shorter strokes and are less fuel efficient as well as can produce more emisions as they tend to have their lubricating oil mixed with the fuel and hence burn it as well.

4 strokes and 2 strokes are a big difference. On a 2 stroke it requires premixed gas with 2 cycle oil where the four stroke the oil gas into the bottom of the block and you run straight gas. 2 strokes also take a different type of exhaust that has a power band this provides an extra boost when you start to climb up in the rpm's 2 strokes normally have more top end and four strokes have more toque. 2 stroke also need the top end rebuilt often.

the two stroke engine does half of its compression in the engine and half in the mid pipe. and four strokes do all their compression in the internals like the piston. The two stroke has 2:1 ratio of the CC (cubic centermeters.) than the four stroke, say you have a 250 four stroke and a 125 2 stroke they would be the same.

2 stroke

4 Stroke

Well there is a pretty big difference. Two strokes are the kind of bike that you hear that are a real high pitched sound. 4 strokes have that deeper sound. Two stroke are to be faster than 4. 4 strokes are way more common though but mantenice is fairly similar. Both bikes are great.

2 stroke completes the firing cycle in only 2 strokes. These engines need oil in the fuel or they will burn out. The 4 stroke, takes just that , 4 cycles to complete. Intake, compression,combustion, exhaust.

A 4 stroke is heavier, has more moving parts, is costlier to rebuild, & does not make as much power as an equal sized 2-stroke.

2-strokes are lightweight, produce a power stroke on every stroke - and therefore make more power, are easier to start, & are simpler & cheaper to rebuild. Just compare a 4-stroke outboard motor's price tag to an equal HP 2-stroke. You'll find the 2-stroke is always cheaper (and lighter!).

In most applications - especially small engines, like weed wackers & chain saws - the 2-stroke is far superior to the 4-stroke. 2-strokes have had a bad rap over the years due to lots of people misunderstanding what they need to operate reliably. Poor maintenance also adds to the bad rap. A properly tuned 2-stroke will start easier, & last just about as long as any 4-stroke.

The 2-stroke engine has been cast aside the past few years in favor of the 4-stroke, due to the new "green" fad that's sweeping the nation. 4-strokes have less emissions due to their lubrication system. A 2-strokes lubrication system is a "total-loss" system -- meaning the oil is burned with the fuel. With the EPA cracking down, most manufacturers find it easier to just build 4-strokes than to deal with ever-increasing EPA regulation. This has lead to companies stuffing bulky 4-strokes into weed wackers, which in my opinion is just ridiculous.

Some companies, namely outboard marine manufacturers, have used technology to "clean up" the 2-stroke & keep the greenies happy. These companies know the value of the 2-stroke, & have spent the money on R & D to ensure it's survival. There's a reason for that!

The main thing between a 2-cycle and a 4-cycle engine is the 2-cycle uses a oil premix in every tank of gas.

In two stoke engine cranke rotate one times and piston moves T.D.C.to B.D.C. two times and In four stoke engine cranke rotate two times and piston moves T.D.C. to B.D.C. four times.

valve in four stoke engine and port in two stoke engine

2stroke has sound pitched than 4stroke engine......2stroke engine the piston moves upward and down twice per cycle ,while the four stroke moves four times

A two stroke motor needs oil in the fuel to lubricate the internal moving parts.

A four stroke motor has oil in the crankcase and does not burn the oil so you don't mix the oil in the fuel.

2 stroke has injection and power only

4 stroke has intake compression power and exhaust

2 is slower than 4

The difference between any two-stroke and four-stroke engine is the number of strokes (times the piston goes from one end of the cylinder to the other) it takes for the engine to go through a whole cycle of:1) intake (sucking the fuel-air mixture into the cylinder), 2) compression (the piston compresses the mixture toward the top of the cylinder), 3) power (the spark plug ignites the mixture and the explosion drives the piston down, supplying power), 4) exhaust (the piston moves up and pushes the burnt gases out of the cylinder).

A two-stroke engine will accomplish this in a single up-down motion, achieving intake, power and exhaust in the first stroke (a downstroke) and compression on the second (an upstroke. This is the greatest animation I've seen for explaining a two-stroke engine: http:/www.animatedengines.com/twostroke.shtml

Two-stroke engines have a much higher power to weight ratio, because every other stroke is a power stroke, supplying force to the axle or whatever much more often. Because of this, it is usually used where a small, strong engine is required, such as in dirtbikes and most gasoline engine-driven power tools like chainsaws.

A four-stroke engine takes two up-down motions to accomplish the entire cycle. The first stroke (downstroke) is intake, the second (upstroke) is compression, the third (downstroke) is power and the fourth (upstroke) is exhaust. Here is a great video for a four-stroke engine animation: http:/www.animatedengines.com/otto.

Four-stroke engines are used in automobiles, trains and larger vehicles for their consistent power, as opposed to the quick torque of a two-stroke.