# liters?

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I don't know much about cars so excuse me for asking this. The 95 Taurus' GL come with 3.0 L and 3.8 L liters.. what does this mean and what is the difference?

Taurus95

the 3.8 L motor is a bigger motor larger piston size or longer stroke than the 3.0L. liters refer to volume in the engine cylinder and combustion chamber of the cylinder head the more volume in engine the more liters the more fuel/air mix in the chamber and cylinder hope this helps

osborste

thanks , i understand it better now

Taurus95

Then you'd be understanding wrong. The litres figure is the combined swept volume (displacement) of each piston moving a full 180° stroke.

So if you have a 6 cylinder 3.8 litre buick motor each piston displaces 0.633 litres or 633cc. The combustion space has nothing to do with displacement.

Wally

While you're at it, why don't you remind him that the stated displacement in liters is merely a rounded up figure and not an accurate measurement? I'm sure that helps figure out the difference between a 3 liter engine and a 3.8 liter one to someone who doesn't know what the terms mean.

ChrisV

ah just forget the whole thing, i dont know what any of that stuff means

Taurus95

No, but one day you will and remember you heard it here first, the forum with the fastest breaking news. :wink2:

Wally

Basically what it means is that as the pistons go up and down, the total (ie all 6 cylinders) change in volume is the litre value.

As a really rough example:
imagine each of your cylinders held 1 litre when the piston was at the bottom. If the piston went halfway up the cylinder before it comes back down again, then the volume of each cylinder with the piston at top dead centre would be 0.5 litres. This means that the other 0.5L has been displaced. If this was a 6 cylinder engine, then the total displaced volume would be 0.5 x 5 = 3.0 litres... so this would be a 3L engine.

If the pistons went 3/4 of the way up before coming back down again (this would have to be a totally different engine), then the final volume of each cyl would be 0.25L, so 0.75L would have been displaced. This engine would be 0.75 x 6 = 4.5L

Hope this helps.

windsonian

Iam a begginer too. The difference in my terms is... The 3.8 liter engine is bigger producing more speed. the 3 liter engine is smaller producing less speed. This is only good if you want to know the speed variation but, if you really want to know how it works go with everyone elses posts.

Fgreco

More displacement doesn't mean more 'speed'. it generally just means greater torque. a ferrari enzo has a 3.5L engine, and hits 60 in 3.5. That's incredibly quick campared to the enzo's 3.3 0-60 time with a 6 liter engine. Displacement does not always mean speed.

Godlaus

My bad .... this should read 0.5 x 6 = 3.0 litres .... simple typo sorry. :oops: :banghead:

windsonian

what exactly is a cylinder ?

Taurus95

Are there any sites where i can learn the basics of cars? lol

Taurus95

A few of the newbies found a site called "howstuffworks". You should be able to find it with a search engine.

Wally

www.howstuffworks.com

It's a really good site for basics, and explaining stuff etc.
It's got lots of models and pictures etc. Look for automotive stuff, especially engines (or internal combustion engines or similar).

windsonian

Thanks for clearing that up for me I always thought a bigger engine means more speed. Thanks.

Fgreco

a cylinder is a cylinder shaped space inside the engine that EACH of the pistons move up and down in.EACH PISTON HAS IT'S OWN CYLINDER.THE AMOUNT OF LITRES IS THE VOLUME OF ALL THE CYLINDER VOLUME TOGETHER. THERE IS ROUGHLY 60 CUBIC INCHES PER LITRE.SO A 302 CUBIC INCH MUSTANG ENGINE IS ABOUT 5 LITRES.THE AMOUNT OF LITRES HAS NOTHING TO DO WITH THE AMOUNT OF CYLINDERS,BECAUSE THE CYLINDERS CAN BE MADE AS LARGE OR SMALL AS POSSIBLE.The BORE is the diameter of the cylinder.The STROKE is the distance that the piston moves up and down inside the cylinder.Compression works exactly like a syringe.THE PLUNGER IS THE PISTON,the seal are the rings .if you plug the end of the needle and push the plunger,it forms pressure.THE EXHAUST VALVE(S) OPEN AND LET OUT THE PRESSURE.The engine has depending on it's design,has 1,2,3,4,5,6,8,10,12, etc. cylinders. AND A 6 CYLINDER WITH 2 VALVES FOR EACH CYLINDER IS A 12 VALVE .IF A 6 CYL HAS 4 PER CYLINDER(2 INTAKE,2 EXHAUST, THE ENGINE IS CALLED A 24 VALVE ENGINE.THIS IS A VERY COMMON TERM TODAY.The HEAD contains the valves that control the flow of air /fuel and exhaust flow.the spark plugs are located in the HEAD. One of todays common size engines are like the 2 engines that you have mentioned, and have 6 cylinders each. A V8 HAS 8 PISTONS .IF THE PISTONS ARE ON AN ANGLE IT IS A V DESIGN. Hence V6 ,OR V8 OR V12. JAGUAR USE A V12,SO DOES BMW,AND A FEW OTHERS.THE DODGE VIPER USES A V10.If all the cylinders are in a row it is called a STRAIGHT 6 ,OR INLINE 6 .THE JEEP 4.0 LITRE IS A STRAIGHT 6 .THE FORD 4.0 LITRE IS A V6.Each piston is connected to a long bar inside the engine called a crankshaft.a connecting rod connects each piston to the crankshaft.
a 6 cylinder engine fires every 60 degrees.each cylinder has a spark plug that ignites the fuel and air at the right time to force the piston downward
inside the cylinder.the moment that the air/fuel mix is ignited is called TIMING
the displacement of all the cylinders is rounded off to the nearest number.for example .a toyota celica 3.0 L 6 CYLINDER IS 2996 CC. OR 2.996 LITRES. THE BIGGER VOLUME DOES NOT MEAN MORE HORSEPOWER.The engine compression ratio and other factors ,such as turbochargers ,dictate just how powerful the output is.a TURBO IN MOST CASES WILL DOUBLE THE TORQUE.HOPE I HAVE BEEN OF SOME HELP

the lobster

A V10 VIPER WITH 505 HORSEPOWER AND 8.1 LITRES DOES 0-60 IN 3.9 SECONDS.

the lobster

THE VOLUME OF THE CYLINDER IS THE DISPLACEMENT .THE COMPRESSION RATIO IS HOW MUCH THE AIR/FUEL IS COMPRESSED.SO IF YOU SHAVE THE HEADS DOWN,YOU RAISE THE COMPRESSION RATIO,BY REDUCING THE COMBUSTION CHAMBER DISPLACEMENT VERSUS THE CYLINDER DISPLACEMENT

the lobster

No need to shout. The cylinder is not the displacement. The cylinder extends past the piston skirt and to the top of the deck, Displacement is simply how much volume the piston displaces as it moves a full stroke.

I don't think we mentioned CR in this thread did we?

Wally

I have to hone up on some of my theory.my expertise is in 2 areas.13 years as an electronics engineer/technician,and over 20 years flying aircraft.I have been working on my own cars for years,but you obviously know your theory very well.yes there is a small area above where the piston travels.but if I was to look at it in a pure physical sense,the volume is actually changing with:temperature,AND
if a strain gauge transducer was applied to the piston,it is actually changing shape at very high rpm.,the combustion area actually gets smaller as carbon
deposits form on the valve seats,and surfaces.,the cylinder volume changes with the viscosity of oil used,the volume of an engine actually increases continually,because the piston rings are wearing the cylinders,and of course the combustion area is reduced by the kind of spark plugs you are using.
my new invention"fatties" spark plugs.can attest to this .

the lobster

That's the first good idea you've presented since joining this forum. Why don't you go "hone up on" some theory and get back to us when you have a clue.

BTW, here's a flying tip for pilots who also need to "hone up on" their theory. Fly in the middle of the air. Stay away from the edges, there are hard things there. :doh:

vwhobo

A 6cyn engine fires/powerstroke every 120 degrees of crank rotation. a 4 cyn 180 degrees, an 8cyn 90 degrees.

As carbon develop in the chambers, the compression ratio would be more.
C/R is the... total volumn of a cylinder diveided by the clearance volumn....Clearance volumn is the volumn when the piston is at top dead center.

To RAISE the c/r, you can get pistons that have heads that stick up and are bigger and form like a dome. To increase the c/r you can also inlarge the cylinder's bore and install a crank with a crankpin throw of a greater length, witch increases engine stroke.

Lobster, how is volumn changed with temperature. Density is changed but not volumn. Oh, and bigger volumn means more torque on each power stroke than an engine with less volumn.

CarEXPERT

Good news for you young dude. We finally have someone on the forum with less of a clue than you. Just don't call him a 12 year old who got his pilot's license out of a Cracker Jacks box. He's actually 13.

Otherwise, I'd sure like him to explain some of his theories. Cylinder volume changes with the viscosity of the oil? How does that happen?

vwhobo

Since lots of people are talking theory, here's mine...the kid just wanted to know what the differnce was between two different engine displacements, not how to flame everyone who dissagrees with your opinions. Lets just stick to the questions asked and beat each other up in the ring, OK?

srober32

Well I was around when PDP11's were the bee's knees, so I guess I'm in front on the electronics side of things if years of experience are the criteria.

I used to rack up lots of air miles as a passenger, but I'm can't and don't claim to be an expert on engines. I can't be fagged looking up Lycoming or Continental sites to see what their definition of displacement is, but I would supect it is the same.

The dynamics of the piston growth, ring wear, oil viscousity, rod stretch, bore wear, etc. may be ever changing but the cylinder is still a cylinder and not all of it is used for stroke. Like most measurement standards I'm sure there will be one for accurate measurement of stroke and what conditions must be met (e.g, 25°C, 50%RH, sea level, etc), but for this exercise it's superfluous.

Wally

Right. And just for curiosity sake, who put you in charge? I don't think there is anyone here stopping you from answering the question, but... Instead of doing so you just added one more non-answer to the thread and on top of that it doesn't even address the question. At least the flames are somewhat on topic.

Do the words pot, kettle and black have any meaning to you?

vwhobo

And he got the correct answer. The rest of this is just sublimation of the facts to try to weasil out of incorrect posting.

Wally

As Wally stated, he got his answer. I just felt that as people who do repairs for a living folks should not try to confuse and demean people who have less knowledge than themselves by having contests to see who can urinate the most accurately or with the greatest distance. And, yes, VW I have heard that phrase, how about this one...if the shoe fits?

srober32

Newsflash for you, Twinkie. You were the one bitching about it and now you have two posts in this thread that didn't answer the question. Wanna go for three?

vwhobo

Yup, pole puffer, fun ain't it?

srober32

What, puffing poles? That would be your department. As a matter of fact you should start a thread about it and you won't have to worry about getting any input from me because that is your area of expertise.

Are you going to go for four? Hypocrite.

vwhobo

Congradulations! You found your calling in life! Typing with one hand!

srober32

I don't even know what that's supposed to mean. You might want to think about hiring a put down writer. :sleep:

Five anyone?

vwhobo

errr. you sure that this is right? because I believe the subaru legacy's 6 piston engine is a flat-plane crankshaft. Same thing goes for the f430.

is there a flaw in my understanding?

Godlaus

depends on cylinder arrangement (ie straight 6, V6, horizontally opposed etc)

the crank angles are determined to balance the engine. Everytime a piston hits the bottom of its stroke, it's applying a force downwards, similarly an upward force at the top. By changing crank angles and crankshaft counterweights, you can stop these forces from shaking the engine to bits.

A straight 4 cyl is easy because its symmetry means that the two in the middle are on the same part of the crank, and the two outside ones are exactly opposite. They fire on consecutive strokes though, not together.

windsonian

Crank angles determine balance of engine?? I thought the couterweights and the flywheel balances out the power strokes.

CarEXPERT

They are used to balance out the forces created by the pistons.

Think about it this way ... (btw everyone, i know this is a dodgy example)
If you've got a ball on a piece of rope. Tie the end of the rope around your wrist and throw the ball. When the ball hits the extent of the rope and starts coming back you will feel it tugging on your wrist. This force is why an engine needs to be balanced.

Imagine that all the pistons went up and down together. Everytime they hit the top of the stroke (all at the same time), they would all try and pull the crankshaft upwards. Then at the bottom of the stroke, they would all try to push it downwards. This makes for a whole lot of shaking in the engine.

The counterweights effectively apply a similar force to the pistons, so between the force of the pistons and the force of the counterweights, there should (in theory), be no overall force trying to shake the engine.

In theory (if I remember correctly), a straight 6 cylinder engine can be balanced without counterweights at all.

Balancing comes in 2 parts, static and dynamic ... but that might be a bit complex for this thread.

windsonian

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