Stupid question please don't laugh

When they say an engine is a litre what does this mean? is it the capacity of all cylinders? Would this not mean than in a 1 litre you would use one litre of fuel every revolution? I know this not to be the case but could someone explain to me how they take this measurement. sorry if i'm being dumb

Hi
I think this refers to engine capacity or size. The cyliders in total could hold a total of 1000cc or 1 litre of fuel/air mix. Only a tiny amount of fuel and air is used to cause a mini explosion.
I think that's the theory. I'm not a tech.
it's dumber not to ask
 
con

richyrich said

When they say an engine is a litre what does this mean? is it the capacity of all cylinders? Would this not mean than in a 1 litre you would use one litre of fuel every revolution? I know this not to be the case but could someone explain to me how they take this measurement. sorry if i'm being dumb

right. i'm going to pretend i never read that, but instead, you are asking how they work out cubic capacity. (cc)

it's basicaly the capacity of the cylinders. e.g. 81mm bore x 86.4mm stroke x 4 (cylinders) = 1781cc (cubic centipedes)

and thats the capacity for fuel and air yeah? So is there only a tiny amount of fuel and loads of air. Sorry of you think I'm a dumb a** but if I don't ask I'll never know. Everyone has to learn things sometime

not quite. it's the maximum capacity of all the cylinders. the air:fuel ratio i think is about 14:1 roughly. i don't know exactly but i'm sure the whole cylinder does not fill with gas (fuel and air mixed). it's kind of to do with vacuum. the valves opening and closing at certain times (piston going up or down) to push the dead gas out and pull the fresh gas in.


that didn't explain anything, did it?

the air and fuel mix gets compressed
then this mix explodes because of sparks from plug.
this explosion forces the pistion back driving cranks eventually turning wheels. Each cylinder  sucks in air, petrol, compresses, fires, pushes out exhaust fumes in a cycle see here
http://en.wikipedia.org/wiki/Engine

there's a diagram on the right

No such thing as a stupid question!!

centipedes are those bugs with 100 legs right?
Bert

Bert said

centipedes are those bugs with 100 legs right?
Bert

 do NOT EVER go shoe shopping with one of those!

ok if I explain why I'm asking it may help you answer my question. Volvo have very kindly given me 1.2 Renault Clio for my time here in sweden. I was filling up today and only 65Kroner about a fiver. that gave me 7.1 litres of fuel. When I looked at the gauge it had gone up by two bars. Two bars will get me to work and back 3 times. I was trying to work out how if I have a 1.2 litre car and I put 7 litres of fuel in it can get me to work and back (about 15km's each way) 3 times. each complete revolution of the engine gives me how much? As the roads are covered in snow and really slippery I have to drive at about 50-70 k's the whole way. It just didn't all seem to add up to me so I wondered how much fuel is used per revolution.

that's a complete different ball of worms

Someone please tell the poor guy (and the rest of us) how an engine works and where the hamsters in wheels come into the equation for certain air cooled VWs!!!

I understand how an engine works I work for Volvo. What I'm trying to assertain is how much fuel goes into the engine for each complete revolution. If I understand the CC is the capacity of all the cylinders.Is it all gas or is any liquid fuel in the cylinder?

hehe I used to work for Vauxhall and I don't have a clue!!!! But then that might make quite a lot more sense when you think about it than at first glance…….

It's all going to depend on carbs/fuel injection + fuel air mix isn't it

ummmm…how do i put this simply

 suck squeeze bang blow….in the order of 1-3-4-2(cylinders) only one cylinder is banging at a time but this happens so close together……….

DAM it I give up An interesting Q?

But Dont think you could work out what your after and get a reliable answer……..lots of factors …..give variables…..how hot or cold engine is outside temp……..gradients……ground resistance(from snow or ice) and so on……:dontknow:

LMAO now as Iv just read the above makes no sense to me at all so think you should all read and laugh at my expense  ops:

An engine takes in its complete 'cubic capacity' in fuel/air mix, every 2 rotations - the engine is 4 stroke, and there's 4 cylinders. HOWEVER bear in mind, only at full throttle are you approaching atmospheric pressue taken in, below that is only a proportion, due to the vacuum, due to the throttle being part closed. So, at full throttle, a bigger capacity engine will theoretically be able to take in more fuel/air, therefore generate more power, all other things being equal.

Obviously, turbocharging or supercharging forces the air (or air/fuel) mix in, so it can be at higher than atmospheric pressure.

When people talk about tuning techniques such as port/polish, bigger throttle body, air induction kit, performance air filter, etc, the aim is to more efficiently be able to take in the gases (flow them better), so it gets closer to atmospheric pressue (normally aspirated, not turbo) at full throttle.

Fuel economy is a function of many variables including throttle position, load, efficency of combustion, engine inertia and ambient temperature. You really need to map the engine to know the economy for a given engine speed.

To answer the question "how much fuel is used per engine revolution",
You would have to conduct an experiment along the lines of….

Fill a car with a measured amount of fuel.

Let the engine run at a CONSTANT rpm until fuel runs out.

By multiplying the rpm value by the total number of munutes the engine ran for, you would have total engine revolutions.

Divide you measured amount of fuel by the total revolutions and you would get volume of fuel used per revolution.

The results would vary greatly depending on what RPM you sat at, the condition of the air you are taking in to the engine etc.

During normal driving conditions, you of course vary the revs constantly, so the results of this test would be completely meaningless!!!

If you want to get more miles from your fiver while driving to work in the snow, select a high gear (3rd or 4th) instead of low gears (1st and 2nd) and stop spinning the wheels and revving the engine!

after some 'back of fag packet' calculations I reckon:

I would do a full tank 35 Litres after about 400km doing 128kph at 4000rpm (converting roughly to metric, and running a bit rich)

Therefore…..(scribble scribble  :scratch:  ……tappety tap on calculator  ….abacus beads rattling  :read:  …)

=0.047 milli-litres of fuel per engine revolution.

If you want to work out the theoretical amount of fuel per cylinder, then here's my rough calcs: -

1.2 litres / 4 = 300cc per cylinder

AFR is approx 15:1, so (300/16) = 18.75cc of fuel, and 281.25cc air per cylinder per power stroke.

18.75 /2 (as four stroke) = 9.375cc fuel per power stroke per cylinder

9.375 * 4 cylinders = 37.5cc per engine rev

As paul_c says, this will only occur under full throttle - anything less than that will give you less airflow, and therefore less fuel flow. As a rough guide, 1/2 throttle should give you half fuel flow rate, 1/4 will give you 1/4 fuel rate, etc…

HTH

Rich